M e s o z o i cr o c k s
Po eozoicrocks
S T A G El - F l q t - l y i n g s e d i m e n l o r yr o c k so r e d e p o s i l e do ! e r
P r e c o m b n o nr o c k s
Mesozolc
rocks
Poleo?oic rocxs
----_
-\
\
\
rocxs
Precombrion
\
milling,
and
Mining,
in
operations
smelting
NewMexico
southwest
of NMBM&MR
NM,lormerly
Hillsboro,
Metallurgist,
Shantz,
byRobert
\
The ultimate goal of mining and min- and open-pit. Open-pit mining is the
eral-processingoperations in southwest method of choice in areas where ore
New Mexico is the production of a depositsoccur at or near the surface.
relatively pure metal or nonmetallic Depositsof this type occur at SantaRita
mineral. Most metals occur in chemical and Tyrone as large, low grade ore
combinationwith other elementsto form bodies.Undergroundmining methodsare
minerals. These minerals are dispersed usedto recoverore in narrow, nearlyverthroughoutgenerallyvaluelessrock-form- tical veinsand chutes(in the caseof the
S T A G E3 - C o n t i n u e d c o m p r e s s i o nc r e o t e s r u p l u r eb y
ing minerals(gangue)to form ore - rock Groundhogmine at Vanadium);or when
r e v e r s ef o u l l i n g
massesof sufficient sizeand value to be the ore body is coveredby too much overprocessed
economically.Theseore bodies burden to remove economically(in the
occur in the surroundingrock or waste caseof UV Industries).Both conditions
and vary in sizefrom very high-gradeore arepresentin the area.
Therearethreemajor open-pitminesin
depositsa few inchesthick in somepredistrict.UV Industriesat Fierro, Kenthe
cious-metalminesto low-gradeore deposS T A G E4 - A f f e r c o m p r e s s i o nr e l o x e d , n o r m of lo u l l i n g
copper corporation at SantaR'ita,
necott
porphyry
copo c c u r r e di n b l o c k w e s t o f r e v e r s ef o u l l
in
its hundredsof feetthick
and PhelpsDodgeat Tyrone. In the pits,
process
removes
per
The
mining
mines.
FrcunE 4-GENERALTZED
sEcrtoN TAKEN DUE EAsr
the ore from the surroundingwasterock; ore and wasteare first broken by drilling
LINE.
FROM POINT A OF CROSS-SECTION
milling separatesthe valuable minerals holesup to 14inchesin diameterand 60 ft
vicinity. The most commerciallyfeasible, from the gangue; and smelting breaks deep at a predetermineddistanceback
simple enterprisewould be a seriesof
down the mineralsto yield the puremetal. from the edgeof the bench.The holesare
greenhouses
locatedbelowthe hot springs Various companyoperationsusedifferent loadedwith explosive,then blasted.The
and heatedyear round for growing vege- equipmentand proceduresto accomplish brokenrock is loadedinto trucksby electablesand flowers.
tric shovels-someof which can moveup
thesesteps.
A more complicated,industrialgenerato 25 tons at a time (fie. l). Suchshovels,
mines,
major
present,
the
someof
At
tion of electricity on a small scalemight mills, and smeltersin southwesternNew at present, cost in excessof a million
be accomplishedthrough the use of heat Mexico are shut down as a result of dollars. Trucks used in the pits have
engines.Apparentlythe temperaturedifdepressed copper and zinc Prices. capacitiesfrom 40 to 150tons each,and
ferential betweenthe hot spring waters Although significant quantities of non- there is a trend towards even larger
and the cold waterof the GallinasRiveris metallic minerals such as fluorspar were trucks.
great enoughto make heat engineseco- producedin the past, presentproduction
With the presentore grade at Chino
nomically feasible,although a substantial is limited,exceptfor theMathis lime plant and Tyrone, about 3 tons of wastemust
for
capitalinvestmentwould be necessary
be moved for each ton of ore mined.
midwaybetweenHanoverand Central.
their installation.
