Search Documents

By J. T. McGrath, G. B. Craig

Tensile tests on aluminum single crystals, grown from the melt, revealed that the yield stress of these crystals was raised as the amount of striation substructure was increased. The number of striation-type boundaries was varied by changing the rate of growth of the crystals. The results are interpreted in terns of a blockage of dislocation movement by striation boundaries. IMPERFECTIONS are known to have a large effect on the mechanical properties of metals. Teghtsoonian and Chalmers 1 studied a block or striation-type substructure in tin and found that the formation of the striations depended upon rate of crystal growth and orientation. They found that the angular misorienta-tion between neighboring striations varied between 15 min and 5 deg. Atwater and chalmers2 investigated striations in tin and lead, and found that purity was another factor which influenced their formation. There was a limiting purity above which the striations were straight and regular. There is little information in the literature concerning how substructures in melt-grown crystals affect strength. washburn3 introduced small-angle boundaries into zinc by a shear process and found a subsequent increase in yield stress which he attributed to the presence of these boundaries. Lauriente and pond4 found the critical resolved shear stress in aluminium crystals grown from the melt, to increase with etch pit density. The etch pits were used as an indication of growth imperfections. In Hibbard's5 work on lineage structure in copper crystals grown from the melt, he tested one crystal containing interlineage boundaries, and found a 50 pct increase in the critical resolved shear stress. Fleischer and Chalmers6, in a recent paper, mention briefly that, in the production of aluminium crystals from the melt when the growth rate was raised from 1.2 to 18 cm per hr, the yield stress increased 50 pct. They felt that the increase in yield stress with rate of growth might be attributed to a higher concentration of impurities in the gage length and also might be affected by the increased number of small-angle boundaries (striations). The present investigation was undertaken to determine the effect of the striation substructure on the strength of aluminum single crystals. EXPERIMENTAL PROCEDURE Aluminum single crystals of 99.9992 purity were grown from the melt using a technique described by Chalmers.7 The growth rate was varied from 0.6 to 20 mm per min, thus producing crystals with varying numbers of striation boundaries. To avoid prior deformation, the crystals were chemically cut to the desired length with a saturated solution of cupric chloride. They were then annealed at 580°C for 24 hr and allowed to cool slowly in the furnace. Finally, the specimens were electropolished using an electrolyte of 5 parts ethyl alcohol and 1 part perchloric acid. Each specimen was approximately 5 in. in length and 0.125 sq in. in cross section. The average orientations of the 5 series of crystals studied are shown on the stereographic projection of Fig. 1. The crystals were strained approximately 2 pct in a soft tensile machine. The strain sensitivity was 3.6 x 10-4 cm over a 5-cm gage length.

Jan 1, 1960

[NORTH AMERICA UNITED STATES ALABAMA America.-Dyar, 0. C. Anniston.-Klugh, B. 0. Ashland.-Pallister, H. D. Auburn.-*Poor, R. S. Bessemer.-Creveling, J. 0. Lindstrom, W. A. McKenzie, W. 0. Mitchell, F. R. Birmingham.-Abbott, C. E. Aldrich, T. H., Jr. Armstrong, 0. R. Beard, A. H. Benjamin, F. S. Blackburn, E. 0. Blair, A. J. Blair, 0. S. Blair. H. W.]

Jan 1, 1946

By Fred N. Kissell, Natesa I. Jayaraman

Introduction This paper describes a recent Bureau of Mines research project that resulted in a simple procedure for reducing the dust exposure of longwall shearer operators. This project involved the development and testing of a water spray and passive shield system to hold dust against the face and away from the shearer operators. This system is known as the Shearer- Clearer.

Jan 1, 1981

The Institute is custodian of funds for support of numerous gold medals and prizes and has representatives on boards awarding still others. Details regarding the Institute Awards are given below. The Institute is represented on the boards of the John Fritz Medal, the Hoover Medal, and the Alfred Noble Prize, in conjunction with the three national societies of Civil, Mechanical and Electrical engineers; and, also on the board of the Washington Award, on which the Western Society of Engineers also is represented.

