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By D. C. Anderson

Utah Construction & Mining Co.'s Lucky Mc mine is one of the major uranium producers in the United States. It is located near the geographic center of Wyoming in Fremont County. The climate is middle-latitude steppe, with an average annual precipitation amount of 10 in.; the temperature varies from 40º below zero to 100º above. The land surface is moundlike, rolling terrain, with sparse grass and sagebrush. The northern slopes of the higher ridges support a scattering of juniper and pi[n]ion growth. DISCOVERY The discovery was made by Neil E. McNeice, of Riverton, Wyo., on Sept. 13, 1953. After prospecting the area and staking a few claims, McNeice reported his findings to geologists of the Atomic Energy Commission (AEC), who immediately began preliminary studies of the numerous surface uranium exposures of the district. The discovery received widespread publicity, resulting in an intensive search for uranium throughout the region ; thousands of claims were staked. The AEC drilled several shallow holes near the discovery outcrop. Assays of cuttings from these holes confirmed the presence of a low-grade, oxidized uranium deposit. McNeice and his partner, L. A. Morfeld, tried to start a mining operation but were plagued by a lack of capital and technical know-how. They sought assistance from a Salt-Lake-City-based mining firm, the New Park Mining Co., engaged in underground base-metal mining in the Park City district of Utah. After a period of negotiations, New Park initiated activities that led to the forming of the original Lucky Mc Uranium Corp. The company started limited development drilling and mining operations in the summer of 1954, with the first ore production being shipped by truck to the Vitro mill in Salt Lake City. The mining

Jan 1, 1969

By H. W. Fox, M. R. Achter

IN a previous study of the effect of atmosphere on creep-rupture properties,' it was shown that the relative strength of nickel in air and in vacuum may be reversed by a change in either stress or temperature, Fig. 1. At low stresses and high temperatures the metal is stronger in air but stronger in vacuum at high stresses and low temperatures. A mechanism to explain this reversal was proposed involving two competing processes; oxidation strengthens the metal while adsorption of gas lowers the surface energy, relative to that in vacuum, and reduces the work required to propagate a crack. The process which controls is determined by stress and temperature. In a number of private communications, however, the objection has been made that even in the vacuum of objection mm of Hg used in this study, the surface of a

Jan 1, 1960

By Minoru Sasabe, Mayurni Sorneno, Kazuhiro Goto

I) The Object of the Present Experiment. When the oxygen chemical potential in the gas phase is changed, the oxygen chemical potential in the liquid metal or in the liquid oxide phase will be subsequently changed. The object of the present experiment is to develop a method of measuring the change in the chemical potential of oxygen in liquid metals and in liquid oxides with respect to time, when the oxygen potential in the gas phase changes. II) The Experimental Method. The following types of the oxygen concentration cells with the solid electrolyte of Zr0z-CaO are used: KAZUHIRO GOTO, MemberAIME.MINORU SASABE,and MAYUMl SOMENO are Associate Professor, Research Associate, and Professor, respectively, Department of Metallurgical Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan. Manuscript submitted March 12, 1968, EMD. Igas phase liquid Ag or Pb ZrO2-CaO electrolyte!, The measured reversible electromotive force can be expressed by the next equation, provided that the transference number of the oxygen anion in the electrolyte is unity: E = RT/nF log (at electrode I)/P~ (at electrode 11) where is the electromotive force, R is the gas constant, T is absolute temperature, n is valence of oxygen anion, and Pq is the oxygen pressure at the electrodes. As shown in the previous work1 of the authors, the electromotive force is determined by the difference in the chemical potential of oxygen at the vicinity of the interfaces between the solid electrolyte and the electronic conductors used for the two electrodes. Fig. 1 shows the two kinds of the cell assembly used to measure the change of the chemical potential of oxygen in liquid metals and liquid oxides with respect to time. In both cases, the change of the oxygen pressure in the gas phase is measured by the independent oxygen concentration cell located above the