Allowing for milling and smeltinglosses,
provide
operators
Most of the major
this meansabout 700 lbs of rock must be
During
public
access.
for
form
of
some
References
cited
Copper Corpora- blasted, loaded, and hauled for each
Baltz,E. H., 1972,Geologicmap and crosssections the summerKennecott
tion normallyconductstours of its opera- pound of copper produced. The Chino
of the Gallinas Creek area, Sangre de Cristo
Mountains, San Miguel County, New Mexico:
tions at Hurley for the generalpublic. As mine producesabout 23,000tons of ore
U.S. Geol. SurveyMisc. Geol. Inv. Map l-673
a rule, given advancenotice, both Ken- per day, Tyroneabout46,000tons.
(sheetI of2)
Because most of the underground
necott and Phelps Dodge Corporation at
gradientsof therBejnar,C. R., 1967,Temperature
in the district have been closed
mines
group
Tyrone are able to arrange special
mal springsat Montezuma,New Mexico, unpubmetalprices,UV's
due
to depressed
down
in
their
tours. Other operators vary
lishedpaper
LasVegas(NM) Daily Optic,20April, 1885
policiesregardingpublic tours. In addi- ContinentalMine at Fierro is currently
Lessard,R. H., and Bejnar, W., 1976,Geologyof
tion, PhelpsDodge, Chino, and TYrone the only one of its kind in operation.
the Las Vegasarea: New Mexico GeologicalSoci
public lookoutsat ASARCO's (American Smelting and
havereadilyaccessable
ety Guidebook,27thFieldConf., p. 103-108
Refining Company) Groundhog unit at
Reinerts,T. H., 1966,A historyof the Montezuma the pits.
Vanadium and Federal ResourcesCorHot Springs,hotels,and bathhouses,1849-1937:.
abandoned
of
The potential hazards
M.S. thesis,New MexicoHighlandsUniv.,97 p.
poration's
BonneyMine at Lordsburgcan
Do
not
many.
and
significant
mines are
of
Summers,W. K., 1965,Chemicalcharacteristics
to openiflead, zinc, and copbe
expected
pits, or workings.
New Mexico's thermal waters: New Mexico enter abandonedmines,
per
prices
rise.
Severalsmallunderground
Children in all mining areas should be
Circ. 83,
Bureauof Minesand MineralResources
amountsof preciouslimited
mines
ship
p.
times.
all
27
under careful supervisionat
metal bearingfluxing ore to the ASARCO
1968,Geothermics-NewMexico's untapv. 21, no. 8
pedresource:
New MexicoBusiness,
Mining
smelterat El Paso,and a few other mines
19'16,Cataloe of thermal waters in New
produce
fluorspar on an intermittent
In general, mining operations can be
Mexico:New Mexico Bureauof Mines and Minbasis.
underground
p.69-72 !
dividedinto two categories:
eralResourcesHydrologicReport4,
S T A G E2 - C o m p r e s s i ocnr e o l e sL o s V e g o s s y n c l i n e
24
May 1979
New Mexico Geology
Mitling
The ores produced are treated locally
by various concentrators and smelters.
Little direct-shipping(high-grade)ore is
produced,thereforethe oresare processed in concentratorsto separatethe metalbearingmineralsfrom the barren rock, or
gangue.The high-gradeproduct, or concentrate,is shippedto a smelterwhere
concentratesare melted with fluxes to
removefurther impurities,and finally to
remove the sulfur by oxidation, leaving
approximately 99 percent pure metallic
copper.
Sincethe bulk of the area'sproduction
is copper,the productionof metalliccopper from ore will be describedfirst; leadzinc treatmentwill be noted later. Basically, the processinvolves three steps:
breakingthe coppermineralsand gangue
apart, separating the copper minerals
from the gangue,and recoveringthe copper from the minerals. Becauseof differencesin concentrator design and ore
composition,the three major operators,
Chino Mines Division of KennecottCopper Corporation, UV Industries, and
Phelps Dodge use somewhat different
equipmentto accomplishthesesteps.
