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By G. Y. Chin, M. T. Dolan, W. L. Mammel

The least work analysis of constrained deformation, first proposed by Taylor and recently modified by Chin, Hosford, and Mendorf to include twinning, has been applied to the problem of axisynmetric flow. Calculations were made, for the case of (111}(110) slip and {111}(112) twinning applicable to fcc deformation. The solutions were obtained by linear programming techniques and with the aid of computer methods. The results show that in axisymnzetric tension the onset of twinning tends to decrease the plastic strength anisotropy as compared with the case of defortnation by slip alone. In compression, however, the strength anisotropy is increased as a result of twinning. The [100] and 11111 orientations and their vicinity are unfavorable for twinning in tension and compression, respecticely. With slight modifications, the present results may be applied to bcc metals deform ing by {110}(111j slip and (112} (111) twinning. Implications of present results to wire texture development of low stacking fault energy fcc materials arc discussed. PREVIOUSLY we' have applied linear programming techniques to obtain solutions to Taylor's least work analysis2 of constrained deformation of single crystals undergoing axisymmetric flow, such as occurs in an axially loaded polycrystalline aggregate. These solutions yielded values of the parameter M = o/.r = Y/w which relates the external stress-strain (u-c) curve to the shear stress-shear strain (7-y) curve for the crystal. The value of M is dependent on crystal orientation and hence enters significantly in texture strengthening considerations.3'4 Recently the Taylor hypothesis was modified by Chin, Hosford, and Mendorf' to include mechanical twinning. The latter has now been applied to the problem of axisymmetric flow and the results are reported in this paper. Calculations have been made for {111 )( 110) slip and {111 )(112) twinning applicable to fcc crystals. With minor changes in the indices of the slip and twin systems, the present results are also applicable to bcc crystals which slip on (110) (111) and twin on {112)(111) systems.

Jan 1, 1970

The Anglovaal Group has released details concerning its new processes for recovering platinum group metals, stating that the Group's system, which involves batch processing and precipitation methods for these metals (PGM's), leads to faster recovery times, increased recoveries, and higher purities than the conventional process. Insofar as South Africa's Merensky Reef is concerned, the Anglovaal method of recovering palladium first (as opposed to platinum in the conventional process) enables it to use a much simpler process in the subsequent recovery of platinum and other metals. Because the processes give cleaner separations, the volume of material to be recirculated -and therefore the total volume of material in the recovery circuits- is reduced substantially.

Jan 3, 1976

By A. H. Daane, B. J. Beaudry

The uranium-antimony system has been investigated by metal-lographic, therma1, and X-ray methods. There are four intermediate phases present: USbz and U,Sb, which undergo peritectic decomposition at 1355°and 1695OC, respectively, and USb and UPSbs which melt congruently at 1850"and 1800°C, respectively. There is a eutectic between U4Sbs and USb which melts at 1770°C. USb,, UsSb4, and USb are line compounds while U4Sbs has a solubility range of approximately 1.5 at. pct at 1770°C. Single crystal studies of the cmpo,und U.,SbS show it to have a hexagonal unit cell with a, = 9.268A and c, = 6.201b;. The solubility of uranium in liquid antimony increases from 0.1 at. pct at 650°C to 1.5 at. pct at 900°C. The solubility of antimony in a, P, and y uranium is approximately 0.02, 0.1, and 0.05 at. pct respectively. IN nuclear reactors, uranium has been used mainly in the form of solid-fuel elements of the pure-metal or uranium-rich alloys. However, in attempts to overcome some of the difficulties inherent in solid-fueled reactors, reactor concepts hive been proposed in which the fuel would be a liquid metal, such as a solution of uranium in another metal. The liquid-metal fueled reactor (LMFR) designed by the Brook-haven National Laboratory of the U.S. Atomic Energy Commission is an example. Fuel for this reactor is a solution of approximately 800 ppm enriched uranium in bismuth.' To design such liquid-fueled reactors, a background of information on the solubility of uranium in various metals is obviously necessary. The present study was undertaken to pro- vide information for such purposes, and in addition, to study the uranium-antimony system as a whole. A preliminary literature search showed that some work had been done previously on uranium-antimony alloys, but no attempts had been made to make a complete study of this system. The solubility of uranium in antimony was studied by Cammack and Bridger' up to 950°C and by Hayes and Gordon up to 900'-C. Their data are plotted in Fig. 1. Ferro, in an X-ray structure study of some uranium-antimony compounds, found USg to be tetragonal with a, = 4.2724 and c, = 8.471A, U3S4 to be b.c.c. with aO = 9.095A and USb to be f.c.c. with a,= 6.191A. Colani reported the compound UsSba; however, work by Ferro and by this Laboratory showed that this compound does not exist. foote' reported several intermediate phases in the uranium-antimony system, but did not identify them. Greninger' re-ported finding an intermediate phase in a 5 at. pct Sb

