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By W. E. D. Stokes

WHEN history is written, the year of the blitzkrieg will go down as giving aviation its greatest impetus. No perceptible drop in military business, even with cessation of hostilities abroad, seems likely. The combined air force of the U. S. Army and Navy on July 1 was approximately 5000 planes, as against 50,000 planes currently discussed as necessary. Observers at the fronts are giving designers and metallurgists back home some realistic ideas to shoot at. As conventional runways reveal the location of airports to enemy raiders, operating bases are now masked. Difficult, often muddy and rough landing strips, requiring strong landing gears and exacting take-off and maintenance characteristics, are the specifications of war. This is "old stuff" to numerous mining operators in mountainous jungle areas where gradients up to 8 per cent are in more or less common use in such mountain landing fields. Although airplane building is not readily adaptable to assembly-line methods, a trend towards mass productions is now in evidence. Incidentally, a U.S. Army "Curtiss P-40" requires about 10,000 man hours of work to complete and is tied together with 75,000 rivets. During the past year a number of aircraft factories adopted the "shot-

Jan 1, 1941

By G. R. Heckman, H. J. Murphy, C. T. Sims

An incestigation has been made of the effects of heat treatment and alloy composition on the long-time stress-rupture properties and structural stability of the similar nickel-base alloys Udimet-500, Lrdimet-520, and Udimet-700. Rupture test data are presented at stresses ranging from 4 to 50 ksi at temperatures from 1450° to 1900°F for times up to 14,000 hr. Ductility response is emphasized. Optical and electron tnicroscopy were complemented by X-ray diffraction analyses of extracted phases to relate microstructural stability to the observed rupture properties. Particular attention is paid to Udimet-520 since structural characteristics of this alloy appear to vary somewhat from its sister alloys. Both cast and wrought performance of Lrdimet-500 are discussed. The computerized PHACOMP calculational technique, based on electron-vacuncy theory, is discussed and related to structural stability where appropriate. Electron microscopy and microprobe techniques were used to conduct evaluation of the oxidation characteristics of Udimet-500 exposed in air for 16,100 hr. The steady advance in strength and reliability of nickel-base superalloys continues to be one of the high points of modern metallurgy. The stress capability of these materials has increased steadily, allowing higher and higher operating temperatures in the highly sophisticated aircraft and industrial gas turbines now on the market. The attendant increase in efficiency, of course, means greatly improved power output. Gas turbines for industrial and marine use have long been designed with these objectives paramount the usual design requirements in terms of time of service being 100,000 hr. High-efficiency, long-life aircraft such as the supersonic transport require superalloy engine materials with high-strength and long-time structural stability. Thus, materials studied for and operating experience from industrial gas turbines provide a good reservoir from which technology of high value to the SST program can be drawn. This study is one such case. Three prominent nickel-base super alloys—Udimet 500, Udimet 520, and Udimet 700 were extensively evaluated for industrial gas turbine bucket use. Particular attention was directed toward structural stability as a requisite property. Within the present context, structural stability is defined as freedom from the propensity to form strength-robbing or embrittling phases such as u,p,x,or Laves, and the ability to maintain useful rupture strength and ductility throughout design life. MATERIALS The three alloys, cast Udimet 500 (U-500C), Udimet 520, and Udimet 700, were chosen for detailed evaluation based on preliminary studies which indicated that U-500C and U-520 possessed comparable rupture strength capabilities, and that U -700 had a greater strength capability but somewhat poorer ductility than wrought U-500. The nominal compositions of the three alloys, along with the compositions of the heats investigated, are presented in Table I. PROCEDURE Dimensionally rejected U-520 buckets from Special Metals Corp. heat 63370 were heat-treated using the four cycles delineated in Table 11. Cycle A was investigated to determine the effects of a shortened 1700°F primary age. Cycle B was considered a "standard" treatment. Cycle C investigated a higher solution temperature in combination with a shortened primary age, while cycle D assessed the effect of the higher solution temperature alone. These heat treatments were designed to produce optimum combinations of rupture strength and ductility through maximum y' development, the development of a y' grain boundary cushion, promotion of MC carbide degeneration reactions, and agglomeration of resultant M23CB. Since one of the premises of the evaluation of U-520 was that rupture strength would be equivalent to U-500, forged U-500 buckets from Special Metals Corp. heat 62916 were heat-treated with cycles A, B, and C to provide comparison. The heat-treated structures of U-520 and U-500 are illustrated in the 8700 times electron micrographs of Fig. l. The U-700 tested was all from 3-in.-diam hot-rolled and centerless-ground rod from Special Metals Corp. heat 2-1426. Two heat-treatment cycles were employed, E and F of Table 11. Cycle E is a standard four-step, triple-age treatment intended to provide an optimum match of strength and ductility through well-developed matrix and grain boundary y', as recommended by U-700 vendors. Treatment F is a shortened , single-age cycle which could provide a significant processing cost reduction should adequate strength and ductility be maintained. Following heat treatment, rupture specimens of U-500 and U-520 were machined from the buckets and tested. Standard rupture bars of U -700 were machined from the heat-treated rod and rupture-tested. Failed and withdrawn rupture bars were prepared and examined by optical and electron microscopy. Select specimens were electrolytically digested, and the residues analyzed for carbide and topologically close-packed phases using CrKa or CoKo radiation. Of the six different U-500C heats evaluated, five were cast by Misco Precision Casting Co. and one was cast by Haynes Stellite Co. Cast-to-size rupture bars

