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By André G. Journel

Geological study of the Prony Nilaterite (New Caledonia) began in 1969 and included drilling, geological mapping and laboratory studies. The deposit is the product of weathering of basic rocks. From top to bottom, the following zones can be distinguished: a compact ferruginous cover; ore associated with yellow laterite, containing 1.0-1.5% Ni and low in impurities (SiO2, Mg); an intermediate silicated ore containing 1.3-2.0% Ni and higher percentages of impurities; garnierite ore much richer in nickel (2-4%) but high in SiO, and Mg contents (Mg up to 20%) ; and parent rock, largely peridotites. Distinction between types of ore is essential because the high grade ore (silicated and granierites) is penalized for its high Mg contents that demand additional acid treatment. All studies made distinguish two types of ore, laterite and silicated.

Jan 10, 1973

By H. H. Podgurski, Hsun Hu

Large cryslals of high-purily iron (99.996+ pcl) cannot be obtained by the usual strain-ameal technique. Repealed phase transformation by thermal cycling prior to crilical deformation improves the capabilily of cryslal growith but fails to yield satisfactory crystals. Imperfect columnar crystals can be produced by the phase-transition method. The addition of a small amounl (0.005 wl pet) of nilrogen IT was reported'-4 that for metals of very high purity the usual procedures of the strain-anneal technique fail to produce large crystals. This was eliminates practically all the difficulties in crystal growth by the normal strain-anneal procedures. An actual example is presented, showing that most parts of a strip have been converted into a large crystal by this method. The addition of nitrogen, which can be removed from iron with less difficulty, is believed to be more desirable than carbon additions for the same purpose. thought to be due to the strong tendency for recovery in the high-purity metals: hence the critically strained matrix undergoes polygonization instead of recrystallization upon annealing for crystal growth. Talbot1,2 succeeded in overcoming this difficulty by adding 0.03 to 0.04 pct C to high-purity iron before critical deformation. followed by annealing in hydro-

Jan 1, 1965

By Franklin G. Pardee

WARTIME depletion of the reserves of iron ore in the Lake Superior region of the grade and character now being shipped down the Lakes was serious. The time has come to take stock of the resources that remain in order to plan our future program of supply for our blast furnaces and protect, as far as possible. the tremendous investment made in the Lake Superior iron mining industry. Hugh M. Roberts and William H. Crago have estimated the reserves of the Lake Superior region in the United States at two billion long tons. These reserve figures are of direct-shipping ore and those concentrates produced by methods now in commercial use or those methods that may be expected in the near future. In their estimate they have assigned 392 million long tons to the Michigan ranges (all reserves in long tons) : 112 million tons for the Gogebic. 140 million tons for the Menominee, and 140 million tons for the Marquette.

Jan 1, 1948

By L. R. Velho, N. A. D. Parlee, J. Gani

THE unsteady-state type of gas-liquid metal diffusion cell1 has found considerable application.2"4 Cells of this general design can function as steady-state cells if allowed to operate long enough to reach steady state. This report tells of some success in the adaption of this type of cell for steady-state work, using the 0-Ag system in which the mass transfer of the gas "species" is basically controlled by diffusion in the liquid. The gas, e.g-., O2, is maintained in the cell tube'-3 at 1 atm pressure, Fig. 1, by buret and sensitive oil manometer. The gas, after diffusing through the stagnant metal, escapes at the annular metal surface around the tube at a lower constant partial pressure, in this case that of O2 in slowly flowing air, 1 atm.

Jan 1, 1970

By M. Metzger, J. C. Bilello

Microyielding in 99.999 pct Cu occuwed in two distinct parabolic microstages and was substantially indeoendent of grain size at the relatiz~ely large grain sizes stzcdied. The strain recouered on unloading was a significant fraction of the forward strain and was initially higher in a copper-coated single crystal than in poly crystals. Results were interpreted in terms of cooperative yielding and short-range dislocation motion activated otter a range of stresses, and a formalism was given for the first microstage. It was suggested that models involving long-range dislocation motion are more appropriate for impure or alloyed fcc metals. THERE are still many unanswered questions concerning the degree and origin of the grain size dependence of plastic properties. In the microstrain region, a theory of the stress-strain curve proposed by Brown and Lukens,' based on an exhaustion hardening model in which the grain boundaries limit the amount of slip per source, accounted for the variation with grain size of microyielding in iron, zinc, and copper.' This theory assumes N dislocation sources per unit volume whose activation stress varies only with grain orientation. Dislocations pile-up against grain boundaries until the back stress deactivates the source, which leads to a relationship between the axial stress and the strain in the microstrain region given by: where G is the shear modulus, D the grain diameter, a the flow stress, and a, is the stress required to activate a source in the most favorably oriented grain.3 If this or other grain-boundary pile-up models are correct, then the reverse strain on unloading would be much larger for a polycrystalline specimen than for a single crystal. Also, the microplasticity would become insensitive to grain size if this could be made larger than the mean dislocation glide path for a single crystal in the microregion. These questions are examined in the present work on polycrys-talline copper and a single crystal coated to provide a synthetic polycrystal. EXPERIMENTAL PROCEDURE Tensile specimens 3 mm sq were prepared from 99.999 pct Cu after a sequence of rolling and vacuum annealing treatments similar to those recommended by Cook and Richards4-6 to minimize preferred orientation. Grain size variation from 0.05 to 0.38 mm was obtained by a final anneal at temperatures from 310" to 700°C. Dislocation etching7 revealed pits on those few grains within 3 deg of (111). For all grain sizes dislocation densities could be estimated as -107 cm per cu cm with no prominent subboundaries. The single crystals, of the same cross section, were grown by the Bridgman technique with axes 8 deg from [Oll] and one face 2 deg from (111). An anneal at 1050°C produced dislocation densities of 2 x 106 cm per cu cm and subboundaries -1 mm apart in these single crystals. A Pb-Sn-Ag creep resistant solder was used to mount the specimens, with a 19 mm effective gage length, into aligned sleeve grips fitted to receive the strain gages. All specimens were chemically polished and rinsed8 to remove surface films just prior to testing. The synthetic polycrystal was made by electroplating a single crystal with 1 µ of polycrystalline copper from a cyanide bath. Mechanical testing was carried out on an Instron machine using two matched LVDT tranducers to measure specimen displacement, the temperature and the measuring circuit being sufficiently stable to yield a strain sensitivity of 5 x 107. At the crosshead speeds employed, plastic strain rates were, above strains of 10¯4, about 10¯5 per sec for polycrystalline specimens and 10-4 per sec for the single crystals. Plastic strain rates were an order of magnitude lower at strains near l0- '. A few checks at strain rates tenfold higher were made for reassurance that the initial yielding of polycrystalline copper was not strongly strain-rate dependent. Test procedures followed the general framework outlined by Roberts and Brown.9,10 An alignment preload of 8 g per sq mm for polycrystals, and 2 to 4 g per sq mm for single crystals, was used for all tests. These gave no detectable permanent strain within the sensitivity of the present experiments; although at these stress levels, small permanent strains are detectable in copper with methods of higher sensitivity.11 12 stress and strain data are reported in terms of axial components. RESULTS General. The initial yielding is shown in the stress vs strain data of Fig. 1. For polycrystals, cycle lc, the loading line bent over gradually without a well-defined proportional limit, and almost all of the plastic prestrain appeared as permanent strain at the end of the cycle. The unloading curve was accurately linear over most of its length with a distinct break indicating the onset of a significant nonelastic reverse strain at the stress o u, indicated by the arrows. The yielding in subsequent cycles, Id and le, had the same general character. The single crystal behavior, shown to a different scale at the right of Fig. 1, was different in that initially the nonlinear reverse strain was unexpectedly much greater than for polycrystals. It should be noted that these soft crystals had a small elastic

