Paper from Straw by the Chlorine Process u m M t l , O I’OSIILIO
L ia
Caraccido 13, Naples, Italy, arid Celulosa Argentina, Kosario de Santa Fe, Argentina
0
FFERIXG at a chlorinating agent. once a profitThen, however, chlcable means of rine water is used, the d i s po s i n g of f a r m reaction is one of oxidation as well as chlowastes, an important new source of cellurination. This results lose, and a commerin deterioration of the cially new method of cellulose, c h a n g i n g cellulose ree o v e r y , some of it to oxycelluthe chlorine p r o c e s s lose, and thus reducas applied to the puriing the yield. Indusfication of cellulose trially, the c h l o r i n e from wheat straw in method r e t a i n s its the plant of the Celuoriginal form as suglosa Argentina n e a r gested by Cross and I i e v a n - - - t h a t is, a R o s a r i o , Argentina, AERIALVIEWOF PLANTAT ROSAHIO is of special imporrapid p r e l i m i n a r y tance from many leaching by d i l u t e points of view. Although the chloriue process is yet in its alkali without pressure, thorough chlorination by gas, and a industrial infancy, experience with it during inany years of final washing by cold dilute alkali. The chlorine water process, development and now in industrial operation have shown it on the contrary, used strong caustic liquor, high tomperature to be far superior to other methods of recovering cellulose and pressure, and prolonged cooking in the digester. It was from the stalks and stems of man nlants. Its nrohable an alkali nrocess comnlicated hv a subseouent elaborate treat-
this, numerous attempts have been made to apply it industrially and many patents applied forduring the past tenyearsorso. Iinmediately after the close of the World War, Benjamin Cataldi, an Italian, and A. R. DeVains, a Frenchman, made serious effortsto perfect methods of applying the method commercially, but without success. Cataldi used gaseous chlorine, but his complicated apparatus and the high consumption of chlorine (partly due to mechanicalleakage) madeit impossible for him to approach the efficiency and low cost of other well-developed methods of cellulose purification. 1kVains hpcame involved in even greater difficulties than Cataldi, for he failed to realize the necessity for dissipating the heat of the chlorination reaction He hoped to solve the problem by abaiidoniiig clilorine gas and using in its stead a water solution which he called “chlorine hydrate.” Several plants were built to-use the IkVains process, hut within a decade thev have all been either abandoned or changed over to another process. The nriter (2) many times during the period 1920 to 1924 stated the profound difkrence between the use of chlorine as a gas and in water solution. Chlorine gas serves as a chemical reagent for attacking bhi: noncellulose part of the material, and in this form acts only as
tb be complicated when compared with any of them, because in each the cellulose is liberated in a single treatment, while the chlorine process requires three alkali cook, chlorination, and alkaline wash. It is in this very appearance of complcxity that the secret of succes~of the chlorine process lies, for i t is absurd Lo assume that a single drastic treatment necessarily incomplete, could possibly free the cellulose economically from the many compounds-organic and inorganic, and acid, basic, and neutral-which accompany it in vegetable fibers. On this point Cross and Bevan (1) have spokeii authoritatively. It is exactly this step-by-step treatment of the chlorine process which makes possible the liberation of the cellulose in a high state of purity without destroying it and thus permits high yields a p proaching the theoretical. Kor does this presumed complication of the scheme of attack add to the difficulty of industrial operation. Although the process involves three steps, each of them is accomplished without p r e s sure, a t relatively low temperatures, and with dilute reagents. The plant equipment now in ~rseoperatescontinuouslywith a miuirnum of attention. The laborious processes of caustic recovery and the elahoration of by-products is eliminated as
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I N I.) tJ S T 1% I A L A N D E N G I N fi: E A I N G C I1 E M I S T R Y
Vol. 24. No. 9