Jan 1, 1940

A. 11. P. WYNNE, San Jose de Gracia, Sinaloa, Mex. (communication to the Secretary): In the comparative tests reported by Mr. Tays, the stamp-batteries were provided with various styles and mesh-sizes of screens, while the Bryan mill was run throughout with a slot-punched Russia iron, equivalent to a 30mesh wire screen. This is a somewhat onc-sided method of comparison. Should not the Bryan mill also have had the chance to show what it could do with other screens? I cannot wholly approve Mr. Tays's proposed improvements upon the Bryan mill. In my judgment, the inventor has given us a machine well-adapted to the work for which it was designed, namely, the crushing and amalgamation of soft ores. In my judgment, the principal cause of failure to amalgamate satisfactorily in the Bryan mill is not, as Mr. Tays thinks, the shallowness of the basin, or the lack of copper plate about the inside periphery of the mill, but rather the want of experience and practical knowledge on the part of most amalgamators. Having had experience, not with one Bryan mill only, but with several, and taking into consideration the experience of other capable mill-men, I am positive that the proper way to save gold ill this mill is: first, to use enough quicksilver to keep the amalgam liquid, thus allowing it to accumulate in the annular space between the dies and the rims of the basin; secondly, to replace the old dies, when a little more than half worn-out, with new ones; and, thirdly, to clean up the mill at least every two weeks—or oftener, if rich ore is being treated. It is evident that Mr. Tap endeavored to amalgamate quite " hard," as is done in a stamp-battery, in which case the swash of the pulp would scour off portions of the hard amalgam adhering to the inside plates and dash it through the screens— after which a considerable amount would be lost through floating on, or in, the pulp in its journey over the outside plates, and

Jan 1, 1900

By Sherwin F. Kelly

In presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geophysics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to its founders, who today are likely to be overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with distant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his laboratory, studying the effects of distant bodies on certain "fields of force" which come to him across interstellar space, or through the rocks that make our earth. The application of these- techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its beginnings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tehou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1940

By Sherwin F. Kelly

In presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geophysics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to its founders, who today are likely to be overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with distant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his laboratory, studying the effects of distant bodies on certain "fields of force" which come to him across interstellar space, or through the rocks that make our earth. The application of these- techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its beginnings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tehou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1940

By J. W. Snavely

WITH all the advantages of handling bulk materials by means of belt conveyor also go some problems, one of the most persistent being that of cleaning. When sticky materials are being carried; the build-up of material on the return idler rolls results in difficulty of belt training. Much attention has been given to the problem of cleaning conveyor belts, and a great variety of cleaning devices have been developed. Even the best involve troublesome maintenance, and none can completely remove the fine particles imbedded in the belt cover, which cause rapid wear of the return idler rolls, and at the same time, of the belt cover as well. One of the major rubber companies has been promoting a two-way belt system, in which the conveyor belt is given two successive 90" twists at each end to enable it to carry material in both directions simultaneously. For many years the flat belt transmission industry has installed quarter-turn and half-turn twists in countless numbers of instances. While quarter-turn and half-turn twists in transmission belts is a familiar application, the 180" twist apparently has never been previously attempted with a conveyor belt. About a year ago, two officials of the National Iron Co. of Duluth, Lester and Lewis Erickson, proposed twisting the return run of a conveyor belt on an installation that they were designing for one of the major iron ore producers. Since then the soundness of the idea has been demonstrated, both in theory and by practical test, with the result that the installation of two conveyor belts involving the twisting of the return run is now under way. These two installations are designed to have the return run of the conveyor belt twisted 180" as it leaves the snub pulley at the head drive. The clean underside of the belt is thus placed against the idlers on the return run as well as on the carrying run. Just before it enters the tail pulley, the belt will be twisted an additional 180°, restoring it to its normal position. Because this twisting of the return run of a conveyor belt is a radical departure from accepted practice, an elaborate and extensive test was conducted early in 1950 to demonstrate that this twisting of the return run could be done successfully, also to establish application data for accomplishing this twisting, and to determine if any special equipment would be required. In studying this concept of twisting the return run of a conveyor belt, a number of problems need to be solved, primarily the ones brought about by deliberately introducing an unequal distribution of stress across the conveyor belt and controlling that maldistribution of stress, while confining it to the return run portion. The tension conditions existing in the return run of a conveyor belt are clear to all designers. First, the return run carries the initial or slack side tension of the conveyor belt, the tension that must be supplied to the return run to provide proper frictional contact between the belt and the driving pulley so that the necessary power can be transmitted from the driving pulley to the belt without slippage. This slack side tension is supplied to the belt by means of takeups, either of the gravity type, which can be vertical or horizontal, or by means of the screw type. With inclined or declined belt conveyors the slope tension also must be considered, which is the tension imposed by the weight of the belt hanging from the top pulley. This slope tension frequently can furnish part or even all of the initial tension required. The maximum value of the slope tension will be at the top pulley, and it decreases in direct proportion to the length. In addition to the foregoing, it frequently is desirable to impose arbitrarily additional slack side tension to provide sufficient tension at the loading point at the tail, so that the belt will adequately support its load between the carrying idlers. Design Conditions for Twisting A number of design conditions exist, which must be satisfied successfully to accomplish the twisting of the return run without exceeding normal working limits in any portion of the conveyor belt. It is obvious that the belt edge, in its relation to the center of the belt, must stretch in making a twist, because as the twist is accomplished, the belt edge travels through a longer path than does the center of the belt. It is further obvious that if the edge of the belt is stretched, a redistribution of stress in the belt is required to allow this edge stretching. Moreover, this stress will be unequal across the width of the belt, having a maximum value at the edges, with a minimum value at the- center of the belt. With correct initial tension in the return run of a conveyor belt, the existing slack side tension will be unequally distributed when a twist is introduced. A condition then exists in which the edge stresses,

