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in the beaters or at the paper machine. By the use of this agent it is possible to produce either waterproof or moistureproof boards of various stiffness or pliability. The results with this method give a higher degree of resistance to water than results when raw paper or felt is saturated in a bath of hot asphalt, in accordance with the usual practice obtaining in a saturating plant. This brief review indicates that the pulp and paper industry
is not without its own problems. Many others purely mechanical and having no place here, also confront it. The de-
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pression of the past two years has made progress in the solution of these problems almost impossible. It is anticipated, however, that the coming years will see the proper recognition of the place of the technical man in the industry and that many changes, some of them almost revolutionary in character, will be made, which will increase the efficiency of the various processes, conserve our raw materials, and give us an improved product. Not the least of these advances, we hope, will be the adoption of the standardization program now being developed through the co6peration of the manufacturers of paper with the Paper Section of the Bureau of Standards.
Hardwood Distillation By Harry C. Merriam , .ENGINEER, E. B. BADGER& CHEMICAL
SONS
CO., BOSTON,MASS.
These blocks, freed of sawdust, are elevated to bins and from there dumped by try is carried on in the United gravity into the retort cars, the sides of States by 80 different concerns, which are carried to the top. The cars are operating 93 plants, with a total daily then run into the predriers, which are of capacity of 5530 cords, 600 of which are in ordinary tunnel construction, either of by-product recovery kilns and 4930 cords reinforced concrete or brick, through which in ovens and retorts. the waste stack gases from the oven4 are During the last ten years great progrcss circulated countercurrent to the wood and has been made in the methods employed in direct contact with it. The driers vary in the wood distillation industry, and it is in size, allowing from one to three carbonthc object of this paper to touch upon izing periods for drying. The two-period the most important. drying is now considered good practice. Ovens have practically replaced smaller Savings effected by this system include: retort types and the tendency of the moddecreased labor due to the mechanical ern plant is toward large units. The larghandling of the wood; interest on the inest oven plant operates twenty-two 10vestment in cord wood in the drying cord ovens, with a total capacity of 220 yards; insurance, taxes, etc.; decrease in cords, which can be increased to practifuel consumption, with the advantage of cally 294 cords per day on a carbonization uniformity in the character of wood enperiod of 18 hours. tering the ovens under all weather conThe larger Dlants are used in conjuncH. c. MBRRrAM ditions: an increase in the output of the tion with charcoal pig-iron blast furnaces and it is on this account that such large units are desirable. plant by shortening the carbonization period; and the elimination of brands from the charcoal. Most of these plants are situated in Michigan, - . although The application of strict temperature control to the ovens during the war four were built in the south. The obtaining of sufficient quantities of cord wood has has been recognized as of great importance, and the installaalways been one of the vital problems of the wood distil- tion of recording pyrometers for accurate control has resulted. lation plant. During the recent war, with the scarcity of This control not only stabilizes the yields of by-products and labor, this factor was very pronounced, and made most increases them in many plants, but prevents the overheating manufacturers abandon the cutting of cord wood in the of the ovens, thereby eliminating in large measure the rewoods and ship the logs direct to the plant, where they were placement of burned bottoms and costly repairs to the oven handled in a sawmill. Some of the original sawmills were settings. It also assures the turning of the ovens in the proper cumbersome and costly, but modifications and improvements cycle of time, this being a most important factor where the have been carried out so that to-day the wood mill of a modern charcoal is used directly in a blast furnace requiring a conwood distillation plant will supply a t reasonable cost wood stant supply. The importance of large scrubbers for the efficient scruhsuitable for distillation purposes. It has, moreover, been found fairly easy to procure log-wood cutters when previously bing of the retort and kiln gases previous to burning of the same has finally been recognized, and scrubbers of adequate cord-wood cutters could not be obtained. The green logs are brought directly to the wood distil- size are now a standard installation in many plants. I n retort practice it, has been found that approximately lation plant, put through the wood mill, cut into approximately 49-in. lengths, and split with band or circular 1 gal. of 82 per cent of alcohol per cord of wood can be resaws to the required size. These pieces, of the same general covered, and in the case of kilns where a much larger volume character as ordinary cord wood, are then passed through of gas has to be handled, due to air leakage, etc., around the block mills and cut to 12-in. lengths. At this point any kiln, an increase in yield of from 2 to 3 gal. per cord has been cord wood available is introduced and also cut to blocks. reported. I n fact, one kiln plant by efficient scrubbing has
HE HARDWOOD distillation indus-
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THE JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
