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By A. Raman

The Nb-Co system was nuestigated in the range 10 to SO at. pct Co with X-rays. A pt phase with the W6Fe.r-type structure occurs in the system between 46 and 52 at, pct Co. Its unit-cell dimensions are nearly identical to those of the p Phases found in the Nb-Fe and Nb-Ni systems. Two Laves phases, one having the MgZnz-type structure and the other the MgCuz-type structure, already t-eported in the literature, are found to exist in the system. The ,l.IgZnz-type phase occurs between 62 and 64 at. pct Co. A MgNi2-type Laves phase, reported in the literature, is no! obtained. A binalry phase is found to exist belozv I000C around 82 at. pct Co. THE cobalt-rich side of the system Nb-Co has been repeatedly investigated by previous inestiators" and the following intermediate phases are known to occur: NbCo, which crystallizes in the MgCu2-type structure and Nbc03,' reported originally by Wall-bam, which has the MgNiz-type structre. Jordan and uwez' as well as lliott' were unable to find the MgNiz-type phase. Two phases, designated as x and y, were reported by Saito and eck.' The phase x was inferred to have a narrow composition range near 77 at. pct Co. No published work is known to the author which reports the investigations in the niobium-rich portions of the system. This paper presents the results of an investigation in the Nb-Co system between 10 and 80 at. pct Co. EXPERIMENTAL PROCEDURE Two or three grams of the alloys under investigation were prepared using niobium (99.9 pct +) and cobalt (98.8 pct + with 0.14 pct Fe and and 0.03 pct C) in a tungsten-electrode arc furnace under commercial argon atmosphere. They were then wrapped in molybdenum sheets and annealed for a period between 5 days and 1 week at 1300°C in high vacuum (10-" orr) or in evacuated quartz amules for 2 weeks at 1000°C. Powders of -325 mesh size were prepared for X-ray work by crushing and grinding the specimens. Subsequent reannealing of the powders was not undertaken since most of the alloys were brittle and broke easily. X-ray powder patterns of the as-cast and annealed samples were prepared in a Siemens cylindrical camera (57.3 mm radius) with Cr-K, radiation. A Siemens diffrac to meter was used to get the X-ray patterns of some new phases. Metal log raphic examination of the alloys supplemented the X-ray findings. RESULTS The results of the X-ray and microstructural analysis Of the alloys are in in Table I. The lattice parameters of the phases are listed in Table 11 for quick reference. A set of micro photographs in Fig. l(n) to (j) show the microstructures of some alloys. A probable equilibrium diagram is drawn in Fig. 2

Jan 1, 1967

By David Turnbull

IN most reactions involving solids the transformation kinetics may be represented by the combination of two processes-those of nucleation and of growth. For example, Mehl and his coworkers 1,2 in their studies on the transformation of austenite to pearlite in steels have been able to describe the kinetics in terms of the rates of nucleation and of growth. By micrographic examination of their specimens they determined the nucleation rate (rate of appearance of pearlite colonies) as a function of time, of percent transformation, and of temperature. They observed that after an incubation period in which no nuclei are observed, the number of nuclei appearing per unit time per unit of untransformed grain boundary area, increases at an increasng rate with time. When recrystallization rates have been interpreted in terms of rates of nucleation and growth and the rate of nucleation determined, an incubation period followed by an increasing rate of nucleation has also been reported. Among the studies in which this phenomenon has been observed are those of Kornfeld and coworkers3 on cold-drawn aluminum wire, of Anderson and Mehl4 on the recrystallization of aluminum sheet, and of Stanley and Mehl5 on the recrystallization of silicon ferrite sheet. The existence of an incubation period during which no nuclei are observed does not appear to have been reconciled with the generally accepted Volmer-Becker theory of nucleation in condensed systems. This theory ostensibly requires the rate of appearance of nuclei to be independent of time. VOLMER-BECKER THEORY In order to form a stable nucleus of a new phase B in a mother phase A, the molecules or atoms of the mother phase must surmount a free energy barrier whose height is determined by the volume free energy change accompanying the transformation and the energy of the surface separating the two phases. The free energy difference between nuclei of various sizes and the molecules or atoms of the mother phase is plotted schematically in Fig I as a function of the radius of the nucleus r. This free energy difference is plotted for two values of the change of free energy per atom, (fB - fA) accompanying the transformation when the volumes of the two phases are infinite. One of these values of (fa-fA) corresponds to a temperature above the temperature To at which the phases A and B are in equilibrium, and the other to a temperature below To. In order for a nucleus of phase B to be stable at a temperature T2 < To, its radius must be equal to or greater than the critical value r* for which the free energy of formation of the nucleus is a maximum, ?f*. Aggregates of phase B having radii equal to or less than r* will be called embryos. Mehl and Jetter,6 in discussing the kinetics of nucleation in solid systems, suppose that embryos of critical size are formed

