Sulfite pulping of Engelmann spruce

MISSING IMAGE

Material Information

Title:
Sulfite pulping of Engelmann spruce
Series Title:
Report ;
Physical Description:
6, 5 p. : ill. ; 26 cm.
Language:
English
Creator:
Keller, E. L
McGovern, J. N
Forest Products Laboratory (U.S.)
University of Wisconsin
Publisher:
Dept. of Agriculture, Forest Service, Forest Products Laboratory
Place of Publication:
Madison, Wis
Publication Date:

Subjects

Subjects / Keywords:
Sulfite pulping process   ( lcsh )
Engelmann spruce   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 6).
Statement of Responsibility:
by E.L. Keller and J.N. McGovern.
General Note:
Caption title.
General Note:
"July 1942"--Cover.
General Note:
"In cooperation with the University of Wisconsin"--Cover.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029314570
oclc - 755791098
System ID:
AA00020575:00001

Full Text


j y
SJLITI IPULIPIN Or ENIIIMANN SPIUICE
July 1942

I















J r







UNITED STATES DEPARTMENT OP AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison, Wisconsin
in Coopemtou with the Uniemty of Wiaoouin








SULFITE PULPING OF ENGELIANN SPRUCE


By


E. L. KELLER, Junior Chemist
and
J. N. McGOVERN, Associate Technologist





ABSTRACT


Sulfite pulps covering a range of bleach requirements from 8 to 24
percentt standard bleach powder were prepared from Engelmann spruce (Picea
ongelmannii) using standard pulping conditions. The pulps showed normal vari-
ttions with degree of pulping. Increasing the maximum temperature, acid
concentrationn and pressure resulted in a reduction in pulping time from 9.25
;o 6.75 hours at a slight expense of yield and pulp strengths. The Erg.elmann
ipruce pulp was produced in higher yield than a sample of white spruce (Picea
laua) pulp made under the same conditions and having the same bleach re-
Luirement. Although the strength values of the Engelmann spruce pulps wcre
higher than those of this particular sample of white spruce pulp, they were
lot appreciably higher than those generally obtained from white spruce.


INTRODUCT I ON


Results from sulfite pulping experiments conducted at the Forest
service pulp and paper laboratory in Washington, D. C., some 35 years ago
t, 6) and from additional experiments m;de at the Forest Products Laboratory
Lbout 25 years Pgo (7) indicated that Engelmpnn spruce yields a sulfite pulp
'qual in practically every respect to that from the eastern spruces. Until
recentlyy the use of Engelmann spruce hps been limited largely to one mill
ocated in the Inlpnd Empire. In 1939, however, Wisconsin pulp mills began
sporting EngelmPnn spruce, and it hos been estimated thnt the 1941 shipments
'ill -nmount to about 40,000,000 board feet (approximately g0,000 cords) (2).

Engelmann spruce grow% in thei mountain ranges in the western pprts
f the United States Pnd Canadn, extending from the Yukon to the Mexican
order (1). In the Northern Rocky Mountain region it is found in extensive
uantlties along with other species. It is estimated (4) thpt there aXe
1,000,000 cords of mature Engelmnnn spruce, 13,700,000-cords of grpnd (white)
ir Pnd 2,100,000 cords of western hemlock in northwestern !Tont,-na and







I vI.nu .J Muuvj. urf .Uurva; WLu. acu X igo jUAV r.L zflUI5 01, 1%tI VL 4 1 J .a ;o uu W1 V p411O4L.n.

At the request of the Station a brief study of the sulfite pulping
S characteristics of Engelmann spruce was undertaken to bring up to date the
information obtained earlier on this species. The present study included (1)
preparation of pulps covering a range of bleach requirement under standard
conditions and evaluation of these pulps. (2) a few experiments to produce
pulps in a shortened cooking time, and (3) a comparison of the Thgelmann spruce
with a white spruce pulp made under similar pulping conditions.


EXPERIMENTAL PART

Three Engelmann spruce trees cut into 4-foot lengths supplied by the
Northern Rocky Mountain Forest and Range Experiment Station were evaluated by
the standard methods of the Forest Products Laboratory. Their physical and
chemical characteristics have been reported by Pew And Schafer (). Eleven
bolts representative of the entire shipment were chosen for the pulping experi-
ments and converted to 5/'-inch chips. The average physical and chemical
properties of this small' lot are given in table 1. Several bolts from a white
spruce shipment from northern Michigan were also chipped for pulping experi-
ments; the properties of these bolts are included for comparison pith the
Engelmann spruce.