obtained an alcohol yield very close to that of the ordinary oven plant. The distillation of hardwood chips, sawdust, etc., has occasioned considerable research work to develop a successful coniniercial process. The difficulties encountered, such as in the drying of this waste, because of its own insulating qualities, the control during exothermic reaction, charcoal dust ddring decomposition, the stabilizing of the fine charcoal so that it will not ignite spontaneously, and the final briquei ting of the charcoal, have all been trying problems. A number of patents have been taken out in conjunction with this work. Three plants have been built on a commercial scale carrying out the various ideas, but only one of these plants, using the Stafford process, has.proved a success. The principle of this process makes use of the hitherto known, but not commercially utilized, heat of exothermic reaction of cellulose when a t the carbonizing temperature. By predrying and preheating the material, and introducing it into a retort in which material already undergoing carbonization is present, the exothermic heat is sufficient under properly maintained conditions to bring the additional material up to the carbonizing point, when this material in turn will be carbonized and liberate heat, which will serve to bring further material to the carbonizing temperature. The Stafford process requires no heating of the retort; in f a d , the retort is thoroughly lagged to prevent escape of heat,. The material is previously dried in contact with the air, and is introduced continuously into the retort from which the charcoal is also continuously removed. The continuous distillation of hardwood waste produces the same yields in methanol and charcoal and about 50 per cent n o r e in acetic acid than the yields from ovens utilizing cord wood of similar species. The drying of the wood to a 1 per cent or 2 per cent moisture content is carried out in large rotary driers in direct contact with the hot flue gases, and efficient dryins of the wood js thus accomplished. The pyroligneous acid obtained from this dried wood is therefore in a concentrated form and subsequent treatment in the stillhouse is accomplished with a minimum of evaporation and distillation. The advantages of the mechanical handling of all products, low fuel consumption, large capacity for small units operated continuoudy, higher yields, etc., make it possible to even hog cord mood and handle in a commercially successful manner. All these advantages point toward the development of this process and a gradual substitution for present practice. Stillhouse operations have undergone many changes, and to-day the continuous treatment of the pyroligneous acid and other liquors is universally employed in the more modern plants, as against the discontinuous method in the smaller and older type plants. The use of multiple-effect evaporators has proved a great economy factor. Early designs of multiple-effect evaporators did not take into consideration the fact that when pyroligneous acid is distilled under multiple-effect conditions the vapor on condensing deposits carbon on the surface of the tubes of the next effect, cutting down materially the transmission of heat and necessitating the dismantling of the tube bundles for the removal of the carbon. This fouling of the surface varies with different woods and is more pronounced in the case of southern hardwoods. The use of triple effects in the evaporation of acetate of lime is a success and gives no particular operating difficulties. It is the consensus of opinion among operators who have used triple effects that double-effect economy in a combination evaporator is all that is desirable in this industry, because of the operating difficulties before mentioned. I n the latest designs the pyroligneous acid is evaporated in one
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effect and the acetate of lime in the other. With proper design this combination gives accessibility to the tube surfaces and permits of the easy removal of the carbon coating without dismantling. Such a double effect gives an easily controlled unit for continuous operation. I n the production of acetate of lime the conversion of the concentrated acetate liquor from the evaporators to the mush state by means of steam-heated rotating rolls, and the final drying of the acetate on screen belt driers traveling in hot waste flue gases, have solved the question of low-cost production of acetate in modern plants and eliminated the troublesome labor problem so often encountered in acetate drying. The elimination of the old acetate pans, which are notorious steam eaters, has been a welcome change. A recent innovation utilizes the acid vapors from the primary stills as a source of heat in the second effect, operating under a vacuum for the evaporation of acetate of lime liquor, the primary stills being operated under atmospheric conditions and the vapors condensed in separate tube chambers in the second effect. This keeps the distillate from each primary still separate and a visual control of each still is possible. This scheme will undoubtedly result in a considerable saving in steam, and, if adopted by old plants having primary stills, will give double-effect economy. The application of continuous stills for the production of high-grade crude methanol of around 92 to 95 per cent (Tralles) direct from the neutralized liquor has become the standard practice. Where there is an exes3 of exhaust steam available, kettles have been eliminated, the steam being introduced directly into the base of the continuous still. This has considerably simplified the apparatus. The grade of crude alcohol produced in a plant of this type is not to be confused with the crude 82 per cent produced in old plants using older methods. The use of low pressure steam in the stillhouse has been so perfected that two plants are now operating all of their apparatus, both evaporating and distilling, on 5-lb. pressure exhaust steam: The successful production of glacial acetic acid from carbide has been a serious blow to the wood distiller, and in his search for somc way to meet thitz menace the production of glacial acetic acid direct from pyroligneous acid has been attempted. It is the writer’s understanding that this has been successfully demonstrated on a semicommercial scale. This being so, it will give the distiller a new lease of life by again making his acetic acid a source of income, whereas a t present it is a problem to dispose of it, a t a profit. In the past the refining of crude 82 per cent methanol has been carried out in central refineries, because of the difficulties encountered and the type of apparatus necessary. With the advent of the modern four-column continuous refining still, conditions have changed and the crude alcohol producer is enabled to instal his own refining unit and manufacture direct the highest grade of refined methanol. The increasing demand for pure methanol in the dye industry, and particularly in the manufacture of formaldehyde, has caused this type of apparatus to come into its own. Chemical treatment was necessary under the old system to separate the alcohol from last traces of methyl acetone, but with the new type of continuous still this is done by fractionation in the distillation process and pure methanol with a Messinger test of less than l / 2 0 of 1 per cent acetone is produced direct from the crude 82 per cent. There is, too, a simultaneous production of high-grade methyl acetone, together with a small amount of oils and allyl alcohol. The production of pure methanol has enabled many of the smaller plants to instal their own formaldehyde apparatus and by this means place their alcohol on the market converted to its highest value.