Jan 1, 1952

By C. S. Blair

THE development of a geological department as an integral part of the Tennessee Coal, Iron & Railroad Co. in the Birmingham district, Ala-bama, in 1908 was an innovation probably unique for any mining organ-ization south of the Ohio River, At that time a few of the oil companies were starting geological departments, but there were no geologists among the larger industrial organizations. The Tennessee Coal, Iron & Railroad Co. had been a substantial producer of pig iron for many years and was just getting a start in the manufacture of steel products from the pig iron. It had large acreages of coal land, ore land and timber land, but there was lacking the detailed knowledge of the possible mineral resources of much (of its territory, and this territory at that time covered an area in the neighborhood of 500,000 acres in the states of Alabama, Tennessee and Georgia. Those responsible for the operations of the mining properties, not being familiar with the kind of help that might be expected from geologic work, were decidedly skeptical of the utility of the work. Therefore it was necessary to develop cooperation with the mining organization, by not infringing upon its functions, and by developing the work in such a manner as to demonstrate to the mining department its practical utility. In the first instance the man responsible for a mining operation is apt to assume the attitude that the geologist is a blockader, because the geologist, unfortunately, is obliged to point out difficulties in the carrying out of mining operations in the way originally planned. He points out the dangers of mining out one coal or metal seam at the ultimate expense of an upper or lower seam, and he develops structural features, such as faults and folds, which call to the attention of the mining operator diffi-culties in his future operations, which the latter had not anticipated. Eventually, however, -the value of having these data became ap to the Tennessee Coal, Iron and Railroad Co., and the operators not only welcomed the geological work and cooperated fully in its acquisition of essential information, but reached the point of asking assistance and advice; and complete coordination of the two activities has existed for many years.

Jan 1, 1933

By Sherwin Kelly

IN presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geo-physics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to Its founders, who today are likely to be overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with dis-tant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his labora-tory, studying the effects of distant bodies on certain "fields of force" which come to him across interstellar space, or through the rocks that make our earth. The application of these techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its begin-nings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tchou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1938

H. H. Hill.—I believe that as petroleum engineers you are all more or less interested in geophysical prospecting. A large number of the papers that have been written on that subject are too detailed or too much involved to be of much value to a person who is not familiar with the subject, so I suggested to Mr. Fohs that he might bring us something that we could all understand. As I take it, we are interested in learning something about the different methods, the places where they have been used, their limitations and in general whether they have given satisfaction in locating oil deposits. F. J. Fohs, New York, N. Y.—I will briefly summarize some of the results as I Bee them from my practical contacts with them and my discussion of the subject with some of the more important rnen both in this country and Europe. Geophysical Methods 1. Seismographs: A. 1. Sonic refracting seismographs of Karcher, McCullom and Reiber. For rapid reconnaissance and also for detail—perhaps, the best type of instrument. 2. Mechanical refracting seismographs of the Weichert-Mintrop type. B. I. Sonic seismographs using reflected sound from contacts of sufficiently unlike beds where latter are thick enough, being used for detail of both salt domes and ordinary structures where a good reflecting key bed occurs. 2. Torsion Balances: Made in three sizes with greater portability and loss of but 20 per cent. in medium size and loss of 40 per cent. efficiency in smallest size. A. Used to best advantage in detailing salt domes, in noting anomalies of deep-seated structures of the Edgerly, La., type (but not always certain here and dependent on interpretation which involves both experience and the human equation to a large degree). R. Used to advantage in mapping faults where a lime or other denser bed occurs upthrown, and the topographic irregularities are not too involved. C. Of use where buried granite plugs and buried-hill structures occur as in the Western Texas fields. D. Believed of little use for other types of structure. 3. Magnetometers or Variometers: Now built horizontal and vertical with declinometer combined in one instrument. A. Practical in mapping granite or basic igneous rock plugs and intrusions, or of detritus therefrom. Adams has recently demonstrated definite results in mapping the well known Panhandle arch.