Jan 1, 1969

By Sherwin F. Kelly

NEW trend in geophysics has been uncovered in these depression years, made evident through the thinning cloak of commercial activity, which, in better times, would have completely obscured it. I refer to the increasing use of these methods for geological investigations by federal and state geological surveys. This is a trend that has been gathering momentum not alone in the United States, but abroad as well. Thus, in Poland, the Geological Survey has been playing an increasing role in geophysical work since 1927, and now has- its own geophysical department. The government petroleum producing organization of Argentina has its Geophysical Commission; Brasil boasts a completely equipped geophysical department in its Mineral Production Service; the government of Chile has contracted with commercial companies for geophysical surveys; Peru is planning an intensive program of geophysical prospecting in its petroliferous regions; and Canada has, for several years, cooperated with

Jan 1, 1935

By John D. Ridge, Robert C. Barwick

The quantities and destinations of the metallic ores and concentrates and partially or fully refined metals in international trade result from the interaction of many factors, of which geographic location is only one. How far the processes of concentration and refining are to be carried in the country in which the mining is done and what dictates the destinations to which the more or less completely processed raw materials will move are determined not only by present-day geologic, political, and economic conditions, but also by the patterns set up by these same conditions as they obtained in the past. The first generalization that can be made regarding trade in metal raw materials-one that affects the form in which the material is transported, rather than the patterns followed by that trade-is that concentration is carried out for all low grade ores, nonferrous or ferrous, in the country in which they originate. (Rule 1.) Economic considerations alone almost always require that this be done; only high grade iron, manganese, and chromite ores can be shipped as they are mined.

Jul 1, 1955

By R. F. Mehl, J. T. Ransom

For many years the Metals Research Laboratory of Carnegie Institute of Technology has been concerned with the statistical nature of the engineering properties of steel from an experimental viewpoint, particularly those properties representing ductility.' In the past three years new work has been directed toward evaluating the statistical nature of the endurance properties. It has been shown that both the fracture curve and the endurance limit in fatigue are markedly statistical in nature. The S-N curve (and the endurance limit) of ferrous materials is often determined with specimens which number as few as ten. The common procedure is to test the first specimen at a stress well above the expected endurance hmit. Each succeeding specimen is then tested at a progressively lower stress, until, after five or six tests, a specimen runs ten million or so cycles without failing. Two or three more specimens are then used to find the highest stress at which failure will not occur; the limiting stress determined in this way is called the endurance limit. It has now been found, however, that the variability in the fracture curve and in the endurance limit in heat-treated alloy forging steels is so great that S-N curves must be drawn on the basis of distribution curves which can be appraised only by statistical methods. Two methods have been adopted in this study: (1) straightforward statistical studies of cycles to fracture of a number of specimens at each of a series of stress levels, and (2) a new abbreviated statistical method, known as "staircase testing."2 The latter corisists in testing a series of specimens, one by one, with the test stress for any given specimen automatically

