906
~
T H E J 0 U R AVA L 0 F I LVD U S T RI il L A X D EAVGISEERILVGC H E M I S T R Y
t h e so-called mechanical treatment of waters of these types is very liable t o bring about this troublesome discoloration. It may be noted here t h a t both these waters examined were of low mineral content and highly colored b y peaty matter. It would be of interest t o follow this matter further with various other types. These figures are in excellent accord with t h e electrolytic theory of corrosion a n d illustrate a n easy means for investigating this subject. A graphic representation could be presented with t h e aid of further figures which would be very interesting. CHEMICAL LABORATORY, DEPARTMENT OF h R I C U L T U R E EXPERIMENTAL F A R M ,OTTAWA.ONT.
SOME EXPERIMENTS ON THE CONVERSION OF LONGLEAF PINE TO PAPER PULP BY THE SODA AND SULFATE PROCESSES' E y SIDNEY D WELLS
I S T R OD U C T I 0 li
During 1912 t h e Forest Service in cooperation with t h e University of Wisconsin undertook a series of experiments on longleaf pine, P i n u s p a l u s h i s , with t h e following objects : I . T o study nThat influence t h e variable cooking conditions have in t h e sulfate process of pulp-making. 2 . T o determine t h e suitability of longleaf pine for paper pulp. 3 . T o compare t h e sulfate process with t h e soda process. This work has been only partially completed b u t since there is urgent demand for information on t h e adaptability of longleaf pine, or southern pine as i t is more commonly called, for t h e manufacture of paper pulp, it has been thought advisable t o give what indications our work has so far made manifest. Longleaf pine was chosen on account of t h e large quantities of this wood t h a t are being wasted in t h e lumber operations of t h e southern states and also because many logs are a t present being sawed into lumber a t little or n o profit on account of their small diameter which would be of admirable size for pulpwood. Furthermore, t h e large amount of resinous matter in this wood made i t desirable as a n extreme test of a cooking process and t h e long, thick-walled fibers of t h e wood assured a strong pulp if i t could be produced without a too drastic treatment. E X P E R I M E X C. A L P R O C E D U R E
1'01. 5 , No.
11
T h e wood used was procured in Louisiana and l l i s sissippi, and was fairly average in rate of growth, size, and content of resinous matter. It was freed from bark a n d reduced t o chips five-eighths of a n inch long with t h e grain. These chips were allowed t o become air-dry a n d were thoroughly mixed a n d sifted t o remove any dirt a n d small pieces. The cooking liquors were made up by dissolving the required amounts of commercial caustic soda, sodium sulfide, Glauber's salt, a n d soda ash t o produce solutions of t h e desired concentration of each of these chemicals. I n studying t h e influence of t h e variable factors entering into t h e cooking operation t h e small autoclave was used. T h e effect t h a t any one variable condition exerted was determined b y a series of cooks made varying t h e condition under observation, a n d maintaining t h e other conditions as nearly identical as possible in each cook. The effects were ascertained by determining t h e yield of pulp a n d carefully treating t h e pulp in a hollander beating engine t o develop a stuff capable of producing as strong a sheet as possible when made into paper. The quality a n d color of t h e pulps were judged b y inspection, feel, amount of beater treatment necessary, a n d t h e strength and wearing qualities of t h e paper produced. T H E E F F E C T S O F VARYING T H E A X O U N T S O F CHEMICALS
The effect of varying t h e caustic soda or sodium sulfide was a decrease in yield a n d a lighter colored pulp with a n increase in either one or both of t h e chemicals. Caustic soda was found t o be about twice as drastic in its action as sodium sulfide and with t h e same yield t h e pulp produced by t h e former was lighter t h a n t h a t produced b y t h e latter. The yields, however, do not decrease directly in proportion t o t h e amounts of chemical used, a n d between 30 a n d jo pounds of caustic per IOO pounds of chips t h e decrease in yield is much less for equal steps t h a n below or above these amounts. The disagreeable odor caused by t h e production of mercaptans increased with t h e increase of t h e sodium sulfide, a n d was much more noticeable where t h e larger proportions of this chemical were used. T h e sodium carbonate and sulfate present in t h e cooking liquor produced no very apparent effect except where t h e former was present in relatively large amounts when a retardation in t h e action of t h e other chemicals present was noticeable. Enough cooks were not made, however, t o definitely establish this indication.
The cooking operations in this work were conducted in two forms of digesters. T h e first form consisted of a small rotary autoclave of about a-gallon capacity which was heated with Bunsen burners. The other T H E E F F E C T O P V A R Y I X G T H E P R E S S U R E , D U R A T I O N O F form was a vertical digester of 60-gallon capacity, C 0 0 K I iX G A N D C 0 h-C E N T R A T 1O S S heated by direct steam. The greater portion of t h e The effect of increasing any one of these variables work was accomplished in t h e former and in all 115 cooks made. The d a t a obtained in these cooks &-ere was t o increase t h e severity of t h e cooking action a t used in determining t h e conditions for t h e larger di- tainable with t h e same quantity of cooking chemicals. gester in which 19 cooks were made t o obtain condi- With any combination of t h e above conditions there tions more nearly comparable with those used in com- is a definite amount of chemical necessary t o produce a pulp of t h e best quality a n d it is possible t o use a mercial practice. wide range of conditions t o produce approximately 1 Paper presented a t the 48th Meeting of the A. C. S I Rochester, t h e same result. September 8-14. 1913.