The digestions were made in a 1.5-cubic-foot alloy-clad autoclave
fitted with a steam jacket for indirect heating. The wood charge averaged
about 1.3 pounds on a moisture-free basis. The Engelmann spruce chips had a
dryness Of g6.5 percent and the white spruce 84.6 percent. The cooking liquor,
which was made up as usual by bubbling sulfur dioxide from a cylinder into a
suspension of calcium hydroxide in a tank, was charged in the amount of 7.5
gallons.

Two sets of digestion conditions were used, one being more or less
standard and the other aimed at a shortened cooking time These conditions
were as follows:
Stanndard Shortened time
conditions conditions
Cooking acid:
Total sulfur dioxide (percent).......... 6.5 7.0
Combined sulfur dioxide (percent)....... 1.25 1.25
Liquor-wood ratio (gallons per 100
pounds of moisture-free wood)........ 58.4 56.7
Temperature schedule:
Time to 110 C. (hours)................ 2 2
Maximum temperature (0C.).............. 135 145
Time from 1100 C. to maximum
temperature (hours).................. 2 2
Time at maximum temperature (hours)..... 3.5 to 6.5 2.75
Total time (hours)...................... 7.5 to 10.5 6.75
Maximum pressure (pounds per square inch).... 85 90
Indirect steam only used.

R1408 -_






*** ^Wt'fb WJ* W.Aaaj. B -^ .d .&Va V.A Ud T VlA u. m h AA Ji \^S C.LI1 A UU& V1AA V UIA U U
all flat screen fitted with a 12-cut plate. The pulp yields and amounts of
reenings are given in table 2. These results, as ,'ell as the other data In
ble 2, are the averages of two or more check dieestions in each instance,
-opt for number 335-

The bleach requirements reported in table 2 are average results of
its made on the respective pulps by the single-stage hypochlorite method,
3 standard TAPPI perranganpte method, and the Roe method, expressed as
*cent standard bleaching powder. Processing of the pulps for strength
iluation wps done in a valley test beater. Strength values of the pulps
freeness levels of 800 and 550 cc. (Schopper-Riegler) PnO chemical analyses
the pulps are given in table 2.


DISCUSSION OF RESULTS


The Wood


Engelmann spruce wood is described as generally light in color, with
e heartwood only slightly darker than the sapwocv! and with a tinge of red (1).
density it is the lightest of the spruces, having an average weight per
?ic foot of 25 pounds air dry. Its fiber length is usually given as 3.0 mm.

The average density of the present shipment was 22.2 and that of the
Ats used for chipping 22.3 pounds per cubic foot on an oven-dry basis, or
.ghtly above the average for the species. The trees had a rapid growth and
,e fairly young for Engelmann spruce. Because of the large .ia.eter, unusu-
straightness, and thin bark, the racked cori had. an unusually high volume
wood, 96.7 cubic feet. This offset the low density and gevo the same weight
dry peeled wood per cord as average white spruce. It should be recognized,
ever, that the charge of Engelmann spruce chips per unit nf 'igester space
.1 be less than a charge of a denser wood. The chermicpl analysis of the
,elmann spruce chips used for the pulping experiments, es ziven in table 1,
)wed them to have lignin, cellulose, snO pentrsen contents normal for
,uces. The materials soluble in alcohol-benzene pni ether, on the other
id, were low in the Engelmann spruce.

The physical and chemical characteristics nf the Engelmann spruce
,e almost identical with those of the white spruce used for cnnp.arison, as
)wn in table 1. This particular lot of white spruce, however, was rapid
)wing and below average in density, and contained relatively small amounts
extractives.


1408









Degree of Pulping Series

Using the standard pulping conditions, a series of digestions was
made with Engelmann spruce in which the time at the maximum temperature was
varied from 3.5 to 6.5 hours, and the total time from 7.5 to 10.5 hours. Th(
yields and chemical and physical properties of the pulps thus produced are
given in table 2. The effect of the variation of the digestion time on the
pulping results are clearly shown for most of the variables by the curves in
figure 1 plotted from the data in table 2. These curves and the unplotted
data in table 2 show the following trends:

An increase in the digestion time from 7.5 to 10.5 hours resulted
a decrease in pulp bleach requirement from 23.5 to 7.8 percent. The bleach-
requirement-digestion time relation deviated slightly from a linear relation
as shown in figure 1. The pulps produced in the longest time had approximate
2.5 percent higher total and alpha cellulose and 1 percent lower lignin con-
tents than those produced in the shortest time. The cellulose content in-
creased more or less linearly with time, whereas the lignin contents shored
little change in pulp digestion longer than 9 hours. The pentosan date were
indecisive.