Jan 1, 1950

By H. Macpherson

Durhm has a well earned reputation for supplying some of the finest coking caals in the world. The caals, in general, vary in rank from 301 to 501/2. Durham has traditionally produced foundry coke for the major proportion of the foundries in Great Britah. Durham coals can be described as clean, soft coals, which yielded, with the old hand methods of coal getting, low ash small coal because the extraneous shale was normally harder than the coal and occurred in larger pieces. Under these conditions, with a plentiful supply of cheap labor, it used to be sufficient, at most collieries, to hand clean the large sizes of coal which could then be remixed with the untreated small coal to produce carbonization coals, ready for the coke ovens, at under 5 pct ash. With the introduction of mechanical methods of coal mining, the coal gradually required more cleaning. The first method adopted to resolve this problem was the introduction of pneumatic dry cleaners for the small coal. Although such machines had little effect on the fine coal (say below 1/8 in.), they could clean the intermediate sizes of coal. This, coupled with hand cleaning the larger sizes above 1-1/2or 2 in., resulted in a combined run-of-mine mixture below 6 pct ash, capable of maintaining the quality and reputation of the cokes produced. In more recent years, the intensification of mechanization and power loading, coupled with gradual exhaustion of the cleaner seams, has created the need for a more complete method of coal cleaning. This particularly applies in the fine sizes (say below 1/50 in.) which normally vary, under present day conditions, between 15 and 35 pct ash and are much too dirty to be included in the raw state in a carbonization mixture. This pronounced change has been accelerated because legislation controlling the dust conditions of mine airs for the prevention of pneumoconiosis has resulted in tk~e extensive use of water underground and a consequent increase in moisture content of the run-of-milie output. The presence of damp fine coal decreast the efficiency of prescreening and dry cleaners, so that this type of preparation for low ash coking coals is decreasing, although it is still used satisfactorily for industrial coals in the medium ash range. Table I shows the gradual increase in mechanization, the reduction in manpower, the increased use of explosives per ton of coal extraction, and the increase in the proportion of coal cleaned by mechanical means in Great Britain. Although similar figures are not available for Durham Div. until after the date of nationalization of the coal industry, it is probable that the increase in mechanical cleaning, particularly by dry cleaners, was more marked in the Durham collieries than elsewhere in the country. As dry clealiers were replaced by coal washeries in the Gritish ccal industry, no special attempts were made to recover the slurry, with the result that large outflows of dirty water were allowed, deposits of slurry came in to lagoons and neighboring streams, and a proportion of fine material was lost from the coking coal. This position, coupled with the higher moisture of the washed coking coal, resulted in adverse effects on coke oven throughputs and coke quality. It is now realized that the natural coal fines are an essential ingredient of coking coals in obtaining the correct coke structure in metallurgical cokes. This, together with economic pressure, led to the introduction of flocculation and filtration plants for the recovery of slurries, and later, when the ash contelits of the filter cakes were too high, to the introduction of froth flotation equipment. After this position had been reached, the tailings from the froth flotation pIants were, in many cases, still allowed to constitute an undesirable effluent. Recent legislation on river pollution has changed this picture; it is now necessary to provide a circuit which is completely closed so far as solids are concerned. The gradual increase in the coal cleaned by wet methods and froth flotation in Durham Div, is shown in Table 11. It is now an accepted feature of new Washeries that. froth flotation should be an integral part of the washing process from the initial installation of the plant.

Jan 1, 1962

By Robert D. Pehlke, Robert G. Blossey

The solubility of nitrogen in liquid iron alloys containing chromium and nickel has been measured in the temperature range 1550° to 1700°C at nitrogen pressures to 1 ah. The solubility surface has been determined for the iron corner of the liquid metallic ternary to 21 pct Cr and 11 pct Ni. The nitrogen solubility increases markedly with increasing chromium concentration. The effect of nickel and the bilinear effect of chromium and nickel are less pronounced. The solubility data are presented, and interaction coefficients are determined from them. THE solubility of nitrogen has been determined in liquid Fe-Cr-Ni binary and ternary alloys. The work in this laboratory has been directed toward a relatively limited composition range, that is to 20 pct Cr and 10 pct Ni. Humbert and Elliott1 studied the entire ternary; but their investigation was, understandably, limited in this region. The region considered here is of the greatest commercial interest. Knowledge of the solubility in these alloys is important for accurate control of the nitrogen levels in various stainless alloys. Also, the solution behavior is of theoretical interest because of its deviations from ideal dilute solution rules at moderate chromium levels. The nitrogen solubility in the iron binaries has been reviewed extensively by Pehlke and Elliott,2 particularly with respect to the dilute solution interaction parameters. More recently, there has been some interest in accurate descriptions of solute interactions in non-dilute solutions. Most of the investigators have adopted a power series fit to accommodate any non-linearity of the data. The Taylor series expansion is adopted here, using Scimar's notation3 for the interaction coefficients. An alternate method, instead of requiring higher-order expansions, is to restrict the range of the composition variables. A planar solubility surface may be fitted to the data and its range of validity determined. If the axes of this region are displaced from the usual origin—the solvent pure iron—a change in standard state is required for the solution reaction. The standard state for nitrogen in iron is commonly taken as the hypothetical 1 wt pct solution of nitrogen in pure iron. However, for an alloy of appreciable solute concentration, e.g., 13 pct Cr or 18 pct Cr-8 pct Ni, it would be convenient to use that base composition as the solvent and redefine the solution reaction in terms of that particular solvent. A brief derivation follows, defining the free energy of solution in an alloy solvent. Following the treatment by Darken and Gurry,4 for a nitrogen pressure of 1 atm: N (pure component) = N (1 wt pct in solvent) [l] AG=RT ln100/ wt pct N in solvent Taking this reaction for an alloy solvent less the same reaction for a pure iron solvent the relation between nitrogen in pure iron and an alloy is: N (1 wt pct in Fe) = N (1 wt pct in alloy) [2] AG = RT[ln(wt pct N in Fe) - ln(wt pct N in alloy)] Adding ½ N2(g) to each side and subtracting N (1 wt pct in Fe) = ½N2(g), the total free energy for solution of nitrogen in an alloy, referred to nitrogen at infinite dilution, is given by: ½N2 (g) = N (wt pct in alloy) L3] AG°3 = -RT ln(wt pct N in alloy )PN =1 atm Interaction parameters have their usual meaning when ?G°/RT is differentiated with respect to the proper composition coordinate. If desired, the dilute alloy treatment may be utilized with the new reference composition as the solvent. This has. indeed, been done by Small and pehlke5 in their analysis of nitrogen solution in liquid 18-8 alloys. The Sieverts' technique was used for this investigation on an apparatus previously described.6 The materials used in this program were: Ferrovac-E iron, 99.95 pct, Crucible Steel Co.: chromium, 99.95 pct, Union Carbide Metals Co.; nickel, 99.9 pct, International Nickel Co. Recrystallized alumina crucibles were used with no evidence of crucible-melt reaction. RESULTS The locations of the ternary compositions investigated are shown in Fig. 1. The data of Turnock7 and small8 have been alluded to in other papers.5'6 There were no departures from Sieverts' law observed for