Jan 1, 1968

By Alfred F. Brainerd

A few months since, Prof. Lawrence C. Johnson, of the U. 8. Survey, discovered in Mississippi large deposits of carbonate iron-ore, geologically located in the Claiborne formation of the Tertiary Epoch. These deposits are not pockets, but continuous layers or beds extending for miles, and can be located with certainty where they have not been removed by erosion. Upon examination, recently made by G. W. West, Birmingham, Ala., the largest deposits and highest grades of ore were found near Enterprise, Lauderdale county, and in Clark county, Miss. These beds measure from 10 to 18 feet in thickness, are superimposed upon a " burr rock," associated with green sand, and dip 30 feet to the mile southeast, at an altitude of 350 feet above sea-level, can be

Jan 1, 1888

By E. W. Parker

Anthracite, as sent to market, comes under three general terms of description: characteristics, source and size. Anthracite is generally classified as white ash, red ash, or Lykens Valley. The white ash coals are sometimes further described as "hard" or "free-burning." Lehigh white ash would come under the former description and Shamokin white ash under the latter. As a rule, it may be said that the nearer the origin of the coal to the western extremity of the anthracite region, the softer and more free-burning it is. Indeed, for many years the coal from Trevorton, at the western tip of the Middle Western field, was classified as "semianthracite" in the shipment reports. Lykens Valley coal is always a red ash coal, with a higher volatile content than the general run of anthracite, and consequently free-burning. The name does not exclusively indicate the neighborhood in which the coal is dug, but rather refers to the beds from which it is obtained. These beds lie, not above the Pottsville conglomerate, as is the rule, but encased in it. The extreme eastern limit of the Lykens Valley beds would seem to be about Tremont, in Schuylkill County, and the Natalie mine, near Mount Carmel. There are, of course, traces of these beds farther to the east, but they do not seem to be workable. There are as many as six of the Lykens Valley measures found in the conglomerate at some points, but to a large extent they are unworkable. Whether this coal is obtained in the Lykens Valley proper, where the beds were first identified, or from the Shamokin Valley, it is always Lykens Valley coal, and it has long been considered a premium coal, especially desirable for domestic use, particularly when a quick, hot kitchen fire is desired. Coals are, of course, frequently marketed under special names—Jeddo, Scranton, Kingston, Old Company Lehigh, Famous Reading, Lacka-wanna, etc.—which, of course, have the trade significance which their producers and vendors have built up. General Description of the Various Coals, with Name of Seam and Producing District This is partly covered in the paragraphs above. Lykens Valley coal is produced from one or another of the six Lykens Valley beds lying within

Jan 1, 1930

By George H. Anderson

A CHAPTER of appealing interest was added to the industrial history of the Southwest early in June, when the War Production Board gave final approval to the erection of a blast furnace, a battery of coke ovens, an ore-beneficiation plant, and other facilities for the production of pig iron in northeastern Texas, just north of the East Texas oil field. For many years the people of Texas and adjoining states have cherished the ambition and desire that eventually an iron and steel industry drawing upon local mineral resources would be established to serve Southwestern markets. The existence in this vicinity of valuable deposits of iron ore, limestone, and coking coal has been known in a general way for many years, and efforts have been made from time to time to use them in the production of iron. The present development promises to bring to realization the dreams of the men who have visualized what the establishment of this basic industry would mean to the region.

