BRITISHCOLUMBIADEPARTMENT
HamHERBERTANSCOMB, Minister
OF MINES
JOHNF. WALKER, Deputy Mini:;teer
"
BULLETINNo.
15
"
Hydraulic Mining Methods
Compiled by
STUART S. HOLLAND
,194:2
This Bulletin is in large parta reprint from United
States Bureau of Mines Information Circular 6787
Pho-offset
VICTORIA. R.C. :
by C H A R L ~ F.
S BANPI~LD.
Printer to the King's Most Excellent Majesty.
1042.
Page
EXTRACTING GOLD FROP
AIMALGAM
Heating
Retortiag
............
:........................................ :...................................................................................... 58
............................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
PROM GOLD
PLATINUM~GROW
SEPARATION
OF i%ETALS
68
69
73
75
BIBLIOGRAPRY
. . ii .
ILLUSTRATIONS
Page
to
Diagram for solving Kutter formula
determineflow of w a t e r i n open channels
or pipes ...............................................................................................................................................................................
10
Figure 2
Weir for small stream
16
Figure 3
Flume f o r h y d r a u l i c m i n e s . .".............................................. ..............................................
20
Figure 4
Air vent f o r p i p e - l i n e s .
24
Figure 5
C h a r t showing l o s s of head i n pipesdue
t o f r i c t i o n . .................................................................................................................................................................
2%
I l y d r a u l i ce l e v a t o r .
33
Figure 1
.......................................................................................................................
:
Figure 6
construction.
Figure 7
............................................................................................................
..................................................................................................................................
Sluice-box
Figure 8
Types of r i f f l e s .
Figure 9
Ap?aratus f o r r e t o r t i n g amalgamand
quicksilver.
..........................................................................................................................................
...............................................................................................................................................................
50
70
PHOTOGRAPHS
Facingpage
Plate I
A.
B.
Plate11 A.
B.
P l a t e I11 A .
B.
A s t o r a g e dam a t t h e o u t l e t
Lake
of Germansen
6
A d i v e r s i o n dam on t h e d i t c h - l i n e of German:;en
VenturesLtd. ..............................................................................................................................................................
6
A f l u m eb u i l t
a s t e e ps l i d e .
7
C o n t r o l g a t e s a t t h e end of t h e d i t c h a t th,a
i n t a k e t o , t h e p e n s t o c k a t B u l l i o n Mine. ...........................................
7
on a t r e s t l e a c r o s s
A b a f f l e box t o check t h e w a t e r v e l o c i t y a t
t h e b o t t o m of s e c t i o n of flume having a
s t e e p g r a d e . ....................................................................................................................................................................... 26
A s e c t i o n of 24-inchpipe-lineleading
from
t h e p e n s t o c k a t CaribooCottonwoodPlacers
Ltd
............................................................................................................................................................................................................
26
Fa cingpage
Plate I V
A.
The p r e s s u r e box a t t h e B u l l i o n Mine. ..............................
27
B.
P a r t o f t h e main 30-inch section
of t h e
Bullion pipe-line showing the foundation -supports.
27
.......................................................................................................................................
Plate
V
A. A No. 1 g i a n t a t a small, o p e r a t i o n . .......
34
~
B. A No. 7 g i a n t and a No. 4 i n t h e
No. 1 p i t ofGermansen
Ventures
Ltd. ...........................................................................................................................................................
Plate VI
A.
Two g i a n t s s w e e p i n g g r a v e l i n
pit.
..........
34
J
a hydraulic
..............................................................................................................................................................................
...... 35
B. A ' h y d r a u l i c p i t w i t h o n e g i a n t f e e d i n g
g r a v e l t o a s h o r t l e n g t h of s l u i c e boxesand a secondmonitorstacking
t h ec o a r s eg r a v e l
a t t h e end o f t h e
boxes ........................................... :.................................................................................................................... :.......... 35
'
P l a t e VI1
A.
B.
P l a t e VI11 A .
The No. 1 p i t a t Germansen Ventures
Ltd., Germansen Creek, B . C .
36
The B u l l i o n ' p i t , on t h e s o u t h f o r k
of t h e
Quesnel River. ........... :................................................................................................................
n
30
Boulder-clayshowingtheirregular
a s s e n b l a g e o f b o u l d e r s i n a compact
clay matrix.
37
A cave a t t h e headof a h y d r a u l i c p i t
showing t h e l a r g e m a s s e s i n t o
which t h e
boulder-clay
37
Wood b l o c k r i f f l e s i n
a small s l u i c e flume. .................................................................................................................................................... :...........
48
.................................................................................................................................................
B.
breaks.
P l a t e IX
A.
~..B.
P l a t e 'X
A.
A large sluice-box paved with.
wood
blocks wedged t o g e t h e r b y b l o c k s i n
t h e i n t e r s t i c e s ................................................................................................................................. 48
A 3-footsluice-boxshowingtheload
ofgravelandbouldersdropped
when t h e
w a t e r was t u r n e d o f f . ............................... :.........................................................................
-
iv
49
\
Facing page
Plate X
B.- A 30-inchsluice-flumeshowing
Plate XI
A.
P i a t e XI1
a central
groove worn i n t h e wood b l o c k r j - f f l e s
a f t e r c o n s i d e r a b l e s e r v i c e . ................................................................ ....... 49
The & f o o t s i u i c e - f i u r n e
a t the Bullion
Mine pavedwith rai.1 r i f f l e s ...................................................................
52
B.
C r o s s - s e c t i o n of t h e B u l l i o n t y p e r a i l s
52
A.
Loosening up the sand and gravel
packed
b e t w e e n b l o c k r i f f 1 . e ~ . ................................................................................................
' B.
H a n d l i n gb o u l d e r si n
a hydraulic pit with
a gin-poleand a handwinch a t Harvey
CreekMines L t d . on Nigger(Pine)Creek
..................
56
D r i l l i n g a iargeboulderwith
a Jackhammer i n t h e h y d r a u l i c p i t a t Spanish
Creek .............................................................................................................................................................................
57
Block r i f f l e s a t t h e
head of t h e s i u i c e box l i f t e d p r e p a r a t o r y t o making a c l e a n up. .........................................................................................................................................................................................
57
A.
Clean-up a t Germansen VenturesLtd
60
B.
Cieaning up t h e g o i d i n ' t h e ' b o t t o m of
a s l u i c e - b o x t o remove a s much black
sand as p o s s i b l eb e f o r es c o o p i n g
up t h e
g o l d i n t o a pan. ..................................................................................................................................
60
A.
Cleaning bed-rock by hand .................................... :................................................
61
B.
R e t o r t i n g amalgam f r o m t h e c l e a n - u p
barro
e lv e r
a b l a c k s n i t hf' os r g e
............:
61
A.
B.
P l a t e XVI
:................. 53
56
B.
P l a t e XV
53
The endof
a sluice-flumeshowing
l o n g i t u d i n a l andt:ransverserail
r i f f l e s f o l l o w e d by anunder' c u r r e n t g r i z z l y niade from 3-inch
s h a f t i n g ,t h e n a s h o r ts e c t i o n o f
t r a n s v e r s e r a i l r i f f l e s a t t h e end
rjf t h e box. ........................................................................................................................
P l a t e XI11 A .
Plate XIV
Undercurrent tables at the
end of t h e
s l u i c e a t C a r i b o o Cottonwood P l a c e r s
Ltd.
.................
- v -
........................................
-
When p l a c e r g o l d was f i r s t d.iscovered in B r i t i s h (Columbia
much o f t h e g r a v e l
was mined'by methods other than hydraulicking.
Subsequently,however,withtheworkingoutofrichshnllow
.Z;rave l , extensiveyardagesoflowergrad.egravelwereleftwhichunder
f a v o u r a b l ec o n d i t i o n sw e r e
minedby
h y d r a u l i c k i n g . T h . i s typeof
r n i n i n gp r o d u c e st h el a r g e s tp r o p o r t i o no fp l a c e rg o l d: a t$ r e s e n t .
P l a c e r g o l d was d i s c o v e r e d j.n t h e P r o v i n c e a t a r , e a r l y d a t e
so t h t i n t h e w e l l known d i s t r i o t s m o s t o f t h e c r e e k s h a v e
been
prospected and worked wherever possible, leaving the
m r e undeminers.
611 t h e
s i r a b l e and lower gradeground for subsequent
t
h
a
t
o
r
i
s
being,
worked.
In t h e
i
s
known
has
been,
r i c h ground
Sast,failuretosampleandproperlyestirnatetheavailableyardage of p l a c e r d e p o s i t s h a s r e s u l t e d i n
a tremendouswa,steof
money and e f f o r t . k l a r g ep r o p o r t i o no fp l a c e ro p e r a t i o n sh a v e
was i n s u f f i c i e n t t o repay
f a i l e db e c a u s et h eg o l di nt h eg r a v e l
In consequence,pret h e c o s t e v e no ft h em o s te f f i c i e n tm i n i n g .
i s more i m p o r t a n t now t h a n e v e r b e liminarytestingandsampling
of a
f o r e .and it i s p a r t i c u l a r l y n e c e s s a r y w h e r e t h e i n v e s t l n e n t
l a r g e m o u n t of money i s i n v o l v e d .
The expenseofpreliminarysampling
and t e s t work shouldbe
regarded as a t y p e ofinsurance,i'romwhich
it i s possi'ble t o g e t
i n making d e f i n i t e p l a n s f o r o p e r a v a l u a b l ei n f o r n a t i o nn e c e s s a r y
t i o n andbywhich
it i s p o s s i b l e t o s a v e t h e l o s s
o fc o n s i d e r a b l y
be
more money i f c e r t a i n unfavourab1.e f a c t s and conditions can
known beforehand.
P r i o r t o m i n i n g S p l a c e rd e p o s i tb yh y d r a u l i c k i n g ,
it i s i m p o r t a n t to obtaininformationregardin:?
t h e followin,g points.
{lj The area anddepth of t h ed e p o s i . t , i t s a v e r a g ev a l u ep e r
cubicyard,thedistributio'nandthenature
o f theval.uablemineral
c o n t e n t . The minimum 'economic valuepercubicyarddependsent i r e l y o nl o c a lc o n d i t i o n s . '
( Z j The supplyof water a v a i l a b l ea n dt h e , h e , a d
or pressure
o b t a i n a b l e , a s t h i s forms a b a s i s f o r e s t i m a t i n g t h e d a i l y y a r d a g e t h a t c a n bemined.
(3) The t o t a l l e n g t h of d i t c h e s ,f l u m e sa n dp i p e - l i n e sr e quired to bring the water to the giants
a$ t h e w o r k i n g f a c e s .
( 4 ) The natureandgrade
froxthesurface.
of bedrock a s w e l l as i.ts d e p t h
- 1 -
( 5 ) The h e i g h ta v a i l a b l e for t h e dumping or d i s p o s a l of
tailings;alsotheavailablearea
s o t h a t t h e t a i l i n g s w i l l not
interferewithadjoiningoperations.
A p l a c e r d e p o s i t may besampled by anyone or a combination
of methods; by panninggravelfromnaturalexposures;
by d r i f t i n g ,
In . ,
by t e s t - p i t t i n g , by s h a f t - s i n k i n g , or b yK e y s t o n e - d r i l l i n g .
everyinstanceinordertogetreliableresultsthe
work shouldbe
s o t h a t t h e ' i n f o r n a t i o n may be
done carefu1Ty and systematically
compiled t o g i v ea sc o m p l e t e
a p i c t u r e of t h e d e p o s i t a s
it i s
p o s s i b l e o r economical t o o b t a i n .
,
A placerdepositof'anyconsiderablesizecanseldom
beadei t s n a t u r a le x p o s u r e s .N e v e r t h e l e s st h e r e
quatelysampledfrom
o r gulcheswhere
p r o b a b l y a r e some exposuresalongcreekbanks
some panning may be d o n e . t oa d v a n t a g e .
The r e s u l t sf r o mp a n n i n g ' .
depend for t h e i r .va-lue l a r g e l y on t h e manwho
takes the gravel
for
thesample.Consequently,theycan
be v e r y m i s l e a d i n gu n l e s st h e
sample i s p r o p e r l y t a k e n a n d t h e r , e s u l t s i n t e r p r e t e d i n t h e l i g h t
of e x p e r i e n c , e .I nt h e
f i r s t p l a c e i t i sn e c e s s a r y t o assume t h e
t o
volume of a pan. f u l l ' o f g r a v e l , t h i s i s g e n e r a l l y t a k e n a s 1 5 0
170 t o thecubicyard,.Secondly
i t i s - n e c e s s a r y to estimate or
assume t h e t o t a l y a r d a g e
of m a t e r i a l t h e pan r . e p r e s e n t s ; it cannot
be t a k e n f o r g r a n t e d t h a t a s i n g l e pan w i l l r e p r e s e n t t h e a v e r a g e
o f a n yl a r g e volume of gravel.Neverthelesspanning
i s valuable
t o be
i n d e t e r m i n i n g from s c a t t e r e d e x p o s u r e s t h e r a n g e o f v a l u e s
e x p e c t e d ,a sw . e l la s
some i n : d i c a t i o na st ot h ed i & t r i . b u t i o n
of
values-invarioussections
of t h e d e p o s i t .
D r i f t i n g on bedrock,where
so frequentlythegreatestproport i o n o f - v a l u e s i s c o n c e n t r a t e d , i s t h e b e s t method f o r g e t t i n g
of a d e p o s i t . If t h ep l a c e rd e p o s i t
is
a v e r a g ev a l u e si no n ep a r t
a buriedchannel,then
it may b e - p o s s i b l e ' t o o b t a i n i n f o r m a t i o n a s
t o b e d r o c kv a l u e sa n dc o n s e q u e n t l ya v e r a g ev a l u e sa c r o s st h ef u l l
w i d t k o f t h e channel; This i s e s p e c i a l l y important i n h y d r a u l i c
mining where it may be n e c e s s a r y t o wash t h e e n t i r , e c h a n n e l f i l l i n g
and n o t m i n e t h e d e p o s i t s e l e c t i . v e l y . I f , t h e
d r i f t be runfrom
s i d e t o s i d e of a channel, it i s b e s t t o s l u i c e t h e e n t i r e s p o i l
f r o m theworkings,making
it p o s s i b l e by measuring the yardage ex,cavated t o c a l c u l a t e t h e a v e r a g e v a l u e p e r y a r d
of gravel mined.
it i s p o s s i b l e t o l o c a t e a n y
By t a k i n g pan s a m p i e s i n t h e d r i f t
pay-streakpresent,and
by s l u i c i n g s e p a r a t e l y t h e m a t e r i a l
from i
e a c ht i m b e r e ds e ta n yv a r i a t i o ni nv a l u e s
w i l l befound.
A foot
t o 18 inches of b e d r o c k s h o u l d b e t a k e n u p w i t h t h e g r a v e l
t o be
c e r t a i n t h a t a l l g o l d i s beingrecovered.
An a l t e r n a t i v e method o f c a l c u l a t i n g t h e v a l u e s r a t h e r t h a n
t h e c,ommon onebasedon
a cu'bicyard of g r a v e l is. t o ' t r a n s p o s e
of' s q u a r e f e e t ofbedrockuncovered
or cleaned,
t h ev a l u e si nt e r m s
- 2 -
o r a l t e r n a t i v e l yi nt e r m s
of per l i n e a lf o o t ofchanne:l.
In
t h i s way, p a r t i c u l a r l y when most 'of t h e v a l u e s a r e on -sedrock and
the overburden i s barren and of v a r i a b l e t h i c k n e s s ,
it m y be
found t h a t . t h e r e i s a u n i f o r m i t y of values which would n o t be a p p a r e n t when t h e c a l c u l a t i o n i s expressedinterms
o f cllbicyards
of g r a v e l .
Shallowuntimbered t e s t p i t s may be dug in instanoeswhere
t h ep l a c e rd e p o s i t
i s shallow and. no t r o u b l e i s experi'ancedfrom
groundwater.
I f it i s p o s s i b l ea l lt h em a t e r i a le x o a Y a t e df r o m
it recoveredand
t h e p i t s h o u l db es l u i c e d ' a n dt h eg o l df r o m
weighed. By t h i s means a more r e p r e s e n t a t i v es a m p l ei , so b t a i n e d
t h a n by a t t e m p t i n g t o t a k e a sample of e x a c t volumefrom t h e s i d e
o r bottomof
the p i t .
If t h e vo1.ume of t h e p i t i s mea.sured a s
or alwellastheare,aofthebottom,thevalueper'oubicya:rd,
ternatively'the value per square,foot
on bedrock may be r e a d i l y
calculated.
I f p o s s i b l e , numerous t e s t p i t s s h o u l d b e d u g
andshouldbe
l a i do u ti nl i n e sa c c o r d i n gt o
a definiteplanestablishedin
l a r g e p a r t by t h e t y p e ofplaceroccurrencebutofcourse
modif i e d and'extendedas
more informa.tion i s obtained.
In many d e p o s i t s it i s . n o t s.lways p o s s i b l e t o d r i f t on bedrock; it t h e n becomes n e c e s s a r y i n o r d e r t o a s c e r t a i n t h e d e p t h
t o b e d r o c k ,a n dt h ev a l u e st h e r e ,e i t h e r
t o s i n k a s h a f t o r put
A s h a f t i s p r e f e r a b l et o a s i n g l e
down a K e y s t o n ed r i l l - h o l e .
drill-holebecausethegreaterarea
o f bedrockcleanedgives
a
much b e t t e rs a m p l e .
However, thecomparativebenefitsshould
be
balancedbetween a s h a f t a n d . t h e number o f d r i l l - h o l e s t h a t m i g h t
posbe p u t down f o r t h e same cost.Shaftsshouldbe.sunkwhere
s i b l e t o checkdrlll-holes.
In l o o s e m a t e r i a l , a s h a f t mustbetimberedbut
may be.s.unk
e i t h e r by d r i v i n g l a g g i n g o r by cribbing,whichever i s p r e f e r a b l e o r more expedient. The v e r t i c a ld i s t r i b u t i o n . or" v a l u e s i s
if
foundby s l u i c i n g t h e s p o i l as thesinkingadvancesandagain
.possible all. the material should be
washed a s a b e t t e r a v e r a g e
sample i s t h e r e b yo b t a i n e d .
S h a f t s a l m o s t i n v a r i a b l ye n c o u n t e rw a t e r
t o a greater or
lessextentand
a pump should be a v a i l a b l e t o k e e p it undercon.trol. Where anexcessiveflow
i s encountered o r canbepredicted
i s t o do t h e
with certainty in advance then the only alternative
t e s t i n g byKeystone d r i l l .
In deep placer ground.where bedrock
i s n o t a c c e s s i b l e by a
d r i f t ,t h el o n g e rt i m en e c e s s a r ya n dg r e a t e re x p e n s ei n v o l v e di n
s h a f t - s i a k i n g make i t a d v i s a b i et o d r i l l t h eg r o u n d .D r i l l i n g
- 3 -
I
g i v e sa c c u r a t ei n f o r m a t i b na s
t o t h e d e p t h o f bedrock, as w e l l a s
t h ev a l u e si nt h em a t e r i a ld r i l l e d .
'However for dependablevaluer e s u l t s much dependson t h e ' s k i l l , e x p e r i e n c e
and r e l i a b i l i t y o f
thedriller.
Closesupervision
i s mostimportant
for t h er e a s o n '
t h a t ' d r i l l i n g r e s u l t s mustbeadjusted
and i n t e r p r e t e d i n t h e l i g h t
of t h e p h y s i c a l c o n d i t i o n s w h i c h a r e e n c o u n t e r e d ; f o r e x a m p l e h a r d
packed gravel and loose caving sand
o r f i n e g r a v e . 1 may give values
that are either too
low o r toohigh,unlessthephysicalconditions
aretakenintoaccount
when t h e f T n a 1 c a l c u l a t i o n i s made.
In o r d e r t o d e t e r m i n e t h e v e r t i c a l d i s t r i b u t i o n
of values,
t h e c u t t i n g s from t h e d r i l l - h o l e a r e c o l l e c t e d
andpanned
o r put
through a r o c k e r a t r e g u l a r i n t e r v a l s
of d e p t h , o r it may b e , f o u n d
a smallsluiceconvenient t o have t h e b a i l e r d i s c h a r g e d i r e c t l y i n t o
box,which i s .cleaned up a f t e r e a c h pumping andwhich w i l l g i v e t h e
v a l u e s for e a c h d r i v e o f t h e c a s i n g a n d
its respectivebailing.
The v a l u e of preliminarysamplingandtestingcannot
beoveremphasizedbutinasmuch
as no ' t w o p l a c e r d e p o s i t s a r e i d e n t i c a l ,
c o n d i t i o n s may v a r y w i d e l y a n d d i s t r i b u t i o n
o.f values be s o d i f f e r e n t , no s p e c i f i c method of t e s t i n g canbe
o u t l i n e d . However,
the'methodshould beadapted t o e a c h p a r t i c u l a r d e p o s i t , ' t h e p r o gramme b e i n g l a i d o u t s y s t e m a t i c a l l y a n d t h e
work d i r e c t e d by a
capableandexperienced
man.
The ' f o l l o w i n g m a t e r i a l i n q u o t a t i o n
marks i s r e p r i n t e d from
I n f o r m a t i o nC i r c u l a r
.No,. 6787 (now o u t of p r i n t ) o f t h eU n i t e d
S t a t e s Bureau of Mines, "Placer lyining in the Western United
by E . D. Gardnerand
C . H.. Johnson, t o which
S t a t e s ,P a r t1 1 , ' "
dueacknowledgment i s made herewith.
"This paper deals with hydraulicking,.
s1uic'e:boxes 'and r i f f l e s , r e c o v e r y of gold and platinumfromplacerconcentrates,and
t r e a t m e n t o f amalgam. The d i s c u s s i o no f ' s l u i c e - b o x e sa n ds u b s e q u e n ts u b j e c t sa p 2 l i e s
t o a l l ' f o r m s of placermining."
- 4 -
HYDRAULICKING
Histo.ryl
Hydraulicmining was d e l i e l o p e d i n C a l i f o r n i a a s e a r l y a s
1852
when Edward E., P l a t t i s o n ,i no r d e rt or e d u c el a b o u rc o s t s ,u s e d
a
rawhidehose t o which a wooden nozzle was a t t a c h e d t o . d . i r e c t a
bank.Thisstep
was followed
stream o f w a t e ra g a i n s tt h eg r a v e l
by t h e u s e of a canvashose bound withwireandrope
an.d t h e u s e
o f a m e t a lr a t h e rt h a n
a wooden nozzle. The canvashose was r e placed by 100 f e e t of s t o v e - p i p e by K. K. C r a i g a t American H i l l ,
Nevada C o u n t y ,C a l i f o r n i a .
The f i r s tm e t a lp i p e
made s , p e c i f i c a l l y
f o r h y d r a u l i c k. i.n g wasmade of wrought iron in
1856 by a company i n
San F r a n c i s c o . D i f f i c u l t y
was encounteredwiththe
f i r s t pipebeit r u s t e d .
cause of the rapidity with which
As h y d r a u i i c k i n g becamemore
and more used,highwaterpressures were wanted and the strength
of t h e p i p e l e d t o i.ts .being
made of s h e e t - s t e e l i n s h o r t l e n i t h s t h a t c o u l d b e
pack:ed bymules
or b u r r o s .
The f i r s t nozzles were attached
t o t h e d i s c h a r g e endof
the
pipe by a . s h o r t l e n g t h o f c a n v a s . h o s e , b u t l a t e r a s h i g h e r w a t e r
2 flexible iron joint
was devised using two
pressures were used
elbows working over each other and held together by
a king-bolt.
Thisarrangement was improved by using a r a d i u sp l a t e .V a r i o u s
t o v h i c h t h e name " g i a n t " was aptypesofmachinewere.devised
plied,culminatingfinallyinthe
modern d o u b l e b a l l - F e a r i n g g i a n t
equippedwith a d e f l e c t o r a t t h e end of t h e d i s c h a r g e b a r r e l .
Aopli'cation
A
2
" I n hydraulic mining a j e t of waterissuingunderhighpressurefrom & n o z z l ee x c a v a t e s andwashes
t h eg r a v e l .
The gold i s
recovered p a r t l y by cleaningbedrock a f t e r t h e g r a v e l hasbeen
s t r i p p e d away b u t c h i e f l y by r i f f l e s i n t h e s l u i c e - b o x t h r o u g h
which t h e washed g r a v e l s and w a t e r f l m t o t h e t a i l i n g : ; aump.
"Almost a l l t y p e s o f p l a c e r d e p o s i t s c a n
be worked by hyd r a n l i c k i n g if w a t e r i s a v a i l a b l e , b u t c e r t a i n p h y s i c a l . c h a r a c "
t e r i s t i c s haveanimportantbearing
on t h e c o s t o f t h e o p e r a t i o n .
If t h e g r a v e l i s c l a y e y t h e w a s h i n g i s
more d i f f i . c u l t b u t more
A.
SeeBowie,
J.
1898, p. 42..
2
HydraulicMining,
. .
Reprinted fron UnitedStatesBureau
cular 6787.
- 5 -
Van Nostrand Co. New York,
o f Mines Information Cir-
important.
If t h eg r a v e l i s cemented it can be c u to n l y by highp r e s s u r ew a t e r .I ft h eg r a d e
of bedrock i s f l a t t h e d u t y ( c u b i c
or o t h e r u n i t ) of t h ew a t e r i s r e l a t i v e l y
yardsperminer'sinch
l o w , andwhere g r a v i t y d i s p o s a l o f w a t e r a n d t a i l i n g s
i s imposbe used t o r a i s e themfrom
s i b l e o r i m p r a c t i c a b l ee l e v a t o r sm u s t
of t h e i n s t a l l a t i o n . "
the p i t , furtherdecreasingthecapacity
As a c o n s e q u e n c e ,t h e r e f o r e ,
a proposedhydraulicoperation
must f u l f i l lt h r e ee s s e n t i a lp h y s i c a lc o n d i t i o n s :
(1) Bn'adefor t h e s c a l e of o p e r a t i o n
quatewatersupplymustbeavailable
i n t e n d e d ; ( 2 ) There m u s t b es u f f i c i e n t
dump space t o disposeof
the iailings from the sluice, or lacking that, sufficientaddit i o n a l w a t e r and space t o enable t h e t a i l i n g s t o be s t a c k e d ; ( 3 )
The b e d r o c k g r a d e s h o u l d b e s u c h t h a t . t h e s l u i c e s c a n b e l a i d w i t h
or,
thepropergradetocarrythewaterandgravelefficiently,
heightmustbeavailable
s o t h a t a bedrockcut may be made i n
which t op l a c et h es l u i c e - b o x e s
on t h e i rp r o p e rg r a d e .
A l l these,
i n a d d i t i o n t o t h e prime r e q u i s i t e of s u f f i c i e n t a v e r a g e r e c o v e r a b l e v a l u e s per y a r d t o wa.rrant the ope'ration.
" A p a r tf r o mt h ed e p o s i ti t s e l f ,t h ew a t e rs u p p l y
is t h e m o s t
o f hydraulicking
importantfactorindeterminingtheapplication
and t h e s c a l e of o p e r a t i o n . Under a n yg i v e nc o n d i t i o n st h ed a , i l y
yardage i s r o u g h l y p r o p o r t i o n a l t o t h e q u a n t i t y of water used."
As a n i l l u s t r a t i o n of t h e v a l u e o f ' o b t a i n i n g t h e m o s t w a t e r p c s s i b l e it i s c l a i m e d t h a t a 5 p e r c e n t i n c r e a s e i n t h e
amount o f
w a t e ru s e di n c r e a s e st h ey a r d a g es l u i c e d
by approximately10per
c e n t . "The q u a n t i t ye x c a v a t e dl i k e w i s e
i s proportional t o t h e
headusedon
t h eg i a n t s ,b u tt h eh i g h e rp r e s s u r ei s
of l e s s v a l u e
i n d r i v i n g andwashingand
of ncne a t a l l i n s l u i c i n g t h e g r a v e l
' t h r o u g ht h e boxes t o t h e dump: A s t h e c u t t i n g andsweepingcapof
a c i t y of thegiantsusuallyexceedsthecarryingcapacity
w a t e r ,a ' s t r e a m
offlowingwater,
known as 'by-wash,' o r 'bank
. w a t e r , ' i s d i r e c t e dt h r o u g ht h ep i ta n di n t ot h es l u i c e s .I fr u n
o v e rt h eb a n k ,a si ng r o u n d - s l u i c i n g ,
it a i d s m a t e r i a l l y i n c u t t i n g t h e grave!..
The prloper r e l a t i v eq u a n t i t i e s ' o fh i g hp r e s s u r e
and
bank
watercanbedeterminedonly
by t r i a l .F r e q u e n t l yt h e
,by-wash i s s u p p l i e d by t h e n a t u r a l f l o w o f t h e s t r e a m a t t h e m i n e ,
thegiantwaterbeingbroughtfrom
a considerabledistanceupthe
stream or fromanothersource.
When'an excess or" bank water i s
a v a i l a b l e it may be u s e df o rg r o u n d - s l u i c i n g ,t h u si n c r e a s i n g
thecapacity o f t h e p l a n t .
"The p r e p a r a t b r y or development work n e c e s s a r y t o s t a r t
h y d r a u l i c k i n g u s u a l l y i s g r e a t e r t h a n t h a t for a n y o t h e r form of
placerminingexceptdredging
or d r i f t mining. C d e p o s i tp r e f e r a b l y i s opened a t t h e lowerend
t o p e r m i tg r a v i t yd r a i n a g e
and
progressive mining of t h e e n t i r e d e p o s i t i n a n o r d e r l y f a s h i o n .
I f t h e g r a v e l i s t h i c k o r t h e g r a d e o f - b e d r o c k f l a t a very long
, c u i may be n e c e s s a r y t o r e a c h bedrock a t t h e d e s i r e d p o i n t . T h i s
.
'
P l a t e I A. A Storage dam a t t h e o u t l e t of Germansen Lake. The
t h r e e s p i l l w a y s at t h e l e f t are c o n t r o l l e d by timbers held i n
v e r t i c a l g u i d e s , t h e main one a t t h e r i g h t by two g a t e s
operated by hand wheels.This
dam 1 8 7 f e e t h i g h and.
impounds sbout 20,000 a w e f e e t , s u f f i a i e n t water
f o r B f u l l season's operation.
P l a t e I B. A d i v e r s i o n dam on t h e d i t a h - l i n e of Germamen
Ventures L t d . The t r a s h raak i s i n f r o n t o f t h e g a b s
leading into the ditch; the waste gates
a t the right;
c o n t r o l flow i n a n a t u r a l w a t e r o o w s e .
Plate I1 A. A flume built on a trestle across a steep slide.
The f l u e is 6 feet wide and 5 feet deep; nota the wellsupported bents of heavy timbers with centre posts.
Control gates a t the end o f the ditch at the
intake to the penstook at Bullion Mine.
P l a t e I1 8.
may i n v o l v e t h e m i n i n g of l a r g e q u a n t i t i e s ofbarren
or a t l e a s t
u n p r o f i t a b l eg r a v e l .A , m o r ei m p o r t a n te l e m e n t
of p r e p a r a t o r y c o s t
i s t h ew a t e rs u p p l y .
As headsof50
t o 300 o r 400 f e e t a r e d e s i r e d ,
a m i l e o r more of d i t c h or flume i s a l m o s t a l w a y s n e c e s s a r y . t o b r i n g
w a t e ro n t ot h ep r o p e r t y
by g r a v i t y f l o w . 9 s i n g l e mj.ne may have.
many m i l e s of d i t c h , c o s t i n g p e r h a p s . $ 2 , 5 0 0 p e r m i l e , a s w e l l a s
or
dams a n d r e s e r v o i r s andthousands of f e e t o f f l u m e s ,t u n n e l s ,
of a h y d r a u l i c mine ori n v e r t e ds i p h o n s .
The mechanicalequipment
d i n a r i l y c o n s i s t s o f a fewhundred t o a few thousand feet
of 10- t o
or more monitors,and a v a r y i n g
30-inch, o r l a r g e r , i r o n p i p e , o n e
number or' s l u i c e - b o x e s ; t h e c o s t o f equipment o r d i c a r i l y is small
compared t o t h e e x p e n d i t u r e s n e c e s s a r y
for d i t c h e s a n d t a i l r a c e s .
of
"Although it i s o b v i o u s t h a t . t h e r e c o v e r a b l e g o l d c o n t e n t
t h e g r a v e l m u s t pay a p r o f i t o v e r o p e r a t i n g c o s t s ( w h i c h u s u a l l y
range f r o m 5 t o 20 cerltsper y a r d ) a s u r p r i s i n g number o f v e n t u r e s
in hydraulicking have failed because the promotors have not sllowed
f o ra l lt h ep r e p a r a t o r ye x p e n s e sn o t e da b o v e .