Jan 1, 1969

By K. Sassa, I. Ito

The dynamic principal stresses induced within rock by an explosion under con fined conditions are analyzed for the case of blasting with one free face by applying the values of measured radial displacement, particle velocity and so on to equations derived from the theory of elasticity. The dynamic stresses on the free face are also calculated from the strain measured by wire strain gauges affixed on the free face. Some results obtained are briefly: 1) The maximum stress on the free face appeared at the intersection between the free face and the burden, and its magnitude was about twice as large as the magnitude of the tangential tensile stress imparted by the incident stress wave within the range related to the breakage by blasting. 2) The maximum value of the compressive stress near the free face was decreased due to the existence of the free face, while that of the tensile stress was increased. 3) At any point near the free face, the directions of the principal stresses in the r? plane using spherical coordinates with the origin at the center of the spherical charge, changed with time except in the direction of the burden. However, at another point near the explosion point where the principal stresses were mainly those stresses caused by the initial longitudinal wave, the directions of the principal stresses coincided with those of the coordinate used. 4) The maximum value of the tensile stress in the F direction was larger than those in the re plane at and near the free face. 5) The tensile stress caused by the Hopkinson effect appeared only near the burden. 6) It is presumed from the results of stress analysis that radial cracks will be produced in the rock mass near an explosion point, but with the approach of the free face, the directions of cracks curve towards a direction parallel to the free face. INTRODUCTION In order to investigate the mechanism of rock breakage by blasting, it is considered to be very im- portant to know how the stresses are generated and distributed within the rock by explosion of a confined charge. As part of a research program concerning the mechanism of rock breakage by blasting, the authors have already published papers on the detonation pressure produced at the inner surface of the charge hole1 and on the behavior of the dynamic stresses within rock caused by an explosion in the case where no free face existed.' In this study the dynamic stresses on and near the free face have been investigated for the case of blasting with one free face. The mechanism of rock breakage in blasting is discussed in the light of these studies.

Jan 1, 1967

By G. G. Biggar

A MATERIAL contribution to the success of our Armies in the field has been the portable pipe-line system. These are the words of Brigadier General R. F. Fowler, chief of the supply division of the War Department. The portable pipe line is one of the "secret weapons" the American forces employed in their swift advances through Tunisia, Sicily, and Italy. Constructed of a light steel so flexible it can be snaked around trees, it can be laid at a rate of ten to thirty miles daily right up to the fighting fronts. It has played a major role in supplying combat troops with products varying from petroleum to water.