Jan 1, 1942

By W. V. Vietti, W. A. Oberlin

Crude petroleum produced in the Texas Panhandle oil field is both an asphalt and a paraffin-base oil and is further characterized by being a high-gravity crude with an extremely high cold test,. An eight-well composite of Panhandle crude showed the following characteristics: Gravity, 36.6° A. P. I. Viscosity: 61 sec. Saybolt at 100° F. 170 sec. Saybolt at 75° F. 1560 sec. Saybolt at 50° F. (stirring) Cold Test, 60° F. Distillation Test: Per Cent. Per Cent. Gasoline........................ 28.8 Wax........................... 19.2 Kerosene........................ 4.8 Asphalt........................ 13 .0 Gas oil......................... 30.7 Sulfur1......................... 0.8 Fuel oil......................... 34.7 Subsurface Conditions The original pressure in the formation in the Panhandle field closely approximated 420 Ib. gage or 435 Ib. absolute pressure. Temperatures taken indicate that the formation temperatures do not exceed 90° F. The temperatures in Table I are typical measurements taken on one lease. * A contribrition from the research department of the Marland Refining Co. of Oklahoma and the production engineering department of the Marland Oil Co. of Texas. 1 Smith [Analysis of Panhandle and Rig Lake Crudes. U. S. Bur. Mines, Circular No. 6014 (December, 1926)] found an average sulfur content of 0.6 per cent.

Jan 1, 1928

By Juptner von Jonstorff

A discussion of the paper by Messrs. Jüptner von Jonstorff, Blair, Dillner and Stead, read by title at the Lake Superior meeting, but presented first at the New York meeting of the Iron and Steel Institute (October, 1904), and here published under a mutual agreement between the two Institutes. Correspondence. MR. R. HAMILTON (Glengarnock) wrote to say that it was known for many years, that unless certain precautions were taken in dissolving the sample, there was a liability to obtain a solution from which the ammonium-molybdate solution would not precipitate the whole of the phosphorus. In 1877 Blair and Finkiner independently attributed this interference to the presence of carbonaceous matter in the solution, derived from the action of acids on the combined carbon of the metal, and they directed that the solution should be prepared in such a manner as to destroy these carbonaceous compounds. This was practically effected by evaporating the acid solution to dryness and roasting the residue. Adolf Tamm, in 1884, accentuated the same view. There are methods founded on the above-mentioned observations which leave nothing to be desired in point of accuracy, but the evaporation to dryness with subsequent roasting and re-solution consumes much time, besides the minor inconvenience caused by large amounts of acid fumes. In 1888 P. W. Shinier suggested that the incomplete precipitation of phosphorus was due to incomplete oxidation of -.the phosphorus, and proposed to render all the phosphorus precipitable by oxidizing the solution with potassium permanganate, etc. Experiments were made to test the accuracy of this view (details will be found in the Journal of the Society of Chemical Industry, vol. x., p. 904), and the results obtained seem to-prove that it is the correct one. It was first proved that carbonaceous matter in solution did not prevent the precipitation of properly oxidized phosphorus

Mar 1, 1905

By Sydney H. Ball

AMERICAN consumption of industrial diamonds has increased five fold in the past 25 years and today accounts for 15 to 20 percent of the world's sale of rough diamonds. In another decade the value of industrial diamonds sold may well equal or exceed that of gemstones. It is generally understood that industrial diamonds are one of the strategic minerals being stocked by the Government in the present crisis to ensure rapid and efficient armament production. Diamond die making is a trade largely confined to artisans in Switzerland and in certain parts of France. Today, in addition to turning out pilots, we should train expert artisans in diamond die making, for thousands of miles of tremendously small-gauge wire will be needed to make the instruments by which the efficiency and safety of these pilots is assisted.