Jan 1, 1960

By A. B. Young

In the original design of the flue system, the flues from the roasters delivered their gases to a large brick dust chamber which discharged into another flue with stack connection, as shown in Fig. 1. The treater is so situated that the gases are taken by it directly from the chamber and discharged again into the flue. The complete installation comprises two treater units, only one of which has been installed at present. The treater is essentially a flue 1.0 ft. high, 12 ft. wide, and 61 ft. long. (3 by 3.6 by 18.5 m.). Suspended inside, vertically and running lengthwise, are four banks of No. 20 corrugated iron plates; each bank is 10 ft. long, making an effective treater length of 40 ft. The spacing from center to center of the rows of plat,es is 9 1/8 in. (23 cm.) giving six-

Jan 1, 1921

By John McDonald

THIS report is a continuation of an earlier one with a similar title,1 to which the reader is referred for such details of procedure as do not appear here. A brief summary will be given of the objects and methods of the research at this time. It was pointed out in the previous paper that properties of magnesium alloys, as re-ported by different workers, often differ. This was thought to be due to differences in the preparation of the specimens tested. The ideal way to compare alloys would be to prepare each of them in so many ways that reasonable assurance would exist that the best properties of each alloy had been developed. The alloys would then be com-pared on the basis of these properties. The treatment actually given the alloys of these studies is necessarily a compromise with completeness. Nevertheless, enough treatments have been given so that a con-siderable degree of assurance exists that the properties obtained are representative of the alloy as such, and not merely of the manner in which it was worked and heat-treated.

Jan 1, 1940

By William B. Plank

IN my studies during the past twenty years of the enrollments in the mining and metallurgical schools of the United States and Canada, I have been struck with the great diversity in the curricula offered by these schools. In 1933 when I made my first complete study of the schools (Mining and Metallurgy, May 1934, p. 211), I discovered 19 different curricula or programs of study, leading to almost as many different bachelor degrees, in the 49 schools in the United States and the 4 schools in Canada. These were: (1) Mining Engineering, (2) Coal Mining, (3) Metal Mining, (4) General Mining, (5) Mining Administration, (6) Mining and Metallurgy, (7) Metallurgical Engineering, (8) Metallurgy, (9) Petroleum Engineering, (10) Petroleum Refining, (11) Petroleum Geology, (12) Petroleum and Natural Gas, (13) Ceramic Engineering, (14) Ceramics, (15) Geological Engineering, (16) Mining Geology, (17) Economic Geology, (18) Geo- physics, (19) Fuel Technology.

