AGRICULTURE
ROOM
SULFITE DIGESTIONS U WESTERN
W11-11 11T PINE
-
January 1940
UNITED STATES DEPARTMENT OF AGRICULTURE
!FOREST SERVICE
L....FOREST —PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the University of Wisconsin
SULFITE DIGESTIONS OF WESTERN WHITE PINE
By
J. N. MCGOVRN, Assistant Technologist
and.
G. H. CHIDESTER, Senior Engineer
Western white pine (Pinus monticola) is an important timber
tree growing in northwestern United States, with the heaviest stand located in northern Idaho. A relatively large amount of western white pine
logging and mill waste and second-growth material is available and has
been suggested as a 'possible pulp raw material. At present this wood finds
very little outlet in the
7'.ndustry ar.d there is little published information regarding its suittiiiiLy for pulp. The limited number of experiments reported by re were urdertaken to amplify the available data on
the behavior of this woodi” ed by the sulfite process.
There is a close resemblance between western and eastern white
pines. A certain amount of information is known about the latter (Pinus
strobus). According to Wells and. Rue l sulfite pulping of eastern white
pine resulted in a dark-colored, harsh pulp containing a large number of
shives or uncooked slivers and bleached with difficulty.
Eçperimental Part
The western white pine material used for these experiments
was supplied by the Northern Rocky Mountain Forest and Range Experiment Station. Three bolts 4 feet long were cut from each of two
trees, to correspond to the top, middle, and butt portions of the
log. These bolts were evaluated according to Forest Products Laborato'ry standard methods.. Pertinent physical and chemical data are
given in tables 1 and 2. Only a small amount of material was available
U. S. Dept. Agriculture Bull. 1485.
rProgress Report, "Physical and. Chemical Properties of Western White Pine
(Pinus monticola), Shipment 1526" by J. C. Pew and E. R. Schafer. Mimeograpdreport, Forest Products Laboratory.
R1412
for the pulping tests. Since the butt bolts of pine are usually the
most difficult to pulp satisfactorily by the sulfite process, owing to
their greater heartwood content and the presence of larger amounts of
resins, they were chosen for these trials. rive-eighths-inch chips
were prepared from two of the butt bolts in the usual manner.
The digestions were made in a stainlesa-steel-linei, steamjacketed autoclave with a capacity of 1.5 cubic feet, under conditions
previously found favorable for jack pine. The pulped chips *ere broken
up with a stirrer and the pulp screened through 0.012-inch slots in a
diaphragm screen.
The digestion conditions are given in table 3. Each charge of
wood, containing abbut 43 percent moisture, weighed. approximately 10
pounds when oven-dry, and the acid charge averaged 90 gallons per 100
pounds of oven-dry wood.
The yield, strength, and bleach requiremettsof the pulps are
given it table 4t
Results and Discussion
The Wood
The trees came from a stand burned over in about l g 50, were
relatively young-65 years as compared to 100 to 150 for a mature tree-and were somewhat lower in density than the average of 27 pounds per
cubic foot reported for this species.
When compared with average figures (tables 1 and 2) for jack
pine (Pinus ban,ksiana) from data recently obtained for butt bolts of
four diameter classes ranging from 5 to 11 inches, the older western
white pine was fpund to have a somewhat slower growth rate, to be appreciably less dense, and to contain about twice as much heartwood. The
higher heartwood content was not reflected in the chemical analysis,
since the western white pine, as compared to the jack pine, had higher
cellulose and lower lignin contents in addition to smaller amounts of
pentosans and extractives.
Chemical data for eastern white pine (Pinus strobus), also
included in table 2, show that this particular wood sample, in comparison with the western pine, had higher alpha-cellulose and lignin contents and more extractives.
•
R114. 12
The western white pine was comparatively light-colored; both.
the heartwood ana sapwood from the present sample had a brightness of
45 percent white.
Sulfite Pulping Experiments
The mixture of western white pine chips from the two butt
bolts was fairly well reduced by the sulfite process, using the 12-hour
schedule. The digestion at 136° (no. 220, table 4) resulted in 4.1
percent screenings and an average bleach requirement of approximately,
18 percent. Since this digestion was continued until the base in the
cooking liquor was , nearly ; exhausted as measured by the Sander test, the
data represent-substantially the miriithuvin screenings and bleach requirements .obtainable under the condittons used.
The application of somewhat milder conditions (schedule 2,
table 3) including a digestion temperature of 1300 C., effected no reduction in screenings when the , digestiori was not continued until the base
was exhausted (no.221),. When the milder conditions were applied and
the digestion carried completely to the end, however, the screenings
content was reduced to 2.9 percent and the bleach requirement was slightly
lowered. .
The lowest bleaching pulp (no. 222) had slightly higher bursting strength values, slightly lower tearing and tensile strengths, and
required slightly less beating to develop a given freeness than the higher bleaching pulp(no.220).
The chemical analyses of these pulps also showed only small
variations (table 5). The lower bleaching pulp in this case had a
slightly higher cellulose content but lower alpha-cellulose and higher
lignin contents.
Table 6 gives a comparison of results recently obtained'
from jack pine to those from western white pine. The jack pine pulps
were prepared from the butt bolts described in tables 1 and 2. The data
on western white pine were taken from table 4. The two sets of conditions,
except for ,total. digestion time, were the same for each of the two woods.
The western white pine required a slightly longer time to
reach the point of base exhaustion than did the jack pine. The difference wasj4.6 haur. At 136° C. and 0.8 hour at 130° C.