Jan 1, 1948

By Charles W. Frey

COMPRESSED air is one of the most useful tools that the mine operator has at his disposal. It is clean, nontoxic, easily handled, and can be distributed anywhere that a man can drag a length of rubber hose. Without it a great deal of drilling would still be a laborious hand process, and although the John Henry of legendary fame could beat a mechanical drill, John Henrys are few and far between, and in the long run the air drill is the victor. As a general rule, horizontal compressors are lubricated by mechanical lubricators, which furnish oil to the cylinder walls, whereas vertical units are splash lubricated. In most horizontal machines oil is introduced at the top center of the piston, from which point it can run down and lubricate the rest of the piston. Some large units introduce oil at more than one point on the cylinder wall, the necessity for this and the number of points of introduction depending upon the size of the cylinder.

Jan 1, 1938

By Walter Miller

DURING the second year of America&apos;s active participation in the war the main objectives of the petroleum refining industry were again to provide the four most important product needs for war: 100-octane aviation gasoline, toluene for TNT production, high-quality lubricating oils for the needs of aviation and the armed forces, and petroleum chemicals for synthetic rubber manufacture. All other materials supplied by the petroleum industry took an inferior priority ranking, depending on the degree of essentiality. To accomplish the above objectives the industry initiated and carried on a building program during 1942 and 1943 which will put those two years down in petroleum refining history as the greatest construction years of all time, a record which will hold for decades to come. Led by an estimated total of $900,000,000 going into 100octane and contributory plant investment, it is easy to picture a total of two billion dollars and more going into additional refining-industry plant investment during 1942 and 1943, most of it privately paid for, but a substantial part covered by R.F.C. Government money financing.