Jan 1, 1941

By A. E. Dwight, A. F. Berndt

ThE published U-Ru equilibrium diagram indicates the existence of six intermetallic compounds in this system.' The structure of only two of the compounds, u2Ru2,3 and URU3,4 have been identified. This communication reports on the crystal structure and density of Uau3, which is formed by a peritectoid transformation at 1025° ± 5°C: U3Ru4 + U3Ru5 = U2Ru3. An alloy with the stoichiometric formula U2Ru3 was prepared by arc melting electrolytic uranium and ruthenium of 99.9 pct purity on a water-cooled copper hearth under an argon atmosphere. After homo-genization at 1000°C for 3 days, a metallographic examination revealed that the peritectoid transformation was complete and less than 5 pct of a second phase was present. A powdered sample, obtained by crushing the brittle compound, was annealed for 1 hr at 1000°C and air-cooled. Debye-Scherrer patterns were obtained with filtered CrKa, FeKa, CoKa, or CuKa radiation. The X-ray patterns of U2Ru3 weFe indexed as an fcc structure with a. = 12.895 0.00lA. The unit-cell constant and its standard deviation were calculated by a computer program described by Mueller, Heaton, and Miller.5 The density, measured by an immersion method, was 14.45 g cm-3. A calculated density of 14.48 g cm-3 was obtained on the assumption that twenty-four formula units (120 atoms) comprise a unit cell. The space group is either oh7 Fd3m, or the less symmetric, T4h, Fd3, since reflections indexed as hk0 with h + k + 4n are absent. All values of h2 + k2 + 12 permitted by both space groups are listed in Table I together with dc, do, and I. values. The calculated d spacings were obtained by the computer program of Mueller, Meyer, and simonsen.6 The observed d spacings above 0.77A were obtained from X-ray" patterns prepared with CuKa radiation, above 0.90A with CoKa radiaaion, above 0.98A with FeKa radiation, and above 1.16A with CrKa radiation. An attempt was made to identify the crystal structure of U2Ru3 by comparison with published data on other A2B3 compounds. A recent compilation7 of intermetallic compounds lists thirty-two structure types with the A2B3 stoichiometry. Only two of the structure types are fcc and they are Sb2O3(r), senarmontite, with 16 Sb2O3 per unit cell, and In2Te3 for which several structures have been proposed.8 However, the two cases cited do not have twenty-four formula units in the unit cell. We therefore, cannot identify UPRU3 with any of the other known A2B3 compounds. Ternary alloys were made in which 5 at. pct Os, Rh, or A1 were substituted for 5 pct of the Ru in U2Ru3. The osmium substitution increased the unit cell constant to 12.899 * .001A, which is to be expected since the atomic volume of osmium is slightly larger than

Jan 1, 1969

By A. C. Fieldner

THE COMMITTEE on Correlation of Research held two meetings in 1931. The first was a luncheon meeting on Feb. 19, at the Engineers Club, New York, attended by eight members and four guests-William H. Bassett, past-president of the Institute; Robert E. Tally, president; H. Foster Bain, secretary; and Alfred D. Flinn, director of the Engineering Foundation. Mr. Bassett gave a short resume of the circumstances leading to the formation of the Committee and expressed his opinion that the objectives as expressed by the Committee in its first annual report were in accordance with the ideas of the Institute officials. Mr. Tally stressed the great importance of research in the mining and metallurgical industries and stated that lie believed the Institute should encourage and promote research, and that this Committee could do a great deal to foster such work in the Institute. Mr. Bain pointed out that this Committee was appointed with a view to correlating and fostering research work. in the field of the Institute's activities. This could be done in various ways, as by encouraging the divisions and committees of the Institute to hold group meetings on research, by forming research subcommittees in the Institute divisions, and by bringing together research interest in. certain projects and the fund or organization that is equipped to carry out the project.

Jan 1, 1932

By C. K. Leith

THE interdependence of nations in regard to mineral supplies has grown apace with the expanded needs of industry, with depletion of reserves, and with advances in technology. This increased mutual dependence raises many questions of foreign economic policy of special importance in our postwar planning. Realization of the urgent need for the development of a general mineral policy broadly based on national requirements led to discussions of the problem between officials of the Department of State and myself, as a result of which it was suggested that I make an informal and unofficial canvass of the views of mineral specialists of the country on foreign mineral policy.

