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INDUSTRIAL AND ENGINEERING CHEMISTRY
nide, for unwanted minerals, and conditioners, such as alkalies. It is now possible to produce concentrates by the chemical froth-flotation process from ores which i t was not economical to treat by gravity methods or by oil bulk-flotation methods. Therefore, the chemical froth-flotation process is recognized as probably the most important factor which has enabled the metal industry to keep its production in line with the large increase in consumption of base metals in the last twentyfive years. The reagents use I in the chemical froth-flotation process are very efficient, and only small quantities are required to effect economic recovery of the minerals. Promoters are often effective when used in amounts as small as 0.05 pound per ton. I n many cases frothers are as efficient, although in general, more frother is needed than promoter.
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The frothers and promoters mentioned above are not the only ones used in the froth-flotation process. Complex and certain types of ores often require special chemicals. It is also possible in many cases to substitute one reagent for another with nearly the same results, The mining industry is not dependent upon manufacturers abroad for flotation chemicals, since chemical companies engaged on this side of the water in the production and distribution of chemical flotation reagents have the facilities to supply any demand for these products brought about by increased production of concentrates from the froth-flotation process. Mining companies employing the froth-flotation process need have no worry that they will be unable to get prompt delivery of the flotation reagents they need for any expansion program they have in mind.
CANNING INDUSTRY c. 0. BALL, American Can Company, New York, N. Y.
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N AN ADDRESS before the Institute of Food Technologists on June 19, 1940, Assistant Secretary of War Johnson indicated the importance of the canning industry in a defense preparedness program. A suggestion as to the role to be played was contained in a few statistics pertaining to the Army alone. The American Expeditionary Forces in France during the first World War consumed 200 million cans of evaporated milk, 150 million cans of corn, peas, and string beans, 190 million cans of tomatoes, 50 million cans of salmon, and 750 thousand cans of sardines-to mention a few items. Secretary Johnson omitted stating how many cans of numerous other important items were consumed-for example, corned beef, bacon, butter, coffee, and even candy. h’or did he say how much, was consumed by the mobilized forces at home. An army of 2 million men, which is said to be planned for muster by October, 1941, will consume a large quantity of canned food but not enough to disrupt the normal tenor of an industry that produces annually from 12 to 15 billion cans of food and is capable of producing much more. The capacity of canning plants is considerably greater than that demanded for annual production equal to that of 1939. Statistics show that the pack of staple vegetables and fruits last year was only about 75 per cent as large as that of 1937; and it is safe to say that even the 1937 pack did not tax available facilities to capacity. Nevertheless, in the course of the preparedness program, expansion of facilities might be necessary. An expansion program presents no difficult problems, except as it is accompanied by the possible exigencies of war. It is on the assumption that war conditions will exist that serious aspects develop and must be considered in the problems, chemical and otherwise. AGRICULTURAL PROBLEMS. Considering the industry from the standpoint of a flow plan, the first problems arise in the agricultural phase. The matters of agricultural machinery and seeds will be passed over with the comment that their supply is not dependent on the destinies of our foreign commerce. The same may be true with respect to insecticides and fungicides. To a considerable extent substitutions are possible in this field. Production in unlimited quantity of rotenone, the insecticide most commonly used on canning crops, is possible by the growing of the derris plant.
The fertilizer supply at present is not entirely of intranational origin, notwithstanding the message that came from the Sixteenth Annual Convention of the National Fertilizer Association, June 3 to 5, stating that the fertilizer industry’s capacity is sufficient to meet the demands of United States’ farms a t reasonable cost. This statement applies t o peacetime conditions. While the importation of chemical nitrogen, phosphates, and potash, as well as of natural organics has decreased materially during the past decade, imports are still considerable. The outlook with respect to fertilizing materials, however, is bright, A Congressional investigating committee last year estimated that our domestic phosphate reserves are sufficient to last for at least 3000 years a t the present rate of consumption. Supplying from domestic sources all demand for phosphorus does not appear to present a serious problem. Perhaps improvements at TVA already recommended by the Stettinius committee of the Advisory Commission on National Defense will take care of this matter. The Bureau of Mines recently announced that, as a result of operations undertaken in California and New Mexico, domestic potash productive capacity is now considered sufficient to meet domestic demands. Production could no doubt be increased readily to meet emergency demands. Increased use of blast furnace coke in steel production means increased production of ammonium sulfate; and together with the potential increase in the production of synthetic ammonia, this gives promise that emergency requirements of nitrogen can be met. However, the major demand for nitrogen will not be for fertilizer but for high explosives. I n case demand grows too rapidly to be met by domestic production, i t is expected that the first stages of war will not shut off the supply of nitrates from Chile, whence our reserve supply is now being enlarged as rapidly as possible under direction of the Advisory Commission on Sational Defense. Augmented production of organic fertilizers, of course, can help to supply the increasing demands. CANNIXG PLANTS.Expansion in food canning capacity is not a long-term proposition. Buildings suitable for canning operations can be quickly constructed, as can also the ordinary machinery for canning, which, in general, is not of complex design and construction.
