Search Documents

By K. C. Mills, E. T. Turkdogan

The results on the rates of vaporization of Fe-Ni alloys, levitated by an electromagnetic field in a stagnant atmosphere of helium, are shown to be in close agreement with those predicted theoretically. AS shown in Part I of this series of papers, the rates of vaporization of metals enhanced by convection currents are increased further by the process of condensation of metal vapor when there is a steep temperature gradient in the boundary layer. At the time this theoretical work was completed one of the authors (K. C. Mills) had already carried out some experimental work on the rates of vaporization of molten Fe-Ni alloys. The experimental work was done under conditions which make it possible to compare the experimental rate data with those predicted on theoretical grounds. EXPERIMENTAL The object of the experiments was to evaluate the activities in a number of binary metal systems. The details of the experimental technique are given in another paper by Mills, Kinoshita, and Grieveson,2 and, for the present purpose, a brief mention of the relevant features of the experimental method will be adequate. Using an induction coil, the metal weighing about 1 to 1.5 g was levitated by the electromagnetic field in a stagnant atmosphere of pure helium. The helium was freed from oxygen and water vapor in the usual manner, and its pressure in the vaporization chamber was maintained at 1 atm through a bleeder device. The vaporization chamber consisted of a pyrex tube, 2.8 cm diam, with a side arm connected to the helium bleeder. The bottom of the tube, shaped conical, was surrounded by the induction coil, and the top was sealed with an optical flat for the purpose of measuring the melt temperature with a two-color optical pyrometer. By suitable adjustment of the high-frequency power input, the metal was brought to the desired temperature in about 30 sec of levitation. After a specified vaporization time, e.g., 3 to 4 min, the alloy was quenched by switching off the power. The amount of metal vaporized was determined from the difference between the initial and final weights of the sample. During the vaporization time, temperature fluctuations of about ±10°C were observed. COMPARISON OF EXPERIMENTAL DATA WITH THEORETICAL VALUES The experimental results are given in Table I. As already mentioned, the attainment of the vaporization temperature took about 30 sec from the moment of levitation. Therefore, the times recorded in Table I are 30 sec less than the total time; this is considered to be a reasonable estimate of actual vaporization times.

Jan 1, 1964

Christopher R. Corning was one of the ablest mining engineers and geologists in America and one whose name was well known also in Mexico, Cuba, South America and many European countries. He was educated at Zurich, Switzerland, and at the Bergakademie, Freiberg, where he was graduated in 1883 with the degrees of Markscheider and Bergingenieur. He continued his studies at Heidelberg until 1886, chiefly in chemistry, under Bunsen, and mineralogy and petrography under Rosenbusch. Although he received a Ph.D. in chemistry, he never used the title. During holidays of 1883-86, he traveled, seeing mines and studying geology in Spain, France, England, Italy, Germany, and Austria. In 1886, he returned to America and in 1887 he was in the Lake Superior iron ore country on the staff of John F. Stevens, then building the Duluth South Shore and Atlantic Railway. In 1889, Mr. Corning was at the Bunker Hill & Sullivan mines at Wardner, Idaho, with John Hays Hammond, and there met E. E. Olcott. Although Mr. Corning was not long connected with the Bunker Hill & Sullivan mines, he left the imprint of his ability and splendid personality upon the men and the property. That his friendship was cherished was manifested by the cordiality, hospitality and frequency of letters of good counsel and cheer. In 1897, Mr. Corning, with E. E. Olcott and Prof. Robert Peele of Columbia University, formed the firm of Olcott, Corning & Peele, consulting mining engineers. Pressure of university duties compelled Professor Peele to withdraw in 1904, and later Mr. Olcott was forced to retire by reason of other important business interests, but the friendship and high mutual regard of the three men continued undiminished. About 1902, Mr. Corning and Professor Peele translated into English Riemer's book on "Shaft Sinking under Difficult Conditions." Mr. Corning's knowledge of structural geology, mineralogy and ore deposits was extensive and accurate. He was a close and intelligent observer. When he became interested in a problem, no amount of trouble was too great in endeavoring to reach a satisfactory solution. He had professional experience in the West, notably in the Coeur d'Alenes, Mexico and South America, and several times was called on to attempt to straighten up mismanaged properties. In 1912, at the request of a large number of members, Mr. Corning headed the "Committee of FiveJ' that investigated the affairs of the American Institute of Mining Engineers and brought about beneficial changes in the organization and its policies. He was one of the organizers