Jan 1, 1928

By H. N. Hall

Various factors must be considered in an engineering evaluation of gravity-drainage reservoirs. Among these are: (1) the effect of producing rate on total oil recovery; (2) the effect upon well productivity and ultimate recovery of the pressure level maintained during the producing life of the reservoir; (3) the economic advantage of full or partial pressure maintenance; and (4) estimate of the rate of gas production and injection and the possible purchase of gas under conditions of full pressure maintenance to ascertain compressor facilities needed. All of these factors can be evaluated only when a reliable method is employed for determining reservoir performance in gravity-drainage reservoirs. The purpose of this paper is to present a general method for calculating the performance of a gravity-drainage reservoir. This method is applicable for conditions of complete pressure maintenance, partial pressure maintenance and normal pressure depletion. Provisions are made to take into account variations throughout the reservoir of reservoir configuration, changes in permeability and fluid composition. Based on the method presented in this paper, an IBM 650 computer program has been developed. The past performance of an actual gravity-drainage reservoir producing under conditions of declining pressure and no gas injection was duplicated using this program. INTRODUCTION In tilted reservoirs the production of oil is influenced by drainage of oil from upstructure to downstructure locations. When this downstructure drainage of oil is sufficient to cause effective segregation of the gas and oil in a reservoir, the reservoir is usually classified as a segregation drive or gravity-drainage reservoir. (Discussion will be restricted to gravity-drainage reservoirs which have no encroachment of edge water.) The important feature in gravity-drainage reservoirs is the density difference between reservoir oil and gas. These phases tend to segregate in the reservoir with the result that in the gas cap the oil saturation is maintained at a higher level by drainage of oil from the gas-cap area. Oil can be produced from the oil zone at a low gas-oil ratio and reservoir energy is thereby conserved. The standard material balance in not adequate for predicting gravity-dramage reservoir performance because it does not take into account the difference in saturation above and below the gas-oil contact. Several authors'.' have presented methods for calculating the performance of gravity-drainage reservoirs in which reservoir pressure is maintained constant by gas injection into the gas cap. Using some simplifying assumptions, these methods can be employed with a desk calculator to give acceptable results. The problem of predicting the performance of gravity-drainage reservoirs under the conditions of declining reservoir pressure is many time more complex than that of constant pressure. fierefore, attempis to develop a method suitable for desk calculation have required excessively simplified assumptions. In the past several years, highspeed digital computers have become more widely available for reservoir engineering problems. These corn puters are well suited to problems such as the prediction of the performance of gravity-drainage reservoirs with pressure decline. Many of the simplifying assumptions necessary for hand computation can be eliminated so that a realistic approach to the gravity-drainage process can be made. CONCEPTUAL PICTURE OF OIL MOVEMENT IN GRAVITY-DRAINAGE RESERVOIRS Before attempting to develop an analytical treatment for conditions occuring in a gravity-drainage reservoir, a concept should be formed concerning the movement of fluids in the reservoir as oil is produced. A review of the literature'.' shows that it is customary to classify gravity-drainage operations into two categories—(1) with complete pressure maintenance, and (2) with declining pressure. The same line of reasoning will be followed in presenting the concept of the movement of fluids in the reservoir because it is easier to visualize the movement of fluids under conditions of complete pressure maintenance. After discussing complete pressure maintenance, an analogy will be made between that and the case of declining pressure. It should be kept in mind throughout that the final aim for the problem of solving gravity-drainage performance with digital computers will be to develop a general program for any kind of gravity-drainage reservoir. COMPLETE PRESSURE MAINTENANCE One feature which is generally common in gravity-drainage reservoirs is a gas cap located at the top of the structure. This is shown in Fig. 1(a). Fig. l(b) shows oil saturations that might occur through the reservoir. In the gas cap, oil saturation is lower than