Jan 1, 1944

By J. W. Byrkit

Design features and operating methods at the new Ajo smelter are described in detail. Successful operation of a novel method of handling and charging wet concentrates to a deep bath type reverberatory furnace contribute to the daily production of 200 tons of anodes with good results from the standpoint of both metallurgy and economy. THE New Cornelia Branch of the Phelps Dodge Corp. is located at Ajo, Ariz. Large scale mining operations were started at Ajo in 1917, when a 5000 ton leaching plant was put in service to treat the copper carbonate ore that overlaid the sulphide ore-body. In 1924 a 5000 ton flotation plant was built to treat the sulphide ore and the leaching operation was abandoned a few years later. Changes in practice and additions to plant facilities have resulted in a gradual increase in the milling rate which now approaches 30,000 tons daily. Prior to the erection of the Ajo smelter, flotation concentrate was shipped by rail to Douglas, Ariz, where it was treated in the Phelps Dodge smelter. Construction of a one reverberatory furnace smelter to produce an average of about 200 tons per day of copper anodes at Ajo was started early in 1949. Initial heating of the reverberatory furnace was begun on June 21, 1950. Charging the furnace was started on july 8, and the first anodes were cast on July 14. Neither the anode furnace nor the reverberatory furnace has cooled since the initial firing. Fig. 1 is a photograph of the new smelter. Built primarily to eliminate the &apos;300 mile haul of concentrate to the Douglas plant, the new smelter was designed to treat the Ajo concentrate, with a minimum of capital investment. A novel, and relatively simple, method of concentrate handling and furnace charging made unnecessary the installation and operation of expensive storage facilities and reclaiming equipment, and obviated the necessity of holding in storage large quantities of copper-bearing materials. (Patents are pending in the United States and abroad on the Ajo process.) In the selection and arrangement of equipment, consideration was given to the full utilization of all smelting facilities, reducing the amount of idle equipment to a minimum. The layout of the smelter is shown in Fig. 2. The important problem of internal transportation was minimized by arranging the reverberatory furnace, converters, and anode furnace in a compact group and providing storage bins inside the smelter building, within reach of overhead cranes, for fluxing materials and other supplies needed in the daily operation. This can be seen in the sectional view of the smelter given in Fig. 3. Incorporated in the design were many innovations in smelting equipment intended to facilitate operations and effect economies in maintenance expense and manpower requirements. Table I gives operating data of the entire plant. Metallurgy The metallurgical practice at Ajo is based essentially upon the use of a single, deep bath reverberatory furnace for smelting wet concentrate, without concentrate storage facilities. The large reservoir of slag and matte maintained in the furnace serves to equalize, to some extent, the day to day variations in the nature and grade of concentrate and permits

Jan 1, 1954

By E. H. Rose

IN these days of the spectacular in research and technological accomplishment, it is easy and natural to overlook some of the applications to everyday life of recent developments of a more pedestrian kind, or to fail to realize that sometimes two or three of the latter may be combined to serve a novel purpose in fields other than those in which they grew. The present remarks are to point out three such developments which might be combined to apply to an everyday function of the A.I.M.E. as an organization. By its Constitution, the A.I.M.E. is organized "to promote the arts and sciences connected with . . . minerals and metals, and the welfare of those employed in these industries . . .; to hold meetings for social intercourse and the reading and discussion of professional papers, and to circulate . . . among its members the information thus obtained . . .; and to . . . maintain . . . a library." By these words of Article I the profession of mining and metallurgy is recognized to involve many arts and sciences, of which the art and science of exchanging information is a leading one. As to methods of preparing or securing papers, the Constitution is silent.

Jan 1, 1944

By H. P. Greenwald

IN the year just passed the Coal Division&apos;s Committee on Rock-Dusting reviewed the status of this safety measure in American coal mines and prepared a paper thereon which will be presented at the February meeting of the Institute. This paper supplements one appearing in Vol. 139 of the "Transactions," page 87 (1940). Because that paper will be issued soon, only a summary is given herein.

Jan 1, 1944

By Paul M. Tyler

MARKETWISE the year 1935 was rather a good one for most of the rare and minor metals; as a class they climbed out of the depression much faster than the common metals. The diamond market, too, was better than it had been for years, attributable only in part to investment buying, as there was a genuine pick-up in consumer demand. Wars and rumors of war tended to speed up purchases of certain metals, but consumption for peaceful purposes was the principal factor. Significant was the important role played by new industrial uses. New discoveries during the year were disappointingly few, considering the broad extent of this research frontier. Scientific developments were far from being at a stand-still, of course, but the dominant note was the cashing in on research consummated in former years. With even a moderate upturn in general business a surprising number of laboratory ideas donned overalls and found jobs in industry.