Jan 1, 1924

By Arthur Dwight

WE NOT have to go so very far back, when measured in actual years, to what may be considered the beginning of the industrial era of the great West, the discovery of gold in California in 1848, just 74 years ago. By a strange coincidence, this event occurred within a few days of the signing of the treaty with Mexico which ceded California to the United States. Needless to describe the mighty wave of humanity that hurled itself toward the setting sun in response to that call. The single thought in every one's mind was gold. The gold as they found it in placers or ledges could be so easily worked, and the product was so readily transportable, and available immediately as money, that practically no attention was paid to deposits of the base metals, in the treatment of which cheap transportation was a paramount con-sideration; consequently little progress was made in anything but gold mining until after the Civil War. The next great step was accomplished when East and West were united by the successful construction of the Union Pacific Railroad from Omaha across the great plains and through the Rockies to meet the rails of the Central Pacific coming eastward across the Sierras. The industrial history of our great West really dates from the day when those two hands of steel were joined, on the shores of the Great Salt Lake at Prom-ontory Point,. May 10, 1869. That seems a long time ago when we think of the enormous changes that have been wrought since that day, and when we regard the rich empire that has sprung up in that western land. Into the new empire thus made accessible, by this first thread of steam transportation, flocked a new brood of adventurous spirits from the older communities of the East. This way walked Fate; and as she, went, flung far the line of destiny, That bound an untracked continent to brotherhood from sea to sea; That long gray trail of dream and hope, marked mile by mile with graves that keep On every barren hill and slope some stout heart lost in dreamless sleep. Patience and faith and fortitude were willed to it and justified; Stern, homely virtues, plain and rude, eternal as the sky and wide. Nor ever sea-king dared the sea in sterner mood than these who went Strong armed to wrest from Mystery their birthright, half a continent.

Jan 4, 1922

By W. A. Mudge

This discussion will be limited to malleable, commercially pure nickel and some high-nickel alloys, containing more than 50 per cent of nickel, which are produced by The International Nickel Company, Inc. at its Huntington works, West Virginia, from electrolytic nickel or from a nickel-copper sulphide matte. The principal sources of nickel are sulphides of nickel, copper and iron, which are found in the large deposit of pyrrhotite-pentlandite-chalcopyrite ores in the Sudbury area of Ontario, Canada. Pentlandite, a complex nickel-iron sulphide, is the nickel carrier. These ores are concentrated, roasted, and smelted to remove considerable iron and sulphur and to produce a nickel-copper sulphide matte. Separation of the component sulphides of this matte, followed by electrolytic refining, results in the production of electrolytic nickel and electrolytic copper; direct refining of a selected portion of the matte gives the nickel-copper alloy, Monel. FUNDAMENTAL OPERATIONS Melting of the metallic materials is done in natural gas-fired, acid furnaces of the open-hearth, or reverberatory, type, having capacities of 6 to 20 tons; in three-phase, basic, electric-arc furnaces, having capacities of 7 to 20 tons; and in basic, high-frequency induction furnaces having capacities of ½ to 3 tons. Malleable, commercially pure nickel is melted in the acid open-hearth furnace. The charge is sulphur-free, electrolytic nickel, containing 99.9 per cent nickel* and clean mill scrap. Monel, containing approximately two thirds nickel and one third copper, is produced by roasting the nickel-copper sulphide matte to an oxide, smelting the oxide with charcoal in a 20-ton, acid open-hearth furnace, adding clean mill scrap, duplexing to a 20-ton, basic, electric-arc furnace, and refining in this furnace with a lime-fluorspar, carbide slag. Inconel, containing nickel, 80 per cent; chromium, 14 and iron, 6, is melted in the 7-ton electric-arc furnace or the 3-ton induction furnace. The charge is electrolytic nickel, ferrochromium and clean mill scrap. These are the fundamental operations. High-nickel alloys are produced from one of these three materials by additions of suitable amounts of manganese, aluminum, silicon or copper. For example, the age-hardenable alloy, K Monel, is produced from Monel by the addition of approximately 3 per cent of aluminum, and D nickel is produced from nickel by the addition of approximately 4.5 per cent of metallic manganese. For conversion to rods, bars, sheet, strip, tubing and wire forms, by hot-working and cold-working operations, the molten materials are teemed into ingots ranging in size from 14 by 14 by 60 in., 3300 lb., to 36 by 36 by 48 in., 18,000 lb. All ingots are overhauled mechanically before hot working.

Jan 1, 1946

By Fred J. Wright

ORIGINALLY, mining machines were actuated by purely mechanical mechanisms comprising cams, levers and gear trains, which became more and more complex as demands were made for additional operations that would increase mine tonnage. To simplify these intricate machines, development engineers began utilizing the principles of high-pressure hydraulics long employed for the control of various machine tools. The resulting specificially developed hydraulic systems are now literally the heart of the mining machine. During World War No. 2, very little fundamental change in design was made in existing mining machines, but because of the recognition of the merits of hydraulic application to the machines of war, it is reasonably certain that hydraulics will be applied to mining machines in the future to a much greater extent. This potential future indicates that a more thorough knowledge of hydraulics and its maintenance must be incorporated in mine operation. Contamination of Oil Maintenance of high-pressure hydraulic equipment varies considerably with respect to mine practice and conditions. The success or failure is largely dependent upon the hydraulic fluid and its care. Since all successful hydraulic systems have been designed around the use of mineral oil as the fluid, a complete analysis of this prime factor should be made to make clear the requirements of the fluid in a hydraulic system. Contamination of Oil Manufacturers of mining machinery usually have specified an S.A.E. rating or viscosity index of the, proper mineral oil for use with their respective machines without considering the fact that many oils will meet these specifications but will not give the desired life or efficient operation. Hydraulic fluid should be specified as a good grade of mineral oil, such as turbine oil, having rust and oxidation resistance. It must have high chemical stability, high lubricity, and proper viscosity. These factors will minimize maintenance costs by reducing wear and the consequent replacement of parts, and at the same time will lower costs for the oil by extending its life. Bulk purchases of oil should be limited to small sealed containers provided with a proper pouring spout, thus reducing the possibility of contamination of the oil before it reaches the mining machine. The introduction of foreign matter, such as sand, water, coal dust and residue oil left in filling containers, will cause untold damage and maintenance expense. Sand, being one of the best natural abrasives, will soon wear the close tolerances of the various hydraulic mechanisms to an extent that will necessitate complete replacement. Water is considered normally insoluble in oil, but because of the churning action of a hydraulic system water is broken down to particles so small that they remain in suspension. This suspension is known as