Jan 1, 1943

By Arthur Taggart

FOREWORD THE tests herein described are part of an extended series of experiments, performed by the authors together with J. F. McClelland and L. W. Bahney, on the reclamation of metallics from foundry and manufacturing-plant scrap. The most obstinate problem encountered was the proper cleaning of the metal. INTRODUCTION In the manufacture of brass and brass products the weight of the finished product leaving the plant is much less than the total weight of copper and zinc entering. A small part of this discrepancy is due to the unavoidable oxidation of the metals in melting, but by far the largest part of the loss is in the form of metallic particles of copper, zinc, and brass. These losses occur principally at three points in the process: (a) in the casting-shop ashes; (b) in the slags from furnaces melting scrap brass; (c) in material spilled on the floor throughout the manufacturing process. The amount of these products in some plants is nearly 100 tons per 24 hours. Casting-shop ashes contain the metal spilled from the crucibles during melting and pouring, and the metal included in the slags formed in the melting process. The ashes also contain pieces of broken crucibles with adhering metal; 20 to 30 per cent. of unburned coal is also present. The metal in casting-shop ashes contains clean pieces of zinc or copper ingots weighing 1 to 2 lb., jagged pieces of metal of all shapes ranging in size from several inches down to the finest dust, and shot and botryoidal shapes ranging in size from 2 or 3 in. down to 0.01 mm. or less in diameter. Slags from furnaces melting scrap brass contain metal in the form of small shot.

Jan 2, 1916

By T. F. Bower, M. C. Flemings, H. D. Brody

A series of experiments are reported which show thai reasonable assumptions for analysis of solute redistribution in solidification of castings and ingols illclr(de: negligible undercooling before nuclcation of solid phases, negligible increase of solute in advance of the tips of growing dendrites, complete diffusion within the Liquid oer distances the order, of dentrite arm spacings, platelike dentrite t/o?$holog?.. Qzmli/ali,e and periment is obtained JOY Al-Cu alloys front measurements of amount of nonequilibrium second phase, minimum solute content at the centers dentrites arms (after solidification), and 3) change in minimum solute content in dentrite arms during solidification. In a previous paper' analyses were given describing solute redistribution in dendritic solidification. The analyses were undertaken primarily to permit prediction of "severity of microsegregation" in a casting or ingot after solidification and cooling to room temperature, but can also be used to predict "local fraction solid' as a function of temperature in the solidifying alloy. Numerical results were given for Al-Cu alloys. The aims of this paper are to examine the validity of some of the assumptions of that analysis, and to compare predictions of the theory with experiments. All experiments reported are on Al-Cu alloys, the bulk on Al-4.5 pct Cu alloy. EXPERIMENTS Experiments conducted were on small ingots, 41/2 in. in diam by about 10 in. high. solidified in a controlled thermal environment (i.e., in a resistance-heated, re-circulating air furnace, whose temperature could be controlled to 1°C). In one series of experiments, the ingots were solidified very slowly (solidification time was varied from 8 to 1000 hr) and at constant rate of heat extraction. In a second series of experiments the ingots were solidified ( 'unidirectionally". Fig. 1 is a sketch of the method of making the two different types of ingots. The unidirectionally solidified ingots were fully columnar, and the slowly solidified ingots had equiaxed structures, Fig. 2. In making the slowly solidified ingots, the mold employed was carbon steel, coated with inert refractory. Typically the mold and its environment were heated to 700°C. The molten alloy was then poured into the mold and the temperature of the system equilibrated above the liquidus. The environment of the mold was next cooled with a controller responding to a differential thermocouple that measured the difference between the temperature of the melt and the temperature of the mold environment. The differential thermocouple consisted of one chromel-alumel junction in the melt connected in opposition with a second junction in the furnace. The potential across the differential thermocouple was input to the controller which acted to keep this potential at a set. constant value; hence the temperature difference between the two junctions was maintained nearly constant. Major resistance to heat flow in the above apparatus was between the metal surface and the furnace atmosphere, not in the metal itself. By maintaining a constant temperature difference between the metal and the furnace atmosphere, the controller maintained an essentially constant rate of heat extraction during solidification, regardless of amount of heat released by the metal per unit temperature change. When the metal temperature dropped just below the eutectic temperature. the ingot was removed from the furnace and water-quenched. The unidirectionally solidified ingots were cast in a similar mold to the foregoing except that provision was made to extract heat through the bottom face of the mold by passing air or water through the mold base, Fig. 1. For these experiments, metal and mold temperature were again equilibrated above the liquidus. Temperature of the mold environment was then held

