1016
IXDCSII'RI-IL A-F-D ENGI,VEERING CHEJIISTRY
the conditions thus outlined to an extent that would seem to forecast successful operation. It is sincerely to be hoped that this will be the outcome, not only because of the improved type of fuel thus to be made available, but also because the successful carbonization of the widely divergent and extensive quantities of coal thus processed is an exceedingly important step in the ultimate production of the ideal fuel-gas. It is of interest to note a few type examples of those processes which are now in or just entering the status of commercial production, making use of that fact as evidence that they have a t least passed through the stage of preliminary experimentation. The Smith Carbo-coal process, as modified by C. V. hIcIntire, engineer in charge, is a three-stage process: first, low-temperature carbonization at 450" C.; second, briquetting; and third, a final carbonization. It is operating within range of a market accustomed to an anthracite standard of cost. The final product for domestic use approaches the ideal, and has reached a stage where operations have been substantially continuous for six months. The McEwen-Runge process, now being installed as an adjunct to one of the large power plants of the country using pulverized coal, operates in a manner to remove the volatile matter by allowing the pulverized coal to drop through a heated vertical tower about 6 feet in diameter by 30 feet in height. The minute granules of low-temperature coke are in suitable condition for burning directly as pulverized fuel in the power plant or for briquetting and carbonizing for the production of a domestic fuel. A throughput is possib:e of 210 tons per unit per day.
Vol. 18, No. 10
The Green-Lauks plant of the Old Ben Coal Corporation, Chicago, which has been operating on a 24-ton-per-day schedule, is being rebuilt for large-scale production. This method employs a spiral movement upward between heated walls approximately 5 inches apart and heated to about 600' C. The process is continuous and delivers solid, irregular lumps averaging about 2 to 3 inches in diameter. This is an ideal domestic fuel, smokeless in combustion and with every desirable quality, since it lends itself to use in ordinary household appliances, including the open grate. The Knowles Sole-flue oven has made upwards of 100 tons of low-temperature coke and is preparing to enter upon regular industrial production. I n the process the floor only of the oven is heated. The layer of coal--8 or 10 inches d e e p receives a considerable amount of heat from the floor but also from the hot gases ascending through the mass. The arch above the floor is not heated; hence the gas after leaving the coal is not subject to secondary decomposition. Both the oven and its operation have the advantage of simplicity and the product is of exceptionally high grade. Indeed, there is a well-founded rumor that one of our large industrial centers stands ready, provided this fuel can be produced at a cost equivalent to other fuels in their market, to require by municipal ordinance that no raw coal be burned in that municipality. These examples, which might doubtless be extended,' are sufficient to afford a general idea of the present trend in the field of low-temperature carbonization. 1 Chapman, F u e l , carbonization.
August,
1926, describes Parr-Layng low-temperature
Future Developments in the Light Metals By Francis C. Frary ALUMINUMC O M P A N Y
OF A M E R I C A ,
T IS especially appropriate for us as chemists to consider
I
this subject since, although broadly speaking the whole subject of metallurgy may be considered a division of industrial chemistry, the production of the light metals has only been rendered possible by the comparatively recent work of chemists and chemical engineers Moreover, it involves relatively complicated chemical changes as compared with the simple reduction processes which generally characterize the metallurgy of the heavy metals. The metals to be considered are those of the alkalies and alkaline earths, together with aluminum and beryllium. With the exception of aluminum, magnesium, and beryllium, these metals are all far too readily attacked by air to be useful in the pure state for any except chemical purposes. Small amounts of them, however, often impart improved properties to the more stable metals and their alloys. With the increasing tendency of nonferrous metallurgists to study the effect of the presence of relatively small amounts of alloying ingredients, it is probable that some of these elements will come into increasing prominence as minor constituents of alloys. Their intrinsic value in this field will probably be all out of proportion to their quantity. While it is also probable that there will be a certain demand for some or all of these metals for chemical purposes, the trend of invention seems to be away from their use in the chemical industry, and it is doubtful whether this market for them will grow much. Magnesium
