C & E N A N N U A L 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 and paper showed a considerable decline

from the all-t ime high of the corresponding period for 1948 . . .

. . The over-all decline in the pro­duction for this period is shown hy tin-following figures. Pulpwood receipts (ex­cept ing for t he Pacific Northwest) were down 17'·/ and pulpwood consumption de­creased 9'/v. Pulp production and con­sumption were also down 9 ' Ί. (An ex­ception to t h e trend was the increase in the consumption of bleached sulfate pu lp . ) Total pulp imports declined 35Λ7. T h e production of paper and paperboard also showed a decline, paper production being down 11.5'ν and board 14'·*.

T h e operating ratios for 1949 are in­fluenced somewhat by the fact that, dur­ing 1949, bet ter than I million tons of new paper capacity came into operation as the result of new construction and modernization programs, bringing paper mill capacity up to 24,325,000 tons, or an increase over 1948 of about 4'Ύ .

T h e devaluation of foreign currency and the Marshall plan, together with Canadian restrictions with regard to pulpwood, have posed problems of an economic nature, all of which have had their effect on the direction of technical work by the indus­try. At home the increased pressure from stream.· improvement groups, the crop suppor t program, and the deplet ion of our supplies of spruce and balsam are im­portant economic factors in dictat ing re­search priorities.

Trade Waste Elimination and Disposal Very real pressure is being exerted by

local, state, and national authorities to re­d u c e extensively the factors in the wastes of the pulp and paper industry which are said to affect adversely our waterways and contr ibute to the subsequent destruction of animal life in and around these waterways.

T h e wastes of the pu lp industry differ in effect in accordance with their source. T h e sulfite pulp mills have as their prin­cipal waste the spent liquors from the digesters , together with the wash water from t h e blowpit. These contain lignosul-ionates , various sugars and soluble poly­saccharides, and the dissolved or soluble extractives of the wood, together with in­organic salts. T h e main cause of pollu­

tion in this case is found in the carbohy­drate fraction which is converted in the stream by biochemical oxidation, with consequent removal of the dissolved oxy­gen from the stream. W h e r e the stream flow is low, oxygen may b e removed he-low the point required by fish life.

Tin· harmful by-products of the kraft process are the toxic materials which are formed during the cooking process or are converted to a soluble form by the action of t he alkaline cooking agent . T h e prod­ucts of the first type are largely sulfur-containing materials, such as the mercap-tans and the thio ethers. Those of the second type are the alkali salts of rosin acids. The sulfur compounds are volatile and are found principally in the conden­sate from the digester or evaporator. Sodium abietate and eglated products are present as skimmings in t h e black liquor. Some of these materials a re toxic to fish in concentrations below 1 p.p.m.

Other materials which may occasionally be in the effluents from the pulp and paper industry and which a re looked upon as sources of stream contamination include the highly alkaline wash waters from the alkaline pidping processes, unrecovered fiber which may be present in the white water from the paper mill, bark, deinking wastes containing fillers and carbon black, and others.

Of these, the one receiving most atten­tion currently is sulfite spent liquor; the

annual volume discharged to the sewers contains between 2 and 3 million tons of lignosulfonate and somewhat less than 1 million tons of carbohydrate. The past year has seen two new avenues of attack on the problem of eliminating or utilizing more effectively the dissolved organic chemicals from the sulfite process.

New Plant for Yeast Product ion

The first is the new plant at Rhine-lander, Wis., for the product ion 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 the sulfite spent liquor from the mill of the Rhinelander Paper Co. for the daily production of 8,000 pounds or more of dr ied Torulop-vi.v utilis. The product is being tested extensively as an animal food. The yeast-free effluent from the process has 90 to 9576 of the hexose and pentose sugars removed and also is freed, to a somewhat lesser degree, of other or­ganic materials which contr ibute to the biochemical oxygen demand. The group responsible for the development, the Wis­consin Sulphite Pulp Manufacturers ' Re­search League, is currently evaluating the potential market for torula yeast so as to determine the practicability of the process for the large-scale utilization of sulfite spent liquor. It would appear currently that the major share of the demand will he in the poultry food field, bu t there are

T T A H H Y F. LEWIS, dean and research associate at A A 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 author­ship of about 45 published papers, as well as 25 patents and a book, along with chapters in others. His hobby still keeps him among the plants, as it is gardening. Before joining the staff at Apple-ton he had taught at Ohio Wesleyan Univer­sity, 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 Ph.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 es­tablish 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 success­ful operation of this plant is based upon the recovery of the major portion of both magnesium and sulfur during the evapora­tion 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 proc­ess 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 Manufac­turers* 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 of 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. The re­moval of the sulfur compounds from con­denser water may be achieved by scrub­bing these liquors countercurrently in a Bergstrom tower packed with ceramic-rings. The toxic sulfur compounds are removed from the water going to the sewer and are eliminated with the stack gases.

Wood 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 prin­cipal fibrous raw material, wood. This concern has manifested itself in a number of ways.

One has been a continuation of the war­time and postwar use of less desirable

wood spceics as pulping raw materials. In 1940 only about 3.5 to 4rA of the pulp-wood 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 the 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 New England is in line wi th 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 in­crease in yield is partly the residt of im­proved 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 fac­tory and mill through integrated opera­tion. 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. Simul­taneously with the construction of tin-container board plant there was built a saw mill and remanufacturing plant han­dling 300,000 board feet per day. The by­products of the saw mill are the raw ma­terials for the pulp mill. The size of the sawmill w a s established b y the amount of timber which was available from the com­pany's holdings on a sustained yield basis. The 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 subse­quent production of its own necessary steam i n the recovery of magnesia and sulfur made the use of the wood no longer necessary and liberated such wood for the kraft operation. In this integrated opera­tion 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 pulp 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

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. The 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 interest­ing 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 appli­cation of the aqueous adhesives necessary in the combining process. By this new method 50 to 60% of sulfur (on the weight of the original board) may be added to the corrugating medium. The board produced with the sulfur-impreg­nated corrugate shows better flat and box compression; these characteristics are evi­dent particularly at high humidities.

It is appropriate to close this review with a mention of the new research build­ing built and opened during 1949 at Rothschild, Wis., by the Marathon Corp. This company has been a leader in a pro­gram 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 wide variety of lignin prepara­tions which find a ready market in the fields of dispersing agents, tanning agents, drilling mud additives, base-exchange materials, and others.

C H E M I C A L A N D E N G I N E E R I N G N E W S