Jan 3, 1950

By M. W. Clegg

The application of the Laplace transformation to problems in the flow of compressible fluids in porous media has provided a large number of exact solutions. For plane radial flow, however, these solutions are either complex integrals or infinite series and are of little value to the field engineer. In the case of production at constant well pressure, the available approximate solutions me valid for large times only. In this paper it is shown that an approximate inversion formula for the Laplace transform, developed for the solution of viscoelastic problems, is applicable to radial flow problems and provides simple analytical solutions to constant terminal pressure problems. The method may be used to obtain approximate solutions to many problems, including media with radial permeability discontinuities, multi-layer formations and pressure buildup in wells after shut-in. The results are compared with the few available computer solutions as well as the large time solutions, and it is shown that this approximate method greatly extends the time interval over which a simple analytical solution is acceptable. INTRODUCTION The study of transient problems in the flow of fluids through porous media has benefited greatly from the application of transform methods. The use of the Laplace transformation for solving parabolic equations has been widely discussed in the field of heat conduction and diffusion as well as in the petroleum literature. Removal of the time variable with the Laplace transformation generally reduces the problem to a boundary value problem which may be solved by standard techniques. A much more formidable problem then faces the engineer, however, for frequently the transform does not possess a simple inverse. The result is that the general inversion integral must be used and this leads to either an infinite integral or an infinite series, both of which are difficult to handle from a computational standpoint. Asymptotic approximations for the inverse have been known for some time and these yield approximate inverse functions that are valid for very large or very small times — but frequently the times of interest lie somewhere between these two extremes. Therefore, some acceptable approximation valid over a larger interval of time is desirable. During the past few years a number of methods for achieving this have been developed and some of these are discussed briefly in this paper. The relative merits of the various methods are not evaluated here, but some general conclusions reached by other authors are given. One of these methods has been applied to problems associated with the radial flow of compressible liquids to producing wells. In the case of production at constant well pressure, the method leads to simple analytical solutions for a number of standard problems; e.g., homogeneous formation, permeability discontinuities, pressure buildup. These solutions greatly extend the range of validity of the asymptotic ones (valid for large times only) and should be of value in studying the behavior of wells producing under constant pressure conditions. METHOD FOR THE APPROXIMATE INVERSION OF LAPLACE TRANSFORMS Much of the work that has been done on the approximate inversion of Laplace transforms has originated in viscoelastic problems. Apart from the asymptotic approximations,1 one of the first approximate methods was due to Alfrey.2 If (s) is the Laplace transform of f(t) defined by

By John Johnston

WHEN I was honored by being invited to give the Howe Memorial Lecture, I decided to read Howe's book, "The Metallography of Steel and Cast Iron," published in 1916-that is, about 25 years ago-in search of a text. I found the book written in fine, clear, attractive, yet precise style, as I expected, knowing that his father Dr. Samuel Gridley Howe, his mother Julia Ward Howe, and all of his four brothers and sisters had lived in a New England literary atmosphere and had written books. This leads me to suggest that many authors of metallurgical papers and books could well study Howe's writings with a view to the improvement of their own. I failed to find a specific text, but did find a subject, for in reading his book I was struck by the few instances in which time is considered explicitly as a factor in the phenomena examined, and by the fact that many of the hottest arguments would have been settled had time been taken properly into account. Indeed, Howe hardly mentions time except in a rather incidental way, as in a few references to lag; for instance: The lowering of temperature at which the transformation occurs by rapid cooling . . . is a phenomenon of undercooling or lag. It is in part explained by the fact that the transformation itself is a time-consuming reaction which, setting in during a rapid fall of temperature, is naturally protracted till the temperature has sunk far below that at which it is due. He does discuss, quite fully, the iron-carbon equilibrium diagram, as known at that time, introducing it by stating: As he is a reasonable man who is not deterred from using a hand' truck for moving his trunk by the consideration that he has thus to move a trunk plus a truck, so am I reasonable in putting into your hands this useful, indeed indispensable, tool for mastering the ABC of iron metallurgy. Somewhat later, in introducing a discussion of the phase rule, which "it would be hardly proper to pass ... by without an attempt to outline its meaning," for "a clear exposition of its applicability or jurisdiction is needed to restrain the half¬initiated from misusing it and the uninitiated from being misled by these misuses," he writes-and I quote his statement because we cannot properly discuss the influence of time on a process until we know the state of equilibrium which would ultimately be reached by the system under consideration: It is a most remarkable and valuable generalization, its conceptions help greatly toward getting a broad outlook on metallography, but its misconception has brought out a flood of obscuring writings. It tells us about the constitution towards which alloys tend, that which they reach when equilibrium is complete, when all tendencies have corrected themselves and have been complied with completely. Its application, in absence of true equilibrium, is like determining density with a telescope or even with a tuning fork; it is like the mad tea party at which the butter put into the works of the watch was the best butter. If the reader learns no more than to beware of attempts to decipher the conditions of inequilibrium by a law which touches only the conditions of exact