Jan 1, 1946

By A. English, M. J. Greaves

This paper is a discussion of pelletizing systems developed over the last 15 to 20 years for the agglomeration of fine iron ore concentrates. Five different pelletizing systems are now in commercial use in the U.S., and for the purposes of comparison, estimated operating costs and capital costs for the construction of four of them are included. Capacities of existing commercial plants are examined, together with the anticipated capabilities of plants presently being built or projected. In just 21 years, the art of pelletizing iron ore concentrates has reached maturity with mastery of the separation of finely divided concentrates from low-grade iron ores and their agglomeration into pellets containing about 65% iron. This accomplishment has firmly established an improved feed for the blast furnace, with resulting benefits in faster reduction of burdens and greater economy of operation. The present production capacity of pelletizing facilities in the U.S. is about 20 million tons annually, and it is expected to double by 1970. The rapid expansion of pelletizing in the U. S. has been closely observed in European countries, notably in Sweden and Germany, where pioneer agglomerating techniques were developed early in this century. PELLETIZING PLANTS AND PROCESSES Twelve commercial pelletizing plants are presently in operation in the U. S. and Canada. An equal number are in various stages of engineering and construction, and many others are being considered. The pelletizing systems currently employed include shaft furnaces, horizontal grates using three different airflow arrangements, and grate kilns. The capacity of pelletizing operations in North America is shown in Table I. All of these plants are integrated with the mine, the ore-crushing facilities and the concentrating plant and are equipped with storage and loading-out facilities for the product. Normally, a pelletizing plant is composed of a shuttle conveyor above the receiving bins; balling equipment; a heat-hardening system including the necessary auxiliaries such as furnaces, burners and controls, ducts, fans, meters and instrumentation; fines recovery equipment; and product handling equipment. Also included are the necessary auxiliaries and utilities such as boilers or power plant; oil unloading and storage facilities; coal unloading storage, grinding and distribution facilities; and bentonite or other additive storage and distribution equipment. Shaft Furnaces: Vertical shaft furnaces used in this country are limited to the treatment of natural magnetite concentrates containing minor quantities of residual fluxing elements. Fig. 1 shows a perspective view of the shaft furnace with balling, feeding and pellet-handling equipment. An elevation of a shaft furnace is shown in Fig. 2. A commercial shaft furnace unit is about 45 ft in height with a 6 x 14-ft rectangular cross section and has a nominal production rate of approximately 50 gross tons of pellets per hour. The upper portion of the furnace shaft is constructed of fire brick as protection from the high process temperatures involved. The lower portion of the shaft is lined with abrasion-resistant brick to withstand erosion from the fired pellets. Rectangular-shaped, refractory-lined and insulated combustion chambers are situated on each side of the shaft furnace. Oil or gas is burned to produce high temperature gases which are forced into the furnace through ports located near the top of the combustion chambers. The shaft furnaces operate at a pressure of approximately 6 psi. Pellets are fed into the top of the furnace by a pantographic feeder designed to produce the desired pellet stockline. The furnace is kept filled at all times and pellets are fed and discharged from the furnace at the same rate. In early development, 10 to 12 lb of solid fuel was incorporated in the pellets. However, the main source of process heat is now derived from the combustion chamber gases. In some instances no solid fuel is used. The pellet movement in the shaft furnace is counter-current to the flow of gases. Ambient air is introduced through louvers at the lower end of the furnace, at about 6 psi, cooling the fired pellets and supplementing the heat of the high temperature gases from the combustion chamber ports. The zone of maximum temperature, located above the ports of the combus-