Jan 1, 1967

By Will Coghill

FLOTATION has been so closely allied with the sulfide minerals and their early and associated oily reagents that the term "oil flotation" has erroneously been applied to the entire flotation process. Today, the term "chemical flotation" might be used to advantage. Flotation literature has dealt primarily with the removal of sulfides from non-sulfide gangues, and the separation of one sulfide from another. Now, the application of the process to the separation of nonsulfide minerals is coming to the fore; and from the standpoint of the number of commercial minerals involved, the flotation of nonsulfides offers the larger field. Here, soap or soap-forming substances, such as the fatty acids and their derivatives, are used; hence there may well be a subdivision of the chemical flotation process called "soap flotation." Early experimenters learned that it was easy to form a froth or foam that would carry a part or all of the ore charge over the lip of the flotation machine; but this could not be regarded as flotation because of the lack of selectivity. Doubtless soap was one of the first reagents tried, and doubtless it was rejected on account of its gangue-carrying properties. Now this same gangue-carrying ability makes soap an acceptable reagent, for we are dealing with that, which among sulfides, is considered "gan-gue." As in the flotation of sulfides, so in the flotation of nonsulfides, the selective flocculation of the mineral and the dispersion of the gangue are the first objectives. In fact, these two phenomena epitomize flotation. They depend upon the unlike surface properties of the respective miner-als; and as long as the components of an ore have unlike surface proper-ties, a separation is possible, at least in theory. Often in nonsulfide flotation it makes little difference which mineral floats and which is depressed; generally only a separation is sought.

Jan 1, 1932

NEW MEMBERS The following list comprises the names of those persons who became members during the period Aug. 1, 1916, to Sept. 10, 1916: ALLEN, Louis M., JR., Chief Mine Sampler, Old Dominion Min: & Smelt. Co., Globe, Ariz. ATKINSON, CHESTER, Min. Engr., Asst. Supt., Smelt. Dept., Cerro de Pasco Mining Co., La Fundicion, Peru, South America. BAKER, CLAIR LINCOLN, Genl. Mgr., Mexican Dept., Amer. Smelt. & Ref. Co., 1108 Mills Bldg., El Paso, Tex. BARROWS, WALTER A., 3d, Asst. Supt., Blast Furnaces, Thomas Iron Co., Hellertown, Pa. BARTHOLOMEW, GEORGE POMEROY, Asst. Cons. Engr., Guggenheim Bros., 120 Broadway, New York, N. Y. BILLOW, ELMER E., Pres., National Supply Co., 416 NN-rest Grand Ave., Chicago, 111. BROWN, SAMUEL ROLLINS, Mill Supt., The Plymouth Cons. Gold Mines, Ltd., Plymouth, Cal.