Eachyardofgravel
mined !nust c a r r y i t s s h a r e of t h i s c o s t , t h e r e f o r e t h e s i z e of t h e
d e p o s i t is of utmostimportance
in c o n s i d e r i n g a hydraulicmining
venture. ,
"Hydraulickingundersuitableconditions
i s a low-cost method
a s it y i e l d s a l a r g e rp r o d u c t i o np e r
man-shift t h a n ;any o t h e r
method except dredging. The i n i t i a l investment r e q u i r e d i s l e s s
o r mediumt h a nt h a tf o rd r e d g i n g ;h e n c e ,h y d r a u l i c k i n gi ns m a l l
s i z e d e p o s i t s may be more economicaleven t h o u g h dredging would
r e s u l t i n a loweroperatingcost.
When t h eo p e r a t i o . n sa r e
on a
very,largescalehydraulickingcosts
may belowerth:indredging
c o s t s on a comparablebasis.
Very c l a y e yo rb o u l d e r , yg r a v e l s
should be hydraulicked as dredging usually
is u n s a t i s f a c t o r y i n
suchground.
"There i s enough s i m i l a r i t y i n a l l h y d r a u l i c o p e r a t i o n s t h a t
The methods
n o - n a t u r a l c l a s s ' i f i c a t i o n s o f t h e method canbemade.
of a t t a c k i n g t h e g r a v e ; v a r y t o o l i t t l e t o
make a n y g e n e r a l d i s t i n c t i o n s .F a c t o r ss u c ha sc o n d i t i o n s
of t h eg r a v e l ,p e r c e n t a g e s
of bouldersandclay,grade
of bedrock, and t h e q u a n t i t y andhead
of t h e h y d r a u l i c w a t e r . a f f e c t t h e c o s t s , b u t
no generalgrouping
i s p o s s i b l e i n accordancewithany
of t h e s e h e a d s .
Ditches
"
"
"Open d i t c h e s a r e used commonly t o b r i n g w a t e r close t o , y e t
high enoughabove,
t h e mine t o f u r n i s h a s a t i s f a c t o r y p r e s s u r e
f o rt h eg i a n t s .
A t s e v e r a lh y d r a u l i cm i n e s
i n t h eW e s t e r nS t a t e s
andAlaskaditches
30 t o 40 mileslonghavebeenbuilt,andeven
relativelysmalloperationsusually
have 5 t o 10 miles of d i t c h line."
- 7 -
I n B r i t i s h Columbia t h e B u l l i o n Mine has about 23 miles of
d i t c h - l i n e , t h e Lowhee 25 milesand Germansen V e n t u r e s i t d . ,
1,O
m i l e s of d i t c h andflume.
"Hydraulicking i s f e a s i b l e w i t h , h e a d s as l o w a s 40 o r 50
f e e t if t h e g r a v e l i s n o t t i g h t : however,headsof
80 t o 200 f e e t
usually.aredesired,and
i f t h e g r a v e l i s cemented it i s n o t uncommon t o employ high-pressure equipment and heads ranging from
300 t o 400 f e e t i f suchcan be o b t a i n e d .T h i sc o n s i d e r a t i o nf i x e s
Its final
t e n t a t i v g l yt h el o c a t i o n
of t h el o w e l end of t h ed i t c h .
l o c a t i o n may be a m a t t e r o f compromise, as t h e head u s u a l l y c a n be
increased only at the
c o s t o f a lengtheneddktch o r a d e c r e a s e i n
t h eg r a d e .
The l a t t e r r e d u c e s t h e q u a n t i t y
ofwaterthatcan.
be
carriedin'aditch
of given size.
4 and
"The g r a d e s ' o f m o s t h y d r a u l i c - m i n e d i t c h e s l i e b e t w e e n
8 f e e tp e rm i l e ,
o r 3/4. t o 1 1/2 f e e t p e r 1,000 f e e t . ' E a r l y C a l i fornian ditches were run'on
much s t e e p e r g r a d e s , b u t t h e c o n s e quenthighvelocitiescausederosion
of t h e b a n k s a n d s e r i o u s
breakswere common. S m a l ld i t c h e s may be run a t g r a d e s of 6 t o
1 2 feetpermilewithoutexcessivevelocities.
limits ofwhich t h e
"Practicalvelocitiesrangebetween
minimum i s d e t e r m i n e d b y s i l t i n g a n d t h ;
maximum by e r o s i o n . If
the entering water contains-sediment
it may be d e p o s i t e d i n t h e
d i t c h .T h i ss h o u l db eg u a r d e da g a i n s tb yi n s t a l l i n g
a s a n dt r a p
neartheintakeand
by designing f o r 8. v e l o c i t y of n o t l e s s t h a n
1 f o o tp e rs e c o n d .
On t h eo t h e rh a n d ,
a v e l o c i t y ofmore
than
3 f e e tp e rs e c o n d
i s a p tt oe r o d et h ec h a n n e la n dc a u s eb r e a k s . "
Yeeds w i l l h a r d l y grow i n w a t e r f l o w i n g
2 t o 2 1/2 f e e t p e r
second.
"The f o l l o w i n g a r e recommended a s maximum mean v e l o c i t i e s
f o r ditches in various materials:
Material
Mean v e l o c i t y
Feet per. second
Loose
0:5
1
Sandy s o i l
2
F i r m s o i l , firm sandy
loam
3
Stiff
4
Silt
sand
gravel clay,
cobbles
gravel,
Coarse
5
Cemented g r arsvooecflkt,
10
6
Hard rock
- 8 -
._
..
"The f i g u r e s o n t h ep r e c e d i n g page r e p r e s e n t mean v e l . o c i t i k s , t h e
correspondingbottornvelocitiesbeing
20 t o 30 p e r c e n t l o w e r ,
and t h e c o r r e s p o n d i n g s u r f a c e v e l o c i t i e s , a s m e a s u r e d
by f l o a t i n g
o b j e c t s ,p o s s i b l yb e i n g
25 t o 3 5 p e r c e n t h i g h e r .
"The v e l o c i t y , h e n c e t h e c a p a c i t y
of a d i t c h , d e p e n d s upon
i t s s l o p e ,t h en a t u r e
of t h e w a l l s , t h e s i z e
andshape
of t h e
w a t e r s e c t i o n , and t h e s t r a i g h t n e s s a n d r e g y l a r i t y
of t h e c h a n n e l .
A l l t h e s ef a c t o r s ,e x c e p ts t r a i g h t n e s sa n dr e g u l a r i t y
of c r o s s s e c t i o n ,a r e - i n v o l v e di nt h eK u t t e rf o r m u l a :
=
1.811
+
n
"
"
1
t
41.65
+
"
"
-
v5
(41.65 +
0.00281
__S
I__
0.00281
-.F--)
. .
( m )
I n which
I,
mean v e l o c i t y( i nf e e tp e rs e c o n d )
V
=
S
=
R
= h y d r a u l i cr a d i u s( a r e a
nI! = c o e f f i c i e n t o f roughness
s i n e of s l o p e( f a l ld i v i d e d
by l e n g t h )
o fw a t e rs e c t i o nd i v i d e d
wettedperimeter
of c h a n n e l ) in. f e e t .
by
" T h i sf o r m u l ao r d i n a r i l y
i s a p p l i e d by means of t a b l e s or
c h a r t s .F i g u r e
1 i s a c h a r td e v i s e d by F. C . Scobey of t h e
UnitedStatesDepartmentofAgriculture.
The propervalue
t o use
f o rt h ec o e f f i c i e n t' n 'i s
a ;matter of judgment. Th,- f o l l o w i n g
designers.
v a l u e s of ' 2 ' a r e recommendedbymodern
Values of RoughnessCoefficient
~
Surface
Best
"
"n"
"
,011
C o a t e dc a s t - i r o np i p e
Cormercial wrought-iron pipe
alack
Galvanized
,013.012
.013
Good
-
Fair
"
Bad
-
0.01.2'' .013'
.015
.014
,014 .017
,015
.017x
R i v seaptnseipd
t.rd,e0ia0p
e1
l1le35 '
pipe
jiood-stave
Plankflumes
Planed
Unplaned
With battens
- 9 -
,010
,011
.Oli
.OlO
.03. I
,012,'
,013"
.014
.013
.015
.014
.012
,015"
.016
.013
.
follow intersection of
~t
and
R
alonghorizontalguidelines
to intersection of S and V, or vice versa
Figure 1.-Diagram for solving Kutter formula to determine flow of water in openchannels or pips.
Reprinted from United States Bureau of Mines Information Circular 6787.
Semi-circuiarmetalflumes
Smooth
Corrugated
Canals and ditches
E asrt trha ,i g h t
.011
and uniform
,017
.025
Rock c u t s , smooth
and
uniform
,012
,025
.OJ.3
,020
.030
. 0225x
.03.3x
,015
.'0275
.030
.0225
,040
,045
..
.025x
,0275
Dredged
. 0c 2
h5
a n enaerl tsh
.0275' .033
.030
Canals with rough stony beds;
weeds on e a r.025
t h banks
.030
Rock c u t s~,a g g e d
and i r . r e g u i ,a0r 3 5
, 0 2cs2aiwu
5nigangldsl m
s hi
.035x
,025
,035
.030
,040
x Values'most used.
" E a r t h c a n a l s for i r r i g a t i o n u s u a l l y a r e d e s i g n e d
with.
' n = 0.025 o r even0.0225;
however t h eu s u a lh y d r a u l i c
mine d i t c h
i s notst.caxght,unlformnorsmooth,andprobablythecoefficient
0.030or0.035shouldbeappiied.
The v e i o c i t i e s anddischarges
f o r a number o f d i t c h e s o f ' s m a i , l t o medium s i z e shown i n Table 1
w e r ec a l c u l a t e d on t h ea s s u m p t i o nt h a t' n !
= 0.035.
Any i n c r e a s e
i n t h e assumed v a l u e o f !n' r e s u l t s i n anapproximatelyequalper.t h e calcuiated-veloc?.ty, or a doubledpercentcentagedecrease+n
a g ei n c r e a s ei nt h er e q u i r e ds l o p e .
Thus t h e v e l o c i t i e s and
o r 20 p e rc e n t
c a p a c i t x e s shown 1.n Table 1 mlghtbemcreased15
for d i t c h e s I n unusualiy good c o n d i t i o n .
of t h e d p t c h h a s
a bearingcn
i t s cap"Sithopghtheshape
a c i t y , i n p r a c t i c e t h e . s e c t i o n is i n f l u e n c e d m o r e by t h e method
of e.xcavation. However, for a g i v e na r e a ,t h es e c t i c ns h o u l d
be
so shaped a s t o have t h e l a r g e s t h y d r a u l i c r a d i u s c o r s l s t e n t w i t h
economicalconstruction.
The u s u a le a r t h
o r graveld.itchfor
a t r a p e z o i d a l s e c t i o n , b a t h a f l a t bottom 2
hydraulic mines has
t o 1 0f e e tw i d e ,s i d e ss l o p m ga b o u t
45 degrees,and
a water
depthofone-third
t ot h r e e - q u a r t e r st h eb o t t o mw i d t h .
The s i d e s
should be excavated a t a s l o p e t h a t w i l l be s t a b l e i r u s e , o t h e r widecavlng w i l l r e s u . l t I n i r r e g u i a r l t y of s.ection ar.d consequent
l o s s of c a p a c l t y . The f o l l o w i n gs i d es i o p e sa r e
recc,m?lended f o r
d i t c h e s l n v a r i o u sm a t e r i a l s :
-
11 -
S i d eS l o p e s
Material
Horizontaltovertical
Firm s o i l , c o a r s e firm g r a v e l
O r d i n a r ys o i l ,l o o s e
gravel
Loosesandy
I
1 : l
45
or f i n e '
1 1/2
soil
1
"Wimmler
who
t h a ts i d es l o p e s
h i g h e rs l o p e sc u t
Degrees
: 1
35
2 : l
25
t a b u l a t e sd a t a on35
A l a s k a nd i t c h e s ,s t a t e s
of 45 t o 65 d e g r e e sa r e common, b u t t h a t t h e
down q u i c k l y .
"On s t e e p h i l l s i d e s r e l a t i v e l y s t e e p e r s i d e s
anddeepersect i o n s may be cut if t h e s o i l i s firm t oa v o i de x c e s s i v ee x c a v a -
rock^ t h e s i d e s may be
t i o n on t h e u p h i l l s i d e of t h e d i t c h . I n
as i n r e c v e r t i c a ' l ; t h e w i d t h shouldbetwicethewaterdepth,
tangularchannelsthisresultsintheleastexcavationfor
a given
'capacityandslope.Likewise,
i n r o c k t h e . s i z e niay be decreased
and t h e g r a d ei n c r e a s e d ,
t h u sr e d u c i n g t h e y a r d a g e ofrockexcav a t i o n . Ditchesshould bedesigned t o run not more t h a n t h r e e f o u r t h s f u l l , a l l o w i n g 1 to 3 f e e t o f f r e e b o a r d .
"Inporous soil c o n s i d e c a b l ew a t e r i s l o s t by seepage.
P e e l e 2q u o t e sE t c h e v e r r ya ss t a t i n gt h a ts e e p a g el o s s e sr a n g e
from a sl i t t l ea s0 . 2 5c u b i cf o o tp e rs q u a r ef o o t
of wettedsur. f a c ep e r 24 ho.urs i ni m p e r v i o u sc l a y
loam t o 1 . 0 c u b i c f o o t i n
sandyloamand
2 t o 6 c u b i cf e e ti ng r a v e l l y
soils. It is easily
computed t h a t a medium-size d i t c h , 5 mileslo'ng,carryipg1,000,
or 2,000miner'sinches,
may l o s e 5 o r1 0p e rc e n t
of t h e i n t a k e
water by seepage,even
i n good s o i l , and i n p o r o u s s o i l , a s
much
a s 20 p e rc e n t . "
As a n i l l u s t r a t i o n ,
a t Germansen Ventures
Limited, Germansen Creek, B. C . , s t a r t i n g w i t h a n i n i t i a l f l o w
:
attheintake
of135cubic
f e e tp e rs e c o n dt h e r e
was a 1os.s of
about- 25 c u b i c f e e t p e r s e c o n d t h r o u g h s e e p a g e i n . 3 m i l e s o f
f l u m e and 6 m i l e s of d i t c h . l a r g e l y i n f a i r l y i m p e r v i o u s b o u l d e r clay.
"Remedieswhere t h e l o s s i s s e r i o u s a r e t o d e c r e a s e t h e . s i z e
ofditchandincreasethevelocity;
t o reducethevelocity
to a
'' h'immler,
N.L., Placer-miningPiethodsand
Costs in Alaska:
B u l l . 259,Bureau
of Mines, 1 9 2 7 , pp.40-56.
Peele,Robert,iliningEngineers'
3rd.ed.,1941,
p.
38-26.
-
Handbook: Johnldiley
12
-
and Sons,
p o i n t a t which s i l t wiil d e p o s i t a n d . t e n d t o s e a l t h e g r o u n d ; t o
l i n et h ec h a n n e lw i t h
s o d , canvas, or c o n c r e t e : or t o s u b s t i t u t e
..
flumes f o r d i t c h e s ,A c c o r d i n gt o
wimmler,sod
l i n i n go f t e n i s
u s e di nf r o z e n
muck i nA l a s k a ,s o m e t i m e sw i t he n t i r es u c c e s s .
Puddling when s u f f i c i e n t c l a y i s a v a i l a b l e w i l l t e n d t o seal'much
of t h e s e e p a g e .
"Veryfew d i t c h e s h a v e b e e n b u i l t i n r e c e n t y e a r s , a n d
no
modern c o s t s a r e a v a i l a b l e .
Xany methods a r e avsilab1.eforsuch
work, ranging frog1 hand-shoveland
pic!: work t o excavation by
A common xethod i s . t o plow
power shovel o r m e c h a n i c a ld i t c h e r s .
t h e s u r f a c e andexcavate as n e a r t o g r a d e a n d c o r r e c t s e c t i o n a s
p o s s i b l e w i t h t e a m sa n ds c r a p e r s ,t h e nf i n i s h
by hand. Some
izstances have. been noted where hydraulic giants were used for
i s p o s s i b l eo n l y when water
d i t c he x c a v a t i o n .T h i s ,o fc o u r s e ,
i s a v a i l a b l ef r o m a h i g h e r d i t c h l i n e . I n c i d e n t a l l y t h e h y d r a u l i c
for e x c a v a t i n g w h e r e v e r p r a c t i c a b l e .
miner uses high-pressure water
"The a l i n e i e n t o f d i t c h e ss h o u l d be s u c h t h a t e x c a v a t i o n
to
grade will provide j u s t enoughbank m a t e r i a l t o f o r m ~i
channelof
t h ed e s i r e ds i z e .X h e r e v e rt h ew a t e rl e v e l
is t o beabove t h e
it is w e l l t o plow t h e surface:beforeexo r i g i n a lg r o u n ds u r f a c e
bankand
c a v a t i o n s t a r t s t o form an impervious joint between the
t h eg r o u n d .
If t h em a t e r i a l i s n o ts u c ha s
t o f o r mt i g h tb a p k s
it !nay be a d v i s a b l e t o e x c a v a t e t h e e n t i r e w a t e r s e c t - i o n
below
t h eo r i g i n a ls u r f a c e .
The grade m u s t bemaintainedexactlyand
thedesiredsectionadheredtoascloselyaspossible,asall
i r r e g u l a r i t i e s have a r e t a r d i n ge f f e c t on t h e f l o w .
'Curves should
benadesmoothand
r e g u l a r for t h e same r e a s o n .
"If t h e r e i s danger o f water from f l o o d s o r o t h e r s o u r c e s
f i l l i n g t h e d i t c h beyond c a p a c i t y ,s p i l l w a y s
must be :?rovided a t
i n t e r v a l s t o p r e v e n tb r e a k si nt h el i n ew h i c h
would s t o p o p e r a t i o n
andbe c o s t l y ~ t c r e p a i r .
Neasuring weirs
"The s i m p l e s t methodof
a c c u r a t e l y m e a s u r i n g a f l o w of water
i n a stream or d i t c h is bymeans of a w e i r . ?!urneraus typesof
weirsareused,andthereare
many f o r m u l a s f o r c a l c u l a t i n g t h e
flowoverweirs.
" A common t y p e of weir i s shown i n F i g u r e 2 . The width of
t h ew e i rn o t c hs h o u l d
be a t l e a s t s i x t i m e s t h e d e p t h
of water
f l o w i n go v e rt h ec r e s t .
The bottom of t h en o t c hs h o u l db el e v e l
and t h e ' s i d e s v e r t i c a l .
The weirnotch is b e v e l l e d on t h e downa s h a r p edge on t h e u p s t r e a m s i d e .
s t r e a n s i d e , so a s t o l e a v e
The w e i r s h o u l d b e i n s t a l l e d
so t h a t t h e w a t e r i n t h e
pond above
i sc o m p a r a t i v e l ys t i l l .
I t !nus'; a l s o b e highenough s o t h a t
- :13 -
TABLE 1.- Calculate& v e l o c i t i e s apd
discharees
1
Width,
Bottom
h............
.......feet/
I
Tap width, f ...................... do. 2.0 2.5 3.0 3.C I
Depth.
do. I .5
,751 1.0
.5 1
Area, 9...........................
s q . It.1 ,751 1.31) 2.0
I 1.251
I
slope. ft.
D** mile
I
1
I
11
0.19
.38
I
1
2
1
1
1
1
1
4.0 5.0 4.0 5.0
1.0 1 1.5 1 .5 1.0
3.0 ! 5.251 1.751 4.0
3
1 6.0 I
I 1.5 I
I
"I
I
1
7.0 6.0
2.0
1.0
6.75110.0 I 5.0
I 7.0
I 1.5
I
4
I
1
I
9.0 (10.0
2.0 2 . 5
3.0
8.25112.0 116.25121.0
8.0
I
Velocity of flow, feet per second
slope. ft.
Der 1.000 ?tJ
21
3 1
41
51
1
I
.
-
f o r small and
medium-size
ditches
I........~.........~..........~........../........../..........~..........~..........~..........~0.564~..........~0.502]0.601~0.6
'
61
7 1
8 1
9 1
10 I
'1.1
12
15 1
I
1.89
2.08
2.27
2.84
___ 20 1
3.79
I
w
tP
I
1
1
1
I
I
,6191 .804( ,9681
,650) .841!1.0151
.74911.169!1.4991
,6811 .882/1.0611
.78511.22511.568!
,7621 .98611.1861
.87611.37011.7561
.802j1.270~1.629~1.932~1.339~1.725~2,048
2.33 12.590
.842/1.328~1.704~2.024~1.402~1~~05~2.145
2.43 12.714
.941~1.484~1.909/2.263~1.~9~2.018~2,397
2.72 13.031
-
. 8 8 2 ~ 1 . 1 4 2 ~ 1 . s I 2 / 1 . 0 1.
4 ! 1 . 5 8 4 [ 2 . 0 2 7 / 1 . 0 8 6 ~ 1 . 7 1 5 ~ 2 . 2 0 4 / 2 . 6 1 2 / 1 . 8 1 1 / 2 . 3 3 0 ~3.15213.502
2.T70
"
D=g&
Cubic feet mr9ecOnd'
............................................................... .I ............................................................... I 5.601.....:....I4.121 7.20 11 2116 2
............................................................................. 1.471 3.311.........I8.121 4.591 8.1012.801 5.94110.32/15:93/ 23:l
..........................................
.....! 1.041 . . . .1
1.801 4.~241
..........I 2.601 5.67110.001 3.45 7.34112 72119501 28.4
.............................................. ~0:661 1.201..........[ 2.10( 4.721..........I 3.041 6.55!11.601 4.001 8.50!14:76(22:75( 32.8
5 ............................................
,731 1.36 0 621 2 34' 5 25 0.941 3.401 7.36113.001 4.501 9.57116.56125.511 36.5
6 ..........................................
,811 1.501 :691 2:581 5:781 1.031 3.721 8.10114.201 4.90~10.48~18.12~27.95! 40.1
1
2
3
4
I:,...............................
7 ..................................
8
9
........................... I
I
I
............................... 1
................................
1 ..............................
10 ..............................
11 I......................
..,....
12
15
20
'TO
0.391 ,881 1..621 ,751 2.791 6.251 1.121 4.041 8.78/15.401 5.35~11.30~19.56!30.06~
a3.5
,411 ,941 1.721
,801 3.001 6.721 1.191 4.321 9.38!16.50]5.70~12:13~21.00/32.18~
46.4
,441 1.001 1.841 ,851 3.181 7.141 1.261 4.60 9 99117 501 6 05112 87\2220134 291 49.4
,461 1.051 1.94
891 3.361 7.511 1.331 4.84)10:53118:401 6:40113:53123:52136:241 51.9
.491 1.101 2.041 1941 3.511 7.881 1.401 5.08111.00!19.301 6.70114.19124.60137.8~~
54.4
,511 1.151 2.121 ,981 3.661 8.241 1.471 5.32/11.48/20.201 7.00114.85/25.68139.491
56.9
,571 1;301 2.38) 1.101 4.111 9rZ41 1.641 5.92112.69122.601 7i85/16.66/28.80144.201 63;6
.66 1491 2.74 1.261 4.74110.661 1.91 6.88114.85]26.101 9.05~19.22~33.?4~51.19~
73.5
convert to miner's inches multiply by 40.
Reprinted from United States Bureau of Mines Information Circular 6781.
.
.
TABLE 1.- Calculated velocitjes ncd dischirpes E o ~ m a l and
l
medium-size ditches
"
5
-I
E
I8
I 9.0 11'2.0 111.0 112.0 113.0 110.0 112.0 114.0 116.0 112.0 116.0 I20.0
I 1.5 1 2.0 1 2.5 1 3.0 I 3.5 1 4.0 1 2.0 1 3.0 I 4.0 I 5.0 I 2.0 I 4.0 1 6.0
1 9.75114.0 /18.75!24.0 /29.75136.0
i16.0 127.0'/40.0155.0 120.0 148.0 184.0
Width.
Bottom
b........ ...:.i..
...Feat!Top width,
do. 7 . 0 j
Depth, ..........................
..............................
1.0
Area. .................................................... f t . 1 6.0
Hydraulic radius, ........................................
,771
1
1
____
-
I
Slow, f t .
1
.............................................
.............................................
..............................................
..............................................
..............................................
15
20 ..............................................
'TO convert t o miner's
_"
__"_
1.061 1.311 1.551 1.781 2.OC/ 2.211 1.371 1.861 2.31: 2.731 1.461 2.481 3.36
ft.
I
Velocity
of
flow, f e e t per second
Fer i.000 f t .
0.19 ~0.402~0.525~0.628~0.720~0.802~0.880~0.952~0.653~0.831~0.988~1.124~0.686~1.047~1.318
.38 I .57 I .75 I .9C 11.02 11.14 !1.2411.35 1 .93 11.18 11.40 11.58 I .95 11.48 !1.87
S1OW.
..............................................
..............................................
..............................................
.............................................
12
8.0
"
"
2
3 ..............................................
4 .............................................
5
6
'i
8
9 ..............................................
10 ..........................................
11
- Continued
1
~-
Discharee. Cubic f e e t D W secmd'
5.11 8.81 13.51 19.21 26.21 34.21 10.41 22.41 39.61 61.61 13.81 50.4/110.9
7.31 12.61 19.11 27.41 36.91 48.61 14.91 31.91 56.01 86.91 19.01 71.01157.1
9.01 15.41 23.61 33.81 45.51 59.81 17.81 39.21 68.81107.2/24.01 87.41192.4
10.41 17.91 27.41 38.91 52.71 69.11 21.11 45.41 79.2/123.8/
28.0/100.8/221.8
5.61 11.81 2o.zj 30.81 43.7 59 21 77 41 23 81 51
88 81138 61 31 41112 81247 0
6.11 12.91 22.01 33.61 47.8\ 64191 84:6(2 6 : i j 55:91 .97:6)152:4/":f\!'"":"\"::!
6:ii 13.Yi 23.81 36.41 51.81 69.9I 91.41 2 8 . 2 60.2jio5.6ji64.41 a , . v l ~ a a . 9 l ~ s ~ . a
7.11 14.91 25.51 38.81 55.41 75.01 97.91 30.1! 64,51112.81176.01 39.61143.01312.5
7.51 15.91 27.21 41.21 58.81 79.4/103.7/
32.01 68.61119.61186.41 42.01151.71331.0
7.91 16.81 28.61 43.71 61.91 83.91109.41 33.81 72.41126.01196.41 44.41159.81348.6
8.31 17.61 30.01 45.81 65.01 87,81114.8135.5/ 75.9j132.0/206.21 46.41168.01365.4
8.71 18.31 31.21 47.81 67.71 91.9!119.91 37.11 79.41138.01215.6! 48.61175.7/381.4
9.71 20.51 35.01 53.41 75.6/102.6/133.91 41.4) 88.61154.0/240.41 54.4(195.4/425.9
11.31 23.71 40.51 61.71 87.81118.71154.81 48.0!102.31178.0!277.2~ 63.01225.6/493.1
2.41
3.4:
4.31
5.01
01
inches multiply by 40.
Reprinted from United States Bureau of Mines Information Circular 6787.
-
16
-
there i s freeaccessof
a i r t o t h e u n d e rs i d eo ft h eo v e r f l o w
s h e e t ofwater.
h s t a k e i s d r i v e ni nt h e
pond 5 o r 5 f e e t above
notc'h of t h e
t h e weir w i t h t h e t o p of t h e s t a k e l e v e l w i t h t h e
w e i r . The d e p t h of f l o w o v e rt h ew e i r
i s measured w i t h a r u l e
or s q u a r ep l a c e do nt o p
of t h e s t a k e .
The F r a n c i sf o r m u l a i s
commonly u s e d f o r c a l c u l a t i n g t h e f l o w .
Q
where
Q
=
w
=
3 . 3 3 wd 3/2
=
q u a n t i t y of water i n c u b i c f e e t p e r s e c o n d
widthofnotch
i n weir
d = d e p t h of w a t e r go:.ng over weir
"The d i s c h a r g e p e r f o o t
of l e n g t h o f t h i n - e d g e weirs i.n c u b i c
f e e tp e rs e c o n da n dm i n e r ' si n c h e s 1f o rd e p t h so f
118 i n c h t o
24-7,'s
i n c h e s i s shown i n Table 2. The t a b l e i s compiledfrom
t h e aboveformula.
"?iost hydraulic-:nine ditch 1.ines contain
some f l u ; n e ' s e c t i o n s .
or
F l u n e s may b e n e c e s s a r y w h e r e t h e l i n e p a s s e s a r o u n d c l i f f s
o v e rr a v i n e s , o rd e s i r a b l eo v e r
porous o r s h a t t e r e d gro..md where a
d i t c h would l o s e much water or t e n d t o c a u s e s l i d e s ( s e e P l a t e
IIA).
On s t e e p h i l l s i d e s or where ditching would require
muc'h c o s t l y
rockexcavation a flume may p r o v e e c o n o m i c a l : f i n a l l y , t h e c o s t
of t h e l i n e may b e l e s s e n e d a n d c o n s i d e r a b l e s a v i n g
male i n t h e
t o t a l f a l l by b u i l d i n g a flumeon t r e s t l e s a c r o s s v a l l s y s i n s t e a d
of d i t c h i n g t h e g r e a t e r d i s t a n c e a r o u n d t h e h e a d .
'
"The
same
c o n d i t i o n ss h o u l db ec o n s i d e r e di nd e s i , g n i n g
a
f1ume"as i n d e s i g n i n g a d i t c h ,a n dt h eK u t t e rf o r m u l a, s e ep a g e
9)
a p p l i e se q u a l l y t o both. The formula i s used most c o n v e n i e n t l y
i n t h e form of t a b l e s or c h a r t s ( s e e F i g . 1 ) .
"The low f r i c t i o n c o e f f i c i ' e n t of boardflumes may beused t o
advantageeitherbybuilding
a fl.ume of smaller s e c t i o n or bydel e s s t h a nt h a to ft h ed i t c hl i n e .
If t h e
c r e a s i n gt h eg r a d et o
l a t t e r i s done a s a v i n gi nh e a d
may be made a t t h e min,?.Usually,
h o w e v e r ,s r n a l l e rs e c t i o n sa n dh i g h e rv e l o c i t i e s
a r e us'sd. t h a n
f o rt h ed i t c hl i n e .
For l o w e s tf r i c t i o nl o s s e st h ew i ( f t ho ft h e
flumeshouldbe
1nad.e t w i c e t h e w a t e r d e 7 t h
and a 'freeboard of 1
t o 2 f e e ta l l o w e d .A c c o r d i n gt oE g l e s t o n zt h eu s u a l
w;%terv e l o c i t y
I n t h i s b u l l e t i n a f l o w of 1 c u b i cf o o tp e rs e c o n d
to 40 miner's inches.
Z g l e s t o n , Thomas,The l l e t a l l u r g y of S i l v e r , Goldand
t h eU n i t e dS t a t e s :J o h nM i l e y
& Sons, New York,1890.
i
i
-
17
-
is e q u i v a l e n t
?iercury i n
.
.
"
0...............................
I
IIBBI PB
-1
..............................
3..............................
4...............................
2
0.01 0.1
0.08
4.0
23
10.0
42
61
25.6
I
26.8
:92
36.8
.70
.96
1.18
48.8
1.48
60.8,
8 .............................
1.m
9.............................
2.16
.89
35.6
e.4
LO3
10............................
11..............................
2.92
12.............................
3.53
13..............................
3.76
14.............................
4.20
15..............................
4.65
.47
17.6
67
................
6............ . . . . . I
7...............................
5
.11
.n
.
150.
L E 8.
186.
3.38
133
0.05
6.8
.18
12.8
.34
1j.6
.37
19.6
29.2
.32
.62
.'76
20.8
.55
-
22.0
.58
30.4
.80
32.0
.83
39.6
1.03
41.2
1.06
42.4
1.10.
11.6
23.2
I
.61
24.4
33.2
.66
34.4
44.0
1.14
48.6
57.6
1.64
65.@
1.68
1.72
68.8
l.n
70.8
16.0
1.94
TL.6
1.99
79.6
2.03
67.2
81.2
2.08
83.2
2.12
84.8
90.0
2.29
91.6
2.34
93.6
2.39
95.6
2.44
91.6
2.45
99.6
.11.
2.83
113
2.81
.15.
3.44
.
121..
.
LO5
1%
210
.
191
247 .
6.25
268
6.77
20.............................
7.17
21.............................
7.71
308:
............................. 1
23.................... ..........I
8.27
331
8.84
354
24
9.42
377
1
. J
5.25
.
.
2 :€a
LO7
3.07
3.49
3.92
157
9.73
10%
2.78
123
0.13
125.
3.18
140
3.54
142.
3.59
3.97
4.03
1n
4.48
4.83
196.
4.95
5.31
215.
5.43
235.
5.93
252
6.83
7.37
311.
7.85
314
334 .
7.92
8.41
336
8.48
8.98
359
9.05
562
9.57
583
9 64
186
I
. I
. I
. I
.
I
285. I
7.30
.
. .I
159.
. I
E92 .
211
.
.
4.36
5.74
I
15.6
64.0
172.
.
.39
1.80
154
380 .
8.0
14.8
2.8
62.4
4.31
356
.20
7.2
1.56
3.86
9.50
....
2.0
1.44
152.
8.91
i
56.4
6.63
. I
. I
1.8
.17
1.41
6.12
.............................
0.04
6.0
54.8
19............................