Jan 1, 1963

By Alfred H. Brooks

PetRoleUm seepages are known in Alaska at four localities, all on Pacific seaboard. These, named from east to west, are Yakataga, Katalla on Controller Bay, Iniskin Bay on Cook Inlet, and Cold Bay on the Alaska Peninsula. Besides these, a petroleum residue has been found near Smith Bay on the north Arctic coast of the Territory. At Katalla, Cold Bay, and Iniskin Bay there has been some drilling for oil, and in the first field several productive wells have been opened up. Alaskan petroleum, so far as its composition is known, is a refining oil, with paraffin base and low sulphur content. Most of what is known of the geology of Alaska oil fields is based on the investigations of Dr. George C. Martin, of the United States Geological Survey. A, G. Maddren, of the same service, has recently made a reconnaissance of the Yakataga oil field. The data to be here presented are chiefly taken from the following publications: G. C. Martin: The Petroleum Fields of the Pacific Coast of Alaska, with an account of the Bering River coal deposits, Bulletin No. 250, U. S. Geological Survey, pp. 9 to 27 (1905). G. C. Martin: Geology and Mineral Resources of the Controller Bay Region, Alaska, Bulletin No. 335, U. S. Geological Survey, pp. 112 to 130 (1908). G. C. Martin and F. J. Katz: A Geologic Reconnaissance of the Iliamna Region, Alaska, Bulletin No. 485, U. S. Geological Survey, pp. 126 to 130 (1912). A. G. Maddren: Mineral Deposits of the Yakataga District, Bulletin No. 592, U. S. Geological Survey, pp. 143 to 147 (1914). Katalla Field The Katalla field is marked by a series of seepages and gas springs occupying an east and west belt, about 25 miles in length and from 4 to 8 miles wide. (See Fig. 1.) This zone skirts the north shore of Con-

Jan 1, 1915

By W. C. McClain

In the design of underground excavations, rock mechanics considerations are nearly always based on an elastic behavior of rock. Most rocks do exhibit a certain amount of elasticity, and the application of principles and concepts of elasticity to rock mechanics problems has been largely responsible for progress in the field over the past 10 or 15 years. No doubt the theory of elasticity will remain the most useful analytical tool available for both the design of underground openings and the interpretation of phenomenological data.

Jan 1, 1967

By D. B. RUSHJIORE

(New York -Meeting, February, 1912.) TORCHES were used by the early Romans for mine-lighting, and these were followed by open lamps or earthen jars filled with tallow or oil, and later by candles. In early coal-mining, explosive gases seldom occurred, and, if they were encountered, the danger of explosion was materially diminished by the absence of any ventilating-system and the consequent insufficient circulation of air to form with the methane an explosive mixture. As the art advanced, the danger of fire-damp became more apparent, and methods for testing the air were resorted to as early as in the fifteenth century. The method of testing consisted in lowering a clog in a, basket down the shaft. As soon as he encountered fire-damp he would commence to howl, after which he was withdrawn, and a leafy bush was fastened to the end of the rope and run rapidly up and clown the shaft. This so disturbed the accumulation of gas as to cause it to rise out of the shaft. Later this odd method of testing was improved upon through the discovery that a light inserted in a body of fire-dam p would produce a blue flame. Candles were used for this purpose, and, when fire-damp was thus discovered, brushing or some other primitive method of fanning was resorted to for driving out the gas. In some instances the gas was burned away, regardless of the danger thereby incurred. A man, wearing a well-moistened coat and a mask with glass spectacles, descended in the mine a few hours before each shift. With a long stick, to which was fastened a burning torch or candle, lie would crawl on the floor with the stick so raised that the light would sweep the roof and ignite the gas which it encountered. In this position the flame of the explosion would pass over him, after which he would retreat from the gases resulting from the combustion. The occurrence of serious accidents resulted in

Jul 1, 1912

NEW MEMBERS. The following list comprises the names of those persons who became members during the month of flay, 1913: Members. BASTIN, EDSON S., Geol U. S. Geological Survey, Washington, D. C BUCHERER, Louis, Cons. Engr Apartado 1471, Mexico City, Mexico. BURDICK, CHARLES A., Min. Engr 74 Broadway, New York, N. Y. CARR, HOMER L., Min. Engr 109 W. 88th St., New York, N. Y. CARTER, RUSSELL S., Mech. Engr. & Asst. Gent Mgr., Ingersoll-Rand Co., 11 Broadway, New York, N. Y.

Jan 6, 1913

By R. E. Grant

THE Cerro de Pasco Railway Co., owned and operated by the Corporation, is a common carrier whose chief functions are transportation of ore and concentrates from the mines at Cerro de Pasco to the smelter in Oroya, and haulage of coal from the coal mines at Goyllarisquisga to the coal washery at Fundicion. Connecting with the Peruvian Central Railway at Oroya, the C. de P. Railway maintains joint, daily freight and passenger service from Lima and the port of Callao to Cerro de Pasco, terminal of the C. de P. main line and gateway to the Huanuco Valley. Extending from Oroya to Cerro de Pasco the main line is a standard-gauge roadbed of 70-lb. rail, 132 km. long with a maximum compensated grade of 2.25 per cent and a curvature of 16°, climbing from an elevation of 12,272 ft. above sea level at Oroya, lowest station on the line, to 14,208 ft. at Cerro de Pasco. The highest point reached by the C. de P. is on the coal branch at Alcacocha where the rails are 14,385 ft. above the sea.