Jan 10, 1916

By J. R. Bell, W. J. Childs, J. H. Bucher, G. A. Wilber

A technique for determining recrystallization times as short as 0.10 sec was developed utilizing the "Gleeble", a commercially available testing system designed for the study of short-time, high-temperaLure themal and mechanical processes. The procedure consisted of heating a small tensile specimen to a given temperature of hot deformation, loading to a given reduction in area, unloading, delaying various intervals at temperature, and then reloading- to failure. The magnitude of the ultimate load obtained upon reloading decreased with delay lime as recrys-lallization proceeded. The technique was applied to austenite recrystallization in AISI 1010 and AISI 1010 uith 0.02 pct Cb steels. For each steel the reduction in area given the specimen on the first pull was mainlairred at 30 ± 5 pct and recrystallization times deterntined at various temperatures. The results indicaled a significantly slower rate of recrystallization for the columbium-modified composition, suggested the presence of- a recovery stage in the softening process , and indicated a greatly increased softening rate at a temperatuve where significant allotropic transformation to a partially ferritic Structure could occur. In recent years increasing attention has been paid to the fact that the process of recrystallization of austenite deformed at elevated temperatures is far from instantaneous at many practical hot-working temperatures.1-3 This realization has given rise to such terms as hot cold-working1 or warm-working,2 These terms generally describe processes where the recrystallization rate at the temperature of deformation is slow enough to have an appreciable effect on mechanical properties despite a relatively high deformation ternperature. The mechanical properties of interest can be either the properties at the deformation temperature as in hot-workability studies4 or the room-temperature properties after cooling as in the many recent studies of various thermomechanical processes172 where heat treatment and deformation are intentionally combined to give a unique set of room-temperature properties. Because of this interest in processes where the austenite recrystallization kinetics can be an important variable, the development of quantitative methods of following the course of short-time, high-temperature recrystallization has received increasing attention.l,3,5 The experimental methods to date have, in general, relied upon rapidly deforming the austenite, holding at temperature for various brief intervals, quenching as G.A.WILBER and W. J. CHILDS, Members AIME,are Research-Fellow and Professor, respectively, Rensselaer Polytechnic Institute, Troy, N. Y. J. R. BELL and J. H. BUCHER, Member AIME, are Research Engineer and Research Supervisor, respectively, Graham Research Laboratory, Jones & Laughlin Steel Co., Pittsburgh, Pa. Manuscript submitted March 13, 1968. IMD. rapidly as possible, and then using room-temperature measurements to follow the recrystallization process. Although such methods can be successfully applied to certain alloy steels, the existence of the allotropic transformation during cooling of plain-carbon or low-alloy steels tends to obscure the results. Thus, such room-temperature measurements as hardness and X-ray line widths do not correlate well with the extent of austenite recrystallization before quenching,5 and results based on room-temperature microstruc-tural observations are dependent upon the success in correlating the observed structure with the prior aus-tenitic grain structure.1,3,5 The purpose of the present work was to develop a quantitative method for the determination of short-time, high-temperature recrystallization rates, based on measurements made at the temperature of deformation. EXPERIMENTAL TECHNIQUE The basic technique consisted of heating a small tensile specimen to a given temperature of hot deformation, loading to a given reduction in area, unloading, delaying various intervals at temperature, and then reloading to failure. The data were obtained in the form of traces of load and elongation as a function of time. Due to the high deformation temperature, the strain hardening introduced during initial loading was progressively annealed out with holding time after unloading and the loads obtained upon reloading decreased as this softening proceeded. Although the value of the second load at any Consistent point On the load-elongation curve could have been used as a measure of the degree of softening, the most convenient to use was the ultimate load. The softening indicated by the decrease in the second ultimate load with time is essentially a process of annealing of cold-worked material at a high deformation temperature. Although some recovery grain growth may contribute to such a softening process, it is generally considered that the major softening which must take place to achieve complete removal of substantial Strain hardening will occur by the formation of new, stress-free grains. As the results of this work indicate that essentially complete removal of strain hardening did in fact occur. the primary softening process will be attributed to recrystallization, and specific reference made where it appears that other mechanisms may be contributing to the total observed softening. It would, of course, be of interest to attempt to correlate the results of this work with the actual austenite fraction recrystallized as determined by other techniques. This was not attempted in the present work because it would have required running a large number of additional specimens and, as discussed previously, there is limited assurance that the results would accurately reflect the prior austenite fraction recrys-

Jan 1, 1969

By Roger E. Barthelemy

PRIMITIVE mining and metallurgy has today almost disappeared. Probably the only remaining tribal tin mining and smelting is practiced by the Laotian natives in one of the less known tin areas of the world. This district lies almost a thousand miles from the sea along the Mekong River, one of the longest rivers in the world, that marks the border between Siam and Laos, one of the five states forming French Indo-China. Less than twenty years ago it took more than two weeks' travel on elephant-back to reach the spot and today it still takes many days of travel, using all kinds of transportation from automobiles to native

