C&EN ANNUAL
R E V I E W OF
Developments in the Chemkal and Process Industries
PULP AND PAPER PRODUCTION DROPS H A R R Y F. LEWIS, Institute of Paper Chemistry, Appleton, Wis.
The production of both pulp a n d paper showed a considerable decline from the all-time high of the corresponding period for 1948 . . . . . T h e over-all decline in the pro duction for this period is shown hy tinfollowing figures. Pulpwood receipts (ex cepting for t h e Pacific N o r t h w e s t ) were d o w n 17'·/ a n d pulpwood consumption de creased 9'/v. Pulp production and con sumption w e r e also down 9 ' Ί. (An ex ception to t h e trend w a s t h e increase in t h e consumption of bleached sulfate p u l p . ) Total pulp imports declined 35 Λ 7. T h e production of paper a n d paperboard also showed a decline, paper production being d o w n 11.5'ν a n d board 14'·*. T h e operating ratios for 1949 are in fluenced somewhat by t h e fact that, dur ing 1949, better than I million tons of n e w paper capacity came into operation as t h e result of new construction and modernization programs, bringing paper mill capacity u p to 24,325,000 tons, o r an increase over 1948 of about 4'Ύ . T h e devaluation of foreign currency and t h e Marshall plan, together with Canadian restrictions with regard to pulpwood, have posed problems of an economic nature, all of which have h a d their effect o n t h e direction of technical work b y t h e indus try. At h o m e the increased pressure from stream.· improvement groups, the crop s u p p o r t program, a n d t h e depletion of o u r supplies of spruce a n d balsam a r e im portant economic factors in dictating re search priorities. Trade Waste Elimination and Disposal
tion in this case is found in t h e carbohy d r a t e fraction which is converted in t h e stream by biochemical oxidation, with consequent removal of t h e dissolved oxy gen from t h e stream. W h e r e t h e stream flow is low, oxygen may b e removed helow t h e point required b y fish life. Tin· harmful by-products of t h e kraft process are the toxic materials which are formed during t h e cooking process or are converted to a soluble form by t h e action of t h e alkaline cooking agent. T h e prod ucts of t h e first type are largely sulfurcontaining materials, such as t h e m e r c a p tans a n d t h e thio ethers. Those of t h e second type a r e t h e alkali salts of rosin acids. T h e sulfur c o m p o u n d s a r e volatile and a r e found principally in t h e conden sate from t h e digester or evaporator. Sodium abietate a n d eglated products are present as skimmings in t h e black liquor. Some of these materials a r e toxic t o fish in concentrations below 1 p.p.m. O t h e r materials which m a y occasionally be in t h e effluents from t h e p u l p and paper industry a n d which a r e looked upon as sources of stream contamination include the highly alkaline wash waters from t h e alkaline pidping processes, unrecovered fiber which m a y b e p r e s e n t in t h e white water from t h e paper mill, bark, deinking wastes containing fillers a n d carbon black, and others. Of these, t h e one receiving most atten tion currently is sulfite spent liquor; t h e
Very real pressure is being exerted by local, state, a n d national authorities t o re d u c e extensively t h e factors in t h e wastes of t h e pulp a n d paper industry which are said t o affect adversely our waterways a n d c o n t r i b u t e t o the subsequent destruction of a n i m a l life in and a r o u n d these waterways. T h e wastes of t h e p u l p industry differ in effect in accordance with their source. T h e sulfite p u l p mills have as their prin cipal waste the spent liquors from the digesters, together with t h e wash water from t h e blowpit. T h e s e contain lignosulionates, various sugars a n d soluble poly saccharides, a n d t h e dissolved or soluble extractives of the wood, together with in o r g a n i c salts. T h e main cause of pollu V O L U M E
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annual volume discharged to t h e sewers contains between 2 and 3 million tons of lignosulfonate and somewhat less t h a n 1 million tons of carbohydrate. T h e past year has seen two new avenues of attack on t h e problem of eliminating or utilizing more effectively the dissolved organic chemicals from the sulfite process. New Plant for Yeast P r o d u c t i o n T h e first is the new plant at Rhinelander, Wis., for the production of the yeast Tortdopsis utilis. This is in e v e n sense of the word a pilot plant, even though it utilizes half of t h e sulfite spent liquor from the mill of t h e Rhinelander Paper Co. for t h e daily production of 8,000 pounds or more of dried Torulopvi.v utilis. T h e product is b e i n g tested extensively as an animal food. The yeast-free effluent from t h e process has 90 to 9576 of t h e hexose a n d pentose sugars removed and also is freed, t o a somewhat lesser degree, of other or ganic materials which c o n t r i b u t e to the biochemical oxygen d e m a n d . T h e group responsible for the development, the Wis consin Sulphite Pulp Manufacturers' Re search League, is currently evaluating the potential market for torula yeast so a s to determine t h e practicability of t h e process for t h e large-scale utilization of sulfite spent liquor. It would a p p e a r currently that t h e major share of t h e d e m a n d will he in t h e poultry food field, b u t there are