(principally scrap and wasbe fruiii bag nianufacture) have been treated eeoironiieally, in spite of a higher ra\r-material cost (30 paper pesos per ton’) because of a higher yield of cellnloso (65 to 70 per cent) and the lower cost of rea.geiits consequently necessary. Flax sbraw as obtained from jilants raised in Argentina primarily for seed lias qnite dXerent c1iar:tctrristics from that o i European flax grown to stipply fiber; cons+ qnently European experience (both that o i tlie nutlior and of others wlio liave tried to ntilizc this wasti: as a soitrce of cellulose) has led to plircing it. in tliird place atiiong the possible raw materials available in Argentina. It has b f m conrludcd that differences betweeti the outer and inncr parts of the flax straw I e ~ dto the trouble in treating it, since the outer portion is easily attacked and tlie inner portion so diffjcult t o treat that the fiber it.se1f is mdkened tnut.erially ctely treated. Experim e n t a l c o o k s with comstillks which are In tliix iit,ti:i(iiiii, tlie iilro almndant h a r e miter, in pniiessim indiratrd that, while of a liighly satisfaca liigii-gradc cellulose tory processof proved can Lie jiroduced from merit which could not tliem, they are much ha operated in Italy less attractive t h a n hecause of ecoooniic the other t h r e e macoiiditions, turiicd to terials available. I n South A m e r i c a as ii thc order of preft?rence possihlc Iocatioti for a the raw material;: are prudiicti~it develcqinvlieat straw, jntr, flax ment in cclinlose straw, and cornstdks. manufacturc. BrgciiTlie p l a n t a t tiiia offered potentiid Rosario utilizes fully location for suchadc.. ilie soda and chlorine velopinent in view of p r o d u c e d by elecits r e l a t i v e l y high ALKALI APPARATUS FOR WASHINGC~r.inr.oar:w m i DILUTE trolysis from pure salt a n n u a l p a p e r cons o p p l i e d rionl tile s u m p t idn (140,OOU tons news print, 23,OU!) tinis writing ;and piiil.ing pwims, and lirovinre of Cdrdoha, not oiily for the manufacture of celhi8000 tons wrapping paper) with no pnlp production, arid the lose and paper but for other products as well. A portion of abundance of wheat and flax straw (grown for seed) aniiuallg the chlorine is made into hypochlorites and hydrochloric burned in its wealthiest and rnost thickly populated provinces, acid; the cathodic liquor, containing unchanged sodiuni Buenos Aires, Santa F6,and C6rdoba. The total amount of chloride, is evaporated to recover this in the form of fine table easily available raw material of these two kinds runs into soine salt for salc. The daily capacity of the plant, in continuous 20,000,000 tons annually, and while the Papelera Argentine operation since early in 1931, is 12 to 15 tons of cellulose, operates a niiniber of plants for niaking paper, practically all 16 to 20 tons of writing and printing paper, 2 to 4 tons of the pulp for tliese operations is imported. Despite the freight hydrochloric acid, 3 to 4 tons of sodium hypochlorite, 6 to 7 charges borne by this imported pulii, it has been found cheaper tons of refined salt, and D t o 7 t.om of concentrated, sirupy to import pulp than to bring suitable woods from reriiotc caustic soda. Electric energy is purchased from outside sources so that points in the interior for domestic insnufacture. These facts and others confirming the favorable possibility the electric power plant consists merely of a group of transof the enterprise were brought out in a thorough investigatioii Sormers for bringing the line current at 6500 volts down tu of the situation made hy the writer a t the request of a coin- 380 volts for plant use, and two groups of rotary converters mittee organized in 1928 by the liolsa del Cornrnercio de for supplying direct current for the electrolytic cells. The Cereales of Rosario, Santa F6. As a result OS this investiga- capacity of the transformers is 3000 lw-amp., and that of tion and Savorable report, the SocietS Anonima Celulosa the converters 1000 kw. The steam plant consists of two Argentina was organized, and the building of its plants begun low-pressure steam boilers (used as reserve) and a singte in 1930 at Juan Ortiz, a village about 15 kilometers from Steinmiiller high-pressure boiler operated a t 22 atmospheres and delivering steam superheated to 375” C. From tile Rosario de Santa 1%on the banks of the l’aran.4 River. latter is operated a turboalternator of 400 k\,-amp. capacity PLANT OF CELULOSA ARGEN~TNA equipped with pressure, back pressure, and teniperature The works a t Juan Ortiz cover am area of 125,000 square regulators, and operated t o supply exhaust steam to the meters, of which about 20,000 are occupied by buildings. process. The electrolytic plant consists of two batteries of 28 cells Four raw materials have been usetl~&wiieatstraw, jute, flax straw, and cornstalks. The first of iliese seems most generally each. The cells are of the vertical Giordani-Pondio type useful and is to be had at the plant at an average cost of 17 with diaphragms and circulation, requiring 3 amp. each. to 18 papcr pesos‘ per ton. Several hundred tons of jute 3 The Argentine peao was quoted Aupuat 6. 1932, st $0.26