Jan 1, 1946

By F. L. Wolf, A. A. Grubb

There is a tendency on the part of practical foundrymen to accept with reluctance the results of tests on sands, binders, and such materials made in the chemical laboratory alone. They feel that such tests frequently emphasize and measure properties that are of minor importance and fail to take account of characteristics that are important in determining the value of the material in actual practice. Experience seems to indicate that the most thorough and conclusive test for any new foundry material is an actual run in the foundry alongside of a standard material of known value. Such a test, however, involves certain difficulties and necessitates certain precautions. It is not always easy to obtain a fail trial for a new material. We all have certain prejuclices, which unconsciously affect our judgment to a marked degree. A practical test frequently involves so many workmen, each of whom reacts in a different manner to the test, that the personal equation becomes very complex and the true results of the test are obscured. There are times, too, when a thorough experimental trial of a material would interfere too much with the. rush of work in a department or would hazard the quality of the product to such an extent as to make it inadvisable. Under such conditions a laboratory test is advisable before the material is sent into the foundry. These tests should be made as practical as possible and so closely related to foundry practice as to give a true index to the value of a product for the purpose desired. Core sands and molding sands are as numerous "as the sands of the sea" and valy as much in quality. Old sources of supply are continually failing and new ones must be opened, so that we must continually search for new and better grades of sand. During the past year, the Ohio Brass Co. has developed tests for sands, cores, and binders which bear a close relation to the particular use to which these materials are put in the foundry and which arc fairly indicative of their value. While the tests thus far have been confined to cores and core sands, it is expected that tests for molding sand will bc developed in the future.

Jan 1, 1921

By Charles H. Morgan

THE process of wire drawing depends upon the property which certain metals possess, termed ductility, 'which is defined in Brande's Dictionary of Science as a property in consequence of which metals may be drawn out at length without interrupting the continuity of their constituent parts. As defined by M. Tresca, it is the property of flowing when subjected to pressure, and is termed by him the "flow of solids," in his paper, read before the Academy of Sciences in Paris, November, 1865 * In the simple language of the wire shop, it is that quality in certain metals that permit, them to be drawn (or stretched) out through a tapering, hole in a metal block or die, the die being more dense and harder than the metal to be reduced. It is a fact well known to those skilled in the art, that to succeed in drawing iron or steel wire, it is of the utmost importance to have thorough lubrication, as a lack of it would caws abrasion of the wire, or of the walls of the tapering hole in the die or plate, and quickly put an end to the operation. In drawing coarse or large sizes of wire, say 2/10 inch diameter, the pressure upon the sides of the tapering hole, where the wire comes in contact with the die, is so great that an ordinary lubricant is squeezed out when the usual reductions in size are made, and abrasion takes place. In order to meet this difficulty, and secure proper lubrication, it has been' a common practice for years to apply a paste made of rye or wheaten flour, or lime, to the surface of the wire to be drawn, and when the paste is dry, to smear the wire with tallow or grease; the wire is then ready to be drawn, the dried paste serving to prevent the lubricant from being pressed out in the. process. Some years since, when Bessemer metal came largely into use as material for wire, "the writer found that its drawing required so much more power than iron wire, that he was led to institute a series of trials to ascertain the difference in power required. It was found that Bessemer wire required from 100 to 200 per cent. more power to make the same reduction in sizes than soft iron wire, the difference depending upon the amount of carbon and other chemical constitu- * Interesting experiments in the flow of metals have been made, by Messrs. Hoopes Townsend, of Philadelphia, in cold-punching iron, published and illustrated in the Journal of the Franklin Institute, of March, 1878, by Mr. David Townsend.

