T
THE GRINDING Of ENGELMANN SPRUCE ECR NEWSPRINT AND
MAGAZINE QUALITY MECHANICAL PUEPS
January 1942
4s
r
UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the University of Wisconsin
THE GRINDING OF ENGELMANN SPRUCE FOR NEWSPRINT
AND MAGAZINE QUALITY MECHANICAL PULPS
By
E. R. SCHAFER, Engineer
and
J. C. PEW, Associate Engineer
Introduction
Interest in the development of a pulping industry in the Rocky
Mountain region with Engelmann spruce as the principal pulpwood as well as
the increasing use of this species by Lake States pulp mills has prompted
the Forest Products Laboratory, in cooperation with the I'orthern Rocky Mountain
Forest and Range Experiment Station, to verify and extend former work- on the
sulfite, sulfate, and groundwood processes. This report describes the
comparative grinding characteristics of Engelmann spruce and white spruce
for newsprint and magazine quality pulps.
Procedure
Bolts 6 inches in length were cut from the 32 logs of the sample
cord selected from Engelmann spruce, shipment 1509 (L-I56I).— The bolts
were divided into two lots, each being a representative mixture of the wood
in the three trees comprising the cord. Thin wood was substantially in the
green state when ground. Ihe white spruce used for comparison was obtained
by cutting six partially seasoned 8-foot logs from shipment 1571 into 6-inch
bolts and dividing into three lots, each of which was representative of the
six logs taken. Two of the lots were used in this study.
-"The Suitability of American Woods for Paper Pulp." U. S. Dept . Agric.
Bui. lUg5 (1527).
"Groundwood Pulp." U. S. Dept. Agric. Bui. 3U3 (I916).
2
—"Physical and Chemical Properties of Engelmann Spruce Pulpwood, Shipment
1509," by J. C. Pew and E. R. Schafer. Problem D-192, project L-168-7,
filed October 8, I9U1.
R1U07
The comparison of the grinding p~c erties of the two species of wood
was made with two conditions of grinder ston.2 surface. The 3760/5, grade N7
Norton stone had previously "been burred with an 8-cut, l-l/2-inch lead spiral
burr and a 1^— point diamond burr, and had been in service until the stone
surface was decidedly dull. The first pair of experiments was made on this
surface. Pressure was adjusted so as to give somewhat above normal energy con-
sumption. In the second set of experiments the stone was dressed with a
10-cut, l-l/2-inch lead spiral burr and then a lU-point diamond burr, and
waste wood ground until the surface was in a stable condition but still quite
sharp. The pressure in this case was adjusted so as to give normal or some-
what below normal energy consumption. Pit temperature, stone immersion, and
consistency were kept substantially constant in each pair of experiments.
The pulps obtained were lapped on the wet machine and samples tested according
to standard methods .-*■
Results
The properties of the wood ground, the grinding conditions and pulp
test results are given in table 1. The two species of spruce had about the
same density but the white spruce was considerably drier. Because of the
difference in diameter it was not possible to charge the pockets in exactly
the same manner with both species so the actual pressures may have been some-
what at variance. The runs on the dull stone surface (grinder runs 393 a-ad 39^<
utilized somewhat above the normal amount of energy but gave exceptionally
strong pulps, with slightly lo\tfer than normal freeness and average fiber
length. With a sharp stone (grinder runs 395 a^d 39^) free pulps of standard
strength were produced at rather low energy consumption. The two species
gave pulps of about equal strength-energy ratios, with both the dull and sharp
stone surfaces; therefore, it is concluded that Engelmann spruce and white
spruce of about the same density will grind similarly and produce similar pulps,
The properties of the two pulps produced at the lower energy con-
sumption were so close to that of standard newsprint groundwood that experi-
ments on the making of newsprint paper from them did not seem to be necessary.
The pulps produced at the higher energy consumption were of sufficiently high
quality to consider them suitable for use in groundwood-containing book and
magazine papers although no experiments were made to prove this. These two
pulps were also interesting from the standpoint of making a newsprint paper
entirely from groundwood. Table 2 shows the results of paper machine runs with
100 percent of the Engelmann and white spruce groundwoods and the average of
commercial newsprints for comparison. The experimental papers compare quite
well with the commercial. The bursting and tensile strengths are higher than
the average standard newsprint but the tearing strengths are lower. The castor
oil penetrations of the experimental papers are appreciably higher than the
standard, indicating there would be less rapidity in absorbing the printing
ink. From the standpoint of machine operation the principal difference as
compared to a standard furnish is the necessity of running the machine slower
because of the lower freeness of the groundwood pulps .
^Manual of standard testing methods for pulpwood, pulp, stuff, and paper,
Forest Products Laboratory.
Rll+07 -2-
I
I 111 1
|j IS
11
T
IT
II.
2
III
If!