22
1.2
.15
&
1.37
170
I ;::
0.03
5.2
.
Irhea.
Jlr
b3.2
3.81
.
289.
d. lacs
OEILeS
I ,ner.
1.33
16..............................
1
G W
aEpBB-assQna
,et pe
51.6
5:13
b.62
17............................
a.s.Qwl
Cub10
'8
1.29
3.03
208
Cublo
Bet Pel:[MI.AB.-
50.0
4.25
4.71
I
.ner,i
BI Pel
1.25
.
227 .
16............................
16.8
28.0
.
.99
2.-
.
.29
.49
.73
10.8
I
-I-
Cublo
her'* IeBt w : iller',
0.8
4.4
hlbio
7/8
_I-
3/4
38.4
2.25
.
119.
135.
1
Cubio
Lner'B f e e t PB'
llGh%LaQzQlLd
0
1..............................
i
Cubio I
Lner's re*t pe.
I
5/8
U3
. I
I
.
255.
6.44
6.90
276.
6.96
7.44
298.
7.50
320.
8.06
342.
8.62
9.13
365.
9.20
9.72
189.
9.79
I
1
1
1
1
11
1
1
1
.n .
.
.
3.23
29
.
3.a
.31
143.
3.65
146.
3.7c
149.
161.
4.08
163.
4.14
iE8
179
4.54
182.
4.58
.a
198.
5.01
!OO
5.01
!17.
5.49
220.
!37.
5.99
MO
6.06
!58.
6.50
.
!60.
6.57
!I8.
1.03
!81.
7.10
500.
1.57
103.
7.M
122.
8.13
25.
8.20
145.
8.69
48.
8.76
28.
59.
.
5.55
.
.
!03.
m.
Mz .
.a
.
e4 .
ob .
.@.
9.27
11
9.35
74.
92.
9.87
95.
9.94
38.
Reprinted'from United States Bureau of Mines Information Circular 6781.
-
i s 4 t o 9 f e e tp e rs e c o n d( 3
t o 6 milesperhourj.
Thesame
author
givestherangein'gradein
28 p r o m i n e n t C a l i f o r n i a f:lumes a s 9 t o
18-2/3 f e e tp e rm i l e .
The extremerangeof
8 6 well-knownflumes
in
to
t h e K e s t e r n S t a t e s was 5 t o 53 f e e t p e r m i l e , t h e u s u a l r a n g e 1 0
1 8 ,a n dt h ea v e r a g es l i g h t l y
und.er 1 4 . Bowiel s t a t e st h a tg r a d e s
of 25 t o 35 f e e tp e rm i l ea r eu s e dw h e r ep r a c t i c a b l e .
Such s t e e p
grades would p e r m i t t h e u s e
o f si. r e l a t i v e l y s m a l l f l u m e s e c t i o n ,
but the authors believe that usually they
would involve inconvenie n t l yh i g hv e l o c i t i e s ;m o r e o v e r ,
a longerflume'wouldberequired
t o g i v e t h e same head.
"The c o n s t r u c t i o n o f wooder! flumeshaschanged
little since
t h ee a r l yd a y s
of p l a c e rm i n i n gi nC a l i f o r n i a .F i g u r e
3 A illust r a t e st h ee a r l yt y p eo f
box.This
was b u i l t i n 1 2 - or I S - f o o t
The
s e c t i o n s of 1 1 1 2 - ' t o2 - i n c h
lb.mber, 1 2 t o 24 inches wide.
- l o n g i t u d i n a l j o i n t s w e r e made t i g h t by n a i l i n g overeach a b a t t e n
1/2 i n c ht h i c k and 3 o r 4 incheswide.Figure
3 B illustrates
a f l u m eb u i l ta b o u t, 1 9 3 0f o rw a t e r
power; it c a r r i e s a b o u t 600
n i n e r ' s i n c h e s on t h e f l a t grade of o n e - f i f t h f o o t p e r 1 , 0 0 0 f e e t
andwould s e r v e e x c e l l e n t l y f o r
a s m a l lh y d r a u l i cw a t e r - s u p p l y
l i n e . I t d i f f e r s i n c o n s t r u c t i o n f r o mt h eo t h e rt y p ei l l u s t r a t e d
of the boxes and
c h i e f l y i n h a v i n gs p l i n e sb e t w e e na l lt h eb o a r d s
l a c k i n g framing i n t h e s i l l s and c a p s . I t was b u i l t over6,800
f e e t of rugged c o u n t r y a t a t o t a l c o s t of $2.50 per f o b t .
'Where t h ef l u m e i s on grad.e t h e box u n i t s s h o u l d be s e t on
or on 2
s t r i n g e r s l a i d on a c a r e f u l l y c l e a r e d a n d g r a d e d s u r f a c e
benchcut i n t h eh i l l s i d e .T r e e so rb r a n c h e st h a tm i g h t
f a l l and
wreck t h e flumeshouldbe
removed.. I nc o l dc l i m a t e st h ef l u m e
t o preventfreez:tng.
Where
may be coveredandheapedwithearth
a line
t h e f l u m e i s on t r e s t l e s a walkmustbeprovided;usually
i s n a i l e do v e rt h ec a p s
o r on a l t e r n a t e s i l l s e x t e n d e d
ofplank
a couple of f e e t t o one s i d e o f t h e b o x .
"The grademustbeuniform,
and a t curves t h e o u t e r edge
o f t h e f l u m e should be r a i s e d s u f f i c i e n t l y f o r t h e s m o o t h e s t
determined by t r i a l . "
p o s s i b l e f l o w of water;the elevation being
An adequate number ofspillwaysshould
beprovided
waterincase
of damage o r b r e a k i n t h e f l u m e - l i n e .
to divert
Diversion Dams
-andReservoirs"Diversion dams f o r h y d r a u l i c d i t c h - l i n e s u s u a l l y a r e e a r t h filledtimbercribsorrock-filledcribsfacedwithboards(see
P l a t e I].
S m a l ls t r e a m so f t e na r e
dammed
by
throwinglogsacross
-
Bowie, A. J . J r . , A P r a c t i c a l T r e a t i s e on i-iydraulioMining
C a l i f o r n i a : U. Van Nostrand Go., New York, 1889 p . 143.
- 19 -
in
I
6"x 8" Oregon fir stringers
wherecarried on trestle
A
B
a n df a c i n gt h eu p s t r e a ms i d ew i t hb o a r d s .D i v e r s i o n
d.ams u s u a l l y
a r e o n l y a few feet high but should be built where posisible
on
solidrock o r hardpan,sufficientlywideto
be s t a b l e andprovided
of t h e
w i t hs u i t a b l es p i l l w a y st op r e v e n te r o s i o n
andscouringout
foundation.
“ A t mineswherethewatersupply
i s i n s u f f i c i e n t f o r 24-hour
or
where
t
h
e
stream
flow
i
s
l
e s s t h a n i s needed t o
operation
o p e r a t e a t t h e d e s i r e d c a p a c i t y f o r one s h i f t , r e s e r v o i r s o f t e n
a r eu s e d .
If it i s . i m p r a c t i c a b l e t o have t h e r e s e r v o i r i n . t h e
s t r e a mi t s e l fa b o v et h ed i v e r s i o n
dam, it i s u s u a l l y 1 . o c a t e d a t
above t h e i n t a k e t o t:hepipe
t h e lower end o f t h e d i t c h , j u s t
l i n e s .R e s e r v o i r s
may be b u i l t bydamming
a canyon, by excavato r merely by e n l a r g i n g ‘a s e c t i o n
i n g a b a s i n on levelground,
As a r e s e r v o i rb r e a km i g h t
be
of t h e lowerend
of t h e d i t c h .
d i s a s t r o u s t o a mine l y i n g d i r e c t l y below i t , t h e work: should be
done c a r e f u l l y ,a l ll e a k a g ec h e c k e d ,s u i t a b l eg a t e s
an.d s p i l l w a y s
provided,andregularinspectionmaintained.
“ h s b o t h d i v e r s i o n dams and r e s e r v o i r s t e n d t o a c t a s s e t t l i n g
t o thebottom
b a s i n s it .may beconvenient t o p r o v i d e g a t e s c l o s e
throughwhichsediment
may b e f l u s h e d a s o f t e n a s n e c e s s a r y .
Mining
Equipment
“The chiefitems
of equipmentused
i n mosthydraulicmines
are pipe-lines to carry the water under pressure to the places
where it i s u s e d ; g i a n t s o r m o n i t o r sf o rc u t t i n g ,w a s h i n g ,a n d
d r i v i n gt h eg r a v e l ;d e r r i c k s ,w i n c h e s ,
o r o t h e rm a c h i n e r yf o r
h a n d l i n gb o u l d e r s ;a n ds l u i c e - b o x e sf o rs a v i n gt h eg o l da n dd i s common
posing of t h e t a i l i n g s . P i c k s , s h o v e l s a n d f o r k s a r e t h e
hand t o o l s used a t placermines.
Power d r i l l s run bycompressed
i f thegravelcontainsanexcessivequantity
Of.
a i r may beused
l a r g eb o u l d e r s( s e eP l a t e
X I V A ) . However,hand
d r i l l s a r eu s e d
a t m o s t mines t o d r i l l boulders and sometimes t o d r i l l cemented
Churn d r i l l s a r e employed occasiong r a v e l o r h a r d - c l a ys t r a t a .
o r may
a l l y f o r d r i l l i n g cemented.grave:Laheadofhydradicking,
be used f o r d r i l l i n g t o u g h b o u l d e r c l a y p r e p a r a t o r y t o
bank
blastingshouldthatbefoundex~pedient.
Pipe-Lines
-
“As d e s c r i b e d p r e v i o u s l y , d i t c h - l i n e s a r e u s e d t o
bring the necessary water to
a convenient point above the mine.
P r o m t h a tp o i n t a p i p e - l i n e i s l a i d down t h eh i l l s i d et ot h e
p i t( s e eP l a t e
111 B). Occasionally,wherethegrade
o f a creek
i s s t e e p , t h e w a t e r will be d i v e r t e d f r o m t h e s t r e a n d i r e c t l y
i n t o a pipe-line.Although
wood s t a v ep i p e i s used a t a few
p r . o p e r t i e s ,s t e e lp i p e
i s p r e f e r r e da tn e a r l ya l lh y d r : a u l i c
mines. I’
-
21.
-
I
The i n s t a l l a t i o n o f t h e p i p e - l i n e i s a veryimportantpartof
thehydraulicplant.Sharpbendsandanglesshould
be.avoided as
of t h ep i p e s .
Above a l l , t h e l i n e
w e l la sr s p i dr e d u c t i o ni ns i z e
s h o u l db el a i d
s o t h a t no p o i n t r i s e s a b o v e t h e h y d r a u l i c g r a d i e n t .
The f i r s t c o n s i d e r a t i o n i n d e s i g n i s
t o have a p i p e o f s u f ficient size to carry
an ample margin of.water over and above,immediate requirements.
"Pipe may be made f r o m s t e e l s h e e t s i n t h e k i n e s h o p s
or
boughtfrompipemanufacturers.Unless
a l a r g eq u a n t i t yo fp i p e
i s t ob eu s e d
or t r a n s p o r t a t i o n i s d i f f i c u l t it u s u a l l y i s more
economical t o buy t h e p i p e a l r e a d y made u p .V a r i o u st y p e so fs t e e l
p i p ea r eu s e d ,
but light-weightrivetedpipewithslip
o r stovei s p r e f e r r e d as' i t i s c h e a p e r ,l i g h t e ra n d
p i p ej o i n t sg e n e r a l l y
more . e a s i l y t r a n s p o r t e d a n d i n s t a l l e d t h a n o t h e r s t e e l p i p e .
will s t a n d g r e a t e r p r e s s u r e s a n d h a r d e r
"Spiralrivetedpipe
t
h
e
s
t
r
a
i
g
h
t
r
i
v
e t e d p i p e , but i t i s more expensive.
usagethan
Moreover, f l a n g e j o i n t s , which a r e a n added expense, g e n e r a l l y
a r eu s e dw i t ht h es p i r a lp i p e .O r d i n a r yr i v e t e dp i p eo f . 1 0t o
16 U n i t e dS t a t e ss t a n d a r dg a g em a t e r i a l ,
7 to 46' i n c h e si n
diameter, was b e i n g u s e d i n w e s t e r n m i n e s ; t h e d i a m e t e r s u s e d
mostwere
3 6 , 32,24,
2 2 , 18,15,
i1 and 9 inches.Largepipes
a r e e a s i l y damaged i f made of material.thinnerthan14gage.'.
o f pipeareused
i n the
Usual1.ytwo o r more diametersandgages.
same l i n e , m a i n l y as a m a t t e r of c o n v e n i e n c e s i n c e . t h i s ' p e r m i t s
n e s t i n gi nt r a n s i t .
A saving may be made i n o c e a nf r e i g h t and
occasiohLllyintruckhauls
by n e s t i n g t h e p i p e .
" S l i p - j o i n t . p i p e i s made i n s t a n d a r d l e n g t h s
of 1 9 f e e t
7 l/'Z incheseach.
The s e c t i o n s may be made longer o r s h o r t e r ,
however, as r e q u i r e d by t r a n s p o r t a t i o np u r p o s e s ;p r o v i d e dt h e y
a slip
a r ei nm u l t i p l e s
of 4 f e e t . The. e x t r ap i p er e q u i r e df o r
j o i n t i s a b o u t 3 i n c h e sp e rs e c t i o n .
The s t a n d a r dl e n g t h
of
s e c t i o n s o f s p i r a lr i v e t e dp i p e
i s 2 0f e e t .P l a c e r . p i p eu s u a l l y
i s coatedinsideandoutwithanasphaltpaint.
"A p i p e ' o f s m a l l e r d i a q e t e r will w i t h s t a n d a g r e a t e r p r e s s u r e t h a n a l a r g e r p i p e of t h e same w a l l t h i c k n e s s ; t h e r e f o r e
it
i s common p r a c t i c e t o u s e s m a l l e r d i a n e t e r s a s t h e p r e s s u r e i n c r e a s e s .R e d u c i n gt h ed i a m e t e ri n c r e a s e st h ef r i c t i o ni nt h e
pipe,and
a balancemustbestruckbetween
l o s s of e f f e c t i v e h e a d
f i r s t costoftheline.'Branchlinesusually
inthepipe-lineand
have a s m a l l e r d i a - e t e r t h a n t h e m a i n s u p p l y l i n e s .
"Table 3 shows t h e w e i g h t a n d s t r e n g t h
of riveted pipe with
s l i p j o i n t s . The w e i g h t sa r e for pipedoubledippedwithasphaltum
coating.
Table 3.
Pi?e
diameter
inches
Gage
No,
~,
8
a
a
9
11
11
11
12
12
12
13
13
13
13
14
1.
Ii
14
14
14
15
15
l5
15
-
Wt. per
foot,
pounds
5.3
6.4
6.2
16
14
7.4
7.0
16
14
8.4
11.6
12
18
16
7.8
9.4
12.9
8.6
10.4
14.3
22
18.1
9.5
11.4
14
12
15.6
19.7
10
16
10.3
14
12
12.4
12
16.9
10
21.4
16
1 11.1
14
13,.4,.
12
18.3
10
23.1
1
I
1
i
I
Safe
head,
Pipe
diameter
inches
340
490
325
450
315
394
553
280
350
490
252
318
443
568
230
16
16
16
11.8
14
12
10
16
14
12
10
14.4
19.6
317
24.8
406
12.6
168
211
15.4
34
297
20.9
26
.5 379
./
I. ;s"
la
'1a
20
287
402
517
210
283
368
473
194
243
340
437
180
,226
Safe
Gage Wt. per
foot,
head,
WO .
feet pounds 'feet
'
20
20
20
14
22
22
22
24
24
24
24
26
28
26
14
12
10
16
14
12
10
2a
2a
2a
10
10
14
12
10
158
198
277
356
140
175
246
316
.126
158
221
284
115
143
201
258
105
131
184
237
121
170'
219
113
158
203
16.3
22.3
20.2
15.1
18.3
24.9
31.6
16.7
20.3
27.5
35.0
18.3
22.2
30.1
38.5
19.8
24.2
32.6
41.9
26.2
35.1
28.2
37.6
48.7
30
14
30.1
30
30
32
32
34
12
10
12
10
12
10
12
10
40.1.
147
52.0
189
42.5
137
55.4
177
45.0 I 129
58.7
166
47.5
,122
62.0
156
36
'
'
106
13.4
45.3
- 24 "
J o i n t s andValves.
" I n making p i p ew i t h s l i p j o i n t s t h e
diameter of oneend=
s l i g h t l yc o n t r a c t e d .T h i sj o i x ti n
s t r a i g h t p i p e - l i n e s w i l l w i t h s t m d most p r e s s u r e s e n c o u n t e r e d
a t p l a c e rm i n e s .S l i pj o i n t s
however become b a t t e r e df r o m f r e quentlayingbut
may be hammered back t o s h a p e .
" R i v e t e de l b o w sf u r n i s h e db yt h ep i p em a n u f a c t u r e r sg e n e r a l l y
a r e u s e d f o r making t u r n s i n p i p e - l i n e s .
I t i s good p r a c t i c e t o
make bends s o t h a t t h e r a d i u s o f t h e
bend i s e q u a l t o 5 times t h e
diameter of t h e p i p e . T a p e rj o i . n t sa r eu s e dw h e r er e d u c t i o n sa r e
made i n l i n e s .
Sudden r e d u c t i o n si ns i z es h o u l db ea J o i d e db e c a u s e
ofthelossofheadandstrain
on t h e l i n e .
" S t a n d a r d v a l v e s a r e used for d i v e r t i n g water or c l o s i n g o f f
f l o wi n . p i p e - l i n e s .V a l v e ss h o u l db ec l o s e ds l o h l y
and w i t h g r e a t
c a r e i n h i g h - p r e s s u r el i n e s ;t h ep r e s s u r ee x e r t e d
by t h e sudden
stoppage o f flow i n , t h e w a t e r column may b u r s t t h e piipe.
"Air v e n t s a r e n e e d e d a t a l l . c r e s t s i n h y d r a u l i c p i p e s t o
prevent a vacuum beingformed ar.d subsequentcrushingofthepipe.
They a l s o a l l o w a i r t o escape when t h e l i n e i s b e i n g f i l l e d .
V e n t i n ga l s o i s n e c e s s a r y t o p r e v e n t a i r . p o o k e t s i n t h e l i n e ,
and
it i s h a r d l yp o s s i b l et oh a v et o o
many a i r v a l v e s .F i g .
4 shows
an a i r v e n t u s e d a t the' Salyer mine
i n TrinityCounty,Ca1if.l
The d e v i c e c o n s i s t s of a l e a t h e r - f a c e d f l a p on a h i n g e b o l t e d 'on
t h ei n s i d e o f t h ep i p e .
fi b a i l a t t a c h e d t o t h e f l a p g o e s t h r o u g h
1 3/4 by 3 i n c h e si n s i z e , c u t i n t h e !pipe. k s
anoblonghole
thewater f i l l s the p i p e t h e f l a p f i t s tightly agains-t the inside;
as t h e water f a l l s t h e f l a p d r o p s , making a v e n t .
"To g i v e . t h e water e n t e r i n g a p i p e - l i n e an
Pressureboxes.
initialvelocitypressure
boxes or p e n s t o c k s a r e u s e d ( s e e P l a t e
IV A).
fi head of 4 t o 6 f e e t usua.lly is provided.
i. l e n g t h o f
l a r g e - d i a m e t e r p i p e may be used a t t h e t o p o f t h e . l i n e i n s t e a d of
a penstock. A s c r e e n or g r i z z l y shouldbeplaced
a t t h e head o f ,
a s e t t l i n g box shouldbe prot h e l i n e t o k e e po u tt r a s h ,a l s o
videdwheresand2ndgravel
may s e t t l e b e f o r e t h e water g o e s i n t o
t h e p i p e , as s u c h n a t e r i a l may c a u s e r a l i d wear' o f t h e n o z z l e s o f
A s p i l l w a y i s n e c e s s a r yi nc a s e
t o o much water i s
t h eg i a n t s .
turnedintothepipe-line.
a n g pipe--%.
"Pipe-Lines are l a i d by beginning a t t h e
bottonandworkingupwards.Sharpcurves
a r e avoidedwherever
possible, and where used
the p i p e m u s t b e a n c h o r e d s e c u r e l y t o
p r e v e n t t h e t h r u s t of t h e water p r e s s u r e f r o m p u l l i n g t h e j o i n t s
a p a r t . Curves i n a v e r t i c a l pla.ne a r e e s p e c i a l l yu n d e s i r a b l e a s
t h e y may c a u s ea i rp o c k e t si n
th.e p i p e . The pipeshouldbe
-__
Ens. and Min. Journ.,Vol.'131,1931,p.161.
-
25
-
,
f i l l e dg r a d u a l l y - f o rt h e
a t r e s t l e s h o u l d be?milt
thecompletedistince.
.
.
same r e a s o n .I nc r o s s i n gs m a l lr a v i n e s
f i r s t and t h e p i p e l a i d
on plank for
" I n l a y i n g new p i p e w i t h s l i p j o i n t s t h e o u t s i d e p i p e
is
s t a r t e do v e rt h e
end of t h e o t h e r , u s i n g c h i s e l - e d g e d p i p e t o o l s .
The upperpipe
is d r i v e n home byhammering on a blockof wood
placed a t t h e upperend.dherethepipehasbeenbatteredfrom
previoushandlinE,wettedburlap
o r sacking may bewrappedaround
t h ej o i n tb e f o r ed r i v i n g .I f
1eak.s developthey may bestopped
o r by d r i v i n g i n
b ys h o v e l l i n gs a w d u s ti n t ot h ep r e s s u r eb o x ,
t h i n wooden wedges;sometimesanoutside
band i s r e q u i r e d . "
Timbersshouldbeplaced
at fairly close intervals beneath
thepipe-linetokeep
it o f f t h e groundand t o g i v e it a f i r m
f o u n d a t i o n( s e eP l a t e
IV B ) .
Bll bends i nt h ep i p e - l i n ee i t h e r
firmly
l a t , e r a l or v e r t i c a l a s w e l l a s a l l g a t ev a l v e ss h o u l db e
anchored t o w i t h s t a n d t h e t h r u s t
of t h e w a t e r by beingloaded
w i t h r o c k or firmly braced against. stumps.
"Inplacingpipeswithflangedjointstheyarelaid
end t o
The f l a n g e s u s u a l l y
endand
t h e b o l t s p u t t h r o u g ha n dt i g h t e n e d .
a r ea t t a c h e dt ot h ep i p ea tt h ef a c t o r y .T h i sp r e v e n t sn e s t i n g
of t h e p i p e i n s h i p p i n g b u t p e r m i t s
a better joint to be
made.
.
,
high o r when t h e p i p e h a s v e r t i c a l
"When p r e s s u r e s a r e v e r y
o r l a t e r a l ' c u r v e s ,l u g ss h o u l d
b e r i v e t e d on t h e e n d s of t h e
two
pipes wired together after the
s
l
i
p
j
o
i
n
t
s
and'
the
pipe with
connection is made t o p r e v e n t t h ej o i n tp u l l i n go u t .S i m i l a r
l u gcs a b
n ue s e fdoar n c h o r i n tgh lei . n e
t o stumps o r p o s t s .
" I ns t r a i g h tp i p e - l i n e se x p a n s i o nj o i n t ss h o u l db ep l a c e d
a t i n t e r v a l s of100 t o 2 , 0 0 0f e e t ;d e p e n d i n g
upon t h e c o n d i t i o n s
t o bemet.
Where p i p e - l i n e sh a v el a t e r a lc u r v e se x p a n s i o nj o i n t s
a r en o tn e e d e d ,a st h ee x p a n s ' i o n
o r c o n t r a c t i o n of t h e p i p e is
takenup
i n t h ec u r v e ds 6 c t i o n s .
A long,emptypipe-line
may
c o n t r a c t s e v e r a l f e e t between a warm day and a c o l d n i g h t , and
u n l e s s p r o v i s i o n i s made f o r t h i s c o n t r a c t i o n t h e p i p e will p u l l
a p a r t . When t h e p i p e s a r e k e p t f u l l
o fw a t e rt h i sc o n t r a c t i o n
d o e sn o to c c u r .P i p e - l i n e sa r eb u r i e di n
some l o c a t i o n sb u t
seldom a t w e s t e r n p l a c e r m i n e s . "
In filling a pipe-lineforthefirst'time
c a r e shouldbe
,takennottoadnitthewatertoofastotherwiseshockfrom
c l u d e da i r o r c o n t r a c t i o n may c a u s es e v e r e damage. New pipel i n e s , when f i r s t p u t i n u s e , o f t e n
show numerous s m a l ll e a k s ;
t h e s ec a no f t e n
bestopped
by f e e d i n g i n small q u a n t i t i e s of
sawdust a t t h e i n t a k e .
in-
-
26
-
P l a t e I11 A. A b a f f l e box t o check t hw
e a t evr e l o c i t aytthP
e late
bottom of s e c t ioofn
flume
having
a steep
grade.
____~-~""______
'
111 B. A s e c t i o n of 24-inch
pipe-line
leading
from t h e
penstockat Cariboo
Cottonwood
Placers
Ltd.
This
is a
well-laidpipe-line;notice
the supportingcribbing
f o r the pipe and the bracing at the change
in
&'.d"rO""r".
~
P l a t e I V A. The pressure box a t t h eB u l l i o n Mine.
o u t l e t p i p e is 54 inches i n diameter.
The
P l a t e IV E. P a r t of t h e main 30-inch section of the
Bullion pipe-line showing the foundation supports.
"The c o s t of l a y i n g p i p e - l i l e s ' d e p e n d s
upon t h e s i z e , o f t h e
p i p ea n dt h et o p o g r a p h ya n dc o v e ro ft h ec o u n t r y .
Ten men worki n g 90 d a y s l a i d 5 , 0 0 0
f e e t of36t o 16-inchpipe a t t h e Browningmine,Leland,Oregon,
i n o p e nc o u n t r yi nt h es p r i n go f1 9 3 2 .
Flowofwaterthroughpipes.
"The q u a n t i t y of w a t e r t h a t
will f l o w t h r o u z h y p i p e - l i n e a t a p
mainly
- lac
. e r minedepend:;
upon t h e d i a m e t e r of t h . e p i p e , t h e e f f e c t i v e h y d r a u l i c h e a d , - a n d
t h e s i z e of t h e n o z z l e u s e d o n t h e g i a n t a t t h e end of t h e p i p e .
i s of such s i z e t h a t t h e p i p e will c a r r y
Generallythenozzleused
t h ea v a i l a b l ew a t e r .
As t h ew a t e rs u p p l y
i s reduced;smallernozz l e s a r e u s e d on t h e g i a n t s .
I
"
"The e f f e c t i v e headon a pi.pe i s t h e s t a t i c headminus t h e
The l o s so fh e a dd e p e d su p o n
(1)
l o s s of headdue t o f r i c t i o n .
t h ev e l o c i t yo ft h e , w a t e r ,
( 2 ) t h er o u g h n e s so ft h ei a t e r i o r
of
( 3 ) t h ed i a m e t e r
of t h ep i p e ,a n d
( 4 ) t h el e n g t h .
The
t h ep i p e ,
p r e s s u r ea v a i l a b l ea n dt h e
anourit of flow a t t h e end 'of a longpipe
d e p e n d sr m i n l yo nt h el a s tt h r e e
items. The p r e s s u r e ,o ft h e
water
i n t h ep i p eh a s
no e f f e c t , by i t s e l f , on t h e l o s s of :nead. Formul a s have been derived
f o r calcul.atingthelossofhead
i n which,
c o e f f i c i e n t 3 of roughness are used.Thesecoefficientshavebeen
d e r i v e d by e x p e r i m e n t f o r d i f f e r e n t t y p e s
of p i p e s ; e s p e c i a l l y ,
how,ever, c o n s i d e r a t i o n m u s t b e g i v e n t o t h e s e r v i c e c o n d i t i o n s
encountered. No s t a n d a r d of r o u g h n e s se x i s t s ,a n dt h sd e g r e e
of
roughness of t h e i n t e r i o r of a p i p e d o e s n o t r e m a i n c a n s t a n t . .
Usually a p i p e i s c h o s e n a b o u t % O p e r , c e n t l a r g e r t h a n
would be
i n d i c a t e d if t h e r e w e r e no l o s s due t o f r i c t i o n .
-Flow through
anunobstructedpipe-lineof.uniformdiametercanbe
calculated
The K u t t e rm o d i f i c a t i o no ft h e
Chezy
from a number offormulas.
formula a p p e a r s t o be p r e f e r r e d by h y d r a u l i ce c g i n e e r s .
The
Chezy formula Gay be s t a t e d a s :
v
=
The K u t t e r m o d i f i c a t i o n o f t h e
c,fi
Chezy f o r m u l a ' i s :
1.811 + 0.00281
41.66
n
s
"
n
1 + - = (41.6:;) + 0.00281
L/R
S
+
"
lJ=
where
a
V * mean v e l o c i t y of f l o w ,f e e tp e rs e c o n d
C = " c o e f f i c i e n t of r e t a r d a t i o n , " s o - c a l l e d
R = mean h y d r a u l i c r a d i u s of t h e p i p e , t h a t i s 1./4 t h e
diameter
S . = h y d r a u l i cg r a d e or s l o p e , i n f e e t p e r f o o t
of l e n g t h
of a p i p e of u n i f o r n s i z e
= $1c o e f f i c i e n t o f r o u g h n e s s "
-
27
-
Reprinted from United States Bureau of Mines Information Circular 6787.
-
28
-
"The va1u.e of I n ' f o r r i v e t e d l a p - j o i n t p i p e
up to and i n as 0.015. G r a p h i c a l soluc l u d i n g 318 i n c h . t h i c kc a nb et a k e n
t i o n s o f t h i s f o r m u l a a r e made c o n v e n i e n t l y by t h e u s e of a d i a gram s u c h a s t h a t shown i n F i g u r e 5 .
-S e l e c t i o n o f d i a m e t e r o f 7 i p e - l i n e
for a g i v e n f l o w of "-w a t e r
"The c h a r t shown i n F i g u r e 5 will a s s i s ti n ma1cir.g a c h o i c e
of t h e d i a m e t e r o f pipe t o b e u s e d i n any given l i n e . As a n e x ample, say that 320miner'.sinches
or 8 c u b i c f e e t per second o f
water i s a v a i l a b l e u n d e r a 100 f o o t h e a d , a n d t h e p i p e - l i n e
is to
b e1 , 2 0 0f e e tl o n g
The u s e o f t h r e e s i z e s i s , p r e f e r a b l eb e c a u s e
o f s a v i n gt ob e
made i n f r e i g h t on t h ep i p e .
To s o l v e , s t a r t a t
t h eb o t t o m of t h e c h a r t on l i n e 8 andfollow i t up t o where it i n t e r s e c t sd i a g o n a ll i n e sr e p r e s e n t i n gd i , f f e r e n td i a m e t e r s
of p i p e . By
followingthehorizontallinesfromtheseintersectionstotheleft
marginthefriction-head
.loss m a y , b e n o t e d f o r e a c h d i a m e t e r o f
p i p e .W i t h .1 2 - i n c hp i p et h i s
l o s s i s 8 0 f e e t p e r 1000 f e e t of
length,which rvoui.d i n z l i c a t e t h a t l i t t l e ,
.if a n y , p i p e o f t h i s d i a m e t e rs h o u l db eu s e di nt h es u p p l yl i n e . ,
The l o s sw i t h1 4 - i n c h
of l i n e . If 400 f e e t o f t h i s d i p i p e i s 33 f e e tp e r1 0 0 0f e e t
ameterpipewereused
in the line the loss of
head would be 1 3
f e e t . With15-inchpipe
t h e loss per1000 f e e t wouldbe23
feet,
and with 16-inch pipe
16 feet
The l o s s e sf o r4 0 0f e e t
of t h e s e
two s i z e s wouldbe 9 and 6 f e e t ,r e s p e c t i v e l y .
With H - i n c hp i p e
t h e l o s s wouldbe E f e e t per1000 or 3 f e e t f o r each 4130 f e e t .
The t o t a l l o s s o f headwith400feeteachof
14-, 16-':1nd 18i n c hp i p e wouldbe
22 f e e t . The e f f e c t i . v eh e a d ,t h e r e . r o r e ,
would
i)y u s i n s a l l 18-inch
beabout 78 p e i c e n t of t h e a c t u a l h e a d .
10 f e e t . If t h e g r a i e l i s e a s y
p i p et h et o t a ll o s s
wouldbeonly
t o c u t and neednot be swept l o n g d i s t a n c e s a 22-footheadloss
:nay n o t be s e r i o u s . I n l i g h t g r a v e l , however i t p r o b a b l y . s h o u l d
be econolmical t o use just t h e 16- and 1 8 - i n c hd i a m e t e r s ,
o r poss i b l y t o c o n s t r u c t t h e whole l i n e o f . l D - i n c h .
If t h e t o t a l a v a i l - .
a b l e head were 200 f e e t , t h e smaller p i p e s probably would prove
as
s a t i s f a c t o r y , a s t h e p e r c e n t a g e , o f l o s s would o n l y beonehalf
nuch a s w i t h a 1 0 0 - f o o th e a d .