The screenings. and screened pulp yields were the same for the
two woods when the digestion temperature was 136° C. At the lower temperature smaller Amounts of screenings resulted from both woods. The
reduction in screening from jack pine corresponded to an increase in
3Growth Rate and Position of Wood in Tree as Faetors Influencing Kraft
and. Sulfite Pulps for Jack Pine, Problems B-190 and A474. Proj.
1168-61 U. S. Forest Products Laboratory.
R1412
•
•
the screened pulp yield with no change in the bleach requirements but
in the case of western white pine the reduction in screenings was accompanied by a decrease in the bleach requirement wits no change in the
screened pulp yield. Because of its higher density the jack pine gave
more pulp per cubic foot of wood than the western 'white pine.
The unbleached pulp colors and bleach requirements of the
western white pine pulps were appreciably higher than those of the
jack pine pulps.
The strength values of the pulps from the two woods were
quite similar in each instandes and were considerably lower than those
of sulfite pulps frompruce.'
In view of the similarity of the behavior of western white
pine to that of jack pine it is to be expected that more complete reduction with less screenings and somewhat stronger pulps would result
from the middle and top portions of the trees than from the butt bolts4
As in the base of jack pine thescreenings from woods-run material
would probably amount to 3 or 4 percent with a 12-hour cooking schedule
and reasonably complete reduction could probably be obtained with a
16-hour schedule.
Summary
Three sulfite digestions of chips from western white pine
butt logs gave fairly complete reduction of this wood and resulted in
screenings amounting to 3 to 4. pounds per 100 pounds of oven-dry wood
with a screened pulp yield of 44 pounds per 100 pounds, of oven-dry wood.
The pulps were light-colored, medium-hard bleaching and had strength
properties characterized by a bursting strength at 550 cc. freeness
of 0.80 to 0.90 point per pound per ream.
Western white pine was reduced to pulp to about the same
degree as jack pine under similar conditions. The pulps were somewhat
more difficult to bleach but had similar strength properties. The
strength properties of the pine pulps were considerably lower than
those of spruce sulfite pulps.
_31412
-4-
•
Table 1 .--EasicalaoppnitEIfstern white and dackpirektItt bolts
•
:Western vhite : Jack pinea
pine–
: Shipment
1504
:Shipment 1526 :
-
:
•
Diameter.•••••••••••••••••••••••• Inches:
8.0
7.2
Years:
65.0
40.3
Rate of growth....4,.......4ngs per filch: 16.2
12.2
Density
ty QLP_t_A9_1) Lb. per cu. ft....:
25.2
26.0
Ag e•
• •••••• • •••• •••••••*••••••••••
He a rt W OOd*
1
*
*•
••
••0
0.0
.0.0
0
110
0
0
41
•ParC e n t ;
65.5
33.3
Average of butt bolts from two trees.
2
– Average of butt bolts from trees ranging in diameter from 5 to 11
inches.
R1412
Table 2.--Chemical anal ses of chips from western white, jack ) and
sr whiteines
:Western: Jack, :
white 11': pines ..
pine--; Ship- :
: Ship- : went ..
:
: ment : 1504
: 1526 ;
:Percent:Percent :
Alpha-cellulose....
ilei.0 46,0****0010041:
141.7:
41.4 :
Eastern
.
white pineShipment
1330
.
Percent
*44.0
,
Cellulose....• • .
04/•••••••01,
Lignin..........
01100011.00....0.09.... :
••.......: 60.4:
Pentosans
--otal..•••••••••••••••••••••••••••*:
I n cellulose... .•• ••••••••••••••••: 25.1
946 :
8.5 :
Solubility inHot 1 percent sodium hydroxide.....: 12.8
Hot
3.6:
4.0 :
Alcohol-benzene,..,. .............,.:
2.1 :
Ether•••••*•••••••00*•• •••• •••••• a•7,
57.4
50.0
26.3
27.5
12.0
10.8
10.6
16.2
3.6 :
5.7
4.1
:
4*6
6.5
3.0
1
--Data on mixture of chips from butt bolts from two trees,
--Average of data from chips of butt bolts from trees ranging in
diameter from 5 to 11 inches.
Sample an average of several bolts selected at random.
•
Table 3.--Conditions for western white • lne sulfite di estions
4
.....
0
•
Schedule : Schedule
1
2
...........
.......
Penetration
Time to 110° C.....s....4„.•,...........libum Time at 110° C$4,0***10. so•oltits.•••••••• ...Houk's:
1 . 5
.0
.
:
136
:
Vale from 110° C. to maximum temperature...Hours: 4 .5
:
Maximum t emperature•••4..44•4
9i f . 0 • .... O•a
••0° G . :
'Time at maximum temperat ure..Hours:
Total. digeztion time ••• ••••
Maximum prosetie••."••••
• • • • • •••••••••••
0•••
1.5
240
7•0
4...4
;
.Eours: 12.4
:
16.3
:
RI
• .*** Lbs, per B. in.:
Cooking liquor
Total sulfur dioxide..... 0 4,1100.• .......Percent:
Combined sulfur dioxide.. 00,0••••••••••• Percent:
g O
6.20
6.20
1.35
1.35
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Table 5.—Chemical aAMgIMIL..91L2TILL271121.1±21.1129_
Digestion no.
220 : 221
222
Alpha-cellulose...........Percent
: 77.8:........._
:
77.0
Cellulose.................Percent :
......__
::
92.4
Lignia....................Percent :
........._
1.5a
2.8
Total pentosans...........Percent
Solubility in
Alcohol-benzene.........Percent
Ether.••••••••••••••••••Percent
9103
ft00.61.4.004,0
:
n•••••••n •••• n••
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2.0
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