By Gopalan Ramadorai

Tailings water from primary flotation concentrators usually contains minor amounts of pollutants such as heavy metals, cyanide and solubilized molybdenum, which are solubilized in the flotation process. A review of various techniques to reduce pollutants to acceptable levels is presented. Generally, molybdenite ores are processed by conventional size-reduction techniques, followed by flotation to produce a metallurgical-grade concentrate of 88% to 92% MoS2. Reagents commonly used in the milling process include: vapor oil (collector); pine oil, MIBC (frother); Dowfroth 250 (water-soluble frother); lime (rougher pH control); and sodium cyanide (Fe and Cu depressor). For lead depression, Nokes reagent is stage-added to the regrind mills and cleaners. Flocculant is added to obtain clear overflows in the intermediate thickeners.

Jan 9, 1978

By P. R. Kalischer

IN the production of alloys by powder metallurgical processes it is often necessary or desirable to include one or more components that tend to form very stable oxides Included in this group of metals are aluminum, manganese, magnesium, silicon, and a few others In many cases it is not necessary for the sintered compact to have full density and the other physical characteristics of a cast alloy and in that event no undue precautions need be taken If, however, it s required that the sintered part be entirely homogeneous, and have maximum density and physical properties, some method must be found to reduce the surface films of oxide, which are always present on the metals, and for the metals mentioned above this is always extremely difficult, if not impossible Since the production of high-density alloys is of particular interest to powder metallurgists, some experiments were undertaken to devise methods of reducing the refractory oxides For this work, alloys of iron, nickel, and aluminum were chosen because aluminum oxide is one of the most stable oxides and because these alloys in the right compositions form excellent permanent magnets All of the pertinent properties of the magnets could be accurately and delicately measured by density measurements and magnetic tests of sufficient scope to give a complete demagnetization curve From such a curve the maximum coercive force, residual magnetism, and energy products could be obtained and compared with the same properties for a cast material Any lack of homogeneity, density, or solid diffusion would be immediately apparent as a decrease in the magnetic properties NATURE AND REMOVAL OF SURFACE BARRIERS The early work of the present investigation was based upon published processes In the published information it was claimed that by intimately mixing iron, nickel, and iron-aluminum alloy (50 per cent Fe, 50 per cent Al) powders, compressing such a mixture into the desired shape and size, and then sintering (heating to a temperature below the melting point of the component metals) in hydrogen at 1200ºC or higher, a sound, homogeneous article could be made having the desired physical size, shape, and strength, and good magnetic characteristics However, this early work showed clearly that something in the powder compress was inhibiting diffusion and the process was almost entirely unworkable In the initial phase of the investigation samples of iron powder, nickel powder, and iron-aluminum alloy powder were pressed into separate bars and sintered in hydrogen Both the iron and nickel powders sintered

Jan 1, 1941

By Alfred E. Hunt

Tars paper is suggested by the appointment on the part of the American Societies of Mechanical and of Civil Engineers of committees upon the subjects of " Standard Tests and Methods of Testing," and " Uniform Methods of Tests of Material used in Metallic Structures," respectively, and by a study of the report of one of these committees, and other papers. Moreover, the writer has had frequent occasion to hear the complahts of tnanufacturers who furnish structural material subject to specifications, that in the tests prescribed, the number of tests required, and the methods of making