'
" T h e r e f o r e ,l a r g e r - d i a m e t e rp i p e
i s needed f o r l o n g l i n e s
t h a n f o r s h o r t ones because t h e l o s s o f head i s direct1.y proport i o n a l t o t h e l e n g t h of t h e l i n e s . Zoreover, wherethe l o s s of
head i s i m p o r t a n tr e l a t i v e l yl a r g e rp i p e
mustbeused.
If t h e
wa.terwould
p i p e i s d e n t e d ,r u s t e d or p o o r l y l a i d , p o s s i b l y l e s s
flowthrough a g i v e n. p i p et h a n
i s shown on t h e c h a r t .
I n new
straightpipeprobablytheflow
would be more t h a n i s i n d i c a t e d
on t h e c h a r t a s ' it hasbeendrawn
t o coveraverageconditions.
- 29 -
Giants
"A g i a n t or monitor is a machine with a n o z z l e . f o r d i r e c t i n g
The
and c o n t r o l l i n g a s t r e a m o f waterunder a hydraulic.head.
monitor can swing horizontally through
a f u l l c i r c l e and from
about 10 degreesbelow t o 5 0d e g r e e sa b o v et h eh o r i z o n t a l .
ii
s t a n d a r dm o n i t o r i s shown i n P l a t e V " The
box
o f s t o n e s i s used
t o c o u n t e r b a l a n c et h ew e i g h t
of t h e d i s c h a r g eb a r r e l .
A monitor
a log
g e n e r a l l y i s s e t up i n a h y d r a u l i c p i t b y b e i n g b o l t e d t o
PTozzles of d i f f e r e n t
or t o t i m b e r s securej.y anchored inbedrock.
diameterscan
beusedup
t o t h e d i a v e t e r of t h e o u t l e t o f t h e
of w a t e r
g i a n t t o make ,allowances f o r v a r i a t i , q n I n t h e q u a n t i t y
u s e d , The m o n i t o ra n dn o z z i e sa r ec o n s t r u c t e dw i t hs t r a i g h tv a n e s
s o t h a t a r o t a r y m o t i o n of t h e j e t i s preinthedischargebarrel
i,s discharged in a s o l i d column. Xonitors
v e n t e d , . a n dt h ew a t e r
a r e made f o r a widerange of s e r v i c e i n s i z e s numbered 0 t o 9
i n c l u s i v e . "P r o b a b l yt h el a r g e s tm o n i t o r
made,? number S-12, i s
i n use a t t h e a u l l i o n > l i n e , B.. c,, i t s l a r g e s t n o z z l e i s 1 2 3/4
inchesindiameterandthetotalweight
of the machine i s 3200
pounds.
~
"Withheads
of 100 f e e t o r more d e f l e c t o r s a r e u s e d F o r
p o i n t i n gt h el a r g e r
g i a n t s . k convnon t y p e of d e f l e c t o r c o n s i s t s
t hne o z z l e .
of a s h o r t s e c t i o n of pipe t h a t p r o j e c t s o v e r
It
turns on a gimbal. ~ ~ i and
n t 1s c o n t r o l l e d by a l e v e r . h s t h e
of t h e s t r e a m t u r n s
deflector i s turne,dagainsttheJettheforce
the monitor in. the opposite dir'ectlon.
and d e f l e c t o r s
"Table 4 shows t h e s i z e s a n d w e i g h t s , o f g i a n t s
companJ.es rnake s m i l a r eqdipment.
made by one m a n u f a c t u r e r ;o t h e r
Sizes and w e i s h t s o f doubie-,]olnted,ball-bearing
Table 4 .
moni-
t o r s and d e f l e c t o r s
"
i5onitors
"_
Diameter o f
pi n
i pbl ew
uttisttsh
inches
S i z e No.
,
,
0
.5
1
2
3
4
5
6
'7
7
9
11
11
13
15
8
9
Diameter o f
3
4
5
s
7
8
9
10
15
i8
18
io
l.i
-
30 -
i
Shipping
i"!
eight
nozzie
detached
inches
Deflectors
'
pounds
350
390
520
890
1075
1475
1850
2?00
I
2300
2450
-
Weight
pounds
Xone r e q u i r e d
30
40
45
55
70
75
80
80
90
0
Adapted from t a b l e i n C a t a l o g u e of Joshua fiendy I r o n Works,
San Francisco, C a l i f .
3ffectivefiead
2.2
1 7 34 . 31 2 03 . 0
2.7
4 .7
"
23.8
19.3 6 540
770
13.9
333
200
343
6.5
23.7770
560
15.7
125
245
11.9
7.1
12.2
12.6
477
283
488
5 04
1100
'
950
570
790
27.5"
960
27.9
19.7
13.5
780
6
7
"
.
8
8
8
55:3 1800
9
9
3.1
5.7
10.3
395
109
__
5.3
1510 37.7 1330 33.2 1070 26.7
24.5 800 20.0 570
7
3 3 '760
.3 io80 26.9
.- 1 9 . 0
19.2
770
1350
2 7 . 233.8
7
'1010 25.2
__
35.3
45.09 1280 32.0
1 0 55.3157039.3
1090
1410
2210
1120
2 4 - . 7
43.7
'
1750
68.2
98 0 1130 28.3
1330
1520
63.7
78.7
3140
'
2210
2730
S i z e sl a r g e rt h a n
a r ee q u i p p e d , w i t h
o r moreheavylugs
,\To. 3 a r e s u b s t a n t i a l l y c o n s t r u c t e d
and u s u a l l y
a b a l l - b e a r i n gk i n g b o l t :
For heads of 400 f e e t
maybe
used a t t h e j o i n t s a s
a safetyprecaution.
Dischargethroughnozzles.."Table
5. g i v e s t h e d i s c h a r g e
__
from 100t,o 400
t h r o u g h d i f f e r e n t s i z e s of nozzlesunderheads
f e e t . I n t h i s t a b l e 40 m i n e r s 'i n c h e s
i s c o n s i d e r e da s 1 cubic
footpersecond.
The t h e o r e t i c a lf l o w ' o fw a t e r - t h r o u g hn o z z l e s
5 by a b o u t1 0 p e r . c e n t ;. a l l o w a n c e s
e x c e e d st h ef i g u r e si nT a b l e
havebeen made for f r i c t i o n l o s s e s .
The f l o w t h r o u g hn o z z l e sn o t
be c a l c u h t e d f r o m
shown i n t h e t a b l e or for d i f f e r e n t h e a d s c a n
t h ee q u a t i o n :
where
Q
A
h
C
c u b i cf e e t
of waterpersecond
a r e ao fn o z z l ei ns q u a r ef e e t
= e f f e c t i v e head a t n o z z l e i f e e t j
= c o e f f i c i e n t o f d i s c h a r g er a n g i n g
f r o m 0.8 t o 0 . 9 4 ( u s u a l l y t a k e n
a s 0 . 9 which makes a l l o w a n c e f o r
friction).
=
=
To c o n v e r t c u b i c f e e t t o g a l l o n s m u l t i p l y
by 7 . 4 8 .
HydraulicElevators
" H y d r a u l i ce l e v a t o r sa r eu s e dt or a i s e . g r a v e 1 ,s a n da n dw a t e r
The ground t o be worked
out of p l a c e rp i t si n t os l u i c e - b o x e s .
should be relatively free from big boulders and tree sturnps,.as
t h e s en o to n l yh i n d e rw o r k ,b u tr n a y . r e q u i r eb l a s t i n ga n db r e a k i n g
up which. adds t o t h e c o s t of o p e r a t i o n . An e l e v a t o r c o n s i s t s of
a p i p e w i t h a c o n s t r i c t e d p o r t or t h r o a t a n d a j e t whichprovides
a h i g h - v e l o c i t ya s c e n d i n g
column of w a t e r . The r e l a t i v ed i a m e t e r
ofpipe,throatandjet
must be p r o p o r t i o n e da c c o r d i n gt ot h ec o n d i t i o n su n d e rw h i c ht h ee l e v a t o r
i s used. A s e c t i o n of a ne l e v a t o r
i s shown i nF i g u r e 6 l . The e l e v a t o r may a l s ob eu s e da s
a water
' l i f t e r .
"The h e i g h t t o w h i c h g r a v e l c a n b e l i f t e d
i s o n e - t e n t h to.
one-fourth of t h e e f f e c t i v e head of t h e p r e s s u r e water a t t h e
nozzle af t h e e l e v a t o
Urs. u a l l y
t h e l i f t will be a b o u t o n e - f i f t h
i t i s found t h a t t h e maximurn h e i g h t o f , l i f t
t h eh e a d ,i np r a c t i c e
i s a b o u t 1 7 p e r c e n t of t h e e f f e c t i v e head a t t h e n o z z l e of t h e
elevator.
"Thevolume o f g r a v e l t h a t c a n
be h a n d l e d ' b y .an e l e v a t o r
depends primarily upon t h e head and volume o f p r e s s u r e w a t e r
After Joshua
Hendy Iron Norks c a t a l o g u e .
,
,
-
32, -
... . .
.
Manna-
Reprinted from United States Bureau of Mines Information Circular 6787.
-
33
-
a v a i l a b l e a n d t o a l e s s e r e x t e t i t upon t h e q u a n t i t y of o t h e r w a t e r
t h a th a st o
be r a i s e d by t h e e l e v a t o r .
The s o i i d s i n t h e w a t e r
u s u a l l y a r e 1 . 7 t o 2 . 5 percentandnot
more t h a n 5 percent of
the total weight
of waterandgravelcombined.
"Where l i t t l e dra.inagewaterhas
t o behandledandothercond i t i o n s a r e f a v o r a b l e ;t h e
the water delivered t o
proportionof
t h e e l e v a t o r and t h e g i a n t , r e s p e c t i v e l y , should be a b o u te q u a l ,
p r o v i d e dt h ep r e s s u r e
is, t h e same inEoth.Usually,however,
abouttwiceas
much water or a correspondinglyhigherhead
is reThe d i s c h a r g e of t h ee l e v a t o rs h o u l d
be
q u i r e d for t h ee l e v a t o r .
highenough t o p r o v i d e dumping ground,otherwise a g i a n t may be ,
needed t o s t a c kt h et a i l i n g s .h h e r ep l e n t yo f ' w a t e r
i s available
a compound or s t e p - l i f t e l e v a t o r may be i n s t a i l e d i n whichonethirdof.thepressurewater
i s usedinthe
f i r s t l i f t andtwothirdsinthesecond,with
a c o r r e s p o n d i n g l yl a r g e ra r e a
ofupr a i s ep i p e .
Thus t h eh e i g h t of t h e l i f t may b en e a r l yd o u b l e d .
is, thedischArge ofone
Double l i f t s sometimes a r e u s e d ; t h a t
e l e v a t o rg o e s t o t h e i n t a k e of a n o t h e r . "
The mouth of t h e e l e v a t o r i s p l a c e d i n
a sump. e x c a v a t e d i n
square by 5 f e e t deepand i n t o
bedrockwhichshouldhe10feet
i s washedby
t h eg i a n t s .
I t i s b e t t e rp r a c t i c e
t h i st h eg r a v e l
t o feedthematerialdirectlyintotheintake
of t h e e l e v a t o r , a s
thisreducesthesuction
head,.whichshould
be k e p t a s low a s poss i b l e . To p r e v e n tt h et h r o a t
,of t h e e l e v a t o r becomingchokedand
it i s n e c e s s a r y t o p l a c e a g r i z z l y
clogged w i t h l a r g eb o u l d e r s ,
o v e r , t h e endof
t h e s l u i c e which d e l i v e r s t h e m a t e r i a l t o t h e i n t a k e .T h eg r i z z l yb a r ss h o u l d
be spacedwithopenings
atleast
1 inchlessthanthe,diameter
o f th.e t h r o a t . .
"The e l e v a t o r d i s c h a r g e s upon a c o v e r p l a t e t o t a k e t h e
a s l u i c e . Boxes may or may n o tb eu s e di n
wear i n t h e headof
i s l i m i t e d by t h e s i z e
t h ep i t .
The s i z e of t h eg r a v e lh a n d l e d
of t h et h r o . a t o f t h ee l e v a t o r .G r i z z l i e sg e n e r a l l ya r eu s e da t
t h e c a p a c i t y of t h ee l e v a t o r .
t h ei n t a k e .C o a r s em a t e r i a lr e d u c e s
"Inclayeyground
a h y d r a u l i ce l e v a t o rt e n d s
c l a y a s i't g o e s t h r o u g h t h e e l e v a t o r , t h u s p e r m i t t i n g
e x ~ t r a c t i o nof t h e g o l d .
t o break up t h e
a higher
" G r a v e lp u n p sh a v eb e e nu s e ds u c c e s s f u l l yi na l l u v i a lt i n
minesand
i n one p l a c e r mine i n B r i t i s h Columbia'.. A8 f a r a s
known t h e y h a v e n o t b e e n u s e d s u c c e s s f u l l y
i n placermining i n
the western States.
Operatiqns of B . Boe on CedarCreek,QuesnelDistrict:
Ann.
R e p t .o ft h eH i n i s t e ro f
Mines of B r i t i s h Columbia,1932,
p. A-112.
-
34
-
P l a t e Y A . A No. 1 g i a n t a t a smalloperation.Thismonitwhas
no d e f l e c t o r , t h e w e i g h t
of t h e d i s c h a r g e b a r r e l i s aounterbalanced by t h e jookey-box, a t t h e r i g h t , weighted
with rooks.
p l a t e Y B. A l a r g e , No. 7. g i a n t and B NO. 4 machine in t h e
NO. 1 p i t of Germansen Ventures Ltd. The l a r g e machine
has a 9-inch nozzle. Notice the
man r i d i n g t h e d i s c h a r g e b a r r e l and t h e heavyload of Took i n t h e
jockey-box.
Plate VI A.
Two giants at work sweeping gravel in a
hydraulic pit.
Plate VI E. A hydraulic pit with one giant feeding gravel to B
short length of sluioe-boxes and a second monitor stacking
t h e ooarae gravel at the end of the boxes.
Sandand
water llui off through a sluiae-flume to theright.
&draulic
Mining P r a c t i c e s
Duty of Water
"The d u t y of a m i n e r ' s i n c h of w a t e r i n h y d r a u l i o k i n g
is
d e f i n e da st h e
number of cubicyardsofgravelwhich
it canbreak
down a n ds e n dt h r o u g ht h es l u i c ei n
24 hours. The f a - t o r s a f f e o t ingthisdutyare
s o v a r i e d t h a t it canbecompared
directly at
Yew mines, An averageduty of a m i n e r ' si n c hc a n n o t
'be c a l c u l a t e d
f o r t h e same r e a s o n . The duty of w a t e ra p p e a r st o
be h i g h e s ti n
or c e m e n t e dg r a v e li s , d i f f i c u l tt o
l a r g e - s c a l eo p e r a t i o n s .T i g h t
break down; a high bank t a k e s less pressurewaterpercubicyard
of
t h a n a low one; a f i a t b e d r o c k r e q u i r e s a n e x c e s s i v e ' q u a n t i t y
w a t e rf o rs w e e p i n g ;a n g u l a rr o c ka n dg r a v e lw i t hf l a to rl a r g e
b o u l d e r s r e q u i r e s morewater t o move it thandoessma:Ll-size,
roundedmaterial;clay-boundgravelsrequireexcessiv'awashing
to
freethegold;
a h i g hw a t e rp r e s s u r ei s
more e f f e c t i - r e t h a n a low
o:f s l u i c e s
one f o r c u t t i n g or sweeping;andthegradeandsize
g o v e r nt h ed a i l yy a r d a g et h a t
Can bewashed throughthem.
The
c a l c u l a t e d d u t y of h a t e r a t t h e C a l i f o r n i a m i n e s o p e r a t i n g
in
1932 ranged f r o m 0.4 t o 4 . 3 cub1.c yardsperminer'si:nch.In
i s included.
t h e s e c a l c u l a t i o n s by-washwater
"Conditions a t t h e m i n e s r a n g e f r o m t h e m o s t d i f f i c u l t t o
atleastaverage.
Wimmlerl r e p o r t s a d u t y o f a s h i g h a s 1 0 c u b i c
i n c h a t some Alaskan.placer mines."
y a r d sp e rm i n e r ' s
AVGermansenVenturesLtd.,
Germansen Creek, B . IC. anaverage
was 4 0 . 8
duty f o r a l l water, i n c l u d i n g t h a t f o r c l e a n i n g b e d r o c k
of g r a v e ls l u i c e d .W h e r e a sa t
cubicyardsofwater2peryard
Bullion Mine ( u s i n ga b o u t 90 c u b i c f e e t of waterper:second)the
d u t yr a n g e df r o m8 . 3t o
35 cubic yards of water per yard of gravel.
There i s a c o n s i d e r a b l e d i f f e r e r c e b e t w e e n t h e d u t y
o f waterused
i np i p i n go v e r b u r d e n ,i np i p i n gp a y - g r a v e la n di nc l e a n i n gb e d rock,consequentlyanave'rageva.luecanseldombeusedexceptfor
anticipating within certain limits the yardage
of g r a v e l t h a t w i l l
be washed.
Piping
"After a mine i s openedup t h e g r a v e l bank i s u n d e r c u t by t h e
g i a n ta l l o w i n gt h eo v e r l y i n gm a t e r i a l
t o c a v ei n t ot h ep i t( s e e
some e x t e n t ; it i s
P l a t e VI11 B). The f a l l b r e a k s t h e g r a v e l t o
f u r t h e r r e d u c e d by beingplayedupon
by t h e s t r e a m , f r o m a g i a n t or
by by-wash w a t e r . As t h e g r a v e l i s b e i n g d i s i n t e g r a t e d it i s swept
Wimmler, Norman L., Placer-Mining 1"Iethods andCostsinAlaska;
B u l l . 259,BureauofMines,
1 9 2 7 , p. 139.
1 c u b i cy a r d
of waterequals
-
202 gal-lons.
35
-
by t h eg i a n tt o w a r dt h es l u i c e - b o x ,
Wbere t h e g r a v e l i s c l a y bound or c o n t a i n s lumps or s t r e a k s of c l a y , i t may bewashedback.
and f o r t h a c r o s s t h e p i t
bottomone or more t i m e s u n t i l f r e e from
t h ec l a y . "
If t h e g i a n t s a r e worked c l o s e t o t h e f o o t
of t h e b a n k s , c a r e
must be e x e r c i s e d t h a t a cave does not 'occur which might bury both
workersandgiants.
I t i s poor p r a c t i c e t o work i n t o a bank w i t h a "horse-shoe"
c u t , for t h i s means t h e g i a n t becomes surrounded on a l l s i d e s by
h i g hb a n k sw h i c hg r e a t l yi n c r e a s et h e
d-anger t o t h e o p e r a t i o n s .
The b e s t way is t o work a c r o s s t h e f a c e of t h e bank m a i n t a i n i n g a
'nose'of'graveiimmediatelyinfront
of t h eg i a n t sa n dw o r k i n g
and i i g h t of t h i s n o s e , b e with a s i d e c u t t i n g a c t i o n b o t h l e f t
causebythis
means t h e d i r e c t i o n ofany
s l i d e s wouldbe p a r a l l e l
t o t h e mainface of o p e r a t i o n , a n d n o t
t,oward t h e g i a n t .
It w i l l generally be'found that
a side cutting action w i l l
excavate a f a r l a r g e r amount o f g r a v e lp e r cubic' f c o t ' o f w a t e r
u s e d ,t h a n by d i r e c t i n g t h e w a t e r d i r e c t l y a t t h e bank.
No . g e n e r a l r u l e c a n
be g i v e n .for t h e a c t u a l l o c a t i o n of t h e
> g i a n t .T h i s w i l l depend e n t i r e l y upon t h ec o n d i t i o n se x i s t i n ga t ,
will v a r y f r o m t i m e t o t i m e a s t h e
work i,s c a r r i e d
themine,and
forward. The a c t u a l s e t t i n h of t h eg i a n t s , however, i s a m a t t e r
of considerable importance and they
must b e c a r e f u l l y a n d s e c u r e l y
braced t o preventaccidentswhich
may o c c u r c a u s i n g s e r i o u s
t r o u b l e and l o s s of time.
be l a i d so t h a t t h e r e
The l a s t l e n g t h of pipe-litieshouldnot
i s a s l i g h t upward t r e n db e c a u s et h e r e
w i l l bean upward l i f t i n g
a c t i n g on t h e g i a n t w h i c h w i l l make it e x t r e m e l y d i f f i c u l t t o h o l d
f i r m l yi np l a c e .
If t h e l a s t few l e n g t h s of p i p e - l i n ea r el a i d
on
some s l i g h t l y r a i s e d p a r t
o f bedrock, or on t i m b e r s , s o t h a t a t
of t h e p r e s s u r e of
thefinaland.termina1connectionthedirection
t h ew a t e ra n d
of the pipe-line has
a s l i g h t downward i n c l i n a t i o n ,
t h e r e w i l l be far f e w e r c h a n c e s t h a t t h e f o u n d a t i o n o f t h e g i a n t
w i l l move.
I t ' i s impossible t o c o n s t r u c t p e r x a n e n t f o u n d a t i o n s f o r
a
The headblockshould
g i a n t . a s it has t o b es h i f t e df r e q u e n t l y .
t o t h e s i z e of t h e g i a n t
be a heavysquaretimber,proportionate
in a t r e n c he x c a v a t e di nb e d r o c k
and from 8 t o 10 f e e t l o n g , l a i d
t o a d e p t h o f 1 2 i n c h e s or more. The g i a n t i s b o l t e d t o t h i s
timber, with the face
of t h e t i m b e r and t h e f a c e of t h e b a s e of t h e
g i a n t on a l i n e d i r e c t l y a t r i g h t a n g l e s t o t h e t h r u s t of t h e
water and t h e t e r m i n a l l e n g t h o f pipe.
-
36
-
P l a t e VI1 A. The No. 1 p i t a t Germansen VenturesLtd.,
Germansen
Creek, B.C.
The p i t is a b o u t1 5 0 0f e e tl o n g ,
150 f e e t d e e p
and about 200 f e e t w i d e a t t h e bottom. Bemuse of t h e
low bedrock grade, the sluice-boxee
are in B bedrock out about 25 feet deep
a t t h e wings of
t h e s l u i c e , in t h e f o r e g r o u n d .
P l a t e VI1 B. The B u l l i o n p i t , on t h e s o u t h fork of t h e Quemel
X i m r . T h i s p i t is a b o u t 8000 f e e t long,about 400 f e e t
deep, from 150 t o 250 f e e t w i d e a t t h e bottom,and
from 1000 t o 1500 f e e t wide a t t h e t o p .
...
Plate VI11 A.
Boulder-clay shaving the irregular assemblage of
boulders in a compacted clay matrix.
large
Plate VI11 E.
A cave at the head of a hydraulic pit showing the
masees into which the boulder-clay breaks.
Insonecasesthe
headb1oc:kmust besecured t o tledrockby
c a b l e s t o e y e b o l t sd r i v e ni n t o
'holes drilledinbedrcokto
a sufThe whole t i m f i c i e n t d e p t h t o h o l dt h et i m b e rf i r m l yi np l a c e .
ber base should' then be heavily weighed
t o eliminate vibration.'
"A s m a l l e r - d i a m e t e r n o z z l e g e n e r a l l y
i s used for c u t t i n &
t h a n for sweeping. Bs anexample,
a q u a n t i t y of g r a v e l may be
brought down w i t h a g i a n t w i t h a 4 lj/Z-inchnozzle.
Then t h e
water w i l l be shut off
and a 5-inchnozzle p u t on t h e g i a n t f o r
d r i v i n gt h eg r a v e l
t o t h e s l u i c e , or a s e p a r a t e g i a n t w i t h
a 5t w o or more g i a n t s a r e s e t up
inchnozzlecanbe'used.Usually
i n a p i t even when only enoughwater i s a v a i l a b l e t o runone a t
a t i m e . One l a r g e g i a n t will do morework
t h a n two smallones
of w a t e r . The g i a n t s a r e p l a c e d a t t h e
u s i n gt h es a n eq u a n t i t y
most s t r a t e g i c p o i n t s b o t h t o c u t t h e
bankandwash.i;hegravel
t o t h es l u i c e - b o x .
!.ihere t w o g i a n t s a r e used a t a timeone may
beused
f o r c u t t i n g and t h eo t h e rf o rs w e e p i n g .
The c u t t i n g
g i a n t i s s e t on a na n g l e t o t h e f a c e .
A t t h e o l d La Grangemine
for both
t h e s t r e a m s f r o m two 9-inch nozzles were used together
cuttingandsweeping.Giants
may be s e t up a t t h e lowerendof
thesluice t o stack the coarse material
.
i nt h et a i l i n g s
where
i
s
n
o
t
s
u
f
f
i
c
i
e
n
t
f
o
r
it
t
o
be
disposed
o
f
n
a
t
u
r
a
l
l
y
.
t h eg r a d e
"Sometimes a p i t i s l a i d o u t s o t h a t a l l o f t h e g r a v e l washed
i s swept t o t h e head of t h es l u i c e .A f t e rt h ec l e a n p i t and s e t up
up t h e boxes are extended through the washed-out
for t h en e x ty e a r ' sw o r k .k to t h e rp l a c e st h eb o x e s
a r e extended'
upward a s room i s made.
i n oneseason
"When a p i t i s s t a r t e d a c u t i s t a k e n a c r o s s t h s channel,
i s advancedupstream.In
a f t e r which a d i a g o n a l o r squareface
widechannels o r b a r s t w o or more p a r a l l e l c u t s may 'be t a k e n .
One p i t may beworkedwhileboulders
are handled or .bedrock i s
cleaned i n t h e o t h e r .
A t t h e Ruby Creekmine
atAtlin,British
Columbia,thechannel
was 250 f e e t w i d e : two 125-footcutswere
made a n d worked a l t e r n a t e l y l . Wing
darns
of t i m b e r ,l o g s ,
qr
bouldersgenerallyarebuilttoguidethewater
andgravel
into
t h e head o f t h es l u i c e . "I fp o s s i b l e
a ground-sluicegradeof
8 t o 1 5 p e rc e n t i s d e s i r a b l e l e a d i n g i n t o t h e s l u i c e - b o x e s .
" O c c a s i o n a l l y t h e form of t h e d e p o s i t a n d t h e c o n t o u r o f t h e
i s washedover t h e s i d e of t h e
b e d r o c ka r es u c ht h a tt h eg r a v e l
boxes r a t h e rt h a ni n t ot h ee n d .
Then t h es l u i c e w a y is sunk i n t o
bedrock.
Lee, C.F., andDaulton,
T.M., The S o l u t i o n of S0rc.e Hydraulic
PiiningProblems onRuby
Creek, B. C . Trans. A m . I n s t . Tiin.and
Met. Eng. v a l 5
. 5,
1917, p . 90:
“ A t some minesoverburdencontaining
l i t t l e o r no go1.dmay
be
mined separately.This-systemhasanadvantage
when dump room a t
t h e end of t h e main s l u i c e i s l i m i t e d , a s t h e h i g h e r m a t e r i a l
may
be disposed of elsewhere. f i t one mine,. t h e Salmon R i v e r ,t h e
l i g h t t o p m a t e r i a l was s t r i p p e d a f t e r t h e w a t e r s u p p l y
was t o o low
for w o r k i n g t h e h e a v i e r g r a v e l s , b u t
was s t i l l s u f f i c i e n t t o supply
one g i a r i t . The u s u a lp r a c t i c e ,
however, i s t o mine t h e r u l l t h i c k n e s s o f g r a v e l a t onetime.
The admixture of t o ps o i l ,c l a ya n d
lightgravelwiththeheaviermaterialfromnearbedrock
may perm i t moving a l a r g e r p r o p o r t i o n of b o u l d e r s t o t h e s l u i c e t h a n
otherwise.
HandlingBoulders
“Where t h e s i z e and,grade o f s l u i c e s p e r m i t , a l l b o u l d e r s t h a t
canbe moved by t h e g i a n t a r e r u n t h r o u g h t h e b o x e s . k t
some o f
t h ee a r l y - d a yl a r g ep r o d u c e r sb o u l d e r sw e i g h i n g
3 or 4 tonswere
successfully put through the sluice.’
“ I n ground-sluicinganyboulder
t h a t canbewashed
i n t o the
s l u i c e by t h ew a t e ru s u a l l yg o e st h r o u g hw i t h o u tt r o u b l e .I nh y d r a u l i c k i n g ,h o w e v e r ,b o u l d e r st o ol a r g e , t or u nt h r o u g ht h es l u i c e
a h i g h head of w a t e r .
may beswept
i n t o it with a large giant using
Boulderstoolargeto
be movedby
t h e g i a n t or t o r u n t h r o u g h t h e
upon t h e nums l u i c e a r e h a n d l e d i h variousways,dependingmainly
of thebouldersencounteredandthemagnitude
of t h e
b e ra n ds i z e
operations.
“Insmall-Scaleoperationsboulders
may b e r o l l e d byhand t o
one s i d e or ontocleaned-up bedrock, or dragged away by teams.
Occasionally, a b o u l d e rt o o l a r g e t o h a n d l e may be l e f t s t a n d i n g
on t h e floor of t h e p i t and bedrockcleaneduparound
i t . The
usualcustom when t h ep r o p o r t i o n of boulders i s small,however,
i s t o breakthem upbymeans
o f hammers o r by b l a s t i n g a n d wash
t h ef r a g m e n t st h r o u g ht h es l u i c e . .I nt h el a r g e ro p e r a t i o n sw i t h
relatively shallow gravel,,the boulders
may be pulled from t h e
p i t by winches or moved by a d e r r i c k mounted on a t r a c t o r . A t
t h e Diamond C i t y mine a drag-linewithan
orange-peelbucket
handledboulders
e x i s t i n cgo n d i t i o n s .
A
very cheaply under the
r e l a t i v e l y narrow c u t was b e i n gr u n .
The d r a g - l i n ew a s . o p e r a t e d
on a benchabove t h e c u t a n d p i l e d t h e b o u l d e r s
on t h e bench
back of t h ed r a g - l i n e .
The most common method o f . h a n d l i n gb o u l d e r s ,
however, i s by means of a d e r r i c k ( s e e P l a t e
XI11 3 ) . The boulders
thatcanberolled
by hand a r e l o a d e d o n t o
a s l i n g or a s t o n e b o a t
MacDonald, i). P . , The Weaverville-Trinity.Center
T r i n i t yC o u n t y C
, alif.:
U . S. Geol.SurveyBull.
pp. 48-58.
,
- 38 -
Gold Gravels,
430, 1910,
and h o i s t e df r o mt h e
p i t . Largeones a r e h o i s t e d by means of
c h a i n s .k t
some mines few b o u l d e r st h a tc a nn o tb e
moved by t h e
of t h e s l u i c e
giantareencountered;derricksareusedatthehead
for removing t h o s e t o o l a r g et o go through. Stumps a r eh a n d l e di n
much t h e same manner as b o u l d e r s . "
In a r i t i s h Columbiawhere most h y d r a u l i c o p e r a t i o n s h a v e t o
of larg,e boulders
wash a good d e a l o f boulder-clay the handling
t a k e s up c o n s i d e r a b l eo p e r a t i n gt i m e .
I t i s p a r t i c u l a r l yi m p o r t off
a n ti nl a r g eo p e r a t i o n sw h e r ee v e r yh o u rt h ew a t e ri st u r n e d
be
neans a c o n s i d e r a b l y smaller y a r d a g e s l u i c e d t h a t t h e b o u l d e r s
b l a s t e d qu.ick1.y. F o r t h i sp u r p o s e a compressed a i rc p e r a t e dj a c k
XIV A).
hammer is e s s e n t i a l for d r i l l i n g s h o r t h o l e s ( s e e P l a . t e
Dynamite i s much more e f f i c i e n t , andconsequentlyrockbreaki n gc o s t sa r el o w e r ,
i f it i s u s e d i n t h i s
way r a t h e r t h a n for
bnlldozing.Bulldozing
however i nt h es m a l l e ro p e r a t i o n s
i s common p r a c t i c e and f o r t h i s purpose60percentdynamite
i s found
more e f f e c t i v e t h a n 40 p e r . o e n t .
CleaningBedrock
"Bedrock u s u a l l y i s cleaned by p i p i n g . A s much a s 2 f e e t or
more of bedrock may b e c u t by t h e g i a n t and t h e m a t e r i a l washed
t h r o u g ht h es l u i c e .O c c a s i o n a l l y
a f i r e hosewith a smallnozzle
may beused for t h ep u r p o s e .
When t h e bedrock i s hardandoonit mustbecleaned
by hand. The crevicesand
t a i n sc r e v i c e s ,
s o f t seams a r e dugout bymeans
o f picksandshovels,brooms,
s m a l l s t i f f brushes andsmall f l a t t o o l s made for t h ep u r p o s e
from s t r a p i r o n or w i r e ( s e e P l a t e
XVI A ) .
-
39
-
COST OF BBDRAULICKING
The c o s t ofhydraulickingdepends
on a number of f a c t o r s of
which t h e mostimportant
i st h ed u t yo f ' t h ew a t e r .T h i s
i s cont r o l l e d by t h e v o l u m e , t h e h e a d , t h e c h a r a c t e r
and amount of
materialbeingsluiced,theheight
of t h e bankand t h e s i z e and
grade of t h es l u i c e - - b o x e s .