The over-all decrease in total yield with digestion time was 2.8
percent. The yield-time relation in figure 1 also deviates from a straight
line relationship, the curve shoring a break toward higher yields for times
shorter than 8.5 hours. Part of this deviation was due to the screenings
(data in table 2) which were very low except for the shortest digestion.
The relatively high screenings in the latter case may indicate that the regil
of the defibering point is being approached and that shorter digestion to
produce harder pulps may result in still more screenings.

The variations in the strength properties of the pulps with di-
gestion time were not large although the data were somewhat erratic, the
general trend was toward a decrease in strength values with increasing di-
gestion time, as shown by the curves in figure 1 and the data in table 2.
Several of the strength characteristics appeared to pass through a maximum;
these included the tearing strength at a freeness value of 550 cc., the
tensile strength at 800 cc., and the folding endurance at both freeness
values.

The relations between the bleach reouirements of the pulps and
their properties are also of interest. Using the data in table 2, the pulp
yields and physical and chemical properties have been plotted against the
respective bleach requirements in order to show these relations graphically
(fg. 2). These "curves 'show'teho ftilowtng trends:


XL-1%



















Effect of Shortened Time

A reduction in cooking time to 6.75 hours, accomplished by increasing
the maxinux temperature, the total sulfur dioxide content of the cooking acid,
and the maximum pressure over that employed for the standard conditions gave a
medium bleaching pulp. The yield and properties of the pulp thus made are
compared in table 3 with the properties of an equal bleaching pulp produced
under the standard conditions. The latter values were obtained by interpo-
lation of the bleach properties curves in fi-ures 2 and 3 and the data in
table 2 at a bleach requirement value of 13 percent. The higher temperature
and acid concentration caused a drop in yield from 4g.g to 47.4 percent. The
strength properties for the lower-yield pulp were slightly inferior to those
f^ei* t-in 1, IATm-iri oi t rnzir- Trio nfnr> oirniowoT 1,niirov. a1rnntoTe JrniT'" fi ikratA jnv


F
















eporn. rrojeci AJoO-j, prouJ.Lmn u-.Yjc VucVIUr.f o, -'j t/.


- -- - I


ger, F. Station
Station


Missoula. Month. Station Paner No.


(March 1941).

Surface, H. E. U. S. Dept. Agr., I


U. S
Wash:

Rue,


ory, Ms
r 20, 1

Dept.
ngton,

J. D. T


isoz


'orest Service. Fo
*, Wis. Project L-


Agr., Fo
D.C. P

. S. Dep


E
(

E


rest Products
73, 1 and 2


iboratory Experiment
December 1909).

lull. 14S5 (1927).


iter


ells


'an


I


I


"""--it. "















: Engelmann spruce : White spruce

Physical Properties
Density (o.d. weight per green
volume) pounds per cubic foot : 22.3 21.1
Growth rate rings per inch 15.3 14.2
Age years 68 55
Diareter inches g8.9 : 7.6
Heprtwood percent 5-.3 :.................

Chemical Analyses
Lignin percent 29.3 28.3
Cellulose percent 59-5 60.2
Alph? cellulose percent : 42.7 43.2
Total pentosans percent 13.5 : 12.3
Solubility in: :
Alcohol benzene percent : 1.5 : 2.0









Table 2.--Yields and properties of Encelmann spruce puls havin varying bleaOh
requ irements



Number tCooking:Screened:8oreenings: Bleach : Chemical analyses of pulps
Time yield : requirement:; ------------------------------------------
t : Lignin $ Cellulose a Total : Solubility in
: ------------------: pentosans -------------------- -----
S : t : Total : Alpha : : Alcohol- Ether
: : : : : : benzene :
------------------- ------ ----- --- ---_------------------------------ --------------------------_----_
SHours i Percent: Percent : Percent : Percent: Percent: Percent Percent : Percent : Percent
t" : standard: t : :
S $ : bleach : : : :
: : : : powder : : : :