On the other hand, magnesium is relatively stable when properly purified. Its physical properties can be consider-
N E W KENSINGTOX, PA
ably improved by alloying it with a few per cent of certain other metals, so that its use for the production of metal parts where extreme lightness is required becomes entirely practical. It is particularly sensitive to the presence of a few tenths of a per cent of certain other metals. The development of magnesium has been and will continue to be slower than that of aluminum. for two reasons. When aluminum was introduced it offered a saving of two-thirds the weight of competing metals. Magnesium or magnesiumbase metals have a weight advantage of roughly four-fifths over the same metals, but only one-third over aluminum, with the weight-strength factor somewhat less when the comparison is made with modern high-strength aluminum alloys. The factor of weight saving is therefore less important in the use of magnesium than it was in the introduction of aluminum. More important is the greater difficulty of fabricating it and its alloys. Magnesium hardens under cold work much more rapidly than aluminum, and the great affinity of the molten metal for oxygen has rendered the production of satisfactory castings on a commercial basis extremely difficult. Patient and painstaking research has, however, gone far in the solution of fabricating difficulties, and alloys have been developed and are now being marketed which have excellent mechanical properties and are commercially stable under normal conditions. Naturally, such alloys are finding their first demand in aviation structures, where the slightest saving in the weight of a part is of great importance. On one airplane engine made in this country, for example, there are seventeen different parts made of magnesium castings. The forged aluminum
October, 1926
INDUSTRIAL A N D ENGINEERIIYG CHEMISTRY
propeller, which recently supplanted the old wood propeller, is beginning t o feel the competition of the magnesium propeller, where the reduction in weight means not only a reduction in mechanical stresses due to centrifugal force, but a quicker “pick-up,” and thus a more rapid rise from the ground. As propeller sizes increase this advanLage becomes much greater, and it would appear that the use of magnesium propellers will be of great advantage in the dehign of larger planes and more powerful engines. The remarkable acoustic properties of this metal, due to its extremely low elastic hysteresis, seem to indicate interesting uses in sound-producing and reproducing equipment. The conversion of the metal into its hydrated oxide by superheated steam, after a ribbon of the metal has been wound about a resistance wire and the whole embedded in a heater, seems to offer great promise as a practical improvement in domestic electric heaters. Commercial experience with such heaters has so far been very favorable and the good thermal and low electrical conductivity of the magnesium oxide, which by virtue of its expansion during its formation wedges the wire firmly in its groove, seems to cooperate in giving the heating unit high efficiency and long life. An increasing tonnage of magnesium is being employed in the refining of certain nonferrous metals, and its power of combining with nitrogen as well as sulfur and oxygen may well decidedly extend its use in this direction. Its use as an important, though minor, constituent of some of the strong aluminum alloys will doubtless demand a n increased tonnage in the near future, with the development of the market for these strong alloys The supply of magnesium ores is ample and their cost moderate. Not only wil1 the use of magnesium-base alloys in aircraft and other fields increase as experience is gained through their adoption, but reduced costs will follow the greater consumption and consequent production. Lower selling prices will in turn open new markets, and gradually this last of the light metals available for structural use will take its relatively small but stable place among the available engineering materials. Beryllium
Beryllium is in a somewhat different position. It combines lightness with a considerable strength, and a melting point much higher than that of either aluminum or magnesium. If its ores were richer and more abundant it might have an important industrial future. As it is, it seems improbable that the cost of producing i t will ever permit its very extensive use. I n limited quantities and for special purposes, however, i t may show itself to be valuable, particularly as an alloying element for use with aluminum and magnesium. Aluminum
.