The l o w e s tp o s s i b l ec o s t sa ta n yo p e r a t i o n w i l l be reached by a t t a i n i n gt h eg r e a t e s tw a t e rd u t y .
It is
impossibletofinddirectlycomparableconditions
a t any t w o mines,
c o n s e q u e n t l yc o s t sa r el a r g e l yg o v e r n e d
by l o c a lc o n d i t i o n s .
For
example t h e o p e r a t i n g . c o s t s a t 2 8 h y d r a u l i cm i n e si nC a l i f o r n i a ,
s l u i c i n g f r o m 3,500 t o 719,000yardsperseason,rangedfrom
2 , 6 3 t o 37.5 c e n t sp e rc u b i cy a r d .T h e s e
do n o t r e p r e s e n t t o t a l
c o s t s ina.smuch a s it was n o t p o s s i b l e t o a s s e s s d e p r e c i a t i o n or
a m o r t i z a t i o nc h a r g e s .
In h l a s k a t h e a v e r a g e c o s t p e r c u b i c y a r d
i s s t a t e d . b y P u r i n g t o n l t o be 23.8 c e n t s .
o f 1 3o p e r a t i o n s
I n t h e Yukon, h y d r a u l i c s t r i p p i n g o p e r a t i o n s
of the.Yukon
Consolidated G o l d C o r p o r a t i o n 2 a r e r e c k o n e d a t
6 centsperyard:
s l u i c i n g would bemore c o s t l y b e c a u s e t h e a v e r a g e
water d u t y
would beless:
so greatly from those
g r e a t e r number of
b o u l d e r s t o be handledand
t h e e v e r - p r e s e n t , tough boulder-clay
t h a t a comparisonofcostscannotbe
made.Bowever,
i nt h ea b it i s probably
sence o f d e t a i l e d c o s t f i g u r e s whichcanbequoted,
Columbia,few,
i f , a n y ,o p e r a t i o n s
safe t o s a yt h a ti nB r i t i s h
c o u l d p r o f i t a b l y work m a t e r i a l a v e r a g i n g 8 c e n t s o r l e s s p e r y a r d
and t h a t f o r most, a t l e a s t 1 2 t o 15 c e n t s or more peryardwould
be n e c e s s a r y t o s u s t a i n a p r o f i t a b l e undertaking.
In British Colunbia'conditions differ
i n C a l i f o r n i a p a r t i c u l a r l y with r e g a r d t o t h e
of hydraulickThe p r i n c i p a l i t e m makingup t h e p e r u n i t c o s t
ing i s labourwhich i n some i n s t a n c e s may c o n s t i t u t e 75 percent
o f t h ec o s t .O t h e ri t e m sa r ew a t e r ,w h i c h
when l a r g ed i t c h and
flumesystems
a r e i n s t a l l e d may b ec o n s i d e r a b l e ;e x p l o s i v e s ,
whichdepend
l a r g e l y on t h e s i z e and number of bouldersencount e r e d and how t h e y a r e h a n d l e d ; s u p p l i e s a n d g e n e r a l . o f f i c e e x a s t h er e d u c t i o n . of costsdepends on
penses. However,inasmuch
sluicingthelargestpossible
amount of' m a t e r i a l , no e f f o r t
should be spared t o g e t a l l t h e w a t e r t h a t i s economically poss i b l e and t o u s e it with t h e g r e a t e s t 2 o s s i b l e e f f i c i e n c y .
Bulletin 253.
Trans., C . 1 . X . H .
U. 5. Geol.
Survey.,
p. 38.
v o l . XLII, 1939, p . 540.
-
40
-
<Clear. 1% 12"x 1T.x
1
a
1
.O
Scale, feet
.
A
lex 12"x 12' boards
4"x 6" sills, 4
' center to center
1
L . . "
0
1
e
3
4
5
Scale, feet
B
Figure 7.."Sluice-box construction: A , Twenty-inch box at Henderson mine, .
GoldCreek, Mont.; B, five-foot sluice box.
Reprinted from United States Bureau of Mines Information Circu1:w 6787.
-. 4 1
-
SLUICE BOXES
AND~
RIFFLES
" _ _
"The s l u i c e - b o x s e r v e s a doublepurpose
i n placer mining:
it c o l l e c t s t h e g o l d or o t h e r heavy minerals s o u g h t w i t h i n t h e
r i f f l e s of t h e s l u i c e andconveys t h e washed m a t e r i a l t o a
dumping ground. I t i s an e f f i c i e n tg o l ds a v e ra n d ' i su n i v e r s a l l y
used i nh y d r a u l i c k i n g and ground-sluicing.
The p r i n c i p l e of t h e
. r i f f l e d s l u i c e i s used for recoveringmost of t h e g o l d on dredges
o f placerminingwherethegravelsareexcaand i n otherforms
vated meohan-ically.
"Othertypesofgoldsavershavenotprovedgenerallysucas a n a u x i l i a r y , m e t h o d and
c e s s f u l i.n p l a c e rm i n i n g ,a l t h o u g h
u n d e rs p e c i a lc o n d i t i o n s
some of thesegold-savingdeviceshave
been found useful.
"Sluices are built
i n a c c o r d a n c e w i t h t h e s e r v i c e t o .bedemanded of them. R i f f l e s a r e of v a r i e d f o r m and a r e made of d i f ferent materials.
Althoughtheform
o f r i f f l e i s ,chosen l a r g e l y
t o f i t p a r t i c u l a rc o n d i t i o n s ,c u s t o mi nv a r i o u sd i s t r i c t sa n d
m a t e r i a l s a t handhave a b e a r i n g upon t h e p r a c t i c e s f o l l o w e d .
'
"The f o l l o w i n g d i s c u s s i o n h a s
a generalapplication
or method o f mining.
notconeinedtoanyregion
and i s
Sluice-Boxes
"
Construction
"Sluice-boxes a r e r e c t a n g u l a r i n s e c t i o n
a.nd a r e n e a r l y a l o r i r o ns l u i c e sa r eo c c a s i o n ways b u i y t of lumber a l t h o u g hs t e e l
ally used.
somewhat
"The c o n s t r u c t i o n o f a wooden siuice-boxdepends
upon t h e s i z e a n ds e r v i c ee x p e c t e d
of t h e box; a number o f t y p e s ,
however, may beused
s a t i s f a c t o r i l y . Common t y p e s of c o n s t r u c t i o n
f o rl a r g ea n ds m a l lb o x e sa r ei l . l u s t r a t e di nF i g u r e
7.
"The i m p o r t a n t f e a t u r e s i n d e s i g n a r e s t u r d i n e s s a n d s i m p l i c may have t o w i t h s t a n ds e v e r e
i t y of construction..Largeflumes
b a t t e r i n g and v i b r a t i o n f r o m t h e p a s s a g e
of heavyboulders,hence
t h e ym u s tb es t r o n g l yc o n s t r u c t e da n dw e l lb r a c e d .
I n small
i s l e s si m p o r t a n t ;b u tt h e
use of l i g h t e r
f l u m e st h i sf e a t u r e
lumber i n c r e a s e s t h e d i f f i c u l t i e s of maintenanceandprevention
of l e a k s .
"The bottom o f a narrowsluiceshould
be a s i n g l e p l a n k if
lumber of t h e d e s i r e d w i d t h
i s o b t a i n a b l e ; f o r widerboxes
t w o or
more bottomplanksmustbeused.
The b o t t o mJ o i n t s may be Amade
-
42
-.
,
t i g h t by t h e u s e of s o f t - p i n e s p l i n e s , by b a t t e n s t r i p s n a i l e d
on
t h e o u t s i d e , of by c a u l k i n gw i t h oakum or o t h e r mtejrial., Bowiel
as m o s t s u i t a b l e f o r t h e c o n s t r u c rocomendshalf-seasonedlumber
t i o n ofboxes.
'Where l o c a lt i n b e r i s used it i s common p r a c t i c e
t o c u t t h e p l a n k d u r i n g t h e d r y season or b e f o r e snow i s off t h e
ground. I t i s customary t ou s es u r f a c e d
lumber forboxes,inasmuch
a s a smoothbottom f a c i l i t a t e s t h e c l e a n - u p .
The lumbershouldbe
c l e a r and o f u n i f o r m s i z e .
"For a n yb u ts m a l l ,t e m p o r a r yi n s t a l l a t i o n st h es i d e s
of
s l u i c e - b o x e ss h o u l db el i n e dw i t h
a w e a r i n g s u r f a c e of roughlumber
or sheet i r o n .O t h e r w i s e
t h e e n t i r e boxmustbereptaced
when t h e
s i d e sa r e worn o u t . Board l i n i n g i s e a s i e r t o p l a c e
and r e p l a c e
t h a ns h e e ti r o n .
In e a r l y C a l i f o r n i a np r a c t i c e some of t h e s i d e
l i n i n g s w e r e made of wide, t h i r b l o c k s n a i l e d on s o as t o p r e s e n t
t h ee n d g r a i nt ot h e
wear. Norn. i r o n or s t e e l r i f f l e s a r eu s e d
f o r s i d e l i n i n g a t some p l a c e s .i J s u a l l yo n l yt h el o w e rh a l f
or
t h i r d of t h e s i d e o f t h e boxneeds t h i s p r o t e c t i o n , and a s i n g l e
2-iach board may s e r v e n o t . o n l y f o r
l i n i n g b u t as a c l e a t ,to
hold down t h er i f f l e s .F a l s eb o t t o m so fp l a n e d
o r roughboards
may be used t o s a v e wearon t h e box p r o p e r .
"Each'boxshould r e s t on t h r e e o r f o u r s i l l s , equal.1.y spaced.
The s i l l s a n du p r i g h t members a t t h e ends o f t h e box s e r v e a s b a t te.ns t o p r e v e n t l e a k a g e a t j o i n t s .
The p r a c t i c e of. t a p e r i n gt h e
boxenough t o p e r n i t a t e l e s c o p e j o i n t i s v e r y c o n v e n i e n t i n small
i f t h e boxesmustbe
moved o c c a s i o n a l l y .S m a l l ,
s l u i c e s ,e s p e c i a l l y
three-boardboxes
may b eb r a c e dw i t ht i e sa c r o s st h et o p ,a l t h o u g h
t h i s hampersshoveliagandclean-upoperations.Largerboxes
s h o u l db eb r a c e de x t e r n a l l yf r o mt h ee n d so ft h es i l l . s ,
8.s i l l u s t r a t e di nF i g u r e
7 , A and B . S i l l ss h o u l db ew e i g h t e dw i t hr o c k s
t o c h e c ka n yt i n d e n c yo ft h es l u i c et or i s e .
If t h e s l u i c e i s
p l a c e d i n a bedrock o r o t h e r c u t , water under it o r s.t t h e s i d e s
h a s a s t r o n gl i f t i n ge f ' f e c t .X o r e o v e r ,t h ev i b r a t i o nc a u s e d
by
t o be
bouldersrollingthroughthesluicepermitsfinegravel
washedunder t h e s i l l s placed on t h e g r o u n d .
-
"As m e n t i o n e d ,t h es i d el i n i n gp l a n k
may s e r v e a s a c l e a t
under which the
r i f f l e sectionscanbe
wedged t o t h e bottom o f
t h es l u i c e .O t h e r w i s e
some o t h e rp r o v i s i o nm u s t
be made a s t,he
r i f f l e s must be h e l ds e c u r e l y .I n
small boxes it i s customary
t ol a yl o n g ,n a r r o wb o a r d so ne d g e
on t o p o f t h e r i f f l e s and
a g a i n s tt h es i d e s
of t h es l u i c e .
These boards are' wedged down
t i g h t l y under c l e a t s n a i l e d p e r m a n e n t l y t o t h e sides o f t h e box.
The p r a c t i c e of n a i l i n g r i f f l e s t o t h e
bottomofthebox,
or
usinganydevicethat
r e q u i r e s d r i v i n g n a i l s i n t h e tmottom o r
Bowie,
X.
J . , Hydraulic Piini;ig i nC a l i f o r n i a :
New YorB, 3d e d . , l E E 9 , p. 220.
- 43 -
Van YostrandCo.,
sidesshouldbeavoided
as it r e s u l t s i n l e a k s
andeventually
damagesboth
s l u i c e and r i f f l e s . doadenblocksarethemost
d i f f i c u l t t o secureinplacebutcanbeheld
by t h e .method describedinthefollowingsection.
Haintenance
"Haintenance workon
s l u i c e - b o x e sc o l i s i s t sc h i e f l y
in align-.
ing and bringing
any
boxes
t
h
a
t
have
moved
out
t o grade
of p o s i t i o n ,
work a t
r e p l a c i n gl i n i n g s ,
a n dp l u g g i n gl e a k s .A t t e n t i o nt ot h i s
clean-uptime will be r e p a i d by g r e a t e r c a p a c i t y and freedomfrom
i s turnedintothe.sluice.
break-downs when t h e w a t e r a g a i n
Size
"As p r e v i o u s l y shown; s l u i c e boxesseldom a r e b u i l t less
t h a nl 0 , i n c h e sw i d e
f o r s t r i c t l ym i n i n gp u r p o s e s .E i g h t - i n c h
i n sampling o r cleaningup.
The quanboxes,however,
may beused
t i t y of w a t e r ,w i t h
i t s accompanyingload
of g r a v e l , t h a t w i l l run
through a s l u i c e of g i v e ns i z ed e p e n d s
upon a number o f f a c t o r s .
of about 75 hydraulicandgroundThe p r a c t i c e a t t h e m a j o r i t y
s l u i c e mines v i s i t e d i n t h e p r e p a r a t i o n
of t h i s p a p e r i n d i c a t e s
that the carrying capacities
of s l u i c e s of v a r i . o u s w i d t h s a r e w i t h i n t h e f o l l o w i n g limits:
Width
box
of
j.nches
..
inches
D.epth
%
Grade
Miner's
inches
of w a t e r
To
From
10
10-12
12-14
12
18
30.
5-7
4.16
6.2
65
24
36'
48 t o 60
3,000
These limits p r o b a b l y r e p r e s e n t
25
100
100
3 00
200
500
1,300
5 00
1,000
good p r a c t i c e .
"ifore t r o u b l e i s e x p e r i e n c e d f r o m c l o g g i n g o f b o x e s t h a t a r e
too.wide,becausethedepth
and v e l o c i t y o f w a t e r a r e i n s u f f i c i e n t , .
thanfromfailure
of boxes t o c a r r y t h e i r l o a d b e c a u s e t h e y a r e
toonarrow.
t o transportdifferent
"The c u r r e n t v e l o c i t i e s r e q u i r e d
s i z e s of m a t e r i a lh a v eb e e ns t u d i e d ;
works of v a r i o u s a u t h o r i t i e s
- 44.
-
.
a r e c i t e d by G i l b e r t 1
The f o l l o w i n gt a b l e i s b a s e dc h i e f l yo n
D u b u a t ' sf i g u r e sf o rc o m p e t e n tv e l o c i t y ;t h ef i g u r e s
are a d j u s t e d
t o approximate mean v e l o c i t yi n s t e a do f
bed v e l o c i t y . The l a s t
t h r e e f i g u r e s a r e taken from Van Wagenen2.
m aoSt fei zr iea l
moved
?lean v e l o c i t y
p e r second
a E x i m a tfee e t
"
Fine
0.5
Sand:
1.0
Coarse
1.5
2.5
Gravel:
Fine
1-inch
Egg s i z e
Boulders:
4.0
3- & 4 - i n c h
6 - & 8-inch
1 2 - & 18-inch
5.3
6.7
10.0
and
; I h e ~ f o l l . o w i n gt a b l ei l l u s t r a t e s t h e r e l a t i o n o f v e l o c i t y
g r a d e . The f i g u r e s a p p l y t o a s l u i c e 2 f e e t wideha.ving a flow 1
infeetpersewnd
and t h e
food
t eep.
The approximatevel.ooity
q u a n t i t yi n ' c u b i cf e e tp e rs e c o n da n d
miner'sinches are given for
v a r i o u sg r a d e s .
6%
__
6.5
13.0
p e r second
520
*h
gradeof 1%i s t h e e q u i v a l e n t
1 2 f o o t box.
of a b o u t 1 7,
"Ne11 roundedpebbles
a r e e a s i e r t o move t h a n a n g u l a r o n e s ,
and rock of
low s p e c i f i c g r a v i t y i s a p p r e c i a b l y easier' t o washthan
or basalt.
heavy,denserocksuchasgreenstone
-
"
d i l b e r t , G. JC., The TransportationofDebrisbyRunningWater:
U. S . Geol.Survey,Prof.Paper86,1914,p.216.
'
Van Wagenen, J . F. Manual of HydraulicHining:
C o . , New Yorlc, 1880, p . 8 8 .
-
45
-
V8.n Nostrand
old
has a b e t t e r o p p o r t u n i t y t o s e t t l e acd be c a u g h t i n
r i f f l e s i n a w l d e ,s n a i l o ws t r e a mt h a ni n
a deepernarrower
streamofthe
samevolume,; t h e w l d e r s i u i c e ,
however, u s u a l l y
m u s t be s e t on a s t e e p e r g r a d e .
lly
"Small o r medium-sizeboxes
a r ea p p r o x i m a t e l ys q u a r ei n
c r o s s - s e c t i o n ;l a r g eb o x e su s u a i i ya r eo n e - h a l ft ot w o - t h i r d sa s
d e e pa st h e ya r e
wl.de. The water 5.n a sl.uI.ce shouldalwaysbe
more t h a n deep enough t o . c o v e r . t h e l a r g e s t b o u l d e r t h a t may be
of t h e s t r e a m i n t h e
main
s e n tt h r o u g h .I np r a c t i c e ,t h ed e p t h
s l u i c e a t h y d r a u i i c m l n e su s u a i i y i s a f i f t h t o a h a l f t h e w i d t h
, o f t h e box s o a s t o prevent s p i l l s i f t h e box i.s t e m p o r a r i l y
plugged by boulders or sand. Where s c r e e n e dg r a v e l i s being
and shallow
washed, a s i n u n d e r c u r r e n t s o r on dredges,wide
f o r t h er e c o v e r y of f i n eg o l d .I n
'booms t r e a m sa r en e c e s s a r y
t o handle
ing'operationsthe'boxesusuallyarerunfullinorder
therelativeiylarge
vo:tumes of w a t e r t h a t flow f o r s h o r t p e r i o d s
only,acdthesluices
commonly a r e a b o u t a s d e e p a s t h e y a r e
wide.
I t wouii3 b ed e s i r a b l e bu-t i m p r a c t i c a b l e t o d e c r e a s et h e
as f l o w s of 125 to 250
d e p t h of w a t e r by u s i n g w i d e r s i u l c e s ,
cubicfeetpersecondare
n o t unusual when t h e g a t e of t h e . r e s e r voir i s suddenly opened wide. 'I
A methodwhich may beused t o e s t i m a t e t h e a p p r o x i r m t e s i z e
of a s l u i c e - f l u m e knowing t h e volume of w a t e r a n d t h e g r a d e
of
t h eb o x e s ,
is t o c a l c u l a t e t h e d i m e n s i o n s , a s s u m i n g t h a t
it is
carryingclearwater,thenadd
30 per c e n t t o t h e w i d t h
anddepth
forthedimensions
of ' t h e w a t e r s t r e a m when it i s loaded with sand
and g r a v e l .M a t u r a l 1 . ys e v e r a lf e e t
of freeboard will be n e c e s s a r y
t o prevent spilla.ge through blockage
o f t h e s i u i c e o r when a surge
comes throughfrom a " d o u b l e . "
. ..
Furthermore'thelength
of t h e s i u i c e - f l u m e i s a n i m p o r t a n t
dimension. The lengthshou~,.d De s u f f i c i e n tf o r a:l g r a v e la n d ,
c l a y t o be thoroughlybroken up and disintegrated and f o r t h e g o l d
t o s e z t l e andbeheid
by t h e r l . f f 1 . e ~ . I n s p i t e
of t h e f a c t t h a t
most of t h e g o l d is f o u n d i n t h e
f i r s t halfdozenhead-endboxes,
250 f e e t l o n g t o make
thesluiceinanylargeoperationshouldbe
s m l i sluices ( 1 2 t o 14
a ne f f i c i e n tg o l ds a v e r .
nihereaswith
inches wide) and with coarse
t o medium gold 36 t o 72 f e e t n a y be
a l l t h a t i s necessary.
Grade
" U s u a l l yt h eg r a d e
of t h e s l u i c e depends upon t h e s l o p e and
contour o f t h eb e d r o c k .I ft h eg r a d i e n t
of bedrock,however,
is
or t u n n e l s
t o o low t o permit s u f f j . c i e n t f a l l for t h e s i u i c e , c u t s
may b er u ni nt h eb e d r o c k
t o overcome t h i s d i f f i c u l t y ;
Very s h o r t
s l u i c e s of o n l y 1 o r 2 boxes sometimes a r e s e t n e a r l y
f l a t . where
- 46
-
t h e r e i s a d r o p a t t h e end o f t h e box; t h e g r a v e l b e i n g f o r c e d
t h r o u g h t h e s l u i c e by t h e i n i t i a l v e l o c i t y and t h e headofwater
in the pit.
"The o p i n i o n o f mostopera-tors i s t h a t a b o u t 6 i n c h e s i n 1 2
f e e t ( 4 . 1 6 p e rc e n t ) i s t h eb e s tg r a d ef o ra v e r a g ec o n d i t i o n s .
Grades a s f l a t as 3 inches i n 1 6 f e e t c a n be u s e db u to n l y
at
g r e a t l o s s of c a p a c i t y . A
t one mine where a gradeof 3 inches i n
14 f e e t i s u s e d ,a l lr o c k so v e r
5 o r 6 i n c h e s i n d i m e t e r mustbe
left inthepit.
B e c a u s eo ft h eg r e a t e rf r i c t i o na n dt h ec o n s e q u e n tl o w e r i n go fv e l o c i t y ,s t e e p e rg r a d e sa r en e e d e d
f o r small
s l u i c e st h a nf o rl a r g eo n e s ;
some o p e r a t o r sf a v o rg r a d e s
of 1 2
i n c h e st o a 12-foot box. For maximum g o l d - s a v i n ge f f i c i e n c y ,
as
w e l l a s f o r economy i n dump room, gradesshouldbe
a s f l a t a s possible withoutloweringthevelocitytosuchanextent
that t h e
. r i f f l e s pack w i t hs a n d .
Any i n c r e a s ei ns l o p ef r o m
t h a t adjustt h e wear
ment w i l l i n c r e a s e t h e c a p a c i t y of t h e s l u i c e , i n c r e a s e
on t h e s l u i c e , a n dd e c r e a s et h ee f f i c i e n c yo ft h er i f f l e s ,
res u l t i n g i n g o l d l o s s e s i f c a r r i e d t o e x t r e m e s or i f t h e gold i s
v e r yf i n e .
If water i s scarce,goldrecovery
may w e l lb es a c r i s t a t e s t h a tg r a d e s of 10 t 3 24 i n c h e s
f i c e d t o capaoity.Bowiel
w e r e ' u s e di n some F o r e s t Hill Dj.vide ( C a l i f . ) m i n e s f o r t h i s
of w a t e r t c s o l i d s d e c r e a s e s
r e a s o n .I n c r e a s i n gt h ep r o p o r t i o n
t h et e n d e n c yo f
r i f f l e s t o pack w i t h sand.
"Sluicecapacityincreaseswith
grade b u t more r a p i d l y ; t h a t
o f s l u i c e - b o x e s w i l l more t h a n d o u b l e t h e
quantity ofgravelthatcan
be put through the boxes by
a given
flowofwater.
The a b s o l u t ei n c r e a s ec a n n o tb ep r e d i c t e dc l o s e l y
as c o a r s e n b s s o i g r a v e l , v e l o c i t y a n d s h a p e
of t h e b o x appear t o
t os l o p e .F o r
inhave s o y b e a r i n g on t h e r e l a t i o n ofcapacity
s t a n c e , Bowie c i t e s a mine a t wh.ich c h a n g i n g t h e trade f r o m . 3 t o
.3 1 / 2 i n c h e s i n 1 6
f e e t i n c r e a s e dt h eq u a n t i t y
o f g r a v e ls l u i c e d
t h r o u g h t h e same b o x e s w i t h t h e same flow of water by aboutone-third.
i s , doublingthegrade
"The establishedgradeshouldnotbedecreasedanywhere
a l o n g a s l u i c e , . o t h e r w i s e g r a v e l may a c c u m u l a t e w h e r e t h e c u r r e n t
loses v e l o c i t y . If t h ew a t e r andgravel.,however,enterthe
f i r s t box w i t h c o n s i d e r a b l e . s p e e d , s a y , f r o m t h e d i s c h a r g e
of a
f i r s t boxes may be placedon1.essthan
h y d r a u l i ce l e v a t o r ,t h e
t h er e g u l a rg r a d e .
Bends o r c u r v e s a r e u n d e s i r a b l e a:: t h e y comp l i c a t ec o n s t r u c t i o na n di n d u c ec l o g g i n g
and runningclver.
'%hen
a curve i s unavoidable it shouldbe a s g r a d u a l a s p o s s i b l e , t h e
outsideofthesluiceshould.beelevated
f r o m 1/8 t o :,/%
inch per
f o o t o f s l u i c ew i d t ha n dt h eg r a d es h o u l d
be increased perhaps an
i n c h p e r ' b o x a t andimmediatelybelow
thecurve.,Similar
ru1e.s
applytoturn-outs
or branchesanddrops
of 3 or 4 inchesshould
beprovided a t j u n c t i o n s t o check t h e d e p o s i t i o n o f g r a v e l a t
t h e s ep o i n t s .
Such d r o p so c c a s i o n a l l ya r ei n s e r t e di ns t r a i g h t
s l u i c e si ft h eg r a d e
i s a v a i l a b l e ,p a r t i c u l a r l yi ft h eg r a v e 1 , i s
d i f f i c u l t t o wash o r i f h e a v y s a n d t e n d s t o s e t t l e
t o thebottom.
A drop of even a few inches f r o m one box t o t h e n e x t h a s
a disi n t e g r a t i n g e f f e c t andmixes t h e m a t e r i a l p a s s i n g t h r o u g h t h e
s l u i c e ,t h u sa s s i s t i n g
go1.d recovery. .lit oneplacewheredrops
wereprovided a t i n t e r v a l s b e t w e e n d i f f e r e n t t y p e s
of r i f f l e s ,
25 p e r c e n t of t h e g o l d r e c o v e r e d i n t h e s l u i c e
was found a t t h e
drops. "
''
A t t h e B u . l l i o n iyine, h. C . , where r a i l r i f c l e s a r e u s e d , t h e
t h r e el e n g t h s
of r a i la tt h e
upperend
a r ee a c hr a i s e d
2 inches
above t h e n e x t down s t r e a m i n o r d e r t o i n c r e a s e t h e g r a d e a n d
give boulders an initial velocity
when s t a r t i n g t h r o u g h t h e
sluice.
.
Riffles
"
"
Theory of gold-saving
by R i f f l e s
"The f u n c t i o n of r i f f l e s is t o h o l db a c kt h eg o l dp a r t i c l e s
t h a t have s e t t l e d t o t h e b o t t o m of a flowingstrearn of water and
g r a v e l . 'Any ' d e a d 's p a c ei nt h eb o t t o m
of + sluide-box,where
loses
t h e r e i s no c u r r e n t , f i l l s q u i c k l y w i t h s a n d a n d t h e r e u p o n
most. o f i t s v a l u e a s a g o l ds a v e r ,u n l e s st h es a n dr e m a i n s - l o o s e
t o s e t t l e i n t o i t ; t h e t e f o r e , t h e s h a p e of
enough t o permitgold
o f t h e f a c t t h a t under some Conr i f f l e si si m p o r t a n t ,r e g a r d l e s s
d i t i o n s ,a sw i t hc o a r s e
.goid andfree-washinggravel,
a l l forms
of r i f f 1 , e sa r ea l m o s te q u a l l ye f f i c i e n t .
The r i f f l e s.hou1d be
andproduce
a modershaped s o a s t o a g i t a t e t h e p a s s i n g c u r r e n t
a t e l ys t r o n ge d d y
o r ' b o i l 'i nt h es p a c eb e h i n d ,
or below i t , t h u s
preventingsand from s e t t l i n g t h e r e and a t t h e same time holding
t h eg o l d f r o n s l i d i n gf a r t h e r down. t h es l u i c e .
In o t h e r words,
,
r i f f l e s , for maximum e f f i c i e n c y , s h o u l d p r o v i d e
a roughbottom
t h a t will d i s t u r b t h e e v e n
flow ofsandandgravel,
w i l l retain
will n o t become packedwj.thsand.
Where grade i s
t h eg o l d ,a n d
l a c k i n g . t h e r i f f l e s must be r e l a t i v e i y smooth, s o a s n o t t o r e t a r dt h ec u r r e n tu n d u l y :u n d e rt h e s ec o n d i t i o n st h es l u i c e
must
be l i n g enough t o compensate f o r t h e l o s s i n g o l d - s a v i n g e f f i c iency of t h e i n d i v i d u a l r i f f l e s .
" N a t u r a ls t r e a mb e d sa c ta sg o l d - s a v i n gs l u i c e s , ' n o t
causetheyareparticularlyefficientassuchbutbecausemost
t o l o s e 'a n dt h es t r e a m sa r el o n g .
g o l di s' h a r d
be-
?lz
:
.
y
t
?
..
c
xCc4 hlnc4 rifflee in n small e l n i c e - f l ~ m a . Each
pair of blocks i s held by a r i f f l e s t i c k which i s t o e nailed to t h e S i d e of the box.
P1e.t.
TX R .
A l m - 9 sluice-box paved w i t h wood blocks wedged
together by blocks in t h e i n t e r s t i o e s . A s a f e t y s t i c k
is nailed a o m s s at t h e end of each 12-foot box.
___"_
-
Plate X A. A 3-foot sluioe-box showing the load of gravel
and boulders dropped when the water was turned off.
Plate X B. A 30-inch sluice-flume showing a central groove
worn in the wood block riffles after considerable service.
Typesof
riffles
" R i f f l e s , ofcourse,shouldbedesigned
s o as t o s a v e t h e
g o l du n d e rt h ee x i s t i n gc o n d i t i o n s .
They shouldalsobecheap,
d u r a b l ea n de a s yt op l a c ea n d
remove. Not a l l t h e s e q u a l i t i e s
a r e found i n a n y one t y p e .
"Sluice-box r i f f l e s may b e c l a s s i f i e d . r o u g h l y as t r a n s v e r s e ,
longitudinal,block,'blanketandmiscellaneousroughlysurfaced
a s wood b l o c k ,p o l e ,s t o n e ,c a s t
ones, o r , a c c o r d i n gt om a t e r i a l ,
i r o n , r a i l , angle iron, f a b r i c andmiscellaneous.Usuallynore
t'nan o n e t y p e o f r i f f l e
i s u s e d ,a l t h o u g hi nC a l i f o r n i av e r yl o n g
on
sluiceshavebeenpavedentirelywith
wood b l o c k r i f f ' l e s , a n d
8 , A, i s usedalmostexd r e d g e st h et y p ei l l u s t r a t e di nF i g u r e
elusively.
"Of about 80 hydraulic, ground-sluice and mechanically
r i f f l e s of
worked placermines,approximately
25 p e rc e n t .u s e d
t h et r a n s v e r s ev a r i e t y ,l o o s e l yt e r m e d' I i u n g a r i a n , 'c o n s i s t i n g
g e n e r a l l y of wooden c r o s s b a r s f i x e d i n a frameandsometimescapped
w i t hi r o ns t r a p s .
About 2 0 p e rc e n t .u s e dt h el o n g i t u d i n a lp o l e
mils, thelast
t y p e ,1 5p e rc e n t . ' w o o d e nb l o c k s ,a n d1 5p e rc e n t .
o r Jengthnpise.Angle-iron
r i f f l e s ; wireb e i n gp l a c e dc r o s s w i s e
mesh s c r e e n o r expanded metal on c a r p e t , b l a n k e t s , o r burlap,rock
p a v i n g ,a n dc a s t - i r o ns e c t i o n st o g e t h e r
made up t h e remainj.ng 25
p e rc e n t .
The o n l yg e n e r a lr u l eo b s e r v e d
was t h a t tkle s i z e of t h e
r i f f l e s was r o u g h l y p r o p o r t i o n a l t o t h e s i z e
of t h e m a t e r i a l t o be
handledandthatforfinematerial,particularlythescreened
g r a v e lw a s h e di nm o s to ft h em e c h a n i c a l l yo p e r a t e dp l a n t s ,t h e
dredge-type riffle found most favor."
I n B r i t i s h Columbiamost medium and larse s i z e d h y d r a u l i c
o p e r a t i o n s u s e wood b l o c k r i f f l e s , and a few(i3ullj.oc.and'
Germansen
A
t t h e Lowhee Hine t h e uFNper 1 2 0 f e e t
V e n t u r e s ju s e s t e e l r a i l s ;
ofs'lcice
i s s h o dw i t h4 - f o o ts q u a r es t e e lp l a t e ss e p a r a t e db y
t r a p s 3 incheswideand
6 i n c h e sd e e p ,t h er e s to ft h ef l u m eb e i n g
paved with wood b l o c k s .