335 10.50: 48.o : 0.3 : 7.8 : 0.6 95.4 : 79.5 5.9 : 0.6 a 0.30
338-42 s 10.00: 348.4 : 2 2 9.6 : .6 : 95-6 79.4 6.3 : .9 35
340-43 : 8.75 : 48.9 : .2 : 15.5 : .6 : 94.3 : 77.9: 5-9 : .9 .35

344-58 : 7.50 : 50.2 : .9 : 23.5 : 1.6 : 92.7 : 7.7.0 : 6.4 1 1.l : .45

StrenRth values from beater tests 25 x. 40-500 ream


: :
Number : Bursting strength: Tearing strength:Folding endurance: Tensile strength : Solid fraction : Beating time
Freeness S.R. : Freeness 5.R. : Freeness 5.R. : Freeness 5.R. : Freeness S.R. : Freeness 8.R.
-.----------------------------------------------- ---------------------------------------------------------------------------
800 cc.: 550 cc.: 800 cc.: 50 c. : 800 cc.:550 OB: 800 co. : 550 cc.: 800 cc.':550 cc.: 800 cc.: 550 cc.
-----------------------------------------------------------------------------------
PjOints gr pound: Grams per pound: Double folds : Pounds per sq.in.: : Minutes
per ream : per ream :

335 ; 0.81 : 0.92 : 1.35 : 0.78 : 220 : 520 : 6,o50o : 8,200 : 0.44 0,55 11 : 34
338-42 t .75 8 .78 : 105 : .64 280 : 415 : 8,200 : ,300 : .47 : .56 t 11 33

340-43 : .98 : 1.14 : l.0 : .84 2 520 : 865 : 7,450 :10,500 .48 : .58 : 13 : 36
344-58 : 1.00 : 1.16 : 1.26 : .79 : 435 : 577 : 6,375 :10,7 00 .45 : .56 : 10 : 35
2 : : t 3 : : .. . : ... : ....... .......... . : : :


Z M 42509 r





t :- ------- -- :pentOB&fnstl
t :Toal Alpha

SPercent:Percent:Percent; Percent 1

I l l I

S0.6 9.8 78.-5 : 6.1 3

S.8 : 95.7 5 81.2 t 5.2 t
t i l : !


, x t40-'.00 ream



bold fraction i Bea
S

Freeness 5.R. F reen

sou 00. 0 COB. 1 800 *.
kiln
I 3
o.047 3 0.57 a 12

Ai5, 3 .38 17
3 3





with white spruce ulfite oulp



chmloal onai yea of pulp$
Cellulose I Total I ac
. ----------- 4 Pentoas I ---,----
I Alpha t lAloohol-
I 1 :benzene


3 3 I
?*Proan% Percent Fepa~n<



i 78.0 s 6.2 I 0.9
3 79.-5 6.0 1 1.0


s R5 x 4-0-"00 rsa

I I
t Solld fraction I Be
- 3- -- - I - - -- - - -
3 reenees b. H. t fi

.I 800 en. Bao. 1 8r0c nt


..... |.......... .. ..-........ ......... .......... ...-^ .. -.
3 g

o 0.48 t 0.8 I 13

3 .4 3 1 -53 1 a










;Q
kts
5%.j
ftK


14j


98
tQ
z 96

^ 94
P
92

90

^ 14
14

S20



9cin
Is/
^ /6


*4. 8


7 8 9 /0
DIGESTION TIME(IHouRS)


K

L'J~

'.4


I~J
K


1.3 -
/2 -

, IJ -- - - -
1,0

40.




O.7 -- - -- -
08
a7


12





0'-
09
S0.8
V

57
5/
5on



45


7 8 9 /0
016ESTION TIME (HOURs)


FIG. I
RELATIONS BETWEEN DIGESTION TIME
AND PROPERTIES OF EN6ELMANN SPRUCE SULPHITE PULPS.


SC2 4.2005 F





idl,,ERcSiT v' OF FLORIDA


ll31$1 1 111262 08925 4816I
3 1262 08925 4816


~~J~44
~Qt:
I4J











I.-


18 20 22 Z4


BLEACH REQu/EMENICT (PERCENT)


6 8 10 /2 /4 /6 /18 20 ??22 4
BL CACH REQUIREMENT (PERCENT)


F1/6.2
RELATIONS BETWEEN BLEACH REQUIREMENT AND YIELD
AND PROPERTIES OF EN6EL MANN SPRUCE SULPHITE PULPS.


Z V.W ?0


to.
09
;k 0G
,1 0.8
K


I *-
L.^


8 /0 IZ


497 -



47


1j -