Jan 1, 1938

By W. Rostoker

The process of diffusion alloying of mixed powders offers attractive possibilities both commercially and experimentally. It avoids the fabrication difficulties arising from high alloy contents. Indeed, the process is facilitated by larger alloy additions. The direct formation of the part or test piece and the opportunlity to perform machining operations under more favorable conditions are of no small importance. However, it is necessary to make only brief mention of the interesting features. As yet there have been few attempts to study this process in detail and to carry it to completion, if such is possible. It was intended not only to measure the intermediate and optimum magnetic properties of sintered alloys but to use magnetic testing itself as a means of following the progress of alloying under various condi-tions. Having established that alloys could be successfully synthesized by this tech. nique, the opportunity was taken to study the magnetic properties of several alloys of iron and silicon which had hitherto been too difficult to prepare in suitable test piece form. While avoiding some of the difficulties inherent in the fabrication of alloys by orthodox methods, the diffusion alloying process introduces a few of its own. The first of these is the evaluation of the approach to homogenization. In recent years some notable contributions have been made to this question, but considerable uncertainty remains in its definition and evaluation. This work has concerned itself with further study of this problem and it is hoped that more light has been shed on it. The second of these difficulties arises from the presence of porosity. It is inevitable that in the consolidation of a loose bulk of powder, there should remain some voids unless extremely high pressures are repeatedly applied. It was therefore of importance to investigate their effect on magnetic properties. Recently this effect has been studied and certain predictions made of its behavior. It is believed that the experimental results presented here provide a sound substantiation of the theoretical treatment. The attempt has been made to synthesize five alloys of the iron-silicon system and three each of the iron-nickel and iron-cobalt systems. A series of experiments was also conducted on some of these alloys to test their susceptibility to heat treatment. Some unfortunate experiences have provided opportunity to report data on the deleterious effects of nitrogen on magnetic properties when present as a a in protective atmospheres. MateRIALS, PREPARATION OF SAMPLES and Testing The purest materials available were em. ployed for this work. A specially purified,

Jan 1, 1949

By Will H. Coghill, J. Bruce Clemer

Flotation has been so closely allied with the sulfide minerals and their early and associated oily reagents that the term "oil flotation" has erroneously been applied to the entire flotation process. Today, the term "chemical flotation" might be used to advantage. Flotation literature has dealt primarily with the removal of sulfides from non-sulfide gangues, and the separation of one sulfide from another. Now, the application of the process to the separation of nonsulfide minerals is coming to the fore; and from the standpoint of the number of commercial minerals involved, the flotation of nonsulfides offers the larger field. Here, soap or soap-forming substances, such as the fatty acids and their derivatives, are used; hence there may well be a subdivision of the chemical flotation process called "soap flotation." Early experimenters learned that it was easy to form a froth or foam that would carry a part or all of the ore charge over the lip of the flotation machine; but this could not be regarded as flotation because of the lack of selectivity. Doubtless soap was one of the first reagents tried, and doubtless it was rejected on account of its gangue-carrying properties. Now this same gangue-carrying ability makes soap an acceptable reagent, for we are dealing with that which, among sulfides, is considered "gan-gue." As in the flotation of sulfides, so in the flotation of nonsulfides, the selective flocculation of the mineral and the dispersion of the gangue are the first objectives. In fact, these two phenomena epitomize flotation. They depend upon the unlike surface properties of the respective minerals; and as long as the components of an ore have unlike surface properties, a separation is possible, at least in theory. Often in nonsulfide flotation it makes little difference which mineral floats and which is depressed; generally only a separation is sought.

Jan 1, 1935

By AIME AIME

BECAUSE of its unequalled skill, your country in- creased its production until, in 1913, it produced 40 per cent. of the world's consumption of coal, iron ore, and cast iron; 45 per cent. of the steel; and 60 per cent. of the copper. Your industrial effort, in a general manner and your mining effort in particular, has been tremendous. In the general economy of the world, you occupy an incomparable position of power and action. All your curves of production, mineralogical, metallurgical, financial, commercial, have taken terrific trigonometrical tangents and you will easily under- stand the sorry position of your competitors. I must, therefore, pay a tribute of homage arid admiration to you all who, each in his sphere, have been the artisans of such prosperity and my earnest wish is that you continue in this way.

Jan 1, 1920

By AIME AIME

ASIDE from the annual dinner-dance, the two outstanding social events of the Annual Meeting were the dinner- smoker on Monday night and the informal dance on Tuesday night, both of which were held at the Commodore Hotel. Approximately 400 attended the former event, compared with 570 a year ago, and about 250, people were attracted to the dance.

Jan 1, 1933