Jan 1, 1942

By F. H. Rhines

Page Foreword. By F. N. Rhines............................525 Design Factors for the Metal Forms with Which Powder Metallurgy May Compete. By Fred P. Peters...................... ......527 Discussion..................................530 Powder Metallargy as Applied to Machine Parts. By A. J. LanghamMer........531 Discussion......................... . Pole Pieces for Electric Motors from Iron Powder. By F. V. Lenel...........535 Discussion....................... . Bearings from Metal Powders. By W. R. Toeplitz.................542 Discussion.........................'.........549 Brushes and Allied Powder-metal Parts. By R. R. Hoffman . .............'550 Electrical Contacts Manufactured from Metal Powders. By E. I. Larsen........554 Sintered Magnets. By C. B. Fulton........................557 Friction Articles from Metal Powders. By C. T. Cox..................565 Discussion..................................567 Certain Characteristics of Silver-base Powder Metallurgical Products. By I?. R. Hensel and E. I. Larsen........................ ....569 Discussion............................... . . . . 579 Some Properties of Sintered and Hot-pressed Copper-tin Powder Compacts. By C. G. Goetzel..................................580 Discussion..................................593 The Sintering of Metal Powders—Copper. By C. J. Bier and J. F. O'Keefe......596 Some Experiments on the Effect of Pressure on Metal-powder Compacts. By Jerome F. Kuzmick..................................612 Discussion.................................. 630

Jan 1, 1945

By S. C. Lindsay, D. J. I. Evans

With each year that passes hydrometallurgical processes are being more widely used to recover base metals from ores and concentrates. Generally these processes involve liquid-solid separation of metal-bearing liquors from barren residues. This may be done by countercurrent decantation, thickening and filtration, or filtration or centrifuging only. Choice of method is governed by chemical and physical characteristics of the pulps; cost of labor, power, materials, and waste disposal; and even by the amount of capital available when building plans are under way. Since all these controlling factors change with time and location and with technological advances, the separation method must be re-evaluated when new plants or expansion programs are contemplated. At the Sherritt Gordon refinery in Fort Saskatchewan, Alberta, an ammonia pressure leaching process recovers nickel, copper, and cobalt from the nickel concentrate produced at Lynn Lake, Manitoba.' Pregnant liquors are separated from the barren leach residues in a thickener-filter liquid-solids circuit. The decision to use this type of separation was based on a summation of economic factors during the pilot plant and design stages. Although countercurrent decantation was not incorporated in the refinery flowsheet, the problems solved in thickening the leach residues and the experience gained in operating the commercial plant are pertinent to countercurrent decantation, particularly where it is applied to slow-settling leach slurries or slurries having a relatively high vapor pressure of a valuable, obnoxious, or poisonous vapor. The nickel sulfide concentrate is leached under pressure with air and ammonia to dissolve the nickel, copper, and cobalt and most of the sulfur, leaving a residue of iron and siliceous material to be discarded.2,3 During a subsequent distillation stage to recirculate part of the ammonia used for leaching, copper is recovered from the solution as a high-grade sulfide. After further purification to remove traces of copper and undesirable sulfur compounds, the nickel is precipitated by hydrogen under pressure at an elevated temperature. The cobalt, together with unreduced nickel, is precipitated as a mixed metal sulfide by hydrogen sulfide for eventual cobalt recovery. The end solution is then evaporated to produce a crystalline ammonium sulfate byproduct. As shown in Fig. 1, the nickel concentrate is leached in a continuous, two-stage, countercurrent circuit. In the first stage, or adjustment leach, the fresh concentrate is partially leached (60 pct) in the liquor produced in the second stage, or final leach. This system is necessary to produce a solution suitable for treatment in the copper sulfide precipitation step. Both stages are carried out at 170" to 180°F under a total pressure, with air, of 100 to 120 psig in large, horizontal, water-cooled autoclaves. The autoclaves are divided by overflow weirs into four compartments to give a certain amount of staging during leaching. In each compartment a relatively slow-speed (100 to 150 rpm) agitator maintains the nickel concentrate in suspension. Adjustment leaching, carried out in two autoclaves in parallel, is followed by a thickener-filter liquid-solids separation. Final leaching is done in two parallel trains of three autoclaves using aqueous ammonia to extract metal values from the adjustment leach residues. This too is followed by a thickener-filter circuit. Here the residues are repulped once with aqueous ammonia and twice with process water and refiltered after each repulping stage, to insure a maximum recovery of soluble metal, before being discarded to the tailings pond. The adjustment leach is followed by a seven-disk Dorr-Oliver American filter, with an agitator in the filter boot to keep the residues in suspension. Agitators have also been installed beneath the four ten-disk filters following the final leach thickener. Slurry Characteristics: A typical analysis of the Lynn Lake nickel concentrate, produced by differential flotation,' is given in Table I. The concentrate comprises 35 to 49 pct pentlandite, (Fe, Ni)S; 3 to 6 pct chalcopyrite, CuFeS,; 1 to 4 pct pyrite, FeS2; and 24 to 42 pct pyrrhotite, Fe1-2S (where x varies between 0 and 0.2) together with various siliceous minerals such as actinolite, hornblende, and talc. During leaching, the sulfur in the pentlandite, chalcopyrite, and part of the pyrrhotite is successively oxidized through the thiosulfate and poly-thionate radicals to sulfate and sulfamate." Simultaneously the nickel, copper, and cobalt are converted to soluble ammine complexes and the iron in the pentlandite, chalcopyrite, and part of the pyrrhotite is oxidized to a spongy hydrated iron oxide. The hydrated iron oxide is readily broken down by the agitation needed to sustain the concentrate in suspension and to maintain a satisfactory mass transfer of the oxygen from the air to the slurry. Table I shows typical chemical, screen, and