NO\7.,
I913
T H E J O C R S --I L 0 F I S D C S T RI -4L S E XI- C 0 IIME R C I .A L C 0 0 K S
I n t h e coolts in t h e large digester t h e object sought was t o obtain t h e best qua::ty of pulp. It was found t h a t easily-bleaching pulps could not be obtained without using a very drastic digestion with a high percentage of alkali, a n d t h a t t h e pulps produced were very low in yield a n d extremely soft and weak. I t was, therefore, decided t o devote attention ton-ard producing t h e strongest pulps possible, a n d treat these pulps in t h e beater t o make t h e highest grade of “ K r a f t . ” Although t h e strength of t h e paper was constantly considered, t h e question of yield was also very i m p o r t a n t a n d t h e best cooks were determined with these t w o objects in view. T h e best cooks secured were made under t h e following conditions: Caustic soda charged p t r 100 pounds bone dry chips. p o u n d s . . . . . . . . . Sodium sulfide charged per 100 pounds bone-dry chips, p o u n d s . . . . . . . Initial concentratioii caustic soda in cooking liquor, grams per liter, , . , Initial volume liquor per pound of chips, jiallon.. . . . . . . . . . . . . . . . . . T o t a l duration of cook, hours. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Duration of COOK a t maximum steam r.ressure, h o u r s . . . . . . . . . . . . . . . Maxinium steam pressure, pvunds per square i n c h . . . . . . . . . . . . . . . .
15.0 7.5 26.5 0.68 3.5 3 .O 100.0
T h e yields of crude pulp under these conditions were 49 per cent of t h e weight of t h e wood a n d t h e
with these pulps using t h e ~ a m or e an even less consumption of power a n d in much less time. SODA COOKS
To compare t h e soda process with t h e sulfate process in cooking longleaf pine several soda cooks were made. It was found t h a t soda pulps could be made t h a t wou!d produce paper capable of resisting bursting pressure t o t h e same degree as t h e best paper made from sulfate pulp b u t t h e wearing qualities were not nearly as good a n d t h e yields were from j t o I O per cent less. T h e unbeaten pulps were soft a n d fluffy for even slightly undercooked pulps, a n d although t h e y could be hardened in t h e beater t h e treatment was longer. a n d much greater care h a d t o be exercised to avoid cutting t h e fibers. Furthermore, although a fairly good grade of kraft can be made of sulfate pulp with a yield of 60 per cent, soda pulp produced with t h a t yield would be so undercooked a n d brittle t h a t only very poor wrapping could be produced. Moreover, i t was found necessary t o cook soda pulp a t least 6 hours t o secure good results while in t h e sulfate process 31/2 hours n-ere found sufficient. T h u s in t h e latter process t h e same digester capacity would produce two-thirds more pulp per day.
COOKINGCONDITIONSFOR FOURTYPICAL SEMI-COMMERCIAL COOKS Beater t r e a t m e n t
Large yield . . . . . . . Medium yield. . . . . Small yield.. . . . . . . S o d a cook.. . . . . . . .
Lbs.
Lbs.
15.0 15.0 20.0 30.0
7.5 i.5 10.0
0.0
Grams per liter Gallons 26.5 26.5 44.6 90.0
68.0 68.0 54.0 40.0
Hours
Hours
3.0 3.5
2.8 3.0 2.5 5.5
5.0 6.0
strength of t h e paper produced as determined on t h e hlullen tester was 9 pounds per thousandth of a n inch of thickness. A n average sheet of 0 . o O j of a n inch tested 4 j pounds a n d weighed 4j pounds per ream of joo sheets 2 4 inches b y 36 inches. Not only was t h e paper exceptionally strong b u t i t was very resistant t o \year a n d folding. T h e latter fact is apparent b y some tests made on i t in a Schopper Folding Tester i n m-hich i t withstood 1 2 0 0 double folds before breaking. T h e pulps under these conditions were very chippy when blown b u t t h e chips were very soft, h a d no hard hearts a n d were readily broken up in t h e beater. An ordinary hollander with steel fly bars was used a n d t h e pulp was beaten t w o hours a t light brush, four hours a t stiff brush, a n d one-half hour was spent in lowering t h e roll from one stage t o t h e other. Stronger papers t h a n these were produced b u t t h e yields fell off considerably. Yields u p t o 61 per cent were obtained b u t t h e strength fell off more t h a n could be compensated b y using proportionately heavier paper. I t is very probable t h a t with basalt lava beater rolls a stronger paper could have been produced
Lbs. per sq. inch 90 100 103
100
P e r cent
Hours
Hours
Hours
61.2 49.0 45.3 39.8
1.5 4.0 1.5 6.0
0.5 0.5 0.5
2.0 2 .5 1.5
0.0
0.0
G E N E R A L C 0 S C L US I O S S
a l t h o u g h t h e experiments performed in this investigation are only a portion of what are contemplated t h e y seem t o make apparent t h e following facts: I. T h a t longleaf pine is well adapted for t h e m a n u facture of natural-color kraft pulps a n d papers. 11. T h a t t h e sulfate process when applied t o this Tl-ood affords pulps of better quality a n d higher yields t h a n t h e soda process. 111. T h a t kraft paper can be made from longleaf pine equal or superior in quality t o t h e imported or domestic kraft papers now procurable. II-. The high specific gravity of t h e wood insures a greater yield per cord t o this wood t h a n is possessed by a n y other commercially important pulpwood. The d a t a of these experiments given in greater detail is contained in a report entitled “ T h e Utilization of Longleaf Pine for Paper Pulp’’ by H. E. Surface a n d R. E. Cooper which is now i n press a t t h e Government Printing Office. FOREST PRODVCTS LABORATORY h f A D I S O S , \\rISCONSIN