Jan 1, 1881

By Frank H. Macpherson

When it became apparent early in 1941 that the United States might be drawn into the war, studies were made of the bauxite situation in Arkansas, principally because 9.5 pct of the known bauxite reserves of the country were located in that State. Bauxite mining was then geared for maximum production to supply ore to meet this country's war requirements and, if necessary, to supply the needs of Canada as well. In view of the comparatively small bauxite reserves, Congress appropriated funds for an extensive exploratory drilling program to be carried out by the Bureau of Mines in cooperation with the Geological Survey. An alumina plant was erected near Bauxite and an aluminum plant near Hot Springs, Ark., by the Defence Plant Corp. The Metals Reserve Co. established a schedule of prices, arranged for stockpile sites and a buying agency. Operators cooperated to step up production and new ones came into the field. Production Record Prior to 1941, the greatest annual production in Arkansas was 562,892 long tons, dry basis in 1918. During the single month of August 1943, 693,596 long tons were mined—130,704 tons more than for the entire year of 1918. In general the Arkansas bauxite deposits are relatively small, irregular in thickness, somewhat scattered and, compared to coal, iron or open-pit copper deposits, are ill-adapted to an expansion in output. Commercial deposits range in horizontal extent from less than an acre to about 40 acres and are usually very irregular in outline. The average thickness of all known workable deposits is between 12 and 15 ft. with a maximum of about 60 ft. The ore bodies are usually somewhat undulating and nearly horizontal although locally some deposits dip as much as IS°. Types of Bauxite Three physical types of bauxite may be recognized: pisolitic, granitic and amorphous. Pisolitic ore is the most common type. It consists of small pebble-like nodules, ranging from the size of a pin head up to several inches in diameter, all set in a fine grained matrix. Transported bauxite is usually- pisolitic. Most residual bauxite is granitic. It is believed not to have moved appreciably from the location where it originally was formed. This is indicated by the fact that it appears to grade into unaltered nephelite syenite, which it overlies. Amorphous ore is the least abundant. It is nonpisolitic and resembles clay, has no characteristic texture, and can be identified definitely only by chemical analysis. Uses of Bauxite Bauxite is chiefly used for, and at the present time is substantially the only

Jan 1, 1948

By John H. Melvin

THE Omaha District, Corps of Engineers, has been doing subsurface exploration work for a number of years, both by contract and with its own forces. Certain practices and procedures concerning the recovery of large diameter cores have been developed which will be described in this paper. GEOLOGY Most of the drilling to date has been in connection with structures on the main stem of the Missouri River above Sioux City, Iowa. A wide variety of subsurface conditions has been encountered. The bedrock formations appear in regular order from the oldest to the youngest, traveling upstream; or in other words, the general regional dip is to the northwest. The oldest formation is the Carlile shale, a compaction or noncemented waxy shale of Cretaceous age. Because of its uncemented, soft nature this shale has a tendency to grind or wash away when drilled. It also has a tendency to rebound or expand when the overlying pressures are removed. A 25-ft bed of sharp, friable sandstone called the Codell member is present near the top of the Carlile shale. This member is a cemented sediment, but in drilling, many of the sand grains are broken loose and exert extensive abrasive action on the core barrel and bit. Above the Carlile shale is the Niobrara chalk, a soft calcareous deposit with shaly horizons and some thin beds of bentonitic clay. The average thickness of this deposit is about 145 ft. It is soft enough to be sawed or bored with ordinary woodworking tools, yet is compact enough to be used as building block. The Pierre shale, the formation above the Niobrara chalk, is over 800 ft in thickness and is the most widespread material in the area. It is a dark colored, compaction shale containing numerous thin bentonitic clay seams and at certain horizons, hard manganese concretions. The shale has numerous faults and in addition, along the valley walls, has undergone considerable - slumping. Joints, fault planes and slickensided surfaces are common features encountered in drilling and add to the difficulties of high core recovery. East of the Missouri River the bedrock is generally covered with from 100 to 200 ft of glacial till, composed of clays, silts, sands, gravels and boulders. The valley itself is filled with alluvial deposits, mostly of the sand and gravel sizes, and contains a buried preglacial or interglacial channel over 100 ft in depth. The overburden deposits require sampling in connection with engineering studies and must also be cased before the underlying bedrock can be cored. The diameter of the required overburden samples can thus have an indirect effect on the size of core recovered from the bedrock. West of the river, which in most cases is the western boundary of glaciation,

Jan 1, 1947

By J. MURRAY RIDDLELL

AN increase of 18 per cent in the production and consumption of all metals last year was readily met by the mines, but more than an average amount of development work was made necessary. Mining methods were improved appreciably; open-pit operations ad¬vanced more than underground practice: and the transportation phase of mining progressed to a greater extent than the other related functions. A new belt-conveyor system of mining was placed in operation at the Spruce open-pit iron ore mine at Eveleth, Minn. The gathering portion of the belt system was installed beneath the surface of the open pit, following closely the bottom rock, in especially provided drifts; beyond it inclined upward to the surface and finally discharged into a 500-ton shipping pocket. Length of the belt was 4500 ft. net vertical lift 386 ft. and capacity 750 long tons per hour. The mined ore found its way to the belt through one of three vertical raises, whose horizontal section was 10 by 10 ft. Each raise was equipped with a grizzly, crusher, pan-type feeder, and auxiliary equipment. Transportation of the ore from the working faces of the pit was accomplished as follows: (1) Two raises were equipped with tower and anchor stations, 3-cu.yd. drag scrapers, and related power units; (2) the remaining raise was provided with electrically driven power shovels and 20-ton trucks mounted on pneumatic tires. This installation has entirely replaced railway pit haulage and partly eliminated power shovels. In a similar