Jan 1, 1961

SOUTHERN CALIFORNIA LOCAL SECTION Executive Committee THEODORE B. COMSTOCK, Chairman SEELEY W. MUDD, Vice-Chairman FREDERICK J. H. MERRILL, Secretary-Treasurer, 631 Higgins Bldg., Los Angeles, Cal. A. B. CARPENTER C. COLCOCK JONES A meeting of the Southern California Local Section, in honor of the presence of Secretary Bradley Stoughton, was held at luncheon in a private dining room of the Sierra Madre Club on Friday, May 21, 1915, 27 members and guests being present. In the absence, through illness, of the Chairman, Dr. Comstock, the vice-Chairman, Seeley W. Mudd, presided. After the luncheon, Secretary Stoughton made a short address on the activities of the Institute. George S. Rice, of the U. S. Bureau of Mines, who was present, then spoke on the activities of his Bureau. Local Secretary F. J. H. Merrill gave a description of the activities of the Southern California Section and its progress, and reported the latter as substantial and its condition as very good. After some informal remarks by other members present the meeting adjourned. F. J. H. MERRILL, Secretary.

Jan 7, 1915

OFFICERS OF THE WOMAN'S AUXILIARY AIME President-Mrs Robert D Coombs, 375 Paramus Road, Paramus, N J First Vice-President-Mrs W McG Peirce, Troy Court 73 F, New England Avenue, Sum¬mit, N J Second Vice-President-Mrs Andrew E Beer, Richardson Avenue, Sea Cliff, Long Island, N Y Third Vice-President-Mrs Ira T Hook, 494 Norton Parkway, New Haven, Conn Fourth Vice-President-Mrs John R Kenney, 427 W Wrightwood Avenue, Chicago 14, Ill Fifth Vice-President-Mrs Alfonso Ballon, Montero Rosas 115, Barranco, Lima, Peru Recording Secretary-Mrs Arnold H Miller, 601 West 115th St, New York 25, N Y Assistant Recording Secretary-Mrs R J Mechin, 66 East 79th Street, New York 21, N Y Corresponding Secretary-Mrs Theodore Nagel, 76 Remsen St, Brooklyn 1, N Y Treasurer-Mrs Robert W Rowen, 116 East 68th St, New York 21, N Y Assistant Treasurer-Mrs Samuel H Dolbear, 11 Broadway, New York 4, N Y Assistant Treasurer-Mrs H A Kursell, 12 Murray Hill Road, Scarsdale, N Y