Each cell produces mure t.haii IOU kg. uE soustic auda u i d 90 kg. of chlorine per 24 liours. The hilie system consists of a store room for salt of 1000 tons capacity and a series of tanks for preparing the brine solution and purifying it from traces of calcium, settling tanks, storage tanks, and finally a feeding tank for supplying the electrolytic cells. The cellulose department begins with a storage shed located outside the plant where baled straw as received is stored. A second shed is provided for shredding and cleaning the straw, and here the wheat grains, remaining in the straw to the extent of 1 to 3 per cent, are separated. Tlie straw, after cutting, rleaning, and shredding, is blown through pipes by a powerful fan to the cliemical plant--some 200 meters. The chemical plant begins with four cyliridrical digesters where the preliminary alkali cook is performed at atmospheric pressure. A crane removes the cooked material and transfers it to a system of presses where it is washed and pressed to remove the solution, Disintegrators tear apart the press cakes, and a fan blows the cooked fiber to the chlorination towers. The chlorinating department consists of six towers which operate continuously on ihe countercurrent principle. The vegetable fiber goes in at the top and descends slowly by the action of gravity, while the chlorine gas, blown in by a fan a t a convenient height, Rows upvard, chlorinating the mass as it descends. The speed of fall of t,lie 111 the rate of ita removal from the bottom of the tower by a mechanical arrangement operated liy rotors having a possible speed variation of 10: I. It is thus possible to treat with this system all classes of vegetable fibers, requiring mild or vigorous chlorination, to prodiice oiifinished pulps or pitre cellulose, and to use concentrated or dilute chlorine iii the treatment. The treatcd f i b e r from the chloriiintiiig towers is stored in tigbt chainbers where chlorination is completed and every trace of chlorine is absorbed. The completely chlorinated inass is then washed with watcr and fed Iiy gravity t,o tlie a l k a l i n e wash department whcre it is waslied free from chlorinated compounds. This is accomplished in B washer where the mass is mixed for a short period with dilute cold caustic soda solution, followed by thorough washing with water. In this, as in all other operations in tbe chemical treatment, the water used is the waste water from the paper mill. Tlie chemical treatment being now complete, t,he pulp is fed by gravity, afterstraining, to the bleaching liollaiiders where bleaching is accomdished bv treatment with a solutionof calciumliypochloritecoritaiiiirig6 to'lpercent available chlorine. The bleached- pulp is stored in tanks from which it goes to the paper mill in the form of 3 per cent pulp. The pulp plant has a capacity of 12 to 15 tons of pulp per day. The paper manofacturing plant varies in no important particulars from the standard practice in this industry and is equipped to produce, by suitahle mixing of pulps, papers of
it wide wricty of iliaractt.ristir:s froiii rough urapping paper, through news print, to fine and superfine types. The entire process is so arranged that gravity is used throughout for the movement of materials under treatment from one &age to the next. In this way power requirements have been minimized. The supplementary operations consist of the manufacture of sodium and calcium hypochlorites in towers cooled by reirigeration; synthesis of hydrochloric acid by burning the pure gases hydrogen and chlorine in special burners with the absorption of the product in water in a silica and stoneware system; and the conceiitration of alkali with the simultaneous preparation of pure salt. This last operation is carried out in a specially designed and operated system to yield a highgrade crystalline salt which is washed and centrifuged first with a nentral and then an acid wash before final drying in a vacuum drier. The water supply of the plant-as much as 10,000 cubic meters per day-is obtained from the Paran& River beside which the plant is located. This is unusually soft and requires the addition of only 20 to 30 grams of aluminum sulfate per cubic meter to assist in removing suspended silica before filtering for use.