Jan 1, 1938

By R. C. Ernrnons, Ray Wilcox

RECENTLY completed experimental work, carried out in the department of geology at the University of Wisconsin, aiming at a prevention of silicosis in industry has been reported in the American Mineralogist. A vast amount of work on silicosis has been reported in the literature, the clinical aspects having been especially well covered. A host of critical observations have been made on the variations in the nature of the silicosis problem in different environments, and a great deal of valuable experimental work has helped to clarify these observations. At present a greater amount of information of a critical sort is available than ever before, which affords a more sound basis for interpretive thought. It has been observed in industry that essentially pure silica dust gives rise to silicosis. Jones would modify this conclusion to place the responsibility on sericite, a silicate mineral present in the siliceous dust. Material such as granite dust, which carries a high free silica (quartz) content, is also a silicosis hazard. But sericite, too, is usually present in granite. In general it is widely believed that silicosis is caused by the presence in the lung of silicic acid regardless of the source. This view is adopted here.

Jan 1, 1937

By E. H. Rose

The question is often pondered whether the flotation process is still an art or has become a science. The fact is that flotation is a science in so many variables that only art can blend them. It is demonstrable that no less than one hundred variables are involved in any flotation operation, most of them immeasurable on a routine basis. The behavior of every one of them is always governed by orderly and unchanging law, as no man can doubt. There is nothing truly indefinite about that behavior; the only indefiniteness is in our knowledge of it, either in general or from hour to hour in the circuit. In dealing with a simultaneous equation in, say, one hundred variables, all not only affecting the outcome to some degree but many influencing each other as well, it is small wonder that the mineral-dressing profession presents a case history of debate and controversial opinion. The statement of the subject of this symposium—a symposium on flotation machines—seems to delimit and define the matters to be considered and at least the general nature of the conclusions sought. Nevertheless, in such a meeting it is not possible to meditate upon all the variables that do in one way or another affect performance of flotation machines. To attempt it would be much like trying to operate a hundred-ring circus. Perverse variables being what they are, one could expect the elephant in ring 36 to squirt a trunkful of water at the tightrope performer in ring 37 to ruin that artist's act, just as our learning to depress pyrite in the early 1920's ruined the act of the formerly faithful old Callows. Honest Disagreements Selective flotation dates from 1922 or 1923, when several plants established their regular flotation operations on a selective basis. Since then, two decades of efforr have gone into the development of better and better flotation machines. Many have come and gone. The competition has simmered down to perhaps a dozen machines, each one of which is staunchly defended by some operators as being the best for their particular jobs, and as scornfully dismissed by at least a few others elsewhere as being positively the poorest for theirs. These disagreements are honest disagreements, honestly arrived at after plenty of sweat. In many a flotation plant, one machine has been tried out against another under conditions as fair as they could possibly be made. Sometimes the results are on a par but more often one machine shows a consistent and unmistakable margin of superiority over the other. In equally honest and enlightened tests, machine A may win over machine B in one place, and machine B over machine A by as great a margin in another. This paper purposes to identify some of the more prominent reasons why this is so,

Jan 1, 1947

By Richard Moldenke

Note.—At the request of the American Society for Testing Materials, this paper wau presented at the New York Meeting, February, 1923, in connection with the "A. S. T. M. Tentative Specifications for Foundry Pig Iron" and The Physics of Cast Iron and Its Bearing on All Cast-iron Products and Specifications for Cast Iron," by William R. Webster. The discussion of this paper was not published by the Institute, having been referred to the American Society for Testing Materials, as these papers were again presented for discussion at the meeting of that Society at Atlantic Cit;, June, 1923. The result of these discussions is shown in the following abstract from the Committee A3 report on cast-iron specifications: During the past year, the adaptability of the tentative specifications for pig iron for the steel and the malleable foundry, in addition to the iron foundry proper, have been studied and suitable changes and rearrangements are being made which appear to cover the situation properly. In spite of the experience of foundrymen to the contrary, there is a persistent call from consumers of castinga for defixute compositions for given lines of castings. To respond to this call for information desired by the consumer—information every modern foundryman should have and guide his procedure with—the committee has requested the Sub-committee on General Cast!rigs to take up this matter with a view of constructing tables of analyses rang? for Important lines of foundry product. These analyses ranges however, are to be given as "recommendgd practice" and not intended for actual spkcification. In this way, the consumer of the foundry product will get the information he wants; the furnace-man will be gulded in the production of his pig irons to prepare for analyses ranges which are more closely standardized and have less of "freak" requirements made by Inexperienced metallurgists; and the foundryman will not be bound by chemical requirements he knows will not work out well with his particular reglonal supphes of melting stock. Doctor Moldenke's paper is published in full as it shows clearly the good results of the Institute's work in 1895 and a comparison of the same with the present knowledge of the metallurgy of cast iron—Bradley Stoughton, Chairman, Iron and Steel Committee. In MaRch, 1895, William R. Webster contributed a carefully prepared scheme for the study of the physics of cast iron to the American Institute of Mining Engineers at its Florida meeting. This summary of the interrelation of the chemical and physical characteristics of cast iron with the operations of daily foundry practice caused a wide discussion of the then little understood though universally used material. Mr. Webster has requested the author to bring the subject up to date and, while glad to comply, he must pay that with all the knowledge that has been gained in the quarter century that has passed since the subject was brought to the attention of the Institute—and we now are pretty familiar with cast iron in all its aspects—there is practically noth-