Jan 1, 1956

By H. E. Exner

This article is a critical review of the influence of surface preparation on crack formation at Vickers indentations in the test used by Palmqvist3-7 to evaluate the toughness of cemented carbides. Experimental results are presented which clearly show that grinding introduces compressive surface stresses into the cobalt phase and thus reduces the crack length. The deformed surface layer is removed by polishing and a stress pattern is approached corresponding to that in the bulk material. Cracks of maximum length are characteristic of this stress state. Deformation stresses can be removed by annealing above 800°C. On the basis of these results , sample preparation for the crack length test can be simplified, the accuracy of measurement is improved, and a simple and significani parameter is found to describe crack resistance of cemented carbides. FOLLOWING suggestions by Ammann and Hinniiber,1'2 Palmqvist3-7 developed a method for testing the toughness of cemented carbides using as a measure the sum of crack lengths at the four corners of a Vickers hardness indentation. This method has several advantages over the bend test commonly used in carbide technology: a) specially formed samples are unnecessary; b) sufficient information can be obtained from one sample; c) the scatter is relatively small; d) the range of actual values for commercial cutting alloys is wide. Thus, this test is both cheaper and more precise than the bend test. Nevertheless, Palmqvist's method is not widely used, mainly for two reasons: a) The relationship between crack length and the technological properties of the material (wear and shock resistance) is not clear. b) The crack length is strongly dependent on surface treatment. It is necessary, therefore, that surface preparation be very precise and reproducible, conditions usually hard to obtain. While any other simple mechanical test has this first drawback, the second became crucial in the application of the crack length method as a practical test. The reasons that this drawback could not be eliminated are, in our opinion, misleading and inconsistent interpretations of the influence of surface preparation on the crack length given in literature. In the following, after a short review of previous experimental results the interpretations given by different authors,4?'-11 cf. Table I, are discussed critically and a consistent explanation is presented on the basis of which improvements of the method of crack length testing are proposed. 1) PREVIOUS EXPERIMENTAL RESULTS In his first attempt to use the cracks at Vickers impressions as a quantitative measure of the toughness of cemented carbides, palmqvist3 calculated the work necessary to initiate cracks by the formula: Sk =k.Pk. [I] where k = numerical constant = 6.49, Sk = critical work to initiate cracks (gf cm), Pk = critical load (load necessary to initiate cracks) HV = Vickers hardness (kp per sq mm). The difficulties involved in experimental determination of the critical load were overcome by the observation that a linear relation holds between the applied load and the sum of the crack lengths at the four corners of the indentation. This linear function, given by Eq. [2] below, was confirmed by Dawihl and Alt-meyer9and by our experiments, see Fig. 1: I = a1.P +a2 [2] where 1 = sum of the crack lengths at a Vickers indentation, P = applied load, al, a2 = parameters dependent on the toughness of the alloy and the surface preparation. The critical load, Pk, is now given by a2, which can be obtained by extrapolating the load vs crack length line to zero crack length, see Fig. 1. This simple relationship, Eq. [2], led Palmqvist1,7 to a parameter which was more reproducible and easier to obtain experimentally than the critical work: the work, S300, put into the sample to produce an average crack length of 300 µm per indentation. This parameter is calculated using the formula: where the load, P3oo, giving a crack length of 300 µm, can be taken from the load-crack length plot, Fig. 1,

Jan 1, 1970

FRIENDS of the late Charles F. Rand presented in 1930 a sum of money from which the income is available to support various phases of the work of the Institute in which Mr. Rand was so deeply interested. At present the fund amounts to $10,000. The specific terms of the deed of gift are as follows: "The fund collected to establish a memorial to the late Charles F. Rand shall be placed in the custody of the Board of Directors of the American Institute of Mining and Metallurgical Engineers, to be set up as a trust to be known as the `Charles F. Rand Foundation,' the income of which shall each year be applied to a distinct purpose to be decided upon in that year by vote of the Board of Directors. This purpose shall be such as to promote the general welfare of the Institute and to constitute a permanent memorial of the usefulness of Mr. Rand, who for many years gave unstintingly of his time and talents in its service.

Jan 1, 1946

By H. D. Wilde

DURING 1934 conditions in the production division of the petroleum industry were reasonably satisfactory but nevertheless a decided feeling of insecurity existed largely because of the uncertainty of controlling production to consumptive demand. Over-production, especially in the East Texas field, threatened a general collapse of crude prices but in spite of this, posted prices were high. Stimulated by the prevailing posted prices, wildcatting activities were wide-spread. Although a number of small discoveries were made, particularly in the Gulf Coast belt and Oklahoma, no fields of major importance, unless it was the Fitts pool in Southern Oklahoma, were brought in. Meanwhile, the Petroleum Division of the A.I.M.E. continued its activities. It sponsored the collection of production and geological data on both foreign and domestic fields. The data on all but a few producing districts in the world were published in the "Petroleum Development and Technology" volume of the "Transactions" and comprise one of the most complete tabula¬tions of this sort ever published. Work of this kind is being continued.