T T A H H Y F. LEWIS, dean and research associate at AA
t h e Institute of Paper Chemistry in Appleton, Wis., claims as his particular field of interest the chemistry of plant products, particularly wood chemistry, and on this subject can claim author ship of about 4 5 published papers, as well as 2 5 patents and a book, along with chapters in others. His hobby still keeps him among t h e plants, as it is gardening. Before joining the staff at Appleton he had taught at Ohio Wesleyan Univer sity, Maine, and Cornell College ( I o w a ) . His education he received from Wesleyan University and the University of Illinois, from which latter he took a P h . D . in 1916.
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other promising outlets in sight. A small sulfite mill with a daily capacity of 100 tons of sulfite pulp would, at the same time, produce 20,000 pounds of Torulopsis tttilis yeast in the same period if all the liquors were utilized. Whether it would be feasible for the sulfite industry to es tablish a number of large-scale torula yeast plants will bo determined only by an economic evaluation of the process. Even more important has been the opening of the Weyerhaeuser plant at Longvicw, Wash., in which magnesium bisulfite is used as the pulping chemical in place of calcium bisulfite. The success ful operation of this plant is based upon the recovery of the major portion of both magnesium and sulfur during the evapora tion and subsequent incineration of the spent liquors of the process to recover magnesium oxide and to provide heat for the boilers. The expected recoveries wen* said to be in the range of 90Γί for both magnesia and sulfur; in September of this year it was reported that the recoveries to date were 74 and 64*>r, respectively. In this process the organic matter, including the carbohydrates and lignin, is converted to gaseous oxidation products with the simultaneous production of heat. A proc ess of this kind is said to be feasible only when the mill is above a certain size. Other developments in the field of sulfite spent liquor utilization or recovery dining the year include construction of a small pilot plant in Appleton, Wis., by the Wisconsin Sulphite Pulp Manufac turers* Research League to study the Rosenblad evaporator and the subsequent burning of the evaporated material without developing objectionable fly-ash. This same group has improved the method for using the spent liquor as a road binder, and, during the summer of 1949, the liquors from two Wisconsin mills were diverted in part to that application. Kraft Liquors Elimination of noxious products of the kraft process has stepped forward during recent y~ars with the expansion of the tall o f usiry; in this, rosin and fatty acids from the skimmings of the kraft process are refined to various degrees for wide industrial uses; this keeps them from becoming pollutional hazards. T h e re moval of the sulfur compounds from con denser water may be achieved by scrub bing these liquors countercurrently in a Bergstrom tower packed with ceramicrings. The toxic sulfur compounds are removed from the water going t o the sewer and are eliminated with the stack gases. W o o d Supply Because of economic considerations, the second broad field of interest to the pulp and paper industry during 1949 has been its concern with the preservation of an adequate and future supply of their prin cipal fibrous raw material, wood. This concern has manifested itself in a number of ways. One has been a continuation of the war time and postwar use of less desirable
wood spceics as pulping raw materials. In 1940 only about 3.5 to 4rA of the pulpwood used, was hardwood; in 1944 this had increased to 9'/ and in 1947 to 139*. Although i t is hard to obtain an exact figure for 1949 at the time this article is written, it would appear that at least 10'/> of the pulp wood used in t h e U. S. in 1949 will be hardwood. An increase in the use* of Douglas fir in kraft pulping in the Pacific Northwest, of gum and oak in the South, and of poplar and birch in N e w England is in line w i t h this program of utilizing available wood species. Not only are other wood species being used, but there has been a definite attempt to increase the amount of wood recovered from a given area of woodland. This in crease in yield is partly the residt of im proved methods for harvesting the wood such as thinning, prelogging, relogging, and salvage logging and partly because of the greater use of waste wood in the fac tory and mill through integrated opera tion. A