"For a s m l l o r medium-size s l u i c e ( i f lumber i s c o s t l y and
a p l e n t i f u l s u p p l y of small t i m b e r ,s u c h a s t h e l o d g e - p o l e p i n e ,
i s a v a i l a b l e jp e e l e dp o l er i f f l e s( P i g .
8 Y and C) a r ep e r h a p st h e
mosteconomicalandsatisfactory
of t h ev a r i o u st y p e s .T h e i rc o n s t r u c t i o n i s e v i d e n t from t h e d:rawing.Those
c f , t r a n s v e r s ev a r i une t y n a y h a v e a somewhat h i g h e r g o l d - s a v i n g e f f i c i e n c y , b u t
d o u b t e d l yt h e yr e t a r dt h ec u r r e n t
more and wear o u tf a s . i e r .P o l e s
2 t o 6 i n c h e si nd i a m e t e r
may beused,spaced
1 o r 2 i n c h e sa p a r t .
wear o u tr a p i d l y .
The s e c t i o n ss h o u l d
Such r i f f l e s a r e c h e a p b u t
be a t h i r d or h a l f t h e box length f o r conveni.enceand 1 o r 2
i n c h o sn a r r o w e rt h a nt h es l u i c e .
A
t o n em i n e$ - i n c hp o l er i f f l e s
.
-
49
-
Figure 8.-Types o f riffles: A, Transverse wooden, steelcapped riffles used on dredges; ' B, transverse pole riffles: C, longitudinal
poleriffles; D, transverse wooden nffles,square section: E,. transverse wooden nffles, bevelled seqtlon; F, transve,rse wooden
riffle, steel-capped, inclined section; G, transverse wooden riffles, steel-clad, with overhang; H, longxtudlnal wooden rlffles capped
with cast-iron plates; I, wooden-blockriffles
for large slulces; J, wooden-blockrlffles
for undercurrents; K, ,stoneriffles;
. L, longitudinal rail riffles on wooden sills; M; transverse angle-iron riffles: N, transverse angle-iron rltlles m t h top hlted upward;
0, longitudinal'ritlles made of iron pipe; P, transverse cast-iron riffles used in undercurrents.
'
had t o b e r e p i a c e d e v e r y
10 days o r a f t e r e a c h 1 , 2 0 0 c u b i c y a r d s
hadbeensluiced.
The s l u i c e was 30 inches.wideandhad
a grade
of 8 i n c h e si n 1 2 f e e t . f i t o t h e rm i n e sp o l e sj a s ts e v e r a lt i m e s
as l o n g .
"If sawedlumber
c a nb eo b t a i n e dc h e a p l y ,r i f f l e s
similar t o
4t h e o n ed e s c r i b e d may be made of 1- by 2 - , 2 - by 2-, o r 2-by
i n c hm a t e r i a l , a s shown i nF i g u r e 8 , 2. and 5. The t o ps u r f a c e s
of t h e r i f f l e s may beplatedwi.th
s t r a p i r o n ( F i g . 8 F. and G . ) .
T r a n s v e r s e r i f f l e s o f t h i s t y p e m.y b es l a n t e d dow;st,ream,
as ,
shown i n F i g u r e 8 , 3 - and t h e t o p s u r f a c e s may b eb e v e l e dt oi n as w i t h t h e d r e d g e r i f f l e s .
The
c r e a s et h e' . b o i l i n g 'a c t i o n ,
know
e f f e c t i v e n e s s of t h i s p r a c t i c e i s n o t known, a n d t h e a u t h o r s
o f no c o n c l u s i v et e s t sh a v i n gb e e n
made. L o n g i t u d i n a lr i f f l e s of
2- by 4-, 3- by 4-, or .2- b y6 - i n c hm a t e r i a la r eu s e d
a t some
is
p l a c e s . k l o n g i t u d i n a l wooden r i f f l e c a p p e dw i t hc a s ti r o n
shown i n F i g u r e 8 , E.
" S l u i c e s i n t h e Rock Creeksapphiremineswere12inches
t o thefoot.
wideand s e t on a g r a d e n o t t o exceedhalfaninch
h r e i a t i v e l y f l a t g r a d e i s n e c e s s a r yt os a v et h es a p p h i r e s .
Riff l e s were 2by
4 i n c h e si n s i z e s e t a c r o s s t h e s l u i c e
4 inches
a p a r t ;, t h e yw e r et i l t e d
downward. The s l u i c e was cleaned up each
day. The s a p p h i r e s w e r e s e p a r a t e d frorn t h e s a n d s i n a j i g . They
were t h e n p u t tinrough a s e t of :seven s c r e e n s , and o t h e r heavy
mineralswerepickedout
by hand. The blacksand
and o t h e rf i n e
heavy minerals were
drawn t h r o u g h t h e s c r e e n i n t h e j i g ; t h e
s a p p h i r e s were t a k e n o f f o n t o p
of t h e s c r e e n .
"Wooden-block r i f f l e s ( s e e P l a t e I X and F i g . 8, I and Jj a r e
h e l d by aowie 1t o be unexcelled i n r e g i o n s w h e r e t h e m a t e r i a l
is
availablecheap."
In B r i t i s h Columbia wood b l o c k s c o s t between
10 and 15 c e n t se a c hd e l i v e r e dt ot h es l u i c e - b o x .
"T'5e blocks
a r e 4 t o 1 2 i n c h e s t h i c k and of corresponding diamkters o r w i d t h s .
They may be round, p a r t l y ' s q u a r e d , or c u t f r o n s q u a r e t i m b e r .
One- o r two-inch wooden s t r i p s : : e p a r a t e t h e rows of b l o c k s ,a n d '
theyareheldsecurelyinplacebynaiisdrivenin
bo-th d i r e c t i o n s . Wooden-block r i f f l e s a r ep e r h a p st h eh a r d e s t
(2.f a l l t y p e s
t o s e t b e c a u s e of t h e i r t e n d e n c y t o f l o a t
away.They
mustbenailed
as stated.,and wedged s e c u r e l y a t t h e s i d e s .
tothespacingstrips,
The s p a c i n g s t r i p s a r e h e l d
down a t e i t h e r end by t h es i d el . i n i n g
of t h e s l u i c e . wooden-block r i f f l e s a r ed u r a b l e ,c a nb ew o r n
down
less, and if made oflongtohalftheiroriginalthicknessor
S r a i n e d wood (such as p i t c hp i n e ,w h i c h
"brooms" i n s t e a d of wearingsmooth)' may c a t c h some g o l d i n t h ee n d g r a i n .
When d i s c a r d e d ,
Bowie, X. J . , k ? r a c t i c a l T r e a t i s e onHydrauliciqininginCalif o r n i a : Van Nostrand c o . , New York, 3d e d . , 1889, p. 2 2 5 .
-
51
-
t h e y a r e commonly burnedandth.eashespanned
torecoveranygold
so caught. The l i f e of 10- o r 12-inohwooden-block
r i f f l e s may
be a fewmonths t o s e v e r a l s e a s o n s a n d , a c c o r d i n g t o
Bowie, r a n g e s
from100,000 t o 2 0 0 , 0 0 0m i n e r ' si n c h e so fw a t e r ;t h a t
i s , with a
f l o w of 1,000inchesone
would l a s t 1 0 0 t o 200 days." A t t h e . LowheeNine,
B . C . , t h e wood blocksmustbereplacedeachseason:these
gradeof
l a s t f o r 200,000 t o 250,000yards of g r a v e l moved."The
thesluiceapparentlyhas
much t o d o w i t h t h e l i f e
of b l o c k r i f f l e s .
A t a minewhere t h e s l u i c e was 48 incheswideandhad
a grade o f
2 3/"4 i n c h e si n 1 2 f e e t a s e t o f b l o c k sl a s t e d t w o seasons, d u r i n g
which time140,000 cubic y a r d s was s l u i c e d . A
t t h e Salmon River
mine t h e g r a d e was 7 i n c h e s i n 1 2 f e e t a n d t h e w i d t h
of t h e b o x e s
30 i n c h e s . E e r e b l o c k r i f f l e s l a s t e d
60 t o 70 days,.duringwhich
18,000 c u b i cy a r d s waswashed.
On account o f d i f f e r timeabout
ences .in t h e w e a r i n g r a t e s o n l y o n e v a r i e t y o f
wood should be used
i n a s e c t i o n o f a s l u i c e . Douglas f i r wearslongerthanother
nativewesternconifers.
"Where l a r g e q u a n t i t i e s o f , g r a v e l a r e p u t t h r o u g h s l u i c e s ,
i r o no rs t e e lr i f f l e sg e n e r a l l ya r ep r e f e r r e d .T h e i rs u p e r i o r
w e a r i n gq u a l i t ya s
compared w i t h t h a t o f wood permitslongerruns
w i t h o u ts t o p p i n gt or e p l a c et h er i f f l e s .T h e i rd u r a b i l i t y
may
more t h a n c o m p e n s a t e f o r t h e i r h i g h e r c o s t .
" S t e e l r a i l s and a n g l e i r o n a r e
common r i f f l e m a t e r i a l s u s e d
i n v a r i o u s ways ( s e e P l a t e X I ) . Old r a i l s or a n g l e i r o n c a n
often
be obtained cheaply i n m i n i n g d i s t r i c t s or n e a r r a i l r o a d s .
Various
o t h e rs t e e lp r o d u c t ss u c ha s' p i p ea n dc h a n n e l sh a v eb e e nu t i l i z e d
f o r r i f f l e s .C a s t
iron i s a l s o usedandhastheadvantage
of a
lower f i r s t c o s t t h a n s t e e l r a i l
or a n g l e i r o n .
" I r o n or s t e e l r i f f l e s s h o u l d n o t b e u s e d i n u n i t s t o o l o n g
or 1 0 - f o o tl e n g t h sa r eu s u a l l yq u i t e
t o be h a n d l e dr e a d i l y . "E i g h t
longenough.
"Rope blocks onmovable t r i p o d s havefoundfavor
at
scme p l a c e s f o r ' l i f t i n g h e a v y r i f f l e s e c t i o n s .
"When used as t r a n s v e r s e r i f f l e s l e n g t h s
of s t e e l r a i l u s u a l l y
o r not more t h a n 1 or
aresetupright,thefiangesalmosttouching
2 i n c h e sa p a r t .
Nher,e g r a d e i s l a c k i n ga n d . g o i ds a v i n g
is not
particularlydifficult,longitudinalrailriffles
make e x c e l l e n t
a smo,oth-sliding bottom for the
paving.for a s l u i c e a s t h e y p r o v i d e
. g r a v e l and b o u l d e r s . The r a i l so r d i n a r i l ya r eb o l t e dt o g e t h e r
by
t i e r o d sp a s s i n gt h r o u g h
wood, pipe o r c a s t - i r o n s p a c i n g b l o c k s ,
formingrifflesectionsthewidth
of t h e s l u i c e a n d
anyconvenient
l e n g t h . "A n o t h e r
method i s t o s p i k e t h e r a i l s w i t h t r a c k s p i k e s
to
4 by 4 i n c h t i m b e r s s e t c r o s s w i s e i n t h e s l u i c e .
" i t t h e La Grange
b i n e i n T r i n i t y County, C a l i f . , 40-pound r a i l s c o s t i n g a b o u t
$125
p e r t o n provedmore
s a t i s f a c t o r yt l i a n wood r i f f l e s 1 . When 16- b y '
Gold Gravels,
MacDonald, O.F.., The Weaverville-TrinityCenter
B u l l . , 430, 1910,
T r i n i t y Coumty, Ca1i.f.: C . S . Geol.Survey
pp.48-58.
'-
52
-
P l a t e XI A. The 6-footsluice-flume
a t t h e B u l l i o n Mine piilved
w i t h r a i l r i f f l e s . The rails w e s p i k e d t o 6 by 6 inch
t i e s l a i d &cross t h e box a t 3 - f o o t i n t e r v a l s .
P l a t e X I B. Cross-section of t h eB u l l i o nt y p er a i l s .
Those
weigh 37 pounds t o t h e y w d , 81-8made of s p e o i a l a l l o y
s t e e l and of t h i ss p e c i a la r m s - s e c t i o n .N o t i c e
how t h i c k t h e web i s as compared t o s t a n d a r d
railway steel.
Plate XI1 A.
Loosening up the sand and gravel packed.
between block riffles.
Plate XI1 B. Undercurrent tablesat the end of the sluice at
Cariboo Cottonwood Plaoers Ltd. Eaoh table is 6 feet
wide, 20 feet long and' on a grade of 1 1/2 inches
The riffles are expanded metal
to the foot.
lath over oorduroy.
t o 'sand1 6 by 13-inch wood blocks were used t h e r i f f l e s t e n d e d
i'loreover, t h e blocks had t o be r e p l a c e de v e r y i o r 3 weeks.
up.'
2 monthsand r a i l s . 5i n c h e s
Lengthwise r a i l s 8 i n c h e s a p a r t l a s t e d
5 , i n c h e sa p a r t
a p a r t , 4 m o n t h s .S t r a n g e l ye n o u g h ,t r a n s v e r s er a i l s
l a s t e d 6 months. The r a i l s werespaced by c a s t - i r o nl u g s and s e t
r i g h t s i d e up on timber s i l l s . >then t h e head of t h e r a i l was worn
T h i s s l u i c e was hano f ft h er e n a i n d e r
wasused for s i d e l i n i n g .
d l i n g a f l o w of about 4 , 0 0 0 inches of waterand 1,000 c u b i c y a r d s
of m a t e r i a l p e r h o u r , b o u l d e r s a s l a r g e a s
7 t o n s b e i n g washed
t h r o u g h .. T h ee d d i e sb e h i n dt h e
r a i l s werebelieved t o be t h ec a u s e
of t h e improvedrecoveryas
com:pared w i t h t h a t u s i n g b l o c k r i f f l e s .
was cleaned up every
The lower p a r t o f t h e b r a n c h i n g s l u i c e l i n e
o t h e rs e a s o no n l y . "
One of- t h e i m p o r t a n t a d v a n t a g e s c l a i m e d f o r r a i l
riffles as
compared w i t h wood block r i f f 1 e : s i n t h e 'same s l u i c e ( o n t h e
same
grade) is t h a t t h e r a i l r i f f l e s a l l o w a b o u t
20 percent more mater i a lb e i n gs l u i c e dw i t ht h e
sameamount
of w a t e r .C o n v e r s e l yt h e
same m o u c t o f gravelcan bewashed through a s l u i c e s h o d w i t h
r a i l r i f f l e s on a f l a t t e r g r a d e t h a n t h e same s i z e s l u i c e paved
w i t h wood b l o c k s . R a i l r i f f l e s s h o u i d notbe l a i d i n a s l u i c e
5 percentbecausethewatervelocity
with a steepergradethan
r e s u l t s i n e x c e s s i v e wear on t h e r a i l s , and a s c o u r i n g a c t i o n
l o s e s a g r e a t e r amount of f i n e g o l d .
A. grade o f 4 . 5 percentgives
good r e s u l t s a l t h o u g h f l a t t e r g r a d e s a s
low a s 3 . 0 percent may be
usedwheresufficientwater
i s available.
Two mines i n B r i t i s h Columbia, t h e B u l l i o n andGermansen
Vent u r e s ,h a n d l el a r g ey a r d a g e se a c hy e a r ,1 , 0 0 0 , 0 0 0c u b i cy a r d s
or
more, and both have sluices lined with
37 pound m m g a n e s e s t e e l
r a i l s of a s p e c i a lc r o s s - s e c t i o n( s e eP l a t e
XI B ) . I t i s b e l i e v e d
t h a t t h e l i f e of t h e r a i l s v i i l l be from 5 t o 6,000,003 cubicyards
a m a i l e r s l l i c e and han-.
on t h e s c a l e o f o p e r a t i o n , a l t h o u g h w i t h
d l i n g less yardageperseason
wj.th somewhat s l o w e r w a t e r v e l o c i t y
andhandlingsmallerbouldersthelifemight
be almostdoubled.
Ordinarysteelrailroadrails,
however, w i l l have a s h o r t e r l i f e ,
thantheaboveillustr,ationwhich
is for a s p e c i a l a l l o y s t e e l of
s p e c i a lc r o s s - s e c t i o n .
"The combination of s t e e l r a i l s and wooden s i l l s used a t t h e
La Grangemine appears t o make a n e x c e l l e n t g o l d save:?,andmodif i c a t i o n s havebeenused
a t many l a r g em i n e s .F i g u r e
E , ' L, i l l u s ' t r a t e s a combination o f l o n g i t u d . i n a 1 r a i l s and t r a n s v e r s e t i m b e r
sills.
"At t h e Round Hountainmlne25-pound
r a i l s wereplaced
longit u d i n a l l y i n a 3 6 - i n c h s l u i c e w i t h a grade o f 4 i n c h e s i n 1 2 f e e t .
Afterabout150,000cubicyardshadbeenrunthrough
!;he s l ~ u i c e
t h e c e n t e r r a i l s showed considerablewearandwerererloved
to the
outside.ktthe
Lewismine
on Rogue River a s e t of r i f f l e s made
-
53
-
o f 40-pound r a i l s l a s t e d 15seasons.
The s l u i c e was 30inches
a grade of E i n c h e s i n 1 2 f e e t . About 7,000 c u b i c
wideandhad
y a r d s was washed y e a r l y .O n l ym a t e r i a lu n d e r
5 i'nches i n diameter
was r u n t h r o u s h t h e s l u i c e s .
"Angle i r o n i s c o h o n l y u s e d for making r i f f l e s , as i l l u s t r a t e di nF i g u r e
8, M and W. Hang methods of a s s e m b l i n gt h e
lengthsof,angleironintorifflesectionsareinuse,
and' no one
method c a n b e s a i d t o e x c , e l .
. The i r o n s may be, s e t w i t h f l a t upper
s u r f a c e s or i n c l i n e d s l i g h t l y t o . i n c r e a s e t h e r i f f l i n g , a o t i o n .
U s u a l l yt h eg a pb e t w e e nt h er i f f l eb a r s
i s 1/2 t o 1 i n c h . The
operators
e f f e c t i v e n e s s of t h i s t y p e of r i f f l e i s believed bysome
t o d e p e n d l a r g e l y on t h e . v i b r a t i o n o f t h e r i f f l e s u n d e r t h e i m p a c t
o f bould-erswhichkeeps
t h e s a n dt r a p p e du n d e rt h ea n g l e si n
a
l o o s ec o n d i t i o nf a v o r a b l e
t o goldsaving.
"Figure 8 , 0 , i l l u s t r a t e s a n u n u s u a l a l l - m e t a l r i f f l e u s e d
a t a Colorado d r i f t mine,which was s a i d t o be g i v i n g s a t i s f a c t i o n
andappears
t o besimple
t o c o n s t r u c t andconvenient t o u s e .
The
r i f f : l i n ge f f e c tc o u l db ei n c r e a s e d ,w i t h
some l o s s of v e l o c i t y , by
spacing the transverse bars closer.
" C a s t - i r o n r i f f l e s of a l l shapesandsizeshavebeenused.
If a v a i l a b l e a t l o w c o s t t h e y a r e v e r y e c o n o m i c a l ,
as t h e y wear
s l o w l y ,c a nb eq u i c k l ya n ds e c u r e l yp l a c e d ,a n da r ee f f i c i e n tg o l d
s a v e r s i f designed s o as n o t t o packwithsand.InanunderH i l l m i n e ,C a l i f o r n i a ,c a s t - i r o nr i f f l e s
currentattheIndian
4 f e e t ' l o n g , shaped l i k e a n g l e i r o n s a n d
had
were in use that were
equal 3 l i 2 - i n c h l e g s 7/8-inch t h i c k (; S e eF i g .
8 , P).
"One p r o p e r t y i n C a l i f o r n i a
was r e p o r t e d t o b e u s i n g o l d c a r
They were l a i d c l o s et o g e t h e r , f l a n g e
wheel's for s l u i c ep a v i n g .
s i d eu p ,i n
a box j u s t w i d e enough t o ' h o l do n e
row o f wheels. The
rifflingactioncaused
by thehubs,webbing,andspacesbetween
adjacentwheelsandundertheflanges
was s a i d t o h a v e r e s u l t e d
i n a s a t i s f a c t o r yg o l dr e c o v e r y .
A gravel-washingplant
i n Arizona was p r o v i d e d w i t h r i f f l e s
made ofstandard2-inchpipeand
2 l/Z-inch angle 'iron welded into
r i f f l e s e c t i o n s resembling
p o l er i f f l e sT
. h i sr i f f l es h o u l d
be f a s t - r u n n i n g and a s e f f i c i e n t
a sa n yl o n g i t u d i n a lt y p e
of riffle, relatively light,
andeasy t o
handle. I t wc'uld n o t be d u r a b l e enough for veryheavygraveland
would b e r e l a t i v e l y e x p e n s i v e u n l e s s s a l v a g e d m a t e r i a l
andwelding equipment were available.
"For s h a l l o w . s l u i c e s t r e a m s c a r r y i n g o n l y f i n e m a t e r i a l
v a r i o u sg o l d - s a v i n gm a t e r i a l sa r eu s e d ,i n c l u d l n gb r u s s e l sc a r p e t ,
cocomatting,corduroy,andburlap.These
may be h e l d down by
c l e a t s o r by w i r es c r e e n .F a b r i c so f t e na r eu s e di nc o m b i n a t i o n
i t s being washedout
with riffles to catch fine gold and hinder
- 54 ' \
of t h e r i f f l e s byeddies.
A corduroy woven e s p e c i a l l y for a
l a r g e Canadianlode-goldmines
to
r i f f l e s u r f a c e i s used bysome
c a t c ht h e i r' c o a r s e 'g o l db e f o r ef l o t a t i o n
or c y a n i d a t i o n . A s
such g o l d would be c o n s i d e r e d f i n e by m o s t placer miners it seems
probable t h a ts u c h a f a b r i c would be u s e f u l f o r t r e a t i n g f i n e l y
screenedplacersands.
The corduroy i n q u e s t i o nh a sp i l e sa b o u t
1/4-inch wide and l/e-inch high, spaced about 1/4-inch apart.
The p i l e s a r e b e v e l e d s l i g h t l y
03 one s i d e .
~,
"Heavy w i r e s c r e e n s u c h a s t h a t u s e d
f o r s c r e e n i n gg r a v e l
makes a n e x c e l l e n t r i f f l e f o r f i n e
o r m e d i u m - s i z eg r a v e li nf a i r l y
shallowsluicestreams,andgene.rally
it is used. w i t h b u r l a p or
o t h e rf a b r i cu n d e r n e a t h .
"Zxpanded metal .lathing and woven m e t a l m a t t i n g a r e common
types of riffles for fine material
and a r e used with carpet
o r burof m e t a ls l a n tc o n s i d e r a b l y
in one d i r e c l a p . If t h et h i ns t r a n d s
t i o n ,t h em a t e r i a ls h o u l db ep l a c e dw i t ht h i sd i r e c t i o nd o w n s t r e a m .
E d d i e s i n back of t h e s t r a n d s w i l l thenformgoldcatchers,whereas
i f therecessesfaceupstreamthey
will a t once f i l l w i t h a t i , g h t
bedofsand
and l o s e t h e i r e f f e c - t i v e n e s s . "
For c a t c h i n g f i n e g o l d , s u c h a s o c c u r s
i n b e n c h e sa l o n gp a r t s
of t h eF ' r a s e rR i v e r ,
5. C . , a n di ni n s t a l l a t i o n s . w h e r em a t e r i a l
c o a r s e rt h a n
3,.8 t o l i 2 i n c h i s s c r e e n e do u t ,t u f t e d ,s h o r t - p i l e d .
c a r p e t ,n o tp r o t e c t e db ye x p a n d e dm e t a ll a t h i n g ,a p p e a r s
t o give
most s a t i s f a c t o r y r e s u l t s when on a grade of 1 1/4 t o 1 1/2 inches
tothe foot.
T h i s t y p e i s used on t h e w a s h i n g p l a n t , o f N o r t h
.4mericanGoldfieldsLimited
a t AlexandriaFerryaswellas
by many of
the"snipers"alongtheFraserRiver.
" S o l i d - r u b b e rr i f f l e sw e r en o t e da to n ew a s h i n gp l a n t .
Spongerubberrifflematerial
i s on t h e m a r k e t , b u t
it was notobservedin
i s known by t h e a u t h o r s c f i t s m e r i t s
or c o s t .
useandnothing
"hnotherformof
r i f f l e o f t e n used a s a n a u x i l i a r y t o o t h e r '
t y p e s is a m e r c u r y t r a p , c o n s i s t i n g o f
a board t h e f u l l widthof
t h e s l u i c e w i t h 1- or 1 1/2-inchaugerholes
i n whichmercury i s
placed.Insteadofroundholes,transversegrooves
or half-moonshapeddepressions,
2 t o 4 inches wide and w i t h theroundeddeep
s i d e downstream, may be c u t i n a wide board and p a r t l y f i l l e d w i t h
mercury.These
r i f f l e s havenoapparentadvantageovertheordinfor f i n e g r a v e l , a s
a r yt r a n s v e r s e - b a rt y p ea n da r es u i t a b l eo n l y
out o f t h e t r a p s .
l a r g e p e b b l e s would s p l a s h t h e m e r c u r y
"Plany ingeniousand odd kinds of r i f f l e s a r e e n c o u n t e r e d
in
t h e f i e l d , some of whichhavebeenpatented:
I t i s v e r yu n l i k e l y ,
o r freakishdesign of
however, that theadvantageofanyunusual
r i f f l e is s u f f i c i e n t t o o f f s e t t h e c o s t
o f r o y a l t i e s cnpatented
investions.
- 56 -
i\,
Undercurrents
"An u n d e r c u r r e n t is a d e v i c e f o r s l u i c i n g s e p a r a t e l y a f i n e r
part o ft h eg r a v e lp a s s i n gt h r o u g ht h e
main s l u i c e . The f i n e mat e r i a l and a r e g u l a t e d q u a n t i t y
ofwaterpassthrough
a stationary
g r i z z l y i n t h e b o t t o m and u s u a l l y n e a r t h e
end o f t h e s l u i c e t o one
o r more widesluice-boxes,
commonly c a l l e d t a b l e s , paved w i t h s u i t a b l e r i f f l e s ( s e e P l a t e XI1 B ) .
I f t h e main s l u i c e i s i n s e c t i o n s ,
with drops between, the water
and sand msy be r e t u r n e d f r o m t h e
u n d e r c u r r e n tt a b l e st ot h em s i ns t r e a m ,a n ds e v e r a lu n d e r c u r r e n t s
m y be i n s t a l l e d a t c o n v e n i e n t p o i n t s a l o n g
a sluice."
.Two i m p o r t a n t p h y s i c a l f a c t o r s
may however prevent an underc u r r e n tb e i n gi n s t a l l e d .F i r s t ,
it r e q u i r e ss e v e r a lf e e t
o r more
of -space below the sluice-box grade and often where
dumping head
i s r e s t r i c t e d t h i s headroom is n o ta v a i l a b l e .S e c o n d l y ,
a cer,t a i n amount of water i s drawn o f f f r o m t h e
main s l u i c e and i n
i n s t a n c e s w h e r e t h e dump needs t o be k e p t c l e a r byhand it may n o t
be p r o f i t a b l e t o d i v e r t t h e w a t e r t h r o u g h t h e u n d e r c u r r e n t
when it
could be used m o r e e f f e c t i v e l y i n a s s i s t i n g t o keep t h e dump c l e a r
o f accumulatedgraveland'bculders.
"The s c r e e n o r g r i z z l y i n t h e 'main s l u i c e may p r e s e n t t h e
nostdifficultprobleminbuilding
a satisfactoryundercurrent.
The s c r e e n s h o u l d d i v e r t a l l t h e u n d e r s i z e y e t n o t t a k e
so much.
w a t e r t h a t it causesplugging
of t h e main s l u i c e belocv t h e u n d e r c u r r e n t o r r e d u c e a t h e amount so t h a t d i f f i c u l t y i s encountered
i nk e e p i n gt h e
dump c l e a r . The p r o p e rs i z ec f , o p e n i n gc a nb ed e terminedonly
by experiment. B screened or b a r r e do p e n i n g ,t h e
f u l l w i d t h of t h e main s l u i c e and a few i n c h e s t o a f o o t or more
long, will u s u a l l y drawoff
a s much w a t e r a s c a n
be s p a r e d . New
water maybe
added t o e i t h e r t h e u n d e r c u r r e n t
o r main s l u i c e if
t h es c r e e no p e n i n gd o e sn o tt a k ec u tt h er i g h tq u a n t i t y . f o r , s u c c e s s f u lo p e r a t i o n .U s u a l l ym i n u s
lb-t o l / ' 2 - i n c hm a t e r i a l is
d e s i r e df o rt h eu n d e r c u r r e n t ,
and e i t h e r p i n c h e d - p l a t e s c r e e n
or
i r o n - b a rg r i z z l i e s may be used t o make t h e s e p a r a t i o n . G r i z z l i e s
shouldbe made o f t a p e r e d b a r s or screenspunchedwithtapered
h o l e s w i t h t h e l a r g e s t o p e n i n g s downward, o t h e r w i s e t h e y w i l l
plug and r e n d e r t h e u n d e r c u r r e n t i n e f f e c t i v e .
"Becauseundercurrentsneed
a wide,shallowstream,grades
of
1 2 t o 18 inchesper 1 2 f e e t mustbeused,dependinglargely
on t h e
t y p e o f r i f f l e .C o b b l e s t o n e ,b l o c k t r a n s v e r s eo rl o n g i t u d i n a l
w,ooden s t r i p s , r a i l s , ' s c r e e n s ,
o r f a b r i c s may beused f o r r i f f l e s .
O f t e ns e v e r a lt y p e so fr i f f l e sa r eu s e d
on s u c c e s s i v e p a r t s of one
u n d e r c u r r e n t .U n d e r c u r r e n t s
may be a few t o 25 or 30 f e e tw i d e
and 10 t o 50 f e e t l o n g . '
"?lost of thegoldrecovered
-
by u n d e r c u r r e n t s i s
56
-
so fine that
.
P l a t e XI11 B.
=---
Handlingboulders
."A
"
"
.._.
"l.
in
B
hydraulic p i t w i t h a gin
pZ"& .../"L
" L jlcl "v> "'"k
on Nigger (Pine) Creek.
I
~~
iiL,r. Lid.,
Plate XIV A.
Drilling a large boulder with a jack-hanrmer in
hydraulic pit at Spanish Creek, 8 . C.
the
plate XIV B. Block riffles at the head of the sluioe-box
lifted preparatory to making a clean-up.
it d o e s n o t s e t t l e i n t h e r e l a t i v e l y s w i f t , d e e p c u r r e n t
of t h e
main s l u i c e , b u t p a r t c o n s i s t s
ofgold
that is freedfromits
matrix of c l a y by d r o p p i n g t h r o u g h t h e g r i z z l y a n d r o l l i n g o v e r
A 1 1 c o a r s e g o l d i s saved :in t h e f i r s t
t h eu n d e r c u r r e n tr i f f l e s .
few boxes of t h e main s l u i c e u n l e s s c o n d i t i o n s a r e r a d i c a l l y
wrong.
i s i n s t a l l e d a t t h e end of t h e s l u i c e , . o r
U n l e s st h eu n d e r c u r r e n t
a t l e a s t belowwheregold
is recovered,notallthesaving
in t h e
u n d e r c u r r e n ts h o u l db ec r e d i t e dt o
i t s i n s t a l l a t i o n . In t h e e a r l y
days when h y d r a u l i c k i n g was a t i t s h e i g h t u n d e r c u r r e n t s w e r e
much
favored,sometimes5,000
t o 10,000 s q u a r e f e e t of undercurrent
beingusedalong
a s i n g l es l u i c e - l i n e .
The goldsaved
in them
more
occasionallyexceeded 10 p e r c e n t . o f t h e t o t a l c l e a n - u p b u t
As t h i sr e c o v e r yu s u a l l y
WBS
o f t e n was l e s s t h a n 5 p e rc e n t .
e f f e c t e d by 5 o r 1 0 l a r g e t a b l e s
and ascousiderable.Nouldhave
beensaved by t h e main s l u i c e w i t h o u t t h e u n d e r c u r r e n t s , t l i e e c o n ony r e s u l t i n g f r o m t h e i r u s e was perhapsdoubtful.Bowielpresents
of u n d e r c u r r e n t s i n e a r l y C a l i f o r n i a n p r a c t j c e
detailsoftheuse
and indicates that their particular field lay in the treatment
'of
cement g r a v e l s . Of t h es e v e r a lu n d e r c u r r e n t so b s e r v e 3
by t h e
a u t h o r si nu s ei n
1932 it i s d o u b t f u l i f many w e r e j u s t i f y i n g
t h e i ri n s t a l l a t i o n .