:s£;:
ill
Jl»8
1 i.i
I «
[Si"
it
|«I..„.
Ittiii
i
. o a ■
■ - r •
- • ■ c
liii
i!
-.
I 9 J «
c a c e
a e e r
a t 5 <
d
fill
lien
d
net:
. v 5 5
o • «J » ©
8 3 3*5
2 £i J
£ C ? * *
2 * * S
£ ft S S
8 8 8
8 S 3 S
5 3 } j
i i i 5
S3- ,1
= * S S ft
a s
..
Id
s * : £ i
* a 3 3 I
ill!
1 1 i 1 5
i' u
Ik til
I
I
is ij
fifti J
" e ■ " 5 »
* il! r
left i
I'lill i
5 m is; -
I Si I
ill
I"
i kK-2»»I
I |: -*tli u : ; i
Hfiiiiii ii
it j J JJJ
p
d
,4
LP>
C
i m
O
co
O
•
i
•
<*i
r-l
CD
rH
r—
1 rH
rH
Ph
t>»
► P
p
d
J*
CO
•H
CD
r^
m
m
VJD
p
s
£
O
o>
cr> cr\
<J>
60
I
1 u
CD
Ph
•
O
>d
1
o
cfl
CO
o
U t,
TJ
>»
*
o h p a
d
to
cr»
60
rH
-p
P -H CD O
o
r—
c
I LTv
J"
Ph
i
CO O d -H
o
r-
rH
•H
CO CD P
CD
-^>
o
O Ph
CO
rH
1
CD CO
P
d
cd
#•
i
a)
J3"
^t
LO
60
o
P CO
o
ViD
^£
• VX3
LP»
o
p
DO
•H CD
*
in
g S
CD
Ph
»
CD CD
^JD
a
rH W ,d
tJ
O
c
O
OJ
r^>
-t->
*■« t-t a o
d
CP>
c
60
CTn
,H
co cd p d
p
OJ
6C
IPi
LTN
X
.C
d P. cr'-H
o
K>
K>
OJ
S
CD CO
Ph
JH-
EH
OJ
d 1
cm
O
•H I
EJ
rH
rH
60
to
>j;
^H 1
cd
,=f
m
J-
Q
C
cd i t)
M
•
•
CO
Cj
0) 1 5 6 I
CJ3
d
CD
g
Eh 1 P CO
M
rH
• ••• | O CD
o
y) i fth
CD
3
a
d 1
•H | ^ fn |
P
rH
j*
cr%
LO
^
w
P 1 CD CD
d
OJ
m
OJ
M
OT 1 Ph P,
•H
•
•
•
P
<H
t-t 1
O
o
o
P 1 1
Ph
P
d
>s
• ••
• •
• <
■ •
•H
r-H
1 1
>H
CD
M co
co
60
OJ
^
o
Ph
M
O CO
r-H
o
fo
OJ
CO
•H
•H CD 1
&
-t-^
,S d
;s
CO
f-\
f^v
CD
G
0)
En i
d
P rHl
5
0)
yj cd co
>gj
in
OJ
o
O
•
rS
P
co
•H P< ©
r~-
60
r-^-
f —
o
0) J-l
P
K>
m
m
o
1
o
Is
PhI
p
1
x;
CO
p
o
1 1
a
U
M
*H
1 CO
§
Ph
CD
>
o
1 t> t\D
CD
T
®
cd
d
g
^ C!
d
(-
d
Ph
o
cd
j O -H
o
c
» o
o
P
1 »"3
S23
r-J
S
P
t
• ••
• •
• *
••
d
o
-^
\ *"•
•H
EH
c
I CD
M
(-.
•^
1 Ti
CD
-3-
j3
m
Ph
b
Ph 1 «
rO
CTN
<T\ CTv
CO
•
P
rH 1 -H
m
r«"\ m
fc
o
(,<;
P 1 >H
P
CD
o
CD
ft e>
^
d
LP.
T* 1
CD
rH
1
1
O I
O
aJ
1
2 !
P
in
•H
o
5
oJ
tJ i w
Ph
CD
(h
d 1 CD
CO
o
CD
X
CD
P 1 -H
p
rH
O 1 o
d
c
. (h
g
in
'S
rH I CD
d
c
1 Ph
o
OJ
aJ
O 1 Ph
CO
CO
o
^
1 CO
3
£3
1
CD
CT>
3
1
1
CD
P
•H
OJ
CD
M
1
1
£
i
o
H
cd
CD
• ?
CD
d
(h
U)
ir)
•h d
1 CD
«,
PC
1
cd
d
•3 P
1 'S
o
c
) rH
u
CO
o M
O^
a
N O^
CD
p
CO
3
r»-
r~
1^
>
to
a
1 SB
rH
r-
1 r-i
«=>{
rH|
R1U07
SITV OF FLORIDA
I I I I
3 1262 08925 4824