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THE JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
The manufacturers of crude alcohol had heretofore only one outlet for their alcohol, namely, the sale of the crude to the refiner. With the modern refinery, he has his choice of a number of markets. In the modern refinery, with its steam regulators, extension stem-recording thermometers, recording pressure gages, and other accessory equipment, one operator can care for a number of stills with more perfect control than was ever possible under the old handcontrolled systems. Furthermore, strict chemical control is possible a t all times, and such control is essential because of the chemical specifications that have replaced the old tests, such as odor, color, specific gravity, etc. The production of pure acetone by the destructive distillation of acetate of lime was worked up to a hiqh degree of efficiency during the war, because of the enormous demand for this product in the manufacture of cordite for the British government, and once again the continuous distillation of
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the crude acetone into the finished product showed the e%ciency and low cost of this method of refining. In order to meet the recent more stringent requirements for various grades of acetone oils, vacuum distillation has been employed, making possible closer cuts through the use of fractionating columns, with the resultant saving in steam. The distillation of creosote oils and wood tars has been stimulated by the great demand for these oils in the flotation industry, and this demand will undoubtedly increase as the flotation process grows in favor. There seems to be a preference for hardwood oils on the part of flotation engineers. The future of many wood distillers, following the decline in prices of by-products, is problematical, and undoubtedly only those plants equipped for low-cost operation will survive. The smaller plants of, say, under 50 cords daily capacity, will be handicapped when compared with the larger plants and these smaller plants may find it necessary to consolidate to carry on.
T h e Ferro-Alloy Industry By B. D. Saklatwalla GENERAL SUPERINTENDBNT,
VANADIUM CORPORATION OF
AMERICA,BRIDGEVILLE,P A .
As a less commonly used deoxidizer HE FERRO-AI,LOY industry has may be mentioned ferro-titanium. This come to the front within the last alloy is manufactured in the electric furfew years, itc. importance being nace snd also by the alumino-thermic recognized during the strenuous times of process, according as a carbon-containing the World War. Advancement in steel or a carbon-free alloy ip dwired. As to metallurgy has been probably the greatest the superiority of the one or the other factor toward the rapid strides of our civilization within the last decade or two, grade thcre is yet considerable controversy between the different users and makers. and when we scan the field of impravements in the mechanical, electrical, and The main metallurgical developments in the manufacture of ferro-alloys within transportation industries for the purpoqes of peace or mar, we cannot help the last couple of years have been in but feel that all such strides have been connection with those alloys that form true alloy steels and persist as a constitdue to the developments of newer and betu m t of the finished metal. Aniong such ter types of steel, produced by the metalalloys may be mentioned: ferro-chrome, lurgist of the present day. While this fact ferro-tungsten, ferro-vanadium, and ferrois obvioiisly apparent, it is not generally recmolybdenum. The greatest and most reognized that these developments have been cent phase in the development of these dependent on the ferro-alloy industry. The function of ferro-alloys in the alloys is the application of the electric furnace to their production, and the workmnnufacture of steel has been twofold. Trinity Court Studzos ing out of the chemical reactions in the Certain alloys have been used for the B. D. SAKLATWALLA , electric lurnace, whcreby an alloy of suitpurpose of deoxidizing and cleansing, wheress others have been used t o impart to the steel cer- able purity and carhon content call be directlyI manufactain nccessary and desirable physical properties, the alloying tured from the natural raw ores. At the beginning of the ferro-alloy industry, the electric element forming an intygral constituent of the st,eel. The most commonly used ferro-alloys, ferro-silicon and furnace was in its infancy, and consequently the field was ferro-manganese, function as deoxidiaers in the ordinary largely usurped by the alumino-thermic process of reduction. course of steel-making. They play a double role, however, This process has the advantage of convenience and simple in the case of high silicon and high manganese steels, where equipment, but necessitates the use of more or less pure these elements are allowed to remain in the steel in appreci- oxides for reduction, which have to be chemically prepared able percentages, in order t o obtain certain requisite prop- by an intermediate operation. Such an operation is costly erties. The electric furnace has practically replaced the blast and wasteful, and the aluminium required for reduction is furnace or the crucible method of production. There also a big item of expense. Recently, however, these deficiencies appears to he a tendency to develop mixtures of silicon and have been overcome by a very marked development in the manganese in the same alloy, whereby several advantages have art of dumino-thermic reduction. The preparation of been claimed. Several compositions of these two elements, pure oxides has been rendered superfluous. Owing to a together with aluminiuni and titanium, have been recom- systeniatic study of the chemical and thermal nature of the mended for the purpose of deoxidation. The use of such deoxi- reactions, it has been possible to reduce a complex ore by dizers appeals to have gained favor in continental Europe, means of aluminium in conjunction with suitable fluxes, but does not seem t o have been taken up in American practice. whereby the desired metal or metals are carried into the
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