Jan 1, 1936

By R. T. DeHoff

A theoretical development is presented which reformulates Fick&apos;s first law for diffusion in the solid state. The diffusion flux of component i in a multi-component system, Ji, is related to its local concentration, ci, and local jump frequency, ri : where a is a geometric factor and d is the jump distance. The product, ciri , is defined as the local concentration of atomic jumps for component i. The analog to Fick&apos;s second law is also derived. A solution to this equation is presented, which permits the experimental determination of the variation of atom jump frequency with composition in multicomponent systems. HISTORICALLY, the description of diffusion in the solid state has been presumed to be best approached as an application of more general diffusion laws, known as the phenomenological equations. These equations relate the flux, Ji, of the various components, expressed in atoms, grams, or volume, to the driving force involved, expressed as either a compositional or chemical potential gradient, sumption that the flux is simply proportional to the driving force is the foundation of this approach. The phenomenological equations take the form: where the concentration gradients are assumed to be the driving force, and: if the chemical potential gradient is taken as the driving force. The coefficients Dij in Eq. [1.] are the "diffusion coefficients"; the elements of the corresponding matrix in Eq. [2], the Mij, are called the "mobilities". Eqs. [I] and [2] may be considered to be definitions of these phenomenological coefficients. A formidable body of literature has been generated about these equations; this literature dates back to their original formulation for the simplest case of binary diffusion in a fluid, by Adolf Fick, in 1855.&apos; This description has been shown to be self-consistent. However, the "constants of proportionality", the Dij or ,Mij, are not constant: they vary with composition in all but the simplest systems. Even in the case of tracer diffusion, wherein it can be shown that the diffusion coefficient is constant, the mobility, which is considered in irreversible thermodynamics to be the more physically meaningful quantity, varies with the concentration of the tracer involved.&apos; In more complex systems, it is necessary to evaluate the entire matrix of phenomenological coefficients, as a function of composition, in order to describe diffusion locally. Further, in order to determine this matrix experimentally, it is necessary to produce diffusion couples that have different sequences of compositions; the matrix may be evaluated only at points where these "composition paths" cross.* Finally, and perhaps most

Jan 1, 1969

By AIME AIME

THE convention which met in Washington at the call of the Joint Conference Committee was called to order at ten o&apos;clock on Thursday morning; June 3, by Richard L. Humphrey, temporary chairman, member of the American Society of Civil Engineers, who made a brief statement of the reason for the meeting. Lieut. Col. Charles W. Kutz, Corps of Engineers, U. S. A., and Engineer Commissioner of the District of Columbia, then welcomed .the engineers composing the convention on behalf of the District of Columbia and, the Washington engineers. Although an elaborate program had been prepared on which were many well-known speakers on interesting and important topics, , it was voted to intersperse this to fill in the usual and unavoidable hiatuses in the business program of such a convention[ Calvert Townley, president of the American Institute of Electrical Engineers, was elected permanent chairman, and J. C. Hoyt, of Washington, was elected secretary of the convention. The following committees were appointed: Consti¬tution and by-laws, Richard L. Humphrey, chairman; resolutions, Philip N. Moore, chairman; and program, F. H. Newell, chairman. Then, Gardner S. Williams, member of the, A. S. C. E. and the Grand Rapids Engineering Society of. Grand Rapids, Mich., and one-time member of the American Association of Engineers, offered the following resolutions:

Jan 1, 1920

E. Hill, South Norwalk, Conn. (communication to the Secretary*) :—The phenomenon described by Dr. Ledoux, involving an apparently abnormal high temperature in the air-cylinders of compressors, has not been, so far as I know, discussed in technical literature. The common formula for the adiabatic compression of dry air does not account for heat suficient to flash ordinarily decent cylinder-oils, nor do the text-books include in their theoretical statements any quantitative consideration of the effect of leaks in the ideal machines which they contemplate. This lack I have endeavored to supply by preparing, in the form of a circular, for the use of the customers and correspondents of the Norwalk Iron-Works, a brief mathematical

Jan 1, 1904

By Clyde E. Williams

THROUGHOUT its history the American iron and steel industry has constantly striven to improve the quality and reduce the cost of its products. No one needs to be told how well it has succeeded. Its success in making steel products at such a low cost has been achieved mainly through large-scale production. While costs have gone down as the rate of production and the degree of mechanization increased, quality of product has been actually improved. Thus high-tonnage records are important only in the light of high quality of the steel. Quality is the watchword! Continual improvement in quality has come as a result of research, not only in the laboratory but in the large commercial units in the plant. In fact, so many operations of the industry are on such a huge scale that experimental work must be done under commercial operating conditions so every progressive steel plant is a research laboratory.