Jan 1, 1935

By P. B. Venuto, E. T. Strom, S. A. Dixon, W. F. Johnson, T. C. Vogt

Prior to assessing potential for in-situ leaching, it is advantageous to identify the nature of the probable reactants in the ore horizon, including both the uranium species and those in the gangue material. We report mineralogical data on an areally-broad suite of samples from the Westwater Canyon Member of the Jurassic Morrison Formation in the Crownpoint area of the Grants Mineral Belt. Optical microscope, electron micro-probe, X-ray diffraction, spectroscopic and wet chemical analyses were conducted. In these samples, the uranium occurs predominantly as either coffinite or uraninite. The host rock is arkosic sandstone, comprised mainly of detrital quartz and feldspar. The minerals kaolinite and chlorite are present in claystone clasts and calcite occurs as a cement. Major trace elements include molybdenum, vanadium, iron, selenium and sulfur. Carbonaceous organic material is present in the ore and is intimately associated with the uranium mineral when it is coffinite. Geochemical, pyrolytic and 13C NMR analyses indicate organic material is probably a very mature, coaly-type kerogen derived from plant components.

Jan 1, 1982

By N. A. Gjostein

The self-diffusion coefficient D, for a surface near the (100) plane in copper was determined by means of the Mullins theory of thermal grooving, and was found to obey the Arrhenius relationship, and Do = 6.5 x 10' sq cm per sec. Suppression of surface diffusion by chemisorbed impurities encounters difliculties as a satisfactory explanation for the large Q, and Do. Instead, a model is presented which indicates that Q,, as determined by a mass-transport technique, may involve both the energy needed to form an adsorbed atom from a ledge in the surface as well as that for the movement of the adsorbed atom.; LITERATURE reviews1-3 indicate that the mechanism of self-diffusion on metal surfaces is not clearly understood. The lack of experimental data on the temperature variation of the surface self-diffusion coefficient DJ has contributed greatly to this situation. Radioactive tracer techniques4-rn have been used to measure Ds, but for many years only Nicker-son and Parker8 had determined (for polycrystalline silver) an activation energy B, and a frequency factor Do for the surface self-diffusion process. Even in this case, a mechanism could not be clearly inferred because it was suspeted7 that a contribution from volume diffusion was not taken into account by the investigators. Some later work by Li and parkere on polycrystalline gold, in which they obtained essentially the same results as for silver and in which volume diffusion could be accounted for, seems to invalidate this criticism. In 1957, Mullins10'11 developed the theory for the thermal grooving process. This advance has opened a new and promising technique for measuring the surface self-diffusion coefficient Ds. Recognizing that a thermal groove may form by several different mass transport processes, Mullins first consideredlo the cases where a) the groove forms by evaporation and condensation or b) by diffusion along the groove surface, in either case, in a system where a metal surface is in contact with only its dilute vapor phase. In a later paper," he extended the treatment to cases where the groove forms by volume diffusion into c) the solid phase or d) by mass transport through a passive gaseous phase at 1 atm pressure. The time dependence of the groove dimensions and the shape of the groove profiles predicted by Mullins' treat-

Jan 1, 1962

By James K. Richardson

Today, the enigma of the "missing man" in the metal mining industry equals, and frequently surpasses in objective importance, the problems of ore development, drilling, sampling, pumping, milling techniques, geophysical prospecting, or any one of a hundred highly technical subjects. Unfortunately, as engineers, we have confined our attentions, in the main, to the scientific phases of mineral technology, relegating our man power problems to the background. But what good has all our scientific study and preparation been if we can't get the ore mined, milled, or smelted? What has happened to our labor supply? Where is the good old miner who could timber, drill a round, lay track, or do any job underground?