Operation of Sluice-Boxes
I
_
-
"Under f a v o r a b l ec o n d i t i o n s a properlydesignedandconstructed
s l u i c e - b o xr e q u i r e sl i t t l ea t t e n . t i o no t h e rt h a np e r i o d i cc l e a n - u p s
andminor r e p a i r s which a r e made a t t h e same time.Unfortunately,
such a combinationrarelyoccurs,andanappreciablepart
of t h e
m i n e r ' s . o p e r a t i n g e x p e n s e i s c h a r g e a b l e t o work a l o n g t h e s l u i c e
lines.
"The b e s t r e s u l t s a r e o b t a i n e d
when a s t e a d y f l o w of waterand
g r a v e lp a s s e st h r o u g ht h es l u i c e .
An excessiveflow
c f c l e a rw a t e r
t h r o u g h t h e s l u i c e will b a r e t h e r i f f l e s , c a u s i n g
some g o l d t o b e
l o s t . On t h eo t h e r- h a n d ,
a continuedoverload
of g r a v e l w i l l plug
for t h e
t h e s l u i c e a t some p o i n t so t h a t s l u i c i n g mustbestopped
may be appretimeneeded t o c l e a r t h e o b s t r u c - t i o n ; t h i s t i m e l o s t
c i a b l e .I fp l u g g i n gc a n n o tb ep r e v e n t e db yi n c r e a s i n gt h eg r a d e
or
theflowofwater
or reducingthefeed,
one o r n o r e s l u i c e t e n d e r s
m u s t work a l o n g . t h e s l u i c e w i t h r o c k ' h o o k s , f o r k s
or s h o v e l s , t o
All
keep it open. T h i s added c o s t may b es e r i o u sa ts m a l lm i n e s .
effortshouldbedirectedtowardgetting'thegravel
i n t o t h e box
and l e t t i n g t h e w a t e r do t h e r e s t .
"Largebouldersareanothercause
of expense and . l o s tt i m e .
When t h e maximum s i z e of b o u l d e r t h a t t h e s l u i c e
will (carry i s
CiliBowie, i. J . P. P r a c t i c a lT r e a t i s e on Nydraulic?liningin
f o r n i a ; Van bIostrsnd Go., Nevi York, 3d ed. 1889, pp.252-262.
-
57
-
,
known, a l l b o u l d e r s . l a r g e r t h a n
t h i s shouldbeprevented
f r o m enteringtheboxes.Relativelylittle
work d i r e c t e d ' . t o t h i s end w i l l
wear
savehours o f d e l a y i n c l e a r i n g p l u g g e d s l u i c e s a n d u n n e c e s s a r y
and t e a r on t h e boxesand r i f f l e s .
"An e x c e p t i o n i s found i n t h eo p e r a t i o n of'booming.'
A necessaryconditionofthis
work is a heavyhead of water which usually
. f i l l s t h es l u i c et ot h eb r i m .
Sometimes l i t t l e or .nowork can be.
done i n t h e p i t w h i l e . t h e w a t e r
i s on,and t h e e n t i r e crew may
p r o f i t a b l yp a t r o lt h es y u i c ew i t hl . o n g - h a n d l e ds h o v e l st og u a r d
.
against stoppages which might
be d i s a s t r o u s b e c a u s e o f t h e l a r g e
f l o w of waterandgravel.Beforeeach
.'boom' a l l 'over-sizeboul' d e r s s h o u l d be moved o u t of t h e c o u r s e of t h e w a t e r .
Cleaning up
"Clean-uptimeshouldbekept
t o a minimum. Thi.scanbedone
by c l e a n i n g up a s s e l d o m a s p r a c t i c a b l e a n d b y u s i n g e f f i c i e n t
if t h ew a t e rs e a s o n
metinods. L a r g eh y d r a u l i cm i n e s , ,, p a r t i c u l a r l y
isshort,clean
up only Once a seasonexceptperhapstheupperone
o r twoboxes.Dredgescleanupevery
10 da.ys or 2 weeks,because
i n relativelyshortsluices
largeamounts o f g o l da r er e c o v e r e d
l o s s when t h e u p p e r r i f f l e s
become h e a v i l y
withattendantpossible
c h a r g e d .T h i sn e c e s s a r yd e l a yi su s e df o rr o u t i n er e p a i r s
on t h e
d r e d g e .I ng r o u n d - s l u i c i n gt h ec l e a n - u pp e r i o dr a n g e sf r o m
weeks
t o months,while
i n shoveling-in-operationsthesluice
may be part i a l l y c l e a n e d up daily:
The danger of t h e f t from t h eu p p e r ,
richerboxescan
be l e s s e n e d by f i l l i n g them w i t h g r a v e l a t t h e
end o f each day's work,
"The g e n e r a l p r i n c i p l e i s t h e same i n a l l clean-upoperations,
i s r u nt h r o u g ht h es l u i c e
b u tp r a c t i c ed i f f e r sw i d e l y .C l e a rw a t e r
untiltherifflesarebare,thestreambeingreduced
enough t o p r e v e n tw a s h i n go u tt h eg o l d .
Then t h e w a t e r is t u r n e do f f
or reduced
' t o a verysmallflow,andtheriffles
of t h e f i r s t box a r e l i f t e d ,
washed c a r e f u l l yi n t ot h e
box,and
s e ta s i d e .
Bny burlaporother
fabricusedundertheriffleslikewise
i s takenup,rinsedintothe
b o x ,o rp l a c e di n
a t u b of waterwhere
it canbethoroughly
scrubbed.
Then t h ec o n t e n t s of t h es l u i c ea r es h o v e l e dt ot h eh e a d
of thebox,anypackedclaybrokenupandthen'.streamed
down' w i t h
a l i g h t ?low of w a t e r( s e eP l a t e
X V , i , j . The l i g h ts a n d i s washed
away,androcksandpebblesareforked-outby.hand.Thisoperat i o n i s repeateduntiltheconcentratesarereduced'tothedesired
Gold o r amalgam may bescoopedup,
a s it l a g s
degree of r i c h n e s s .
at thisstage(seePlate
XV R ) , o r
behindthelightestmaterial
alltheblacksandwiththegold,mercury,
and amalgam may be removed.and s e t a s i d e for f u r t h e rt r e a t m e n t .S u c c e s s i v eb o x e sa r e
i s b a r e . The l a s t ' s t e p i s t o
t r e a t e ds i m i l a r l y ,u n t i lt h es l u i c e
work o v e r t h e w h o l e s l u i c e w i t h b r u s h e s a n d s c r a p e r s t o r e c o v e r
.
1-
goldand
amalgam c a u g h ti nc r a c k s ,n a i lh o l e s ,
or c o r n e r s . A t
onemine a small boxwas s e t up i n t h e main s l u i c e a:nd t h e conc e n t r a t e from t h e r i f f l e s s h o v e l e d i n t o
it t or e d u c et h eb u l k .
At
a n o t h e r t h e c o n c e n t r a t e from t h e lower s e c t i o n of t h e s l u i c e was
a quartz m i l l ,
.
t r e a t e di n
D i s t r i b u t i o n of Gold i n t h e S l u i c e
The d i s t r i b u t i o n of t h e g o l d i n a s l u i c e i s control1,ed by i t s
c o a r s e n e s s ,t h el e n g t h
of t h e s l u i c e , and by i t s g r a d e , t h e
amount
of waterandprobably
t o some e x t e n t by t h e t y p e of r i f f l e u s e d .
The s l u i c e s used i n h y d r a u l i c m i n i n g
a r e as a r u l e mwh l o n g e r t h a n
t h o s e common i np l a c e rm i n i n g .T h i sg r e a t e rl e n g t h
i s n o tn e c e s s a r y
for s a v i n g t h e g o l d b u t r a t h e r
for c a r r y i n g t h e g r a v e l
to t h e dump
which may be a c o n s i d e r a b l e d i s t a n c e from t h e p i t .
I n t h ef o l l o w i n g
t a b l e t h e r e s u l t s of c l e a n i n g u p s e p a r a t e b o x e s a l o n g , t h e s l u i c e
l i n e a t t h e La Grange m i n d a r e g i v e n .
The g r e a t e r p a r t o f t h eg o l d
was caught i n t h e f i r s t 250 f e e - t of t h e s l u i c e .
The b o x e sa r e 1 2
f e e tl o n g ,t h eg r a d e5 . 5 p e r c e n t ,w i d t h
of s l u i c e 6 f e e t .
Use of Q u i c k s i l v e r i n S l u i c i n g
"
"
I!
Quicksilver i s used at nearly all placer mines in California.
If it i s n o t u s e d t o c a t c h g o l d
:in t h e s l u i c e s , a t l e a s t
it i s
probablyusedinextractingthegoldfromtheconcentrates.
"The c h a r a c t e r i s ' t i c s of q u i p k s i l v e r t h a t make it of v a l u e t o
(1) I t s power of a n a l g a m a t i n gw i t hg o l da n ds i l v e r ;
t h em i n e ra r e :
( 2 ) i t sh i g hs p e c i f i cg r a v i t y
(1.3.5), whichcauses
it t o l i e
Bouery, P . , Eng. andNin.Journ.,vol.
-
59
-
35,
VG.
21;
.L913, . p . 1059
s a f e l y u n d e r a stream o f water and g r a v e l , f l o a t i n g o f f on i t s
s u r f a c ee v e r y t h i n gb u tt h en a t i v em e t a l s ;a n d
(3j its relatively
675 degrees i'. ) , f a r below r e d h e a t ,
low b o i l i n g p o i n t ( a b o u t
from the gold with which
whichallows it t o b e d r i v e n o f f b y h e a t
it hasamalgamated.
"fmalgamation i s a process i n which mercur-y a l l o y s w i t h
a n o t h e rm e t a l A
. l l , m e t a l sb u t
i r o n and platinum amalgamate more
or l e s sr e a d i l y .C l e a n
and c c a r s ep l a c e rg o l da l l o y sr e a d i l y ,b u t
i f t h e g o l d i s p a r t l yc o a t e dw i t hi r o no x i d e
o r o t h e rs u b s t a n c e s
it a m a l g a m a t e sw i t hd i f f i c u l t y .
The
( f o re x m p l e ,' r u s t y 'g o l d )
mercury i t s e l f s h o u l d b e . c l e a n
enough t o p r e s e n t a smoothshiny
s u r f a c e ;t h ep r e s e n c e
of some gold o r s i l v e r i n t h e q u i c k s i l v e r ,
i s , t o make it
however, i s s a i d t o f a c i l i t a t e a m a l g a m a t i o n , t h a t
more ' a c t i v e . '
" Q u i c k s i l v e r i s p l a c e dc a r e f u l l yi nt h es l u i c e - b o x e s ,w h e r e
it f i n d s i t s way t o t h e many r e c e s s e s i n t h e r i f f l e s and l i e s i n
scatteredpools,readyt'oseize
a n dh o l da n yp a r t i c l e
of g o l d t h a t
manner i n almost a l l importanthytouches it. I t i s u s e di nt h i s
d r a u l i co p e r a t i o n s ,b u t
some o p e r a t o r sp l a c e it i n t h e boxesonly
shortly before the .clean-up evidently believing that the
added
i t s u s ed u r i n gs l u i c i n gd o e sn o t ' c o m p e n s a t e
for t h e
goldsavedby
loss of the mercury that passes through the sluice with the
taili n g so r ' e s c a p e st h r o u g hc r a c k s
or o t h e rl e a k s .I ne x c e p t i o n a l
i n s t a n c e st h ec o n d i t i o n sa r es u c ht h a tt h em e r c u r y' f l o u r s , 't h a t
i s , b r e a k si n t o minute, d u l l - c o a t e d d r o p s .
F l o u r i n g i s aggravated
by a g i t a t , i o n o r exposure o f t h e mercury t o a i r . The common pract i c e o f ' s p r i n k l i n g ' it i n t os l u i c e - b o x e sn a y
be condemnedon
for thereasonthatthefineparticles
thisground,aswellas
formed by c a r e l e s s s p r i n k l i n g a r e mere r e a d i l y washedawayand
l o s t . F l o u r i n g i s r e s p o n s i b l e f o r t h e m o s t s e r i o u sl o s s e s of
quicksilver with the tailings.
5 t o ,1 0p e rc e n to ft h e
mer"Even u n d e r t h e b e s t c o n d i t i o n s ,
curyused
i s l o s t . If s t e e pg r a d e s ,h e a v yg r a v e lw i t hc o n s e q u e n t
o r o t h e ra d s e v e r ep o u n d i n ga n dv i b r a t i o n ,o l da n dl e a k y . s l u i c e s ,
v e r s ec o n d i t i o n se F i s t ,t h e
l o s s of mercury may be 20 or 25 per
cent.
"Oniy c l e a n m e r c u r y s h o u l d b e . p l a c e d i n
a s l u i c e ; e;en t h i s
t e n d s t o become f o u l e d o r s l u g g i s h a n d t o l o s e
i t s effectiveness.
i s r e t o r t i n g , which is d i s c u s s e d l a t e r .
The b e s t c l e a n s i n g p r o c e s s
However, s t r a i n i n g t h e m e r c u r y t h r o u g h c h a m o i s
or t i g h t l y woven
c l o t h removes 'some of t h e s u r f a c e scum and f o r e i g n m a t e r i a l , o r
t h e m e r c u r y may be t r e a t e d w i t h p o t a s s i u m c y a n i d e
or o t h e r chemiI t shouldbehandled
aslittle
c a l st od i s s o l v et h ei m p u r i t i e s .
as p o s s i b l e a n d k e p t f r o m c o n t a c t w i t h g r e a s e o r ' o t h e r o r g a n i c
material.
- 60
-
\
/
Plate XVI A. Cleaning bedrockby hand. At Gemansen Tenturea
the bedrock is hard and irregular
so that it is impossible
to clean it adequately with the giant.
One man is
continuously employed cleaning out all
the craoks by hand.
Plate ](VI B . Retorting amalgamfrom the clean-upbarrel over
a blaoksmith's forge. The mercury is condensed by the
sacking immersedin the water bucket at the right.
"Wilson1 suggests a cow's.horn, sawed o f fn e a rt h es m a l l
end
t o l e a v e a holethatcan
be stopped w i t h t h e f i n g e r , :as a u s e f u l
implement f o rc h a r g i n gs l u i c e s .
Most miner's charge t:he S l u i c e
f r o m stoneware o r h e a v y g l a s s b o t t l e s .
"Mercuryshould
be kept o r c a r r i e d o n l y i n i r o n , g l a s s ,
or
of i t s t e n d e n c y t o i m a l g a m a t e w i t h
earthenware containers because
z i n c( g a l v a n i z e di r o n ) ,t i n ,
o r o t h e rm e t a l s .
"The q u a n t i t y of q u i c k s i l v e r u s e d . d i f f e r s a c c o r d i n g t o c o n d i t i o n s andcustom.According
t o Bowie2, 200 or 300 f e e t of 6-foot
s l u i c es h o u l dr e c e i v ea b o u tt h r e ef l a s k s
( 2 2 5 pounds)as a f i r s t
chargeand a 24-footsquareundercurrent,80
or 9 0 pounds. A t t h e
Depot Hill mineone f l a s k i s p l a c e d i n t h e
f i r s t 4 o r 5 boxeseach
A
t t h e P l a t a u r i c a two f l a s k s
'month duringthewashingseason.
wereused
i n a seasonduringwhich100,000cubic
yard:;was.washed.
Dredge t a b l e s , w i t h a r e a s
of 1,000 t o 10,000 s q u a r e f e e t , a r e
t o 3,000 pounds of mercury.According
t o J a n i n 3,
charged with 150
a 7-foot dredge with
a t a b l e a r e a o f 2,800squarefeetusesabout.
1,000pounds on t h e s l u i c e s and , i nt h et r a p s .
Probab1.y i n common
p r a c t i c et h er a n g e
is 1/10 t o 1 / 4 pound p e rs q u a r ef o o t
of s l u i c e
area.
'
"The s l u i c e s h o u l d b e
r u n longenough t o p l u g a l l . l e a k s b e f o r e
o n l y t h eu p p e r 2 or 3 boxes o r a
themercury i s added.Usually
q u a r t e r o r h a l f of t h e s l u i c e a t most i s charged with mercury, as
o t h e r w i s ec o n s i d e r a b l el o s so c c u r s .D u r i n g
a run more mercury i s
a d d e dp e r i o d i c a l l y .
Whenever t h e s l u i c e i s r u n down mough t o exshow
p o s et h er i f f l e st h em e r c u r y . c a n
be examined. If i t doesnot
surfaces nearly to the t o p cf the rifhereandtherewithclean
f l e s , more i s added. As t h e q u i c k s i l v e r t a k e s up goldnear $he
head of t h e s l u i c e it becomes p a s t y a n d f i n a l l y q u i t e h a r d ,
and
more shouid beadded t o keep it i n a f l u i d c o n d i t i o n . "
In B r i t i s h Columbia t h e u n i v e r s a l p r a c t i c e
is not t o usemerc u r yi n t h e s l u i c e - b o x e s , buton.lyforamalgamating
t h k concent r a t e s from theclean-ups.
The probable reason for t h i s i s t h a t
withanefficientsluice-boxthegold
i s c o a r s e enough t o be saved
r e a d i l y and t h a t t h e mercury l o s t c o s t s more t h a n t h e a d d i t i o n a l
amount o f f i n eg o l dt h a t
it mightrecover.This
i sp a r t i c u l a r l y
o f mercury.
trueatpresentwiththeconsiderablyincreasedcost
-
Wilson, E . B . , HydraulicandI'iacer
New York, 3d e d . , 1918, p.240.
H m i n g : JohnWiley
& Sons,
Bowie, A. J . , work c i t e d , p . 244
J a n m ,C h a r l e s ,
Gold iiredging,intheUnlted
BureauofXines,1918,
p 143.
- 61.
-
S t a t e s ; B u l l . 127,
~
"The use o f k e r c u r y i n r e c o v e r i n g
g o l d i'roni sluic'e-boxconc e n t r a t e s i s d i s c u s s e di nt h ef o l l o w i n 5s e c t i o n .
"&nalgamating plates should be'used
only i n t r e a t i n g f i n e mat e r i a l , g e n e r a l l y w e l l under a q u a r t e r o f a n i n c h i n , s i z e andpref
e r a b l yn o tc o a r s e rt h a n
1 0 - m e s h ,a sl a r g e rp a r t i c l e sa b r a d et h e
o r t h e amalgam.Consep l a t e s t o o r a T i d 2 y andpreventbuildingup
of p l a t e s ' t o p l a c e r m i n i n g
i s limited t o
quently,theapplication
thestampmilling
of some d r i f t - m m e g r a v e l s a n d t h e t r e a t i n g
of
The use,of
plates i n
f i n eu n d e r c u r r e n t or otherscreen.edsands.
stalnp m i l l i n g i s a phase of m e t a l l u r g y beyond t h es c o p eo ft h i s
i s made t o any s t a n d a r d t e x t o r hand.boolc on
pa?er,andreference
goid mil'ling.
of amal.gam p l a t e s t o p l a c e r
"None of t h e o t h e r a p p l i c a t i o n s
mining is of p a r t i c u l a ri m p o r t a n c e ,p r o b a b l yb e c a u s et h er e c o v e r i e s
seldomhave j u s t i f i e d t h e l a b o r
andexpense.Plates
may be s e t i n
u n d e r c u r r e n t st r e a t i n gf i n e l ys c r e e n e ds a n d s ,s u c ha sb e a c hs a n d s
or theSnake-Rivergold-bearingsands.
They u s u a l l ya r ec o v e r e d
w i t h b u r l a p t o a s s i s t i n r e t a i n i n g t h e g o l d u n t i l i t has come i n
contactwiththe'amalgam.
Nany o t h e r ama1.gamating deviceshavebeen
none i s known t o t h e a u t h o r s t o have
applied t o suchmaterial,but
been of g r e a t e r v a l u e t h a n p r o p e r l y d e s i g n e d s i u i c e s a n d r i f f l e s . "
- 62
-
SEPARATION OF
-
GOLD AND PLATINUH-GROUP METAL?
FROM
CONCENTRATES
General
"
I
"No s l u i c e - b o x o r o t h e rt y p e o f goidsaverused
j.n l a r g e - .
vE.luable
s c a l e p l a c e r m i n i n g makes a c l e a n s e p a r a t i o n of t h e
m i n e r a l s . The c o n c e n t r a t e obtainedmust be t r e a t e d f u r t h e r t o
make a marketable.product.Concentrateobtained
i n cl.eaningbedr o c k in some typesofmining
i s treated.similarlytosluice-box
concentrates.
"The c o n c e n t r a t e may becleaned
by panning, o r r o c k i n g , i n
.
a u x i l i a r ys l u i c e s , o r by blowing, o r it may be amalgamated in a
s p e c i a lt y p e o f apparatus,. The t r e a t m e n t will dependmainly upon
t h e s c a l e of o p e r a t i o n s , t h e p r o p o r t i o n
of blacksand
in t h e conc e n t r a t e ,a n dt h ec h a r a c t e r i s t i c s
of t h e g o l d . The generalmethods of c l e a n i n g c o n c e n t r a t e w i t h p a n s , r o c k e r s ,
o r s m a l ls l u i c e s
that more
a r e t h e same a s t h o s e i n s m a l l - s c a l e o p e r a t i o n s e x c e p t
care i s required and smaller quantities are treated at, one time.
I nt r e a t i n gs m a l lq u a n t i t i e s
ofconcentrate,however,
it should
beremembered
t h a t c o l o r s of g o l d s o f i n e a s t o p r e s e n t g r e a t d i f of
ficulty in their separation
by panning o r rocking are probably
smallvalue,
and t h e i r l o s s would beinconsequential.
"If p r e c i s e r e s u l t s a r e d e s i r e d f o r s a m p l i n g
or testing, the
c o n c e n t r a t e s s h o u l d beamalgamated r a t h e r t h a n a s s a y e d by t h e
u s u a l f i r e methqd.
Pam:%
"Panning is t h e s i m p l e s t method of s e p a r a t i n g t h e v a l u a b l e
c o n s t i t u e n t s from t h e w o r t h l e s s m a t e r i a l and g e n e r a l l y i s used
i ns m a l l - s c a l e . o p e r a t i o n .
The method,however,
i s t e d i o u s if t h e
gold i s very f i n e and t h e c o n c e n t r a t e c o n t a i n s
much bl.%ck.sand.
Hercury may then be used
i n t h e pan t o c o l l e c t t h e g o l d .
R0ckj.s
" L a r g e r q u a n t i t i e s o f c o n c e n t r a t e may be t r e a t e d :in a rocker
and t h er e s u l t i n gs e m i f i n a lp r o d u c tc l e a n e df u r t h e r
iri a pan.
h
finaloralmostfinalproduct,
however,canbe
made in a r o c k e r ,
t h e f l a t , smoothbottom o f w h i c h , s e t on a g e n t l e g r a d e w i t h s c r e e n
andcanvasbaffle
removed, o f f e r s an i d e a l s u r f a c e f o r t h ep u r p o s e .
"The. c o n c e n t r a t e s a r e p l a c e d a t t h e u p p e r e n d , a n d
a small
i s swayed
stream of water i s pouredoverthesandwhlietherocker
f o r t h . The l i g h t e r m a t e r i a l i s washed down t o t h e
g e n t l y backand
- 63
2
I
I
r i f f l e a t thelowerend,andthecoarserpartic1es.ofgoldare
up with a s c r a p e r ,a n dt h eo p e r a t i o n
l e f t behind.Thesearepicked
i s r e p e a t e d , a p o r t i o n of t h e c o n c e n t r a t e s p r e s e n t l y b e i n g d i s c a r d e d
with each washing until at length all'gold of appreciable value has.
beenrecovered,This
method i s s a t i s f a c t o r yw i t ho r d i n a r yc o n c e n i f t h eg o l d i s v e r y f i n e , f l a k y ,
or p a r t i c u l a r l y , l i g h t ,
t r a t e s ,b u t
i s t e d i o u sa n du n s a t i s f a c t o r y ,
porogs, o r a n g u l a r ,t h es e p a r a t i o n
andamalgamation i s t o be p r e f e r r e d .
-
"Thesame
cover the bulk
g e n e r a l method may beused
of t h e g o l d amalgam.
i p t h e mine slui,ce
t o re-
Auxiliary Sluices
"Sometimes a n a u x i l i a r y s l u i c e
i s used t o r e d u c e t h e
volume of
concentratefromtheminesluice
or t o treat concentrate after
it
i s amalgamated. The small s l u i c e i n t u r n
m u s t becleanedup.
.4t
onemine a 12-inch box was s e t up i n t h e main s l u i c e i n t o which was
shoveledtheriffleconcentratefrom
below.
"The g r a i n s of s a n d r e m a i n i n g i n a n a l m o s t f , i n a l p r o d u c t
may
be removed from t h e g o l d by blowing. A f l a t m e t a l or papersheet;
2 feet
5uc.h as a p i e c e o f drawingpaper o r a l a r g e f l a t t i n a b o u t
s q u a r ew i t ht h ee d g e sb e n t
up a b o u t h a l f a n i n c h , i s b e . s t f o r t h e
purpose. However, w i t hc a r e and s k i l lt h eo p e r a t i o nc a nb ep e r formed i n a common goldpan,as
i s done by many'prospectors..The
m a t e r i a ls h o u l db ep e r f e c t l yd r y .
Xuch e f f o r t i s saved by u s i n g
a magnet t o t a k e o u t a n y m a g n e t i t e s a n d i n t h e c o n c e n t r a t e s : o f t e n
t h i sm i n e r a lc o m p r i s e sa s
much a s ,9O percent
o f t h em a t e r i a l .
k
p i e c e of paperfoldedaround
or heldagainstthe
end of themignet
w i l l k e e pt h em a g n e t i t ef r o ms t i c k i n g
t o t h em e t a l .
When a l l t h e
magnetite i s removed, blowing gently on the remaining sand and
t o t h e f a r e d g eo ft h es h e e t ,l e a v i n g
gold w i l l d r i v e t h e f o r n e r
m o s t i n s t a n c e s t h e l o s s of a few f i n e c o l o r s
t h eg o l db e h i n d .I n
isnotserious.
Amalgamation
InOrdinary
Gold Pans
"A smal'l q u a n t i t y of q u i c k s i l v e r , r a n g i n g f r o m a n o u n c e t o
a
quarterof a teaspoonful, w i l l c a t c h a l l t h e g o l d
f r o m a pan of
s l u i c ec o n c e n t r a t e s .
The mercury i s s i m p l yp l a c e di nt h e
pan w i t h
about5.pounds of c o n c e n t r a t e s and a g i t a t e d u n d e rw a t e ru n t i l
no
more f r e e g o l d c a n
beobserved.
Then t h es a n d sa r e
panned o f f ,
carebeingtakennottoloseany
of t h e amalgam o r f i d e d r o p s . o f
w i l l r u n ,t o g e t h e ri n t o
a singlemass.
mercury,whichgradually
If t h e c o n c e n t r a t e s
are n e a r l y a l l b l a c k s a n d o n l y
should be washed a t a time,but
if much l i g h t s a n d
entlargerquantitiescanbewashed.
a small q u a n t i t y
or rock i s p r e s -
or p a n s w i t h s t e e l
rims andcopperbottoms
"Copper-platedpans
for s a v i n g f i n e g o l d i n c o n c e n t r a t e s .
a r e a v a i l a b l e a n da r eu s e f u l
The copper i s coated with mercury by f i r s ' t c l e a n i n g it w i t h emery
paper,thenrubbingclean,brightmercury
or amalgamon it u n t i l it
p r e s e n t s a smooth,shinysurface.
The gold i n t h em a t e r i a lb e i n g
t r e a t e di sp i c k e d
up q u i c k l y by t h e amalgam s u r f a c e . Only f i n e
or g r a v e l will
s a n dc a nb et r e a t e dt oa d v a n t a g ea sc o a r s es a n d
s c o u r t h e amalgam o f ft h ec o p p e r .
As f a s t a s amalgam accumulates
on t h ec o p p e r it i s scraped o f f w i t h a smcoth,dull-e3ged,iron
s c r a p e r s u c h a s a p u t t y k n i f e . Hore mercury may t h e n be added t o
k e e p t h e s u r f a c k b r i g h t a n d i n a ' r e c e p t i v e ' conditi0.n.
Amalgamators
t
" I n l a r g e - s c a l eo p e r a t i o n sw h e r e? o s t
of t h e g o l d i s amalgamated i n t h e s l u i c e - b o x e s
or on t h e r i f f l e - t a b l e s , t h , ? amalgam i s
s e p a r a t e df r o m t h es a n d sd u r i n gc l e a n - u po p e r a t i o n s
o r from t h e
or r u s c yg o l d o r
c o n c e n t r a t e s by rocking or panni.ng.Tarnished
v e r yf i n eg o l d ,
however,doesnotamalgamate
r e a d i l yb e c a u s e it i s
Such
d i f f i c u l t t o make contactbetweenthegoldandquicksilver.
g o l d ,g e n e r a l l yi n c l u d e di n
a b l a c k - s a n dc o n c e n t r a t e ,r e q u i r e s
of q u i c k s i l v e r , or, if r u s t y ,g r i n d i n g
a g i t a t i o n i nt h ep r e s e n c e
t o remove t h e i n t e r f e r i n g c o a t for s a t i s f a c t o r y amalgamation.
"ifechanicalamalgamatorsareusedtotreatsuchmaterials.
wj.11 be treated
O c c a s i o n a l l y a l l of t h e c o n c e n t r a t e f r o m t h e s l u i c e
i na na m a l g a m a t o r ,p a r t i c u l a r l y
i f it c o n t a i n s r u s t y @ ; o l d . The
charges for t h e amalgamator should be kept clean; gre&;se especially
i n t e r f e r e s w i t h anialgamation.
i s t h ec l e a n - u p
"-4 commcn typeofamalgamator
par.,whichconor tub 1
or 2 feetindiameter
f o r s m a l l - s c a l e work a n d h t o 6 f e e t i n
diameter for nil1 s e r v i c e . The. o o n c e n t r a t ew i t h 1 or 2 percent
q u i c k s i l v e r by weight i s placed i n t h e pan w i t h s u f f i c i e n t w a t e r
t o make t h e mass f l u i d and a g i t a t e d by a r e v o l v i n g s p i d e r .
The
q u a n t i t y of wateraddedshould
be s u f f i c i e n t o n l y t o p e r m i t a g i t a t , i o nw i t h o u tt o og r e a ts t r a i no nt h em a c h i n e .
The p u l p should
be t h i c k enough t o h o l d p a r t i c l e s of mercuryinsuspension.Shoes
on t h e lowerend of t h e s p i d e r arms s l i d e on a f l a t , c i r c u l a r r a c e
i n t h e b o t t o m of t h e b a r r e l , t h u s a d d i n g
some g r i n d i n g t o t h e a g i t a t i o n . .After running f o r 1 o r 2 h o u r st h eb a t c h
may be emptied
of t h e b a r r e l and t h e m e r c u r y
through a d r a i n p l u g i n t h e b o t t o m
and amalgarn s e p a r a t e d f r o m t h es a n d by panning. Some pans a r ep r o vided with s i d ed r a i n plugs a t v a r i o u s e l e v a t i o n s . The r . o t a t i o n
s i s t s of a c a s t - i r o n , c y l i n d r i c a l , f l a t - b o t t o m e d b a r r e l
'
-
65
-
may t h e n beslowedfrom
i t s usualspeed o f about 60 '.p.m.,
the
,Aop t h eg r i n d i n g .a n dw a t e ra d d e d .T h i s
s h o e sr a i s e de n o u g ht o
w i l l s e t t l e t h e q u i c k s i l v e r andamalgam; t h e w a s t e s l u d g e c a n t h e n
be f l u s h e d o u t t h r o u g h t h e u p p e r d r a i n p l u g s a n d a l m o s t c o m p l e t e
c l e a n i n g o f t h e amalgamandmercury
made i n t h e pan i t s e l f .
"Another device, the
'amalgam b a r r e l , g e n e r a l l y i s used a t
largestamp n i l l s and i s employed i n p 9 c e r o p e r a t i o n s , p a r t i c u l a r l y
i nd r e d g i n ga n dl a r g eh y d r a u l i co p e r a t i o n s
t o t r e a ta c c u m u l a t e d
b l a c ks a n d s ,s c r a pm e t a l ,a n do t h e rp o s s i b l eg o l d - b e a r i n gm a t e r i a l
fromclean-upoperatiqns.
I t i s merely a c a s t - i r o n o r s t e e l drum
revolving on a h o r i z o n t a l a x i s l i k e
a b a i l m i l l and f i t t e d w.ith
or removableends,des u i t a b l ed r a i np l u g s ,h a n d h o l e s ,m a n h o l e s ,
pending on i t s s i z e a n d u s e . T h e , m a t e r i a l t o b e t r e a t e d
i s placed
inthebarrelwithquicksilver,water,
and a few i r o n b a l l s o r
rocksandthebarrel
i s t u r n e d s l o w l y f o r a n h o u r or s e v e r a l h o u r s . "
I f , however, t h eg o l d i s t a r n i s h e d anddoesnotamalgamate
readilythebarrelshouldbechargedwithoutthemerpuryand
rot a t e d for a n hour o r two t os o o u rt h eg o l d .