E c o ~ o ~ VALUE ic OF THE CELOXINE PROCESS The chlorine process, when properly applied either in the laboratory or industrially, produces the highest yield and the best quality of cellulose. If to this we add that the process can be employed, using reagents which are raw and unconcentratcd (salty cathodic liquor and moist chlorine gas), that it can be arrariged to operate continuously, and that the recoverv of waste and by-products has been completely eliminated. the economy of the process becomes ohvious. The operation, too, is self-contained so that in conducting it the only necessary purchases are vegetable fiber, salt, and energy or fuel. The consumption of reagents and raw material per unit of cellulose produced depends naturally on the character of fiber and the quality of cellulose produced. Results from a year's operation st Rosario provide about the following average figures: for each 100 kg. of bleached wheat straw cellulose (12 per cent moisture) there are consumed 15 to 16 kg. of soda for cooking, 22 to 24 kg. of chlorine for ch~orination,3 to 4 kg. of soda for the alkaline wash, and 2 to 3 kg. of active chlorine for bleaching. The cellulose yield from wheat straw at Rosario has averaged about 46 per cent. Enerev consumntion forms a considerable item of cost, and hence must be included in this calculation. A t Rosario the energy requirement of the plant is approximately 0.8 kwhr. of direct current for electrolysis and 0.4 kw-hr. of alternating current for motive power per kilogram of cellulose produced. The paper plant consumes 0.4 to 0.5 kwhr. per kilogram of fine paper produced. The production of this plant has continuously increased
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INDUSTRIAL AND E N G I N E E R I N G CHEiMISTRY
1010
from July, 1931, to date; for the month of January, 1932, it had reached 314 tons of cellulose, 439 tom of fine papers, 54 tons of hydrochloric acid, 82 tons of caustic soda (for sale), and 115 tons of refined table salt (for sale). Based on these January figures, the yield of cellulose has been 45 per cent on the basis of wheat straw used, and the cost has been 17.49 paper pesos’ per 100 kg. This compares with a market price of 24 to 25 paper pesos per 100 kg. for imported bleached wood cellulose delivered at Rosario. The cost of paper of fine quality was 34.29 paper pesos per 100 kg. and the types based on straw cellulose have a good market in Argentina. Other plants are being planned to apply the Pomilio process, one in Chile for treating wheat straw, one in Brazil using rice and other straws, and others in Europe.
COXCLL-SION Despite the fact that fifteen years have been spent in developing the chlorine process, much remains to be done, and it is apparent that it is now only a t the beginning of its industrial expansion. It links three great industrieshydroelectric chlorine, cellulose, and paper-and its future depends on bringing these three into closer cooperation. The value of the chlorine process is enhanced by the fact that it is especially suited for the treatment of annual straws for the production of fine papers without increasing the
Vol. 24, No. 9
demand upon wood resources as the growing demands of civilization require larger and larger quantities of cellulose and paper. Despite the conviction of many paper makers that only wood cellulose can produce satisfactory papers, the Rosario development has amply demonstrated that these are easily made from 100 per cent straw cellulose to meet all demands of the market. The chlorine process offers an outlet for some of the excess hydroelectric energy of those countries where power development has exceeded demand. Its application is unquestionably desirable in those countries when suitable vegetable fibers and salt can be cheaply obtained, since energy is an important economic factor in the cost of cellulose made by this process. Those countries having large productions of cereal straws (Argentina, Canada, Russia, the United States, Australia, etc.), or of rice (Japan, China, Brazil, Spain, Italy, etc.), or of esparto (Spain and North America), have in the chlorine process a potential method of recovering a valuable agricultural waste of considerable economic importance. LITERATURE CITED (1) Cross and Bevan, “Cellulose,” Longmans, 1918; “Text Book of Paper Making,” 5th ed., E. & F. iY.Spon, London, 1920. (2) Pomilio, Chimie & industrie, 6 , 267 (1921); 8, 41 (1922); 11, 423 (1924). RECEIVED June 2, 1932.
Hydrogenation of American Coals W. L.
BEUSCHLEIX AKD C. C. WRIGHT,University of Washington, Seattle, Wash.