Jan 1, 1923

By Walter Miller

Petroleum refining, like other industries in the United States in 1940, focused much attention on its duties and opportunities in the field of national defense. In crdiiter-distinction to the situation during the World War, the industry is well constituted as to existing equipment, processes, and capacity, together with planned additions, to handle any demands that may be made upon it by the defense program needs. Evident throughout was the growing sense of ability to manipulate oil molecules for the production of materials not hitherto considered as being available commercially from petroleum. The development and application of catalytically induced reactions on a broad front is one of the distinguishing characteristics of refining progress during the year. In the hands of the refiner, catalysis has developed into a most important means to secure higher antiknock motor fuels and 100-octane fighting grade aviation gasoline in greatly increased quantity. One illustration of the importance being assigned to catalytic refining is the construction by the Houdry group of an experimental laboratory at a cost of $7'307'30'3, to be staffed with over 100 research men7 solely for the purpose of studying catalytic reactions. In the aviation gasoline picture a modification of specifications by the Government widened the field from which acceptable fuel can be secured, and the continued expansion of the alkylation process in itself promises to go far in filling the demands expected from 50,000 fighting planes. It is conservatively estimated that eyen now the industry can turn out 1,300,000 gal. of 100-octane aviation gasoline daily. The upper limits of octane numbers for regular grades of motor gasoline reached in 1939 were not exceeded, but the average octane number approached the upper level more closely. A survey made of the 1940-model cars showed no rise in average octane requirement of the engines. The trend throughout the year was for greater reliance on the A.S.T.M. method for octane determination. The "1939 Research Method" is less widely used, although still considerably in evidence; the older L-3 method seems to have lost considerable ground and to be on the way out. Re-forming Capacities Increased Interest continued to grow apace in re-forming low-octane naphthas into high-octane gasolines. Some additions, although not great, were announced in thermal re-forming capacity. Interest in catalytic re-forming was greatly stimulated by the technical success of the operation of the converted hydrogenation unit at the Bay-way, N. J., rehery of the Standard Oil Company of New Jersey, mentioned in last year's review, and also by the knowledge that recoverable proportions of toluene are present in the hydroformed (catalytically

Jan 1, 1941

By R.K. Matheson

The Nivloc mine is 9 miles west of Silver Peak, Esmeralda County, Nevada. It has been operated by Desert Silver, Inc., since the summer of 1937. The cyanide mill treats 190 tons of silver-gold ore per day. In March of this year the main operations were about 2000 ft. west of the main shaft, which served as the downcast air passage for the mine. The mechanical blowers in use were sufficient to ventilate the west end at that time, but it was foreseen that as the mining area was extended ventilation would be an increasingly difficult problem, especially during the summer months. It was decided, therefore, to continue a raise from a point 100 ft. above the highest mining level (440-ft. level) to the surface; a distance of 443 ft. at approximately 65°. From this point 40 ft. of drifting would be necessary to connect with a shallow shaft on the surface. (Fig. I.) All the raise was serviced from the 440-ft. level; costs and progress obtained in the initial 100 ft. are included in the following pages. Choice of Raise A raise in this locality would have four objects: (I) to provide an ample supply of fresh air to the working places; (2) to explore the vein from the highest mining level to the surface; (3) to provide waste fill for stopes in the area, and possibly provide a transfer for waste from the surface; (4) to provide an emergency exit in the west end of the mine. Before the mining of an ore shoot in the eastern part of the mine, a similar raise had been driven for purposes of ventilation and exploration. This raise and subsequent mining showed the vein to be noncommercial for a distance of about 250 ft. below the surface. However, in the area under operation, old surface workings showed occasional values. Thus from a development standpoint the raise was an excellent prospect. The raise chosen was a three-compartment, stulled raise having two chutes and a manway. The manway inside timber measured 4 ft. 8 in. by 4 ft. 6 in.; it carried air and water pipes, a ladderway and a slide for a timber skip. The two chutes would be used for drawing off the muck and the cleaning of the bulkhead, as well as for ore and waste passes, which would be especially useful for lateral exploration from the raise. The fairly large cross section of the raise (6 by 15 ft.) would provide a large quantity of waste for backfilling, and more could be obtained from a glory hole on the surface. Time Schedule As speed in completing the raise was the main requisite, three shifts were considered, but two shifts were decided upon when it was found that three would necessitate considerably larger fans than those available for clearing the raise. The main diffi-