good illustration of this is a pulp mill set u p in conjunction with a lumber mill. One such mill opened in 1949 in Springfield, Ore., as the latest in the group of Weyerliaeuser Pulp Division pulp mills. This Springfield mill will make 150 tons per day o f kraft container board. Simul taneously with the construction of tincontainer board plant there was built a saw mill and remanufacturing plant han dling 300,000 board feet per day. The by products of the saw mill are the raw ma terials for the pulp mill. The size of the sawmill w a s established b y the amount of timber which was available from the com pany's holdings on a sustained yield basis. T h e size of the container board plant, however, was established on the basis of using the by-product material available from the sawmill and logging operations of the company, together with farmer logs, trim, edgings, and slabs from other sawmills in Lane county where over 100 sawmills are located. During 1949 the same company opened a kraft mill at Long view. Wash., to supply kraft pulp to the trade. This mill uses high quality wood waste from the Longvicw sawmill and logging operations which w a s formerly cither unused or burned. This is a good illustration of the value of an integrated operation, because the wood, used in this n e w kraft mill was formerly burned to provide steam for the operation of the Longview calcium-base sulfite mill. Conversion of the latter mill to use magnesia-base liquor with subse quent production of its own necessary steam i n the recovery of magnesia and sulfur made t h e use of t h e wood no longer necessary and liberated such wood for the kraft operation. In this integrated opera tion at Longvicw are three hydraulic barkers, three sawmills, a plywood plant, a plant for converting waste bark to bark by-products, one 275-ton and one 200-ton sulfite p u l p mill, and a forest products development laboratory. Still another approach to the problem of getting more pulp from a given stand of wood is to-terease the yield of pulp
CHEMICAL
per digester and per unit of wood used. The desire to achieve this end has led to the conversion of certain pulp mills within recent months from chemical processes to scmicheniical processes. The yields of pulp obtained by the scmicheniical process are 20 to 30' Ί higher than those achieved by the straight chemical processes. T h e semichemical pulp has to be handled in a different manner before it is acceptable for general use. Its principal use is in the manufacture of paperboard, such as nine point. In fact, one of the interest ing developments of 1949 has been the improvement in the quality of nine-point board as the result of the increased use of neutral sulfite semichemical hardwood pulp. These high-yield pulps are also finding their way into glassine paper and special boards. Other Developments Space will not permit more than a sum mary review of some of the other trends in the pulp and paper industry during 1949. The use of sodium peroxide as a bleaching agent has been adapted to the continuous bleaching of mixtures of groundwood and unbleached sulfite pulp. The combined use of hydrogen peroxide and sodium peroxide has given results of interest. Continued attention has been paid to the development and use of better beater additives. In this connection the return of locust bean gum to the market has again made this material available to the paper industry to be used to increase sheet strength and as a deflocculating agent. Improved carboxymethylcellulose preparations have been developed, and the use of neoprene for increasing both the wet and dry strength of paper has been found to have definite possibilities. The trend toward the wider use of paperboard containers has continued. One interesting development in this field during 1949 has been the discovery of a method for adding sulfur to nine-point corrugating medium, at the same time leaving the fiber surface free for the appli cation of the aqueous adhesives necessary in the combining process. By this new method 50 to 60% of sulfur ( o n the weight of the original board) may be added to the corrugating medium. The board produced with the sulfur-impreg nated corrugate shows better flat and box compression; these characteristics are evi dent particularly at high humidities. It is appropriate to close this review with a mention of the new research build ing built and opened during 1949 at Rothschild, Wis., by the Marathon Corp. This company has been a leader in a pro gram for conserving the chemical values of the sulfite spent liquor. More than half the vanillin manufactured and used in the U. S. is made from sulfite spent liquor by a process developed by this company. In addition, they produce and distribute to industry a w i d e variety of lignin prepara tions which find a ready market in the fields of dispersing agents, tanning agents, drilling mud additives, base-exchange materials, and others.
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ENGINEERING
NEWS