T
HE pioneering work of Bergius on high-pressure coal hydrogenation has opened to chemists a new and profitable field for research. The major portion of the literature thus developed appears in the form of patents claiming distinctive merits for some particular type of equipment, method of operation, or catalyst, but making little or no mention of the type of coal used. Fundamental researches on the mechanism of hydrogenation, and upon the relationships existing between hydrogenation and constitution, however, have been conducted by several investigators, among whom may be mentioned Arend ( I ) , Kling and Florentin ( 5 ) , and Graham (4). I n these latter researches many coals from widely separated sources have been investigated, and much valuable information has been made available to the scientific investigator and to the industry. Commercial methods of hydrogenation involve treating the coal in a dispersion medium of saturated oil with hydrogen a t high pressure and a t temperatures between 450” and 550’ C.; the separation of products is based for the most part on distillation. Investigators in the theoretical field have usually resorted to phenol or some similar, easily removed dis-
persion medium; they have separated the products by methods based upon extraction in order to eliminate the effect of cracking coincident with distillation. It is the purpose of this investigation (1) to effect a correlation between the commercial and theoretical methods by hydrogenation studies on a series of American coals when dispersed in both type of media, and (2) to show the relationships existing between the degree of hydrogenation and the ranking of the coal according to the more common methods of classification. This paper will deal with the investigations in which phenol was the dispersion medium.
INSTALLATION AND EXPERIMENTAL METHODS A detailed description of the laboratory installation, the method of operation, and the separation of the products has appeared in a previous publication (2); a brief summary follows: The reaction chamber (0.3 liter capacity) is of the stationary type, employing no stirring, and is heated electrically by means of external coils. A thermocouple well is immersed directly in the charge, and temperatures are determined by means of a thermocouple and pyrometer. Con-
TABLEI. DESCRIPTION OF COALS STATE
COUNTS
Washington Washington Alabama Pennsylvania West Virginia Kentucky Washington Illinois Washington TTtah iv&ington Washington Washington Washington
Pierce Pierce Jefferson Allegheny Logan Letcher Kittitas Franklin King Carbon Kittitas King Thurston Lewis
SAMPLE 2 3 11 13 12 10 14 9 4 fi
i
5 7 8
BED
5 7 Mary Lee Pittsburgh Chilton Elkhorn Roslyn Illinois 6 2 Castle Gat e Roslyn Jones 1
Foron
PROXIMATE ANALYSES A S RECEIVED Volatile Fixed MINE Moisture matter carbon -4sh % .. % % % 10.8 2.0 23.9 63.3 Fairfax 8.1 26.8 63.7 1.4 Wilkeson 8.3 59.9 4.2 27.6 Flat Top 7.5 34.2 56.7 1.6 Ocean 2 4.3 57.9 1.3 36.5 Boone 2 2.2 59.0 2.2 36.6 204 11.2 2.8 38.3 47.7 Roslyn 3 12.3 32.1 47.7 7.9 Orient 1 14.1 46.9 35.1 3.9 Occidental 49.1 7.1 40.9 2.9 Rolapp 12.2 43.5 38.8 5.5 Roslyn 7 44.4 5.4 38.2 New Black Diamond 1 2 . 0 39.3 5.8 33.9 21.0 Tono 7.6 32.4 30.8 29.2 Ford’s Prairie
--ABHS
ULTIMATE ANALYSES, A N D MOISTURE-FREE0 H C N
% ..
%
%
%
%
0.5 0.4 0.9 1.2 0.6 0.6 0.5 1.0 0.8 0.5 0.6 0.4 0.5 0.9
5.4 5.5 5.3 5.7 5.5 6.1 6.3 5.3 5.8 5.9 6.2 5.7 5.6 5.6
88.1 87.7 87.1 85.6 84.8 84.6 82.6 82.2 81.3 81.1
2.6 2.5 1.8 1.8 1.7 1.6 2.1 1.7 1.6 1.5 1.7 2.0 1.5 1.3
3.4 3.9 4.9 5.7 7.4 7.1 8.5 9.8 10.5 11.0 11.5 14.8 18.5 20.5
80.0
77.1 73.9 71.7