Jan 1, 1943

By Edward H. Robie

SUBJECT to formal Board approval in September, AIME dues will continue indefinitely at the present scale of $20 for Members and Associate Members; and $12 for Junior Members for the first six years of such membership, thereafter $17. That is the wish of the Board of Directors and the will of the membership, as expressed in the recent referendum. Though the official returns, as reported by the tellers, are not available as this is written, the data are sufficiently complete to give the results to the nearest percent. The total vote was approximately 93 pct for continuance of the present scale. Metals Branch members voted about 94 pet for continuance; Mining Branch members slightly less than that; and Petroleum Branch members about 91 pct. As in the referendum of 1949, there was no particular difference of opinion on the question of dues as between the three Branches. The percentage of ballots returned was about 61 pct, only slightly more than in the 1949 referendum. But the affirmative vote was much greater, 93 pct against 78 pet in the earlier referendum. Looked at another way, a majority of those to whom ballots were sent, 56 pct, voted to continue the present scale of dues, whereas only 46 1/2 pct of those canvassed voted to raise the dues in the previous referendum. But approximately 600 , members expressed their opinion that the dues should go back to $15 for Members and Associate Members and to $10 and $15 for Junior Members. This is a substantial group of members who either do not think they are getting their money's worth from AIME membership, or believe that a more businesslike conduct of Institute affairs should provide current services at less cost, or believe that more service is being provided for their dues than they need. As to the first point, it is probable that some members are not getting their money's worth. They perhaps have only a fringe interest in. AIME activities, or they do not or cannot participate in such activities at the Local Section, divisional, or national level, so that all they get out of the Institute is the monthly journal, which they do not have time to read. If they did read it intelligently, and acted upon the professional information thus gained, it is difficult to understand how one or more ideas cannot be gained that would be worth $20 to them professionally. But the 600 members who want lower dues offer a challenge to the Directors and to the staff to do a better job; to make Institute membership so rewarding that every. member will be thoroughly satisfied. Twenty 1935 to 1939 dollars are worth only $11.60 now, according to the latest government data, but that makes it all the more necessary for us all to appraise the value of what we buy. To the 93 pct of Institute members who expressed a vote of confidence, so to speak, the staff, and we feel sure the Directors as well, are most appreciative and thankful.

Jan 1, 1952

By Stanley D. Michaelson

The selection of the proper size of grinding mill for a given installation has long been a subject of discussion by mill manufacturers, consulting engineers, and their clients. It would be presumptuous for the author to propose a simple cure-all. Instead this paper describes a method that has been used over a period of years to determine mill size with a reasonable degree of accuracy. Furthermore, this method claims no theoretical background, for ball milling, as practiced today, is still an art. The selection of the proper size and type of mill must, therefore, be made on an empirical basis. A ball mill, in order to grind, must deliver power through its grinding media to the material to be ground. Assuming that a mill is properly supplied with grinding media, ore pulp, and power, the amount of grinding done is closely proportional to the power expended. With this as a basic premise we can, for the moment, forget about type of mill (i.e., overflow, low-level mill, or other design) and base our calculation of mill size on the total power required to grind a ton of a particular ore from a given size of feed to a given size of product. When this is determined the type and size of mill, its speed, and the weight of the load of grinding media can be selected to absorb this amount of power. Development of Technique Some years ago, W. L. Maxson, F. Cadena, and F. C. Bond, working in the Minerals Research Laboratory of Allis-Chalmers Co., Milwaukee, developed and described a laboratory technique for comparing grindability (or relative ease of grinding) of various ores at different mesh sizes of grind.' Additional papers2 have described the work done since that time, and the most recent paper3 summarizes results for hundreds of tests on many ores and materials. The essentials of the testing method are: a 12 by 12-in. laboratory mill operating at a constant speed of rotation, using a constant volume of ore, and a constant ball load having a relatively constant grinding surface. Tests are run at 250 per cent circulating load with the feed, circulating load and products screened on calibrated Tyler standard screens. Certain ores from operating mills, representing various mineralogical types, were selected for reference and designated "standard ores." In most cases, detailed studies of the grinding circuits were made when samples of mill feed were taken for grindability tests. Each analysis formed a basis for comparison of the grindability in the laboratory with actual power requirements for a particular grinding circuit. In addition, a critical study was made to evaluate the differences in the various grinding circuits so that two or more field installations having different layouts (single-stage grinding, two-stage grinding, or others), and using mills of various diameters operating at various speeds with differing circulating loads, etc., could be compared. Large-scale tests by mill operators complemented by laboratory investiga-

Jan 1, 1947

By E. H. Rose

The question is often pondered whether the flotation process is still an art or has become a science. The fact is that flotation is a science in so many variables that only art can blend them. It is demonstrable that no less than one hundred variables are involved in any flotation operation, most of them immeasurable on a routine basis. The behavior of every one of them is always governed by orderly and unchanging law, as no man can doubt. There is nothing truly indefinite about that behavior; the only indefiniteness is in our knowledge of it, either in general or from hour to hour in the circuit. In dealing with a simultaneous equation in, say, one hundred variables, all not only affecting the outcome to some degree but many influencing each other as well, it is small wonder that the mineral-dressing profession presents a case history of debate and controversial opinion. The statement of the subject of this symposium—a symposium on flotation machines—seems to delimit and define the matters to be considered and at least the general nature of the conclusions sought. Nevertheless, in such a meeting it is not possible to meditate upon all the variables that do in one way or another affect performance of flotation machines. To attempt it would be much like trying to operate a hundred-ring circus. Perverse variables being what they are, one could expect the elephant in ring 36 to squirt a trunkful of water at the tightrope performer in ring 37 to ruin that artist's act, just as our learning to depress pyrite in the early 1920's ruined the act of the formerly faithful old Callows. Honest Disagreements Selective flotation dates from 1922 or 1923, when several plants established their regular flotation operations on a selective basis. Since then, two decades of efforr have gone into the development of better and better flotation machines. Many have come and gone. The competition has simmered down to perhaps a dozen machines, each one of which is staunchly defended by some operators as being the best for their particular jobs, and as scornfully dismissed by at least a few others elsewhere as being positively the poorest for theirs. These disagreements are honest disagreements, honestly arrived at after plenty of sweat. In many a flotation plant, one machine has been tried out against another under conditions as fair as they could possibly be made. Sometimes the results are on a par but more often one machine shows a consistent and unmistakable margin of superiority over the other. In equally honest and enlightened tests, machine A may win over machine B in one place, and machine B over machine A by as great a margin in another. This paper purposes to identify some of the more prominent reasons why this is so,