Jan 1, 1892

By F. Forward, H. Veltman, A. Vizsolyi

Activities of oxides in the ternary FeO-MnO-SiO system are calculated from data on the binaries, using the Gibbs -Schuhmann method. These activity data are used, together with thermodynamic relations, to calculate the contents of oxygen, silicon, and manganese in liquid iron, and the composition of the corresponding oxide phases in equilibrium with it. Excellent agreement was found between calculated and experimental metal compositions, indicating that thermodynamic methods, such as those presented, can supply useful data on slag-metal equilibria, and are therefore capable of wider application. When molten steel containing oxygen is treated with a deoxidizer, the product of the reaction is composed of the oxides of the deoxidizing elements together with more or less iron oxide. This assemblage of oxides is presumably very close to equilibrium with the melt since it is formed directly from elements dissolved in it. Therefore, it is likely that metal analyses corresponding to a given oxide phase composition are calculable with considerable precision where sufficient information is available on activities in both phases. The present study was made to test this hypothesis in the case of deoxidation by silicon and manganese. Here experimental data on the relationship among oxygen, silicon, and manganese in the metal phase are available, as are activity data for the MnO-SiO2, FeO-SiO2, and FeO-MnO binary systems. A further objective was to demonstrate in a specific example how gaps in the data may be filled by judicious interpolation, and how the Gibbs-Schuhmann method is applied to obtain activities in ternary systems. The rigorous derivation of the latter, requiring considerable facility in handling partial differential equations, tends to mask the real simplicity of the method, and repel the very engineers and experimenters who would benefit the most from its use. I) GENERAL PROCEDURE Deoxidation of steel with silicon and manganese results in the formation of two phases, metal and oxide. The number of components is four—Fe, Mn, Si, and 0. The phase rule then gives the number of degrees of freedom: If temperature and pressure are fixed, 2 deg of freedom remain. Consequently, it suffices to fix the concentration of two of the components of the system for all the concentrations to be determined and, at least in principle, calculable. The practical problem is then to discover a straightforward method of calculation with a minimum of trial and error solutions. The type of reactions to be dealt with are like the following: Si (in steel) + 2 O(in steel) = SiO2(in oxide phase) The standard free energy of this reaction is readily obtained from the literature, so that the equilibrium constant can be calculated by the expression: Since the metallurgist is concerned with percentages rather than activities, a real solution requires information that will permit activities to be converted to concentrations. This information is fairly adequate for the elements dissolved in molten steel, but is not available for the FeO-MnO-SiO2 oxide system. Therefore, the first step in this study was to find the relation between activity and concentration for the three oxides making up the system. The next step was the calculation of slag and metal compositions that are in equilibrium with one another. As shown by the phase rule, it is sufficient to assume the values of two composition variables in order to calculate the rest. But which two are picked makes a vast difference in how difficult the calculation turns out to be, so that it is necessary to make preliminary trial of several routes to find the easiest one. A convenient method is to begin with the slag, and to pick FeO concentration and that of one of the other oxides. Starting with the relation between oxygen dissolved in the liquid steel and FeO in the slag permits a good first estimate to be made of the oxygen content of the steel in equilibrium with FeO, because the iron content being fairly close to 100 pct, Fe has an activity close to unity. Using this first estimate of oxygen activity, approximate values of the manganese and silicon contents of the melt are readily calculated from the appropriate equilibrium constants. A minor correction for the depar-

Jan 1, 1963

By W. A. Hustrulid, N. A. Ross

An analysis of the design of medium to hard rock tunneling machines is presented. The developed equations are used to compare performances and machine requirements using kerf and fixed pick cutters to bore a given rock. With the use of pick cutters, required thrusts can be greatly reduced and still achieve the same boring rate as with present day tooth or kerf cutters. It appears that the cutting coefficient, which for most boring machines is of the order of 0.1, should be increased to one or larger to facilitate rock removal by cutting rather than grinding. The depth of cut and the indexing distance should be greatly increased to make use of inherent rock weakness.

Jan 1, 1971

By S. Acar, P. Somasundaran

The results obtained for the selective flocculation of natural ores do not usually agree with the corresponding properties of the constituent minerals when present alone. This is mainly due to the presence of dissolved mineral species which can interact in many ways with other components in the system and alter their behavior. In this paper, the effect of dissolved species on the flocculation and electrokinetic properties of sulfide minerals is discussed. Dissolved iron, copper, and nickel (Fe, Cu, and Ni) species are found to affect the properties of natural chalcopyrite and pentlandite in certain pH range. These effects are interpreted in terms of species adsorption leading to activation or depression of reagents, surface precipitation, and complexation of species

Jan 1, 1986

By Otto C. Kopp, Thomas B. Crattie, Dennis R. Owen

Whole-rock analyses of limestones, fine-gralned dolostones and coarser-grained dolostones adjacent to mineralized breccias (Coy mine, Mascot-Jefferson City district) were compared with similar lithologies adjacent to apparently non-mineralized breccias at the new Thorn Hill section located approximately 39 km north of the Coy mine. Specimens were analyzed for Ca, Mg, Si, Al, K, Fe, Mn, Sr, Br, C1, S, Ti and P using X-ray fluorescence analysis. The concentrations of the major and most minor elements for Thorn Hill specimens fall within the range of concentrations for Coy mine specimens; however, significant differences (probability < 0.05) were noted for Fe, C1 and Br for fine-grained dolostones and for MgO, Fe and Mn for the coarser-grained dolostones. No significant differences were detected for the limestones.

Jan 1, 1985

By William H. Emmons

Jan 1, 1912