Jan 1, 1938

By J. F. Myers

A bit of old philosophy: The optimist, the pessimist, The difference is droll; The optimist, the doughnut sees, The pessimist, the hole. This is a neat summation of the viewpoint of those engaged in "treating the crude mineral crust of the earth." Many of those in high places have reminded us during the year of the diminishing supply of the resources so essen-

Jan 1, 1948

By N. V. Hansell

l. INTRODUCTION. THE last few years have shown an increasing interest in the subject of beneficiating iron-ores -in all iron-producing countries. In the United States, this movement has been slower than in certain parts of Europe, for the obvious reason that the abundance and relative cheapness of the Lake Superior iron ores has hindered the development of enterprises for the preparation of low-grade ores. Gradually, however, conditions have changed. The world&apos;s consumption of iron is increasing enormously. Being in 1900 about 40,000,000 tons, in 1910 ii was already 60,000000; and there is no reason to doubt that for the near future the increase in iron-consumption will continue at the same rapid rate, especially with, the development of China, certain parts of Africa, and other regions which have hardly been touched as yet by modern industrialism. It is. therefore, not surprising that apprehension is felt that the known available iron-ore resources of the world are gradually being depleted. Signs of this feeling are the recent investigation, under the direction of the U. S. Geological Survey, of the iron-ore resources of the United States, and the estimate presented to the last International Geological Congress, at Stockholm, Sweden, of the iron-ore resources of the world. These investigations have emphasized the fact that the known high-grade ore-deposits are limited in extent, and will, at a not distant future, be exhausted, compelling the iron industry to depend for raw material on the enormous deposits of low-grade ores which are distributed over almost all the world. The discovery of new deposits of high-grade ore, in countries not yet thoroughly explored, will not materially change this prospect. Of course, the part which such new deposits will play in the future cannot be forecast. The difficulty and cost of transportation will probably exclude many of them from use at the present centers of the iron industry.

May 1, 1912

By AIME AIME

THE annual fall meeting of the Institute of Metals and the Iron and Steel divisions, in conjunction with the American .Society for Steel Treating and the Metal Congress and Show, at Boston was from many standpoints the most successful we have had to date. While many faces were missing from the various gatherings, the Institute registration reached the high mark of 324 members and guests. Cooperating with the Steel Treaters were also the American Society of Mechanical Engineers, the Society of Automotive Engineers and the American Welding Society. ,The meeting was, as usual, a three-ring circus with technical sessions &apos;galore, plant .trips, visits to the Exposition, social events such as lunch- eons and dinners as well as entertainment for the ladies present.

Jan 1, 1931

By LIONEL E. BOOTH

ORE tests are made for the purpose of determining the correct methods of treatment for any particular ore. They should be conducted so as to insure that the results obtained in actual mill practice, on ore of similar grade and physical nature, will duplicate the results obtained in the test work. As the expenditure of many thousand of dollars may be involved in the building of the necessary mill, the testing of ores calls for extreme care and skill in handling laboratory machines, and a knowledge of actual practice to guard against the danger of obtaining results in test work that would be impractical to duplicate on a commercial scale. The importance of a correct sample of the ore is at once apparent. No matter with what degree of care the test 4rk is done, it loses its value when made on an unrepresentative sample. It is the first safeguard against future disappointments in the loss of capital and time. A number of failures in the past have been traced directly to faulty or lax methods in obtaining the ore sample.