Xeither beryllium nor magnesium can as yet be properly classed among the common metals The world’s production of aluminum, however (estimated at about 150,000 tons in 1925), and its growing use for all manner of purposes entitle it to membership in this class. The tremendous available deposits of rich aluminum ores furnish a sound economic basis for a continually increasing production and consumption of this metal. As the youngest of all the common metals in point of commercial availability, aluminum will probably be the most rapid in its development during the next fifty years. The impossibility of reducing its ores by any simple smelting operation kept this metal entirely hidden from mankind until about a hundred years ago, while the other common metals have been known and utilized for many centuriesmost of them indeed, for many thousands of years. Modern
1017
science has introduced refinements and improvements in their production and fabrication, and modern engineering has created a demand for them that would have amazed the metal industry of a century ago, but their essential properties and advantageous uses have been almost universally known and appreciated for centuries Aluminum, on the other hand, has only become commercially available within the past fifty years, and the industries concerned in its production and fabrication are still young, some of them scarcely out of their infancy. A large part of the engineering and manufacturing world is still practically unaware of the advantages which this metal offers, and of the best methods of adapting it to their needs. The next fifty years will undoubtedly see great advances in the structural use of aluminum and its alloys. One of the economically important advances will be along the line of conserving, by the use of this abundantly occurring metal, other metals which are relatively rare; especially in connection with uses where such metals are put into a form from which they cannot later be commercially recovered. d good example is the replacement of the comparatively rare metal tin for foil and for collapsible tube manufacture. This rapidly increasing demand for aluminum is saving tremendous quantities of tin for future employment in other forms where i t may later be recovered for repeated use. The problem of supplying the world’s needs of several such metals, which are known to form only a n extremely minor proportion of the outer crust of the earth, is one which may well become serious within the relatively near future. To the extent that part of this demand can be supplied by aluminum, the time of the occurrence of this shortage may be postponed and its seriousness diminished. For the production of the metal it seems certain that for many years we will still be dependent on the rich natural hydrate ore (bauxite); although, as has been the case in the iron industry, the gradual exhaustion of the purest of this ore will lead to the use of lower grades not now considered commercially desirable. An intensive study of the processes of producing the pure oxide from these ores will doubtless lead to some reductions in cost, especially where lower grade material is to be utilized. The Bayer process or some modification of it, involving the separation of the hydrate from the impurities by the formation and decomposition of a solution of sodium aluminate, will probably continue to be the cheapest and best of the chemical processes, in spite of the labors of many inventors of acid processes. The intrinsic difficulties of handling acid solutions and recovering the acid for reuse, and the cost of making a satisfactory separation of iron from aluminum if both are put into solution by the treatment of the crude ore, seem to be a handicap too great to be overcome. However, competition will probably develop between the chemical process and the electrothermal, where instead of extracting the alumina from the impurities the impurities are removed by reduction to the metallic form and separated from the fused purified alumina. I n the reduction of the purified aluminum oxide to the metal, the electrolysis of this oxide in a bath of fused fluorides seems certain to remain our chief reliance. It would be unreasonable to assume, however, that the present electrolytic cells and practice represent the best that can be done along this line; important improvements in efficiency may confidently be expected in this as in other electrochemical processes. It is probable that the Soderberg continuous electrode, which has proved so valuable in other types of electric furnaces, may be of real service here also. The careful studies of the reduction process which are being made, and the opportunity to introduce improvements without great expense for scrapping existing plants because of the
INDCSTRIAL A-VD E,VGINEERISG CHEMISTRY
1018
rapid growth of the industry and the resultant necessity of building increased capacity, should bring about improvements in both the quality of the product and the efficiency of its production. Uses
I n the utilization of the metal, the greatest advances will probably be made in the production and consumption of the strong alloys. The possibility of the production of an aluminum alloy having the strength of mild steel and considerable ductility with only about one-third the weight of steel has been of great interest ever since Wilm discovered the heat treatment of alluminum alloys some twenty years ago, and has contributed not a little in the past to the growth of aviation. However, it is only since the war that the intensive study of the scientific and technical problems involved in the commercial production of these alloys, carried on chiefly by E. Blough, Zay Jeffries, R. S. Archer, and C F. Nagel, Jr., and their assistants and co-workers in the laboratories and works of the Aluminum Company of America, has made possible the commercial production of large quantities of these alloys, in the form not only of sheet but also of castings, forgings, structural shapes, stampings, bar, rod, and tubing, of uniformly high quality and in a variety of grades adapted to serve different purposes. This develop ment offers to the designing engineer the opportunity to improve efficiency, reduce wear and tear, increase output, and reduce operating costs by the use of these materials in moving parts, especially in reciprocating parts. “It costs money to haul pig iron on wheels,” and some one has calculated that it costs 5 cents per pound per year t o haul the dead weight‘ of a street car. Similar costs for railroad passenger service and the much higher corresponding costs for