The first step, breaking the minerals
and gangueapart, involves crushing and
grinding (comminution). The ore, which
comesfrom the mine as rocks up to 6 ft in
diameter, is dumped into a primary
crusherthat reducesthe rock to 8- to 12inch pieces.Both UV and Chino usejaw
crushersfor this step,while PhelpsDodge
usesa large gyratory crusher. From the
primary crusher, the ore goes to secondary and tertiary crushersat Chino and
PhelpsDodge. Both use gyratory (cone)
crushersfor the secondaries
that reduce
the ore to approximately2 inches.Phelps
Dodgethen usesshortheadconecrushers,
and Chino, roll crushers,to reducethe ore
to 3/8-inch pieces.Typically, motors of
about 500-hpare usedon thesecrushers.
At UV, the ore goes from the primary
mill, a
crushersto a semi-autogenous
large diameter (30-ft) rotating drum in
which the physicalaction of the ore itself
tumbling with large steel balls combines
to reducethe ore. At UV's No. 2 concentrator, a 5000-hpmotor drives the mill.
Finally, PhelpsDodge and Chino useball
mills - large,drum-shapedrotatingmills
filled with steelballs - to grind the ore to
the requiredfinal size$te. 2).At Phelps
Dodge, there are 20 of these 1250-hp
primary ball mills, each12 ft in diameter
x 12 ft long, holding 80 tons of steel
balls. The dischargefrom these mills is
classified (sized) by cyclones at Phelps
Dodge and rake classifiersat Chino; the
larger particles are sent back to the ball
FrounE l-ElecrRtc
Corporation.
sHovEL LoADrNc lsG.ToNTRUcK.Courtesy Chino Mines Division, Kennecott Copper
Frcunp 2-GnrNDrNc sEcrtoN ar Cxrxo; ball mills in foreground, cyclone classifiersat upper left.
CourtesyChino Mines Division, KennecottCopperCorporation.
mill for further grinding, smallermaterial
goes to flotation. (At Phelps Dodge,
about95 percentof the dischargewill pass
a 65-meshscreen.)UV usespebblemills
for fine grinding. Here the final grind is
achievedusinglumpsof ore about2- to 3inchesin diameterrather than steelballs.
After the first (rougher)flotation, Phelps
Dodge regrinds the rougher concentrate
to separatethe pyrite (iron sulfide) and
chalcocite(copper sulfide). This two-step
approach is far more economical than
grinding all the ore to the sizerequiredfor
the final concentrate.
The second step, separatingthe valuable minerals from the waste,is done by
r=F
May 1979
NewMexicoGeology
25
froth flotation. Here the water-oremix- verters (- 9g percentCu) is treated in nessbeyond; and the incomprehensible
ture (pulp) comingfrom the grindingsec- reducing(anode)furnacesto removemost beautywrought over the eonsand lost to
tion is agitatedin a seriesof flotation cells of the remainingimpurities (mostly ox- the world until an explorer's lamp
that also introduce small air bubbles. ygen). The copper is cast in molds and discoveredits breathtakingsplendor. It
Chemicalscalledcollectorsare addedto eithersold directlyfor brassmanufacture conveysthe surgeof pridein knowingthat
the pulp to coat the small mineral par- or sent to an electrolyticrefinery for fur- no human footstep has disturbed the
ticles.Other chemicalscalledfrothersare ther processing.Lead and zinc concen- silenceof centuries.
addedto makea stablefroth that risesto trates are treated out-of-state by sigThe author has kept a concisevisual
the top of the pulp. The coatedmineral nificantly different methodsto produce and written recordof his explorations,inparticleattachesitself to the foam rising metallicleadand zinc.
timatelyreflectingwhat theseyoung men
to the top whereit is skimmedoff. The
saw, said, and felt during their advenSummary
concentrate from these first cells is
tures.An outstandingphotographicessay
The major improvementsin miningand sectionrevealsthe awesomebeautyof the
refloated to produce the final concenequipmenthaveallow- caverns.The photographs,dating from
trate. Material which did not float in the mineralprocessing
first cells (tailings)is sent to thickeners ed mining of muchlowergradeore, there- the late 1880'sthrough the 1940's,reprewheremost of the wateris recovered,and fore extendingthe life of many minesin senta cross-section
of the author'swork,
thenon to tailingsdams.The concentrates the district. The undergroundmines, for togetherwith a few contributions(now in
are thickened,filtered, and dried before example,and the first PhelpsDodgecon- Nymyer's collection) by other photogshipping to the smelter. The ASARCO centrator at Tyrone discontinuedopera- raphers.