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o rob ably tlie most intricate is ttre can-sealin2. ni
facturers. I n case of shortage, this system
I re$earcli is gradually eliminat.ing tiic reason ior tlie nuance of this custom, which has been iollowed in order that t e sealing compounds in the can seams, at the cans re fillcd, will have the sealing efficiency of pplied compounds. The aging quality of these matebeen so improved that they will retain their original s iorblmoch loneer time aitcr thev are annlied to can seams than was formerly the case. Production in can manulants could be greatly increased, therefore, wit,hont a sac.rific in quality oi cans, by operating the plants at unifacturin7. i & n rate throughout the year. Tliis could be done rvith very litt,le additional skillerl labor. Vastly enlarged storage iacilities would be required, however. Can-making machinery is intricate and requires many dies for the performance of delicate and precise operations; huildings for housing can-making operations must be of substaiitial construction. Sevcrt.lreless, if necessary a large increase in manuiacturing facilities coiild be effected within a year provided there were no labor restrictions. Considerable skilled labor would be required in construction of buildings and macliinery. A handicap 01 considerable magnitude soui id be imposed, tiowever, if changes in design of macliinery were made necessary by war exigencies such as stoppage of the supply of tin or of other raw materials which are essential in present methods oi manufacture. TIN. Our hope ior no int.erfercnce with operation under normal methods rests primwily on our ability to obtain adequate snpplies of tin. For making food cans, tin which is practically free from impurit.ies must be used. Tin from the Federated Malay States and the Netherlands East Indies only i s used. At present this high-grade tin is used in the Cnited States for some piirposcs for which a metal of lower grade w-ould be satisfactory. On the strength of the belief that we sliall not be cut ofE from the Bolivian supply of tin ore and that a sufficient reserve supply of t.in can be provided beiore an emergency arises, to care for the needs of industry until smelters can be built to handlo Bolivian ore, we can count on Bolivian tin being available for general use, so that a larger proportion of the tin of the purest grade will be available for food cans. Therc is said to be a larger stock of pig tin i n tliis country than ever before, and the stock i s being au,ment,ed as rapidly as possible. A considerable part of the pure tin needed coirld be obtained by recovery in detinning operations, of which only a small part of the possibilities has
$
”. ” rienced in rapidly increasing food-canning capacity. CANNINGMETHODS. Secretary Johnson spoke pendons import of weight of iood for an army in fie d opera stu: tions. He said: “Every ounce saved in transportatidli miglit prove invaluable when men and guns most, move to the front.” I n the interest of reduced weight in the food slipply for the Army, war conditions might justify the usc of a newly developed type of sterilizing process which has not been used commercially, because under normal conditions its use bas not appeared to be sound practice economically. The new process is the high temperature-short time sy8tem. Certain ioods, which usually are included in rations for the armed forces, can be produced in more highly concentrated form, in larger cans, and in cans of lighter weight material than those in which similar foods can be produced by present commercial processcs. Moreover, the quality oi ioods processed by the new method would be better than that of similar foods as canned today. IntTOduction of “high-SllOTt” processing would constitute a major innovation that moiild call for the designing and building of complicated and expensive machinery wlrieli coiild be amortized only over a period oi years. Production of this machinery would make the increase in canning Sacilit.ics a slower process than it would be mitliont, the inti.oduct,ion of the new method. CANMANUFACTVEING. I n the field oi can making, to an even greater extent than in canning itself, tlre avaihble iacilities exceed present requirements. If an increase over normal operating rate becomes necessary, a logical step would be to pot factories onto a threeshiit hasis. By this move alone production could probably be doubled. A further Iarge increax? in production could be brought about hy ironing out the peaks and valleys in the production curve. Cans ior seasonal products at present are not manufactured long in advance of the time they are intended to be used; therefore, wide fluctuations exist in volume of operation tiirnugll the seasons in factorirs which make cans for food.