auto-busses, trucks, etc., point to the great savings which the use of aluminum structural members may bring about in the field of rapid transportation. The high-strength aluminum alloys lend themselves admirably to employment for this purpose. The possibility of saving 8 or 10 tons or even more, of the dead weight of a railroad passenger car is one which is attractive not only because of motive-power savings, but also because of the reduced wear and tear on the track and structures and the possibilities of quicker starting and stopping in suburban traffic. I n one auto-bus now under construction the body will contain no wood or steel whatever, and it is estimated that a t least a ton will be saved in dead weight. Some kinds of freight cars and trucks can also probably be advantageously lightened without sacrificing ruggedness and strength of construction. The use of forged aluminum connecting rods in engines of all sorts, from small internal combustion engines to the largest locomotives, may be expected to increase and become common practice and to prove its value by the reduction of alternating stresses in the machinery, the higher allowable engine speesd, and the reduced likelihood of burning out a bearing, because of the higher thermal conductivity of the material. I n the case of locomotives the reduction of the impact load on the rails is of tremendous importance, on account of the operating economies made possible by the use of more powerful and heavier engines, provided this destructive stress on the rails can be reduced. There is no doubt that the use of aluminum alloys in the reciprocating parts of many of our modern factory machines will also introduce economies by permitting decided increases in speed of operation and consequently in output. The use of heat-treated castings, brought about by the research and development work of Jeffries and Archer, has already reached a large annual volume, and seems certain to become a very important factor in the production of strong,
T701. 18, NO. 10
light castings of all sizes. The increasing use of automobile fire engines and passenger busses, which demand a reliability in operation and a continuity of service considerably beyond that of the pleasure car or truck, has caused a lively demand for crank-case castings in these alloys, which have a higher strength and ductility than the alloys ordinarily used, and thus a greater margin of safety against accident. Crankcase castings for the largest fire engines made are regularly and successfully produced of heat-treated alloy. The successful record which this type of casting is making will undoubtedly lead to its general use where high strength and ductility combined with lightness are required, and will open to aluminum castings many uses from which they are now barred because of insufficient ductility. The field of marine engineering, and especially its naval branch, will doubtless see extensive developments along this line. The recent improvement in aluminum alloys for die-casting has enabled this young industry to make rapid progress, and we may confidently expect it to find a large field in the production of small parts which must be made in large numbers The rapidly increasing utilization of the hydroelectric resources of the world has required large tonnages of aluminum cable, steel-reenforced, for high-tension overhead lines. Already one company alone has sold over 150,000 miles of such conductors; and the development of the superpower projects which is bound to come in the near future will mean a heavy demand for this purpose. It may truly be said that the use of aluminum conductors is vital to the practical transmission of large amounts of power over long distances, since only by their use can the necessary high voltages be carried without undue corona losses, and the savings in cost due to the lighter construction and longer spans amount to important items on the long lines which are necessarily involved in any superpower system. The electrification of the steam railroads, which is bound to proceed with increasing speed as fuel prices mount, will also demand large tonnages of aluminum cable for the same reasons Cheap gasoline and easy-money conditions among the purchasers in this country have permitted our automobile industry to sacrifice operating economy in favor of a lower first cost, by building much heavier cars than the European manufacturers. The use of aluminum to reduce weight and increase mileage per gallon has gone so much further abroad than here that it is estimated that if the American manufacturers should use as much aluminum per car as the European makers do, the automobile industry alone would consume more than the present world’s production of this metal. The end of this cheap fuel cannot be very far away, and with rising gasoline prices and the compelled use of the more expensive and less powerful substitutes for gasoline there will come a demand for lighter and more economical cars, which will throw a great load on the aluminum industry. Developments now made indicate the possibility of easily reducing the weight of an average car by a t least one-fifth, through replacement of heavier metals with light, strong aluminum alloys, and the trend in this direction may be expected to develop increasing speed with the years. Furniture made of strong aluminum alloys, for use in offices and public buildings, is another important development which is already in sight. The records of insurance companies show that wood furniture in fireproof buildings is a definite hazard, and higher premiums will force the use of noninflammable equipment. The steel furniture business already amounts to over $25,000,000 per year. The higher first cost of aluminum as compared with steel is partly offset by the greater ease of forming and greater convenience on account of the lower weight. The maintenance cost on
October, 1916
I-\-DUSTRIAL A-YD ESGINEERISG C H E M I S T R Y
an ordinary wood chair in constant use runs from about $1.00 to $3.00 per year, which justifies a reasonably high first cost of the metal chair. Conclusion
These seem to be the directions in which, in the light of present knowledge, the light metals will make the most prog-
1019
ress in the near future. However, the intensive scientific study of their production and utilization has only just begun, and there may be many new developments in the near future that will open still other avenues of growth and usefulness. This is the lure of scientific research-the striving for the discovery of the unknown which, in its success. brings new happiness, ease, and comfort to mankind.