Jan 1, 1949

By K. N. Weaver

In the early 1950's the cement industry began putting a new emphasis on geology. This article points up some of the industry's raw materials problems that geologists are uniquely qualified to handle. Portland cement can be made from relatively abundant industrial minerals and rocks, and this may explain why cement producers placed little emphasis on geology during the early days of the industry. After World War 11, however, the industry began to recognize the need for geological exploration and some of the larger companies began to build a permanent geological staff. This development has its roots in: 1) The rapid expansion of the industry. After World War II and continuing into the early 1950's the demand for cement far exceeded the production capacity. This placed a great deal of pressure on the producers to enlarge capacity at their plants and to develop new sites. 2) The closing of many cement plants due to inadequate raw materials. Producers feared lack of raw materials due to inadequate exploration and evaluation. 3) An ever increasing pressure for upgrading of the quality of portland cement, necessitated upgrading the quality of raw materials. 4) The increasingly large capital investment needed to build new cement plants required a higher degree of accuracy in reserve calculation. These reasons are more or less self explanatory and will not be elaborated on. They are outlined to illustrate the probable evolution of thought among cement management to justify the development of a geological staff. In the author's personal experience the geologist must continually readjust to changing conditions within the industry. For example, cement production capacity grew so rapidly that today production is only about 70% to 75% of rated capacity (73.8% in 1963). Therefore, whereas the geologist's function during the active expansion of capacity was primarily one of exploration, one of his major functions today is the development of existing reserves. This assumes of course that reserves at existing plants have been proven to be adequate in terms of the company's reserve policy. Through the proper development of raw materials, the geologist can markedly influence quality control, production and long range planning. Examples of several of the operations of Medusa Portland Cement Co. will illustrate how proper attention to geologic detail pays off in the above areas. Because limestone is the major raw material of port-land cement, the examples will be concerned with it. DEVELOPMENT OF GEOLOGIC DETAIL One of the prime objectives of an exploration or development project should be the establishment of the stratigraphy and structure of the deposit. The basic tool for exploration and development is still the core drill, and the geologist must gain a maximum amount of information from a minimum amount of drilling. In order to obtain this objective the following is essential: 1) Adequate detailed geologic logging of cores. The core is first logged and separated into lithologically distinct units. In order to make the lithologic breaks as meaningful as possible, representative pieces of core (not all) are etched in dilute HCI. This removes the "drill polish", brings out the structure of the rock and indicates the proportion of dolomite and argillaceous material because dolomite and argillaceous material etch in relief. In this way the lithologic breaks become clearer and one gains a general idea of the chemical makeup before analysis. This method of logging lessens the probability of including two types of stone, e.g. limestone and dolomite into the same sample for chemical analysis. 2) Representative sampling for chemical analysis. After logging, the lithologic units are sampled for chemical analysis. A representative analysis can be obtained by extracting a 1-in. sample for every foot of core. For example, a lithologic interval of 10 ft to 20 ft would yield ten 1-in. samples taken at 11 ft, 12 ft, 13 ft... and 20 ft. These samples are then crushed, pulverized and split into a sample for chemical analysis. This sampling method represents a significant saving of time over splitting the entire core. 3) Preparing the core as a record. Because of the expense of storage and the difficulty of handling large amounts of core, only representative samples of each lithologic unit are saved for reference. An

Jan 1, 1965

By Frank Feuille, Edward Schuster

As the time allotted is short, we can present only a general idea of the oil laws in the Latin-American republics, as a supplement to Bulletin 206 of the Department of the Interior compiled under the direction of J. W. Thompson of the Bureau of Mines and entitled "Petroleum Laws of All America." We shall not discuss the European colonies in Latin-America nor the island republics. As to the countries discussed, we shall attempt to give the main features of such special petroleum legislation as has been adopted prior to the early part of this year; where no special petroleum laws exist, we must look to the mining codes for light on the petroleum policy. As the laws and regulations for the extraction of the metals are often difficult of application to, and are lacking in many essentials for, the petroleum industry, it is best for persons or companies desiring to enter, on a large scale, into the petroleum exploration and development of countries not having special petroleum legislation, to obtain a concession contract from the executive of the country under consideration, and to have the concession approved by the congress. If this concession, which would then be a special law, contains nothing contrary to the constitution of that country and does not infringe on vested rights of third parties, it should be reasonably safe. If in such country there is some doubt as to whether the petroleum subsoil is owned by the nation or the private surface owner, only public lands should be covered with the concession. Guatemala is the only republic in the group that discriminates directly against foreigners. Bolivia, Ecuador, Mexico and Venezuela require waivers of diplomatic protection.' Colombia requires foreigners to agree to be bound by its alien law. In addition,Mexico makes it unlawful for foreigners to acquire direct ownership of real estate, including mines, within a zone of 50 km. along the coasts and one of 100 km. alongitsland

Jan 1, 1923