Then t h em e r c u r y
shouldbeaddedandtherotationcontinued
for a f u r t h e r 1 t o 2
I n t h i s way e x c e s s i v e" f l o u r i n g " of themercurycan
be
hours.
prevented.
"The b a r r e l may t h e n b e f l u s h e d w i t h w a t e r f r o m
a hose.to
wash away t h e l i g h t e r p r o d u c t s
of grinding,turnedover,and
empt i e d i n t o a t u b , t h e amalgamandmercurybeingrecoveredbypanning, or b e t t e r s t i l l byrunningthrough
a verysmall,riffled
is
s l u i c ec o n t a i n i n g a mercurytrap.Potassiumcyanidesometimes
added t o b r i g h t e n t h e g o l d , u s i n g o n l y
enough t o make a v e r y weak
l y e may be added i f t h e c o n c e n s o l u t i o n , a l s o a small amountof
tratesaregreasy.
1 ounceof
To make up a c y a n i d e s o l u t i o n d i s s o l v e
98 per
centpotassiumcyanideinhalf
a g a l l o n of w a t e r , t h e n use 4 ounces
(0.r a b o u t h a l f
a t e a c u p ) of t h i s s o l u t i o n t o 30 g a l l o n s o f w a t e r .
"An amalgamator t h a t o c c a s i o n a l l y i s u s e d , e s p e c i a l l y i f a
part o f thegold i s a t t a c h e d t o p a r t i c l e s
of q u a r t z , ' i s t h e Berdanpan,which
i s r e l a t i v e l y s i m p l e i n c o n s t r u c t i o n andcheap t o
o p e r a t e . Thepan
c o n s i . s t s of a r e v o l v i n gc a s t - i r o n bowl,usually
3 t o 5 ,feet in diameter, with
a r a i s e d c e n t r a l hub f o r t h e d r i v e
'it the':forh. of
a:. c i r c u l a rt r o u g h .
The
bowl
is
S h a f t ,g i v i n g
s u p p o r t e d e i t h e r by t h e d r i v e s h a f t
o r by r o l l e r s and i s s e t w.ith
20 o r ' 3 0 , d e g r e e sf r o mt h eh o r i z o n t a l .
It is
a tilt ofabout
d r i v e n a t 10 t o 30 r . p . m . e i t h e r
by a c r c w n g e a r o n t h e i n c l i n e d
s h a f t of t h e bowl o r by a r i n g g e a r o n t h e b o t t o m o f t h e , b o w l .
bowl
One o r two l a r g e c a s t - i r o n b a l l s r o l l i n t h e t r o u g h a s t h e
r e v o l v e s .Q u i c k s i l v e r .
i s p l a c e d i n t h e bowl w i t ht h ec h a r g e ,
and
asthedevicerevolves
a stream of w a t e r is d i r e c t e d i n t o it and
of t h e rim. The m a t e r i a J t o be
o v e r f l o w sa tt h el o w e s tp o i n t
amalgamated may beadded in b a t c h e s o r , i f it i s t o beground a s
w e l l a s amalgamated, by a na u t o m a t i cf e e d e r ,t h es l i m e sa n df i n e
a classifier.
m a t e r i a lo v e r f l o w i n gt ow a s t e ;t h e
bowl t h e n a c t s a s
F o r p l a c e rc o n c e n t r a t e st h eb a t c hp r o c e s s
i s used,100pounds
or
more b e i n g t r e a t e d a t
a time. Too l a r g e a q u a n t i t y of s a n dl e s sens the'grinding effect
of t h e b a l l s .
"A 1-, o r 2-cubicfoot,handor power-drivenconcretemixer
i s a convenient amalgamating devic~e for the
small- to medium-scale
p l a c e rm i n e ,p a r t i c u l a r l y
i f p a r t of t h e go1.d is rust:y. The charge
f o rs u c h a machine i s two o r t h r e e p a i i s of c o n c e n t r a t e s , 1 o r 2
pounds of q u i c k s i l v e r , a few roundcobblestones 3 o r 4 inches i n
diameter,andwater.
About a 1-hourtreatment
w i l l a.na1gamat.e
p r a c t i c a l l y a l l of t h e g o l d . The charge i s e m p t i e di n t o a s e t t l i n g
t u b and t h e n washed i n a pan or small siuice-box t o r e c o v e r t h e
amalgarn and mercury.
" R e g a r d l e s so ft h ea m a l g a m a t o ru s e d ,t o ov i o l e n ta g i t a t i o n
the mercury mustbeavoidedotherwiseexcessiveflouringhinders
amalgamation andmakes
it d i f f i c u i t o r i m p o s s i h i e t o : r e c o v e r t h e
quicksilver.
of
C l e a n 1 2 Amglgam
"The mixture of q u i c k s i i v e r andamalgam f r o m sluice-box cleanups u s u a i i y c o n t a l n s much more nlercurythan amalg%?. It canbe
f r e e d f r o m sand,scraps
of i r o n , a n do t h e rs o l i di m p w r i t i e s
by
carefulpanningandbywashlngwith
a j e t of cleanwa.ter.
The
amalgam canthen be s e p a r a t e d f r o m t h e q u i c k s i i v e r by s t r a i n i n g
themixturethroughbuckskin,chamoisskj.n,close
wovdn canvas,
o r o t h e rs t r o n g ,
t l g h t c l o t h . 31his g e n e r a l i y i s donebyhand,
preferablyunderwater
t o p r e v e n ts c a t t e r i n g of themsrcury.
The
q u i c k s i l v e r t h u s f i l t e r e d o f f c o n t a i n s a t t h e most on'iyaboutoneof g o l d :t h i sm e r c u r y
i s d e s i r a b l ef o rr e c h a r g i n g
t e n t h percent
t h eb o x e sa st h es m a l l
amount ofgold makes i t more a c t i v e . The
amalgam, a f t e rs q u e e z i n g ,
s t i l l c o n t a i n s some mercury,partof
which may d r a m o f f i f t h e mass i s suspended f o r s e v e : r a l h o u r s i n
a f u n n e l o r o t h e rs i m i l a rc o n t a i . n e r .W i t h
o r w i t h o u tt h i sl a s t
refinement,whichonedredgeoperatorusedwithsucce:;s,thestiff,
p a s t y amalgam is now ready f o r f i r e t r e a t m e n t t o s e p a ? a t e t h e
gold.
I t c o n t a i n s 25 t o 55 p e r ' c e n t comon.1.y about a t h i r d .by weight of
g o l d and s i l v e r .
- 67 -
,
I
"-
EXTRACTING GOLD FROM AiULGAH
"
,
,
Heating
"Although r e t o r t i n g i s t h e common methodof
separating the
g o l df r o mt h eq u i c k s i l v e ri na m a l g a m ' a td r e d g e sa n do t h e rl a r g e scale operations, the mercury in, small quantities
of amalgam may
R cornmon method i s t o h e a t t h e
be v o l a t i l i z e d by s i m p l e h - a t i n g . ,
amalgam on a c l e a n i r o n s u r f a c e o v e r a n o p e n f i r e
or f o r g e , o r i n
a f u r n a c e ,u n t i la l lt h em e r c u r y
i s d r i v e no f f .T h i s
i s t h eu s u a l
expedie.ntofthesingleminer
o r s m a l l o p e r a t o r who d o e s n o t o b j e c t
t o t h e l o s s of t h es m a l lq u a n t i t y
of q u i c k s i l v e ri n v o l v e d .
The mercuryvapor may appearasheavywhitefumes.Whethervisi.ble
o r not,
mercuryvapor
i s exceedinglypoisonous,andthe
work mustnotbe
done.exceptwhere a d r a f t c a n bedepended on t o c a r r y a l l t h e v a p o r
A s s t a t e de l s e w h e r e ,m e r c u r yb o i l sa t
67.5
away f r o mt h eo p e r a t o r .
degrees F., a temperature about half-way between the boiling point
o fw a t e ra n dt h ef i r s tv i s i b l er e dh e a t
of i r o n . However, it v o l a tilizes at the boiling point
of waterenough t o bedangerous t o t h e
to i>Consequently,
it shouldbehanh e a l t h ofpersonsexposed
t.,
i t s vapors.
t oa v o i di n h a l i n g
d l e dc a r e f u l l y ,p a r t i c u l a r l y
" I n a n o t h e r methodof
r e c o v e r i n g t h e g o l d fr.om small amounts
o f amalgam, a p o t a t o i s u s e da s a condenser.This
is a d e v i c e
popularwithprospectorsbecause
it i s v e r y s i m p l e , y e t s a v e s p a r t
ofthe.mercurythat
wouldbe l o s t by t h e method previously des c r i b e d . k l a r g ep o t a t o
i s c'utsmoothlyinhalf,and
i n theflat
s u r f a c e o f one h a l f a r e c e s s i s hollowed which shouldbe consid.e r a b l y l a r g e r t h a n t h e m o u n t of amalgam t o be t r e a t e d . The amalgam i s placedon a c l e a n s h e e t - i r o n s u r f a c e , t h e h a l f p o t a t o
is
p l a c e do v e ri t , , a n dt h ew h o l e
i s s e to v e r a h o t f i r e .
For convenience it may bedone i n a f r y i n g pan o r t h e s c r a p o f s h e e t
ironputon
a f l a t shovel so t h a t it canbewithdrawnreadily
of
f r o mt h ef i r e .
Some mercuryvapor will escapeundertheedges
t h ep o t a t o ,a n d ,a sb e f o r e ,t h e s e
fumes m u s t beavoided.After
15 or' 20 minutes o f s t r o n g h e a t i n g t h e p o t a t o
may be '.lifted .off
If a l l t h e mercury i s gone f r o m t h e g o l d t h e
pof o ri n s p e c t i o n .
a c o n s i d e r a b l ep a r to ft h e
t a t 0 may becrushedandpanned,and
mercury w i l l be r e c o v e r e d . I t may b e d e s i r a b l e t o h e a t t h e g o l d
furthertoanneal
i t ; t h i s c a n bedonewithoutrernoving
it f r o m
t h ei r o np l a t e .
Any t i n n e d o r g a l v a n i z e dm e t a li n t e n d e df o ru s e
inthisprocessspuldbeheatedredhotandthenscoured
t o remove a l l t r a c e s of t h e c o a t i n g so t h a t a c l e a n i r o n s u r f a c e w i l I
be p r e s e n t e d .
"A l a b o r a t o r y methodof
separatingthegold
is toputthe
a 1 to 1
amalgaq i n a small beakeranddissolvethemercuryin
s o l u t i o n of n i t r i c a c i d andwater.
When a l l t h e mercury i s d i s s o l v e d ,t h eg o l d
may remain as a sponge,whichcanbewashed
-
68
-
g e n t l y i n waterandannealed
i n a s m a l lp o r c e l a i nc r u c i b l e .
Xore
a f i n e d u s t , w h i c ha l s o
f r e q u e n t l y t h e g o l d will b e r e c o v e r e d a s
canbewashedandannealedbut
i s l e s se a s yt oh a n d l e .
."
Retorting
"A very s r n a l l amount of amalgam can be r e t o r t e d q u i c k l y and
t o 24 incheslong,
e a s i l y i n a l a b o r a t o r y i n a g l a s st u b e1 8
s e a l e d a t oneendand
b e n t 2 o r 3 inches f r o m t h a t end t o a
k l a r g et u b et h r e e - q u a r t e r s
of a ni n c hi n
s l i g h t l ya c u t ea n g l e .
d i a m e t e ri sb e s t .
The amalgam i s b r o k e ni n t op i e c e s
small enough
t o be d r o p p e d i n t o t h e c l o s e d
en.d where it i s t h e n h e a t e d , t h e
fumescondensinginthelongopen
end o f , t h e t u b e .
The goldcan
be annealed by heating the tube
t o redness after all mercury
is
driven o f f .
" A r e t o r t f o r t r e a t i n g a fewounces a t a timecan be made
cheaplyof3/8-inchpipe,pipeconnections,and
a l a r g eg r e a s e
cup. The lowerandopenendof
the3/8-inchpipe
i s i n c l o s e di n
a l a r g e r pipe. Coolingwater i s pouredthrough thespacebetween
i n t h e t o p o f t h eo u t e ro n e .
t h e t w o pipes from an open connection
is
The charge of amalgam i s placed in the grease-cup cover which
thenscrewed
i n t o p l a c e ;g r a p h i t el u b r i c a n t
i s placed on t h e
i s a p p l i e d t o t h eg r e a s ec u p ,
t h r e a d s t o make a t i g h t j o i n t . H e a t
and t h eq u i c k s i l v e ri sc o n d e n s e di nt h el o w e r
endof
t h ep i p e .
The
of t h e d e v i c e a r e
simmethod o f u s i n g a n d j t h e g e n e r a l a r r a n g e m e a t
i l a r t o t h o s e of the next retort described.
f o r placermines ( F i g . 9 , C
"The t j i p i c a l q u i c k s i l v e r r e t o r t
and D j i s a c a s t - i r o n p o t w i t h
a t i g h t - f i t t i n g c o v e r 1.n which a
The c a p a c i t i e s
h o l e i s tapped t o acc.ommodate thecondenserpipe.
of s u c h r e t o r t s r a n g e
f r o m a few t o 200 pounds o f amal-gam, o r
about a q u a r t e r p i n t t o
2 g a l l o n s . The condenser commonly used
w i t h t h i s t y p e o f r e t o r t i s a n i r o n p i p e 3 o r 4 f e e t 1.ong l e a d i n g
from the hole in the retort cover
a t a downward a n g l e of 20 t o 30
d e g r e e s ; it i s e n c a s e df o r m o s t o f i t s l e n g t h i n a c o n s i d e r a b l y
largerpipethroughwhichcoolingwater
i s c i r c u l a t e d . When h e a t
i s appliedtothechargedretortthemercuryvaporentersthe
condenserpipewhere
it coolsandcondenses;
it t r i c k l . e s down $he
p i p ei n t o a vesselplacedundertheopen
end o f t h e p i . p e .I nt h e
t r e a t m e n t o f a l a r g e amount of,amalgam the temperature
o f the pipe
m i g h t b e r a i s e d t o a pointwhere some of the vapor wouldescape:
t h e r e f o r e , a cooling device i s necessary.
"The r e t o r t may be heatedover
a largebunsenburner,
by a
g a s o l i n e blow t o r c h , i n a f o r g e ( s e e P l a t e
X V I B ) , or i n oneof
s e v e r a lt y p e s of f u r n a c e sb u i l - t for t h ep u r p o s e .
Very hightemp e r a t u r e sa r eu n n e c e s s a r y ,a n d
a wood f i r e i s c o n s i d e r e d b e t t e r
The flameshouldcover
as much of t h e q e t o r t
t h a n a' c o a l f i r e .
a sp o s s i b l e .
-
69
-
'
Alternative form of watersealed vapor trap
A
I
B
-3
0
I
Figure g.-Apparatus for retorting anialgam and quicksilver: A , Amalgam retort; B, Nevada-type retort;
of Small retort; D, water-sealed vapor trap; E, graphite crucible; F, bullion mould.
Reprinted from United Strites Bureau of Mines Information Circular 6781.
c,set-up
"A r i g i d , s t b o n g s t a n d
for t h e ' r e ' t o r t andcondenser(Fig.
9, A ) s h o u l d b e c o n s t r u c t e d i f t h e a p p a r a t u s
i s t o be u s e d r e g u l a r l y .
"The r e t o r t s h o u l d b e c o a t e d
on t h e i n s i d e w i t h c h a l k ,
or
p a i n t e dw i t h i t h i n p a s t e o f c h a l k , c l a y ,
m i l l s l i m e s , or a mixture.
o f f i r e c l a y a n dg r a p h i t ea n dt h o r o u g h l yd r i e db e f o r e : p u t t i n gi n
t h ec h a r g e .
T h i s preventsthe€;oldfromsticking
t o t h ei r o n ,
whicksometimescausestrouble.
S l i n i n g o f paperse:rvesthe
same
purposebuttendsto
form an ob;lectionable deposit in the condenser
pipe.
.
-"The r e t o r t s h o u l d n o t
be f i l l e d overtwo-thirds
f u l l o f amalgam ( a t h i r d or h a l f f u l l when r e t o r t i n g l i q u i d m e r c u r y ) , o t h e r w i s e
t h e r e i s danger o f some of t h e c o n t e n t s b o i l i n g o v e r
:Into t h e oondensertube.?he
amalgam i s b r o k e ni n t op i e c e sa n dp i l e d . l o o s e l y .
i s p u t onandclamped
t i g h t l y w i t h t h e wedge or
?henthecover
thumbscrewprovided, f i r s t m3king s u r e ' t h a t t h e a t t a c h e d c o n d e n s e r
of o b s t r u c t i o n s . The ground j o i n t between
p i p e i s o l e a na n df r e e
thecoverand
body of t h e r e t o r t i s seldom t i g h t enough t o prevent
leakageandshould
be l u t e d w i t h c l a y
o r some s e a l i n g compound.
One s a t i s f a c t o r y cement i s made r e a d i l y by moistening a mixtureof
g r o u n da s b e s t o sa n dl i t h a r g e( r e dl e a d )w i t hg l y c e r i n .
"A l o w h e a t i s a p p l i e d a t ' f i r s t , t h e n a f t e r 10 o r 15 minutes
t h e t e m p e r a t u r e i s i n c r e a s e d j u s t enough t o s t a r t t h e m e r c u r y v a p o r Too r a p i dh e a t i n g harms t h e r e t o r t , andonly
izingandcondensing.
enough h e a t s h o u l d b e u s e d
t o m a i n t a i n a s t e a d y t r i c k l e of quiokWhen no more mercuryappea.rsthetems i l v e r f r o m t h ec o n d e n s e r .
p e r a t u r es h o u l db ei n c r e a s e df o r
a few minutes t o r e d h e a t t o d r i v e
t h e l a s t of t h e q u i c k s i l v e r o u t
of t h e r e t o r t ; t h e n t h e f i r e s h o u l d
be withdrawn fr.om t h e r e t o r t and t h e l a t t e r a l l o w e d t o c , o o l .
Some
in t h e r e t o r t , and t h e o p e r a t o r s h o u l d
mercuryvaporalwaysremaifis
takecarenottobreathethese
fumesupon t a k i n g off t h e cover.
"The likelihoodofdangerousamountsofmercuryvaporpassing
through a longcoldpipewithoutcondensing
i s verysmall.
Howe v e r , i f much amalgam i s t o be r e t o r t e d , o r if t h e o p e r a t i o n i s of
d a i i y o r f r e q u e n t o c c u r r e n c e , . it u s u a l l y i s d e s i r a b l e t o provide
some form of w a t e r s e a l a t t h e
end o f the condenser tube
t o prevent
theescapeofsuchfumes.
Hany minershavefollowedthedangerous
p r a c t i c e of submerging t h e end of' thecondenserpipe
i:n thebucket
of waterused t or e c e i v et h ec o n d e n s e dm e r c u r y .? h i sa h c u l dn o t
be
done,as a s l i g h t c o o l i n g o f t h e r e t o r t
would c a u s e w a t e r t o
be
sucked i n t o t h e p i p e ,
and i f t h e w a t e r r e a c h e d t h e r e t o r t
an exSuch
an
experience
has
taught
more
.than
one
plosion would follow.
' o l d t i m e r 't h ed a n g e r
of t h i s p r a . c t i c e .
"If' t h e volume o f t h e r e c e p t a c l e i s verysmallcomparedwith
i f t h ed i s c h a r g ep i p ei sb a r e l y
t h a t of thecondenserpipeand
- 71 -
I
I
submerged t h ed a n g e r i s a v o i d e d , a s . a n y l a r g e r i s e o f w a t e r i n t h e
pipe wouldlower
thewatersurface
enoug.h.tobreak t h e s u c t i o n .
A t some p r o p e r t i e s t h e e n d o f t h e c o n d e n s e r p i p e
i s i n a large
s h e e t - i r o nc y l i n d e r ,
a few i n c h e s i n d i a n e t e r ,
open a t t h e lower
end,which may beplaced
2 o r 3 inchesinto t h e w a t e r i n a recept a o l e of o n l y s l i g h t l y l a r g e r d i a m e t e r , t h u s
making a good w a t e r
danger o f e x p l o s i o n s . A l a b o r a t o r ya d a p t a s e a ly e ta v o i d i n gt h e
t i o n o f t h i s d e v i c e i s shown i n F i g u r e 9, B .
"The sim9lest method consists merely
of t y i n g a p i e c e of
c l o t hs u c ha sc a n v a s
o r b u r l a pa r o u n dt h e
end o f t h ec o n d e n s e r
it d i p i n t h e w a t e r 2 or 3 inchesbelow,forming
p i p ea n dl e t t i n g
a damp f i l t e r which w i l l condense any escaping vapor yet not be
be sucked into t h e r e t o r t .
phis
t i g h t enough t o p e r m i tw a t e rt o
d e v i c e i s shown i n F i g u r e 9 , A.
" L a r g eg o l dm i n e su s ec y l i n d r i c a lr e t o r t s ,u s u a l l ys e th o r i z o n t a l l y i n s p e c i a l l yb u i l tf u r n a c e s .
Such i n s t a l l a t i o n sp r o b a b l y
wouldbeneeded
i n placerminingonly
by largedredgingcompanies.
The o p e r a t i o n i s s i m i l a r t o t h a t of a p o t r e t o r t , e x c e p t t h a t t h e
amalgam u s u a l l y is p l a c e di ns e v e r a ls m a l li r o nt r a y s ,r a t h e rt h a n
a door o r
on t h e f l o o r o f t h e r e t o r t p r o p e r , a n d c h a r g e d t h r o u g h
removablecover a t one end o f t h e r e t o r t , w h i l e t h e c o n d e n s e r
is
attachedattheoppositeend.
- 72
-
SEPARATION OF PLATINUil-GROUP
NETALS
FROM GOLD
" I ns e v e r a ll o c a l i t i e ss l u i c ec o n c e n t r a t e sf r o np l a c e rm i n i n g
arelikelytocontainplatinum
or i t s a s s o c i a t e d m e t a l s i n s u f f i c i e n t
q u a n t i t i e s t o be ofeconornic
i n t e r e s t . ?he s e p a r a t i o no ft h e s en i n e r a l sf r o mg o l d
i s d i f f i c u l t .T h e i rs p e c i f i cg r a v i t y
i s t o on e a r
t h a t of g o l d t o permit a soparat,ion by panning.Coarseplatinum
o f thegoldbyhand,but:nostplacer
p a r t i c l e s canbepickedout
azalgaplatinum i s exceediriglyfine.Althoughplatinumdoesnot
mate, q u i c k s i l v e r c a n be made t o c o a t a n d h o l d p l a t i n l m ? a r t i c l e s
b;r t r e a t l a e n t witl; chemicals; t h u s i t i s p o s s i b l e t o s e s a r a t e suecessively the gold acd ?latinxi
from the conce?trstes
"One dredging company i n C a l i f o r n i a w h i c h r e c o v e r s p l a t i n u m
m e t a l su s e st h ef o l l o w i n gc l e a n - u pp r o c e d u r e : l
" I n c l e a n i n g u p , t h e r i f f l e s a r e removedfrom t h e s l u i c e s ,
them offandwashing
s t a r t i n g a t t h eh e a de n d ,c a r e f u l l yw a s h i n g
t h e s l u i c e dovrn w i t hw a t e rf r o m
a hose.Thiswashes
away t h e l i g h t
s a n d sa n dc o n c e n t r a t e st h e
ma1ga:n andheavysands,whicharecaref u l l y scooped u p i n t o b u c k e t s a n d c a r r i e d t o
a ' l o n g t o m 'f o rf u r t h e rt r e a t m e n t .I nt h el o n g
torn mostofthemercurysad
amalgam
and some of t h ep l a t i n u m - g r o u pm e t a l s
a r e c a u g h ti nt h eu p p e r
Sox.
!'lost of t h ep l a t i n u m , some r u s t y g o i d , s c a t t e r e d p a r t i . c l e s
of merc u r y andamalgam,and
thesandandrefuseare
washedc,utover
riff l e s where t h eh e a v i e r components a r ec a u g h t .
The s2r.d f i n a l l y
p a s s e s t h r o u g h a s c r e e n a t t h e e n d of t h e tom, i n t o a sandbox,and
t h eg r a v e lg o e st ow a s t e .
The mercury andamalgam frcmtheupper
box a r e t r a n s f e r r e d t o a b u c k e t , i n w h i c h t h e
:gold arnalgam s e t t l e d
t o t h e bottorn; t h e l e a d o r o-therbase-zeta1 maisms f l o a t o n t o p .
Phe l a t t e r i s p a r t i a l l y c l e a n e d by panning,whichseparates
some
! n e t a l l i c! > l a t i n u n ,t h e nr e t o r t e d .
The gold a n a l g a 3 i s squeezed
free ofmercuryandlikewiseretorted.
"The g o l da q a l g a n ,u s u a l l yc o n t a i n i n ga b o u t
55 p e r c e n t g o l d
and s i l v e r , i s r e t o r t e d i n a starldard make of g a s o l i n e - f i r e r e t o r t .
a
The mercurycocdenses i n a w a t e r - J a c k e t e d 2 i p e a n d d r a i n s i n t o
bucket of water. The goid remaining i n t h e r e t o r t i s t r a n s f e r r e d
, t o a c r u c i b l ea n df u s e di nt h e
same f u r n a c e . I t i s thenpoured
i n t o molds,producingbarswhich
a r e shipped t o t h e S e l b y s m e l t e r .
?he b u i l i o n a v e r a g e s e90 p a r t s g o l d , 90 parts s i l v e r , and 2 0
p a r t si m p u r i t i e sp e r
1,000,
"The r i f f l e c o n c e n t r a t e s and, s a n d f r o m t h e e n d o f t h e l o n g
tom a r e p l a c e d i n small b a t c h e s i n a s t e e l b a r r e l m i l l 4 f e e t
1
Patman, C . G. Nethod and Costs o f DredgingAuriferousGravels
a t Lancha Plana, h a d o r County,Calif.,
In."., C i r c . 6659,
Buresu o f ;lines,1932,
pp. 12 - L .
-
73
-
,
longand 2 1/2 . f e e t . i n d i a m e t e r . Mercury i s added and t h e b a t c h
ground f o r 1 or 2 hours. Then t h e amalgam i s removed by panning
andadded
t ot h eo t h e rb a s e
amalgam for r e t o r t i n g . F u r t h e r
panand c o n c e n t r a t e s t o a
ningandrockingreducetheremainingsand
productcontainingabouthalfblacksandandhalfplatinuy..,
by
volume.This
i s t r e a t e d by t h ea d d i t i o n of water,mercury,zinc
s h a v i n g s , and s u l p h u r i c a c i d ; t h i s c a u s e s t h e p l a t i n u m m e t a l s t o
be.coatedandheld
by t h e m e r c u r y , so t h a t a f i n a l s e p a r a t i o n
f r o m t h es a n d i s p o s s i b l e . The f i n a lc o n c e n t r a t e i s t h e n washed
withwater 6n.d d r a i n e d t o remove a c i d ar,d e x c e s sm e r c u r y ,a f t e r
whichtreatmentwithnitricaciddissolvesthemercury,leaving
a f i n a l r e s i d u e of p i a t i n u h ,i r i d i u m ,a n d
osmium.
“‘Theba-se
m a l g a m ,w h i c hi n c l u d e ss h o t ,b u l l e t s ,
and s m a l l
p a r t i c l e s ofcopperand
b r a s ss c r a p ,a sw e l la s
some precious
m e t a l s , i s r e t o r t e d , t o recoverthemercury,melted,andpoured
i n t o molds t o form b a r s f o r shipment t ot h es m e l t e r .
These
bars
range in value from
$1 t o $8 p e rt r o yo u n c e .
, .
,
.
’
“Zachert’state,sthatplatinum-groupmetalscanberecovered
on zinc-ama1ga.n p l a t e s by u s i n g a s o l u t i o n o f 0.05per:centcopper
o r by a g i t a t i n g w i t h
s u l p h a t e and 0.05 p e r c e n t s u l p h u r i c a c i d
i nS o u t h
z i n c amalgam i ns u c h a s o l u t i o n . A t t h e Onverwachtmine
A f r i c a a p r o c e s s 2s i n i l a rt ot h ea b o v e
‘ i s used t o . t r e a t a p o r t i o n
of t h e t a b l e c o n c e n t r a t e s :
“The concentrates of the primary and secondary Wilfleys and
o f t h e Jamesandcorduroy
t a b l e s a r e t r e a t e d i n l o t s of 1,000
l b . i n a revolving amalgamating barrel, the. amalgamation
of t h e
platinum being promoted
by a c t i v a t i n g a g e n t s i n t h e f o r m of zit10
arnalgm:, copper. s u l p h a t e ,a n ds u i p h u r i ca c i d .
The b a r r e l i s r e v o l v e d f o r 2 hoursandthendischargedviabateaamalgamation
plantandcurvilineartab1.e.
“The d i r t y a m l g a ~ o b t a i n e d i s reamalgaqated for h a 1 f . m
hour w i t hz i n c anialgam, c o p p e rs u l p h a t e ,a n d . s u l p h u r i ca c i d .
Thus
cleaned it i s now pressed arid t r e a t e d i n e a r t h e n w a r e j a r s w i t h
dil.ute sul.phuric acid
t o remove zinc and iron.
“ A f t e rt h i sh a sb e e na c c o m p i l s h e d ,
it i s r e t o r t e d i n s m l l
potretorts.
The r e t o r t s p o n g e , a f t e r b e i n g s u b j e c t e d
t o further
p a n n i n g ,s o r t i n g ,a n da c i dt r e a t m e n t ,
i s washed and d r i e d ,g i v i n g
’
Z a c h e r t , V . J . , P r o c e s s f o r 2ecoveringPlatinum:
117, Oct. 1 2 , 1918, p p ~489-490.
. P r e s s ,v o l .
‘Wagner, P. f i . , PlatinumDepositsandIlines
London, 1923, p. 274.
Min. and S c i .
of SouthAfrica:
,
a product assaying about
which i s shipped.
70 p e r c e n t
o f platinum-group metals,
"The r.ecoverg by amalgamati.on i s about 98 p e r c e n t and t h e
from 8 2 t o 85-56 p e r c e n t . "
a l l - o v e r r e c o v e r y of t h e p l a n t r a n g e s
An a l t e r n a t i v e method of t r e a t i n g s l u i c e - b o x c o n c e n t r a t e s
containingbothgoldandplatinum
would. be t o e x t r a c t ' a l l t h e r e coverable gold by t r e a t i n g t h e c o n c e n t r a t e s i n a n
amalgam b a r r e l .
The r e j e c t s f r o m t h e b a r r e l would contain platinum and the heavy
s a n d s .T h i sc o n c e n t r a t ec o u l di nt u r n
be t r e a t e d on a W i l f l e y
table to eoncentrate the platinum further
andproduce a high grade
concentrate which could
beshippedandsold
t o a platinumbuyer.
Canadianproducers of p l a t i n u m c a n o b t a i n i n f o r m a t i o n r e of concentratesfromJohnson,
g a r d i n gp r i c e sa n da c c e p t a b l eg r a d e
ifatthey & Co. (Can.)Ltd.,
198 C l i n t o nS t . ,T o r o n t o .
-
~775
-
.
*
BIBLIOGRAPHY
Bouery,P.
Study of R i f f l e s f o r Hydraulicking, Eng.and
Min. Journ.,Vol.95,
No. 2 1 , 1913, p.. 1055.
Bowie, A. J .
P r a c t i c a l T r e a t i s e on HydraulicMining - 8 t h
E d i t i o n , Van Nostrand, New York, ,1898.
I
Gardner, E . D. and
Johnson, C . H.
P i a c e r iTini.ng i n t h e Western United States
Bureau of Mines, I n f .
( P a r t T). U n i t e dS t a t e s
C i r c u l a r No. 6 7 8 6 : . 1934.
P l a c e r , M i n i n g in the Western United States
( P a r t 11). U n i t e dS t a t e s .Bureau of Ifines,
I n f . C i r c u l a r No. 6787,1~934.
G r i f f i t h , S. Y ,
Alluvial Prospecting and Hining,
c a t i o n s Ltd.,, London, 1938.
Mining P u b l i -
Gold P l a c e r s of C a l i f o r n i a . B u l l . No. .92,
C a l i f o r n i a S t a t e MiningBureau,1923.
MiningEngineers
JohnWileyandSons,
Peele,Robert
Purington, C .
Sharpe
'
tj.
R . F.
Handbook. 3 r d E d i t i o n ,
New York, 1941.
Gravel and Placer Mining in Alaska,
B u l l . No. 263,1905.
U.S.G.S.
The B u l l i o n H y d r a u l i c Mine,
Trans. C . I . M . M . v o l X L I I , 1939,p.593-598.
Thorne W . E . and
Hooke, A. W .
Mining of A l l u v i a l D e p o s i t s
MiningPublications
L t d . London, 1929.
Wilson, E . B.
Hydraulic and P l a c e r Piining,JohnWiley
New York, 1918.
Wirmler, N . L .
Placer-mining Xethods andCosts i n A l a s k a :
Bull.. Yo. 259, U.' S. Bureau o f Mines, 1927.
Young, George J .
Elements of Xiriing,McGraw-Hill,
1932.
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-
& Sons,
New York,