mill at Demingdifferedfrom the othersin tions in the early twentiesand did not
The clarity, quality, and originality of
that two concentrateswere produced.A reopenuntil mining was reintroducedin this publicationare outstanding.Followby the recentclosureof ing the caption of eachphoto is the page
lead concentratewas first floated from 1969(asevidenced
ASARCO's
Deming
Concentrator).Min- number where the narrative appears,expulp
using chemicalsthat will not
the
float zinc minerals, then an activator ing is still very cyclical,however,with the plaining the site and purpose of the pic(copper sulfate) was added and another profitability of the operation dependent ture. The photo numbers appear in the
seriesof cells produced a zinc concen- on fluctuatingmetalprices.
margin near the appropriate passagesin
Future projections for most metal the text (a particularly helpful feature).
trate.
In addition to the flotation plants, both prices, as well as recentexploration activappreciate Robert
AcxNowreocprprr-We
Chino and Tyrone have leach plants ity, indicate that the district has conto reviewthis
Nymyer's
kindness
for
the
opportunity
potential.
siderable
future
!
which also recover copper. A solution
valuablecontribution to New Mexico's history and
containing sulfuric acid is spread on the
geolo gy . - Ne i la Pe ars o n
leach dumps: some of the copper is dissolvedas the solution drains through the
dumps into holding ponds, from which it
is pumpedto the precipitation plants. The Carlsbad, Caves, and a Camera,
copper-bearingleach solution is passed by Robert Nymyer, published by
over scrap iron in launders at Phelps ZephyrusPress,Inc., Teaneck,NJ, first
Dodge and cone precipitatorsat Chino. printing 1978,318 p., 185 illustrations,
$14.95,softcover,$8.95.
The copper in solution replaces the hardcover,
Corlsbad,
Caves, and a Camera is a
metallic iron in the scrap, producing a
fine copperpowder (precipitateor cement deeply felt tribute to a way of life and a
copper).After drying, the cementcopper part of nature that have almost disappearedin this day and age.In 1927Aaron
is sentto the smelter.
Nymyerbeganworking for Ray V. Davis,
Smelting
pioneer photographer of Carlsbad
The concentratesfrom the mills are Caverns, and has been active in cave
mixed with silica and limestonefluxesand photographyand explorationeversince.
meltedto producea moltenbath containThe adventure,fascination,and beauty
ing an upper wastelayer (slag)floating on of this publication will appeal to
a lower copper-ironsulfidelayer (matte). geologistsand non-geologistsalike. The
Chino mines at Hurley usesa reverber- author recallshis cave explorationas a
atory furnace for this step; PhelpsDodge young man in the 1930's-in thosedays,
at Playas, a flash furnace. The molten despite an abundance of outstanding
slag is hauled to waste dumps directly cavesto be discoveredand exploredin the
from the reverberatoryat Chino. After Carlsbad region, caving lacked its
cleaningin an electricfurnaceat Phelps present-day
sophistication.
Dodge, the molten matte, containing
This is the storyof youngamateurswho
about 40 percentcopper,is transferredto ventured underground-inexperienced,
convertersin large ladles. Here, air is unadvised,and unguided-into an unblown through the molten matte, oxidiz- known world. They facedtheir problems
ing the sulfur to sulfur dioxide and pro- as they arose,and eventuallyacquireda
ducing metalliccopper.The sulfur diox- high degreeof technical competencein
ide in the exhaustgas is convertedto caving.The book capturesthe thrill of exTne CllNsurrN rN NEw C,c.vn,with the author
sulfuric acid which is shippedto various ploringthe unknown,accompanied
by the crouchingin front. This is one of the more awesome
markets. Blister copper from the con- ever-present
threat of dangerin the dark- sightsin the cave(photo takenSeptember24,1938).
New books
26
May 1979
New Mexico Geology