PRODUCING SODA PULP FROM ASPEN, 
35 
CHEMICALS PER TON OF PULP. 
The chemicals directly employed in the manufacture of soda pulp 
affect cost of production, in that the full amount of alkali charged to 
the digester can not be recovered, while the bleaching powder after 
being used is of no further value. The curves iu figures 18 and 19, 
expressing the effects of the 
cooking conditions on the 
amounts of chemicals em- 
ployed per ton of air-dry, 
bleached pulp, were derived 
from the experimental data 
as explained on page 48, ap- 
pendix. The amounts shown 
are less than those generally 
employed in commercial prac- 
tice, for several reasons: (1) 
The yields of pulp are higher; 
(2) the losses on bleaching 
i are less; (3) the amounts of 
chemical charged per pound 
of wood are less; and (4) the 
amounts of bleach required 
are less. Whether or not 
pulp mills can duplicate or 
approach these results, the 
general trend of the curves 
would not be affected. 
2200 
2000 
1800 
1600 
j 1400 
1200 
o 
Ui 
= 1000 
3 800 
-33=- 
9 ^8 
.10 
.20 30 .40 
POUNDS NaOH PER POUND OF WOOD 
1800 
1600 
ItJ 
a. 1400 
a 1200 
1000 
+ 
1 
!—* 
\ 
\ 
Sft 
il 
10 
• 
■ 
ar- 
*& 
2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 
SODA ASH. 
1400 
1200 
1000 
60 
1300 
19 
18, 
n 
22 
2lj 
20 
70 80 90 100 110 120 
MAX. PRESSURE-PDS. PER SO. IN. 
1100. 
Fig. 18. 
The amounts of caustic 
soda and sodium carbonate 
charged to the digester in the 
several groups of tests have 
been calculated to show the 
equivalent amounts of com- 
mercial soda ash (58 per cent 
Na 2 0) per ton of bleached 
pulp produced. (Fig. 18.) 
Increasing the amounts of 
caustic soda charged per pound of wood obviously results in increas- 
ing amounts of soda ash per ton of pulp, and the decreased yields 
of pulp resulting from the more thorough cooking make the effect 
more pronounced. A bend is found in the curve at the point of 
maximum yield, since for amounts of caustic below this point the 
yields decrease rapidly and their influence on the amount of soda 
ash employed per ton of pulp becomes more apparent. 
SO 60 70 80 90 .00 110 
CONCENTRATION NaOK- GRAMS PER LITER 
-Effects of cooking conditions on amount of 
soda ash employed per ton of pulp. 