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SEPTEMBER, 1940
INDUSTRIAL AND ENGINEERING CHEMISTRY
been utilized in the past. If it were made compulsory to collect and detin used cans, there would be an annual recovery of 10 to 20 thousand tons of pig tin. If the worst imaginable condition should arise and all external supplies should be shut off, and if our reserve and recovered tin were not sufficient to meet requirements, methods of manufacturing cans of plain steel plate, or a t least with greatly curtailed use of tin, would have to be perfected. Preparation to manufacture tinless cans for food packing mould involve a major change which would present great difficulties to the industry. The magnitude of the difficulties would depend upon the degree of reduction in the use of tin that would become necessary. By virtue of recent improvements in the quality of base plate, a reduction in the amount of tin used in coating plate for food cans could be made, as an emergency measure, with little departure from present methods of operation, and without substantially impairing the effectiveness of the cans in preserving the quality of foods. A further material saving in tin could be accomplished, without major alteration in manufacturing methods, by using tinless steel plate or tin plate with a reduced weight of coating for some nonedible products for which regular tin plate now is used. Tests have indicated that the quality of many canned foods will not suffer if black steel plate cans, protected by enamel, are substituted for tin plate cans. Further technical developments will be necessary, however, before all products can be packed successfully in tinless steel cans. Protecting processes alone, such as the phosphating or Bonderizing process and the chromium process, are not regarded as adequate to give steel plate the required amount of resistance to chemical attack by some foods. Phosphating treatment in combination with a baked enamel coating, reported to be used on food cans in Germany, appears to be adequate for some products. For some applications nonmetallic materials, such as glass and fiber, will receive a full share of attention as possible substitutes for tin plate, in case a shortage of tin becomes acute. INKSAXD PROTECTIVE CO.4TING h/IATERIALS. During the past seven or eight years tremendous advances have been made in the development of synthetic resins. These mate-
1175
rials have come into use in the manufacture of both printing inks and materi$s. used in the protective coating of metal containers. Jd the case of inks, synthetic resins have already been used to such an extent that no serious difficulty is anticipated if the foreign supply of natural resins should be cut off entirely. -4lmost the same condition exists with respect to protective coating materials in so far as resinous ingredients are concerned. The extent to which vinyl resins have come into use as ingredients of these materials is indicative of the possibilities along this line. Work still has to be done in perfecting synthetic resins having the resistance to heat treatment which is required for use in connection with some canned products. Much progress is reported, however. Another type of imported raw material that is extensively used in manufacturing lacquers is Chinese tung and perilla oils. Production of these oils is now practically under Japanese control. The finding of suitable substitutes seems to be more difficult than that of substituting for the natural resins. Nevertheless, some oils produced in the western hemisphere have been studied with fairly satisfactory results. There are large reserve supplies of all raw materiaIs needed for lacquer production, and these supplies are being increased daily. Therefore, time is still available for perfection of domestic production of substitutes for these materials in case their use should become necessary. The basic ingredient of many sealSEALIXG COMPOUNDS. ing compounds is rubber. Natural rubber is another of the important raw materials of American industry for which we are dependent upon foreign sources of supply. As in the case of tin, a high reserve supply of rubber is being accumulated under the direction of the Advisory Commission for National Defense. The results of attempts to substitute various synthetic rubbers for natural rubber in sealing compounds have not been altogether encouraging. Indications are that some other domestic materials, such as synthetic resins, might be used. Sufficient progress has been made toward the solution of problems that must be faced if the use of natural rubber in sealing compounds should have t o be discontinued, to remove reasons for serious apprehensions of possible interference with the operations of the industry by such a contingency.
TANTALUM ROBERT J. AITCHISON Fansteel Metallurgical Corporation, North Chicago, Ill.
F
AXSTEEL’S function in the chemical industry is to manufacture acidproof equipment which is used in heat transfer processes involving heating, evaporating, cooling, condensing, and absorbing such reagents as hydrochloric and nitric acids and their compounds, many of which are used in the manufacture of explosives and materials of chemical warfare. I n all such equipment which we manufacture, the elementary metal tantalum is used in vital spots to resist corrosive attack and transfer heat efficiently. Several months before hostilities began in Europe, the management realized the necessity of fortifying our sources of ores and raw materials, and constructive steps were taken. Inventories of high-grade tantalum and tungsten ores were increased, and favorable contracts were consummated assuring large stocks of ore for an extended term. New sources of supply for tantalum ore hare been uncovered in the United
States and other parts of the western hemisphere, largely as a result of intensive prospection sponsored through our company. To facilitate the design and manufacture of special chemical equipment, additions have been made to our research engineering and sales staff. Understudies have been trained or are being trained for important technical positions in our organization. The result of this work in the past eighteen months undoubtedly will prove helpful and necessary in connection with the current defense program. Since this company is the only producer of tantalum in the United States, and since i t mould probably take months or years to duplicate its activities elsewhere, our important position is fully realized and every necessary step is being taken t o assure continued smooth operation, with provision for expansion of facilities.