The Future of the Chemistry of Petroleum By James F. Norris hfASSACHtiSETT5
T
I N S T I T U T E OF
HE outlook i;, bright for the rapid development of the chemistry of petroleum. The increasing appreciation of the value of science to the industry leads to confidence in what is ahead, and one approaches with enthusiasm a look into the future. The use of chemistry, geology, and physics in the detailed study of petroleum in all its aspects will greatly enhance the value of this important product, both financially and from the point of viem- of furnishing the world with useful substances. I t is a fundamental fact in industry that a detailed knowledge of the properties of the raw material used is essential for the best results. This knowledge has been lacking in the case of petroleum and the first task of the chemist is to acquire it. I n the future the study will not be limited to the investigation of those properties that come into play in handling petroleum by the methods now in use, but attention will be paid to the enriching of our knowledge of the fundamental chemistry of the hydrocarbons and their many types of derivatives related in any way to the parent compounds. The subject must be approached from this point of view if marked advance is to follow. A very promising start has been made in this direction, and it takes no prophet of the first rank to forecast the success of the research program lately undertaken under the auspices of the American Petroleum Institute. Up to the present the work is being financed by the father of the petroleum industry and one progressive company But it will not be long, in the judgment of the writer, before the organizations forming the institute will be mhole-heartedly behind the plan. What can be expected in the immediate future? What problems need the first attention? The study of the genesis of petroleum is of more than academic or geological interest ; for when we know the way or ways in which Sature has produced such a valuable substance. we may be in a position to duplicate the processes or improve upon them. The chemist, geologist, and physicist will cooperate in this study. The chemist will furnish the facts in regard to the components of the raw materials from the several sources. The geologist will describe the history and nature of the rock formations that yielded the deposits, and the cahanges that these formations have undergone. The physicist will bring to bear on the problem his knowledge of the value of the pressure, capillary action, and physical forces involved, and with the chemist find out the effect of these forces on the probable,ultimate source of the petroleum studied. We shall see as a result new or improved theories of the genesis of petroleum based on wide observation-theories that can be suhjected to experimental examination. While this work is in progress new knowledge will be accumulating in university laboratories that may help to solve the problem. The study of the chemical action produced by the alpha particles emitted by radium when they come into contact
TECHNOLOGY, C A M B R I D G E , MASS.
with molecules may seem far afield from petroleum; but recent work shows that this type of energy changes methane into a mixture of compounds that resemble crude petroleum. This observation taken along with the fact that helium occurs in the natural gas from certain sources makes the study of radioactivity from this point of view of the first importance. It may turn out that one type of petroleum a t least had its origin in vegetable matter that was converted into marsh gas and finally into higher hydrocarbons. The formation of hydrocarbons from vegetable material through action of bacteria or other agencies will some day be studied, and the results may lead to important industrial developments. Heptane is produced by a certain type of tree and other hydrocarbons have been shown to have a vegetable origin. Some day me shall know more of such chemical processes. The world must eventually turn for help to the tropics with their limitless supply of energy in the form of sunlight; and petroleum or something to do the work now done by petroleum will be made from the vegetable material so abundantly and quickly supplied with energy from the sun. The study of the genesis of petroleum will lead to the discovery of facts that will help in devising systematic methods for the search of new deposits. The progress already made leads to confidence in the future. The physicist with his torsion balance and seismograph is now as necessary as the geologist in prospecting for new fields. The future will see added interest in the study of oil shales which will eventually prove to be an important source of power. This field is a fascinating one for study, as much chemical work is to be done. Problems Awaiting the Chemist
Let us now turn our attention specifically to the problems before the chemist. One of the most pressing needs is a definite knowledge of the composition of the various types of petroleum. The time is propitious for a reexamination of this problem. The pioneer work in this very difficult field was carried out when there was little knowledge of the physics or chemistry of the components of the material being studied. The use of distillation, solubilities, and test for unsaturation by unreliable methods could not advance the subject very far. But today the established laws and experimental methods of physical chemistry are tools that make the attack of the problem a hopeful one. With temperatures at command as low as the boiling point of hydrogen and with the use of accurate criteria of the purity of crystalline substances, it is possible to obtain definite knowledge impossible twenty years ago. The old-fashioned method of fractional distillation has been replaced by one based upon the significance of vapor pressures of mixtures. It will not be long before the technologist knows more about the composition of the material with which he is working