Jan 1, 1945

By Frank F. Aplan

INTRODUCTION Coal is a solid, combustible mineral substance resulting from the degradation and alteration of vegetable matter largely in the absence of air. In this natural process of coalification, some non-combustible mineral matter is always associated with the combustible material. Coal preparation or cleaning is the process of removing this inert mineral matter from the coal. Preparation is highly successful in removing the large fragments of inert material, but is not very effective in removing the fine inorganic mineral matter intimately associated with the coal. Of the 600 million tons of coal produced in the United States every year, approximately one-half is produced by coal cleaning methods (1). The bulk of this tonnage is cleaned by coarse or intermediate gravity preparation methods (5 inches to 28 mesh, Tyler). Fine cleaning, say, -28 mesh, is done by shaking tables, washing cyclones, and flotation, or, until recently, the fines were either incorporated into the clean coal or simply discarded--not infrequently, the latter. In 1972, only 13 million tons of raw coal were cleaned by flotation in the United States, and from this 8.4 million tons of clean coal were produced (1). The percentage of clean coal produced by flotation in Europe (England, West Germany, Poland, U.S.S.R., etc.) is substantially higher. However, coal flotation has grown rapidly in the United States from only a few plants in 1950 to 31 in 1960 (2) and 66 in 1970 (1). Virtually all new preparation plants incorporate flotation into their basic flowsheet. The essential difference between ore and coal flotation is that for ores the entire tonnage is ground to flotation size, whereas for coal

Jan 1, 1976

By Donald B. Gillies

WE HAVE come a long way since the time of the old steel master who declared that chemistry would ultimately bring the steel business to ruin. Yet I sometimes doubt whether even now we fully recognize the great debt we owe to the institutions that today are initiating young men into the fascinating mysteries of science and training them in the art of engineering. I am not sure that we recognize the importance of the contribution that the schools of applied science and the technical colleges are making to our industrial economy. That contribution is neither narrow nor restricted. It covers the whole range of industry. Dr. Compton, himself, has shown in his survey of leading American corporations that the engineer is twelve times more likely than the nonengineer to become president, five times more likely to become treasurer, and thirty times more likely to become an officer. So the hand of the engineer not only is all-powerful in the laboratory and in the drafting room but his control is increasing in all departments of management.

Jan 1, 1940

By J. W. Eckerd, P. S. Lewis, N. H. Coates

USBM designed, constructed, and operated an 18-in.-diam fluidized-bed combustor for highly caking coals to evaluate the method for possible application to power generation. In initial tests, combustion was carried on successfully, with carbon losses as low as 0.8%+ Coal ash was not satisfactory as a bed material, but mullite proved to be acceptable. Overall heat-transfer coeffients from the bed (-20 t 50 mesh mullite) to a water-cooled tube were about 75 Btuper hr-sq ft. Fluidized-bed combustion is being investigated by the U. S. Bureau of Mines (USBM) as a potentially cheaper method of firing power plant boilers. Lower combustion temperatures in fluidized beds—only 1400" to 1800°F-—should reduce fireside deposition and corrosion and nitrogen oxides production. Fluidized-bed combustion also offers possible advantages in the use of additives to control SO, emissions and amenability to processing of high-ash, high-moisture coals without special preparation. This paper describes development of a fluidized-bed combustor and the results of preliminary tests. Equipment and Procedure Fig. 1 shows the 8-ft-high combustor. A cone-shaped plate perforated by I/8-in.-diam holes supports the fuel bed and admits the fluidizing air; water passing through the 3/4-in. pipe extracts heat from the combustion bed. Fig. 2 is a flow diagram of the system. Coal is fed pneumatically to the base of the fuel bed. Combustion products are passed through two centrifugal separators to remove most of the entrained solids, then to a water

Jan 1, 1971