Jan 1, 1924

By A. CHESTER BEATTY

MAGNESIUM oxide is by far the most refractory of the common oxides, since it has a melting point of 5072 deg. F. as compared with 3110 deg. F., the melting point of silica (crystobalite) ; 3722 deg. F., the melting point of alumina (corundum) ; and 4127 deg. F., the melting point of chromite (Cr2O33FeO). Its large-scale use in the lining of metallurgical furnaces dates back to the latter part of the nineteenth century, when extensive deposits of magnesium carbonate were discovered in southern Austria in the province of Styria. Before the development of Austrian magnesite, calcined dolomite, a mixture of lime and magnesia, was used in basic steel-making furnaces. The lime in the dolomite was quite objectionable, since it slaked on exposure to the atmosphere, and dolomite therefore could not be made&apos; .into permanent furnace bottoms or into brick. The Austrian magnesite, with its very low lime content, was free from these objections and soon displaced much of the dolomite. With the extensive development of basic steel-melting, the rise of the copper industry, and other metallurgical and chemical processes which dealt with chemically basic substances, the use of magnesite grain and magnesite brick increased rapidly.

Jan 1, 1931

By AIME AIME

THE second session on geophysical prospecting at the February meeting of the Institute was a discussion of the mining law and the bearing of the new method of search on location of claims and assessment work thereon. Allen H. Rogers was chairman of the meeting, which he opened by reviewing the present law and the proposed changes. W. R. Ingalls commented (by letter) on the Arentz bill, as introduced into the House of Representatives in 1921 and the need for revision of the present mining law. L. W. Douglas explained (by letter) the bill that he introduced and which has been passed by the House. SAMUEL S. ARENTZ, Nevada: It is my opinion that if the American Institute of Mining and Metallurgical Engineers is to sell this proposition to the people in the West, they have to sell it to the lawyers, because, after all, they are heard loudly when it comes to speaking in Congress. One man tells the other, "This thing is a vicious piece of legislation"; it might not be, but they will pass it on if it affects them. If the Institute would impress on the people affected that we need a re-codification of the mining law and that such is necessary along certain lines; that things have changed during the past decade or two, so today instead of doing our prospecting alone through the sinking of a shaft, through a discovery that may be seen, we are now moving on to more modern means of discovery through geophysics, through the churn-drill, through geology, through geological inference, I think we could get somewhere.

Jan 1, 1929

By Arthur A. Center

AT the beginning of 1944 it was expected that the production of metallic zinc in the United States from domestic and foreign concentrates would exceed the 1943 figure though domestic production of concentrates was expected to drop below the 1943 rate, mostly in the Tri-State area. Imports of concentrates were estimated to more than take care of such deficiency. North American concentrate production, available for import to the United States or elsewhere during the year, was estimated at over 200,000 tons recoverable zinc content; South American at about 65,000 tons; Australian at about 50,000 tons. Production of both concentrates and metal in the United States, however, did drop, attributable in considerable part to man-power shortage in the industry. However production exceeded consumption, which fell off, and stocks of metal increased. These stocks have increased since the middle of 1942 but production and consumption are coming nearer to a balance. The A, B, and C premiums, which have played an important part in keeping up domestic production of concentrates, extend only to the middle of 1945 by present legislation. Congress is being asked for their continuance during the war and

Jan 1, 1945

By Lawrence K. Nordell

This paper reviews practices used In the selection and sizing of belt conveyors and stacker systems commonly used in crushing and grinding plant facilities. Historical and modern methods of sizing this equipment are presented. The new methods Include: 1) probability theory applications for establishing component reliability, 2) "Monte Carlo" simulation techniques used in evaluating alternative system designs and in establishing service factors and corresponding availability Indices of each system, 3) quantifying the system and component operating characteristics using computer assisted modeling tools simulating rigid body and elasto-mechanic behavior for starting and stopping large and/or complex belt conveyors.

Jan 1, 1982