Jan 1, 1947

By Walter Miller

Petroleum refining, like other industries in the United States in 1940, focused much attention on its duties and opportunities in the field of national defense. In crdiiter-distinction to the situation during the World War, the industry is well constituted as to existing equipment, processes, and capacity, together with planned additions, to handle any demands that may be made upon it by the defense program needs. Evident throughout was the growing sense of ability to manipulate oil molecules for the production of materials not hitherto considered as being available commercially from petroleum. The development and application of catalytically induced reactions on a broad front is one of the distinguishing characteristics of refining progress during the year. In the hands of the refiner, catalysis has developed into a most important means to secure higher antiknock motor fuels and 100-octane fighting grade aviation gasoline in greatly increased quantity. One illustration of the importance being assigned to catalytic refining is the construction by the Houdry group of an experimental laboratory at a cost of $7'307'30'3, to be staffed with over 100 research men7 solely for the purpose of studying catalytic reactions. In the aviation gasoline picture a modification of specifications by the Government widened the field from which acceptable fuel can be secured, and the continued expansion of the alkylation process in itself promises to go far in filling the demands expected from 50,000 fighting planes. It is conservatively estimated that eyen now the industry can turn out 1,300,000 gal. of 100-octane aviation gasoline daily. The upper limits of octane numbers for regular grades of motor gasoline reached in 1939 were not exceeded, but the average octane number approached the upper level more closely. A survey made of the 1940-model cars showed no rise in average octane requirement of the engines. The trend throughout the year was for greater reliance on the A.S.T.M. method for octane determination. The "1939 Research Method" is less widely used, although still considerably in evidence; the older L-3 method seems to have lost considerable ground and to be on the way out. Re-forming Capacities Increased Interest continued to grow apace in re-forming low-octane naphthas into high-octane gasolines. Some additions, although not great, were announced in thermal re-forming capacity. Interest in catalytic re-forming was greatly stimulated by the technical success of the operation of the converted hydrogenation unit at the Bay-way, N. J., rehery of the Standard Oil Company of New Jersey, mentioned in last year's review, and also by the knowledge that recoverable proportions of toluene are present in the hydroformed (catalytically

Jan 1, 1941

By J. S. Aronofsky, R. Jenkins

A simple means of predicting the flowing well pressure history in a natural gas reservoir has been developed. The differential equation for unsteady radial flow of gases through porous media was solved by numerical methods using electronic punch card machines. The results obtained from these calculations are presented in a generalized form which is believed to be most convenient for engineering use. These results are compared with those presented in a paper by Bruce, et al4. An effective radius of drainage has been defined which permits the equation of steady state gas flow to be used easily to predict well pressures in gas reservoir depletion. An equivalent effective radius of drainage is defined for liquid flow systems and a comparison is made of the gas solution to the liquid solutions. INTRODUCTION This paper presents a numerical method for describing the transient flow of gases radially through a porous medium from which the production rate is specified. The results obtained from these calculations are presented in a generalized form which is believed to be the most convenient for engineering use. The principal application of these calculations should be to flow in natural gas reservoirs, in the interpretation of pressure drawdown tests, in the estimation of reserves, and in calculation of injection pressures required in gas injection and cycling operations. The evaluation of natural gas wells is based upon back-pressure tests in which measurements of production rate and flowing well pressure are made for periods of one, two, or more days. The flow is assumed to have stabilized at this time, and the observed values of pressure and production rate are used with standardized formulae to determine the well's allowable production rate. Furthermore, the results obtained from such a test of short time duration are extrapolated in such a manner to allow a prediction of what the well pressure will be at some future time for a specified (but possibly untested) flow rate. The manner of conducting such back-pressure tests suggests several questions as follows: 1. 'What is the definition of stabilized flow and what factors determine the length of time required for the flow to become stabilized? 2. How may the recorded values of pressure and rate be utilized? 3. As the well is produced and the reservoir pressure falls, how will the flowing well pressure change? Can this flowing well pressure be predicted from the back-pressure test? 4. Are the results obtainable from the test influenced by a particular procedure used in obtaining the results? 5. Is it possible to estimate the gross reservoir permeability from back-pressure data? It is not within the scope of this paper to provide solutions Or even to discuss adequately all the above questions. However. in considering such matters, the

Jan 1, 1955