Jan 1, 1970

By H. R. Skewes

IN the course of small seale experiments on the electrodeposition, of copper, extremely brittle deposits were obtained from electrolytes prepared by leaching calcined chalcopyrite with aqueous sulfuric acid. It was not possible to strip the metal without fracture after it had been deposited from such electrolytes onto smooth oiled copper sheets, the usual plant procedure for the production of so-called starting sheets. The embrittlement did not occur with electrolytes made either by leaching the calcine with water or by treating an acid leachate to remove iron as hydrous ferric oxide. The electrolytes which produced brittle deposits were found to contain molybdenum in concentrations of 10 to 25 mg per 1, whereas those which produced ductile deposits contained <0.5 mg per 1. Synthetic electrolytes having the composition: Cu", 40 gpl; Fe", 0.5 to 1.0 gpl; Fe3+, 0.5 to 1.0 gpl; and H,SO,, 10 to 50 gpl, were prepared from reagent-grade salts; by adding ammonium molybdate, the embrittling effect of the higher concentrations of molybdenum (VI) was strikingly confirmed. The brittle deposits contained up to 0.03 pct Mo. The importance of oxidation state of the molybdenum was demonstrated when the electrolyte containing it was circulated continuously through a bed of fine copper metal during deposi- tion. Under these reducing conditions, the cathode deposit was ductile and molybdenum could not be detected. Molybdenum has not been recognized as one of the metals causing embrittlement of copper nor is it listed among the usual impurities. In most elec-trowinning plants there is a purification step which removes iron from the leachate before electrolysis. In these cases molybdenum would be coprecipitated with hydrous ferric oxide. In the case of the large leaching plant at Chuquicamata, Chile, where the leachate is reported to contain considerable molybdenum, it would be reduced to a lower oxidation state during removal of chlorine by means of cement copper. This may explain why the embrittling effect of molybdenum has not been reported previously. Moreover, in copper refining plants where soluble anodes have been prepared by a high temperature smelting process, it is most unlikely that any molybdenum would remain with the copper, whereas the calcines in this work were prepared in a fluidized bed reactor at a temperature not exceeding 720°C. Acknowledgment This work is part of an investigation on the roasting and extraction of copper from sulfide ores sponsored jointly by Mt. Morgan Ltd., Queensland, and the Mt. Lyell Mining and Railway Co. Ltd., Tasmania.

Jan 1, 1958

By M. G., Corson

1. In addition to the alloys of copper with iron previously found by Hanson and Ford to show an increase in the concentration of the alpha range with increase in temperature the following binary and ternary systems have been found by the author to exhibit: the same feature: (a) Copper-chromium. (b) Copper-cobalt. (c) Copper-silicon. (d) Copper-nickel-silicon and its pseudo-binary section Cu-Ni2Si (formula of compound definitely established). (e) Copper-cobalt-silicon and its pseudo-binary section Cu-Co2Si (formula of compound established with some probability but not as definitely as for Ni2Si). (f) Copper-chromium-silicon; formation of a compound definitely established (compare Figs. 1 and 2). The formula of this compound may be either Cr2Si or Cr3Si. (g) Copper-iron-silicon; presence of a phase containing both iron and silicon established in an indirect way only. No definite microconstituents observed. 2. RANGES OF SOLID SOLUBILITY (percentage at various tempera¬tures). (a) For copper-chromium: 0.8 at 1000° C.; 0.5 at 900° C.; 0.25 at 800° C.; 0.05 to 0.1 at 500° C. (b) For copper-cobalt: 3.4 at 1000&apos;C.; 2.4 at 900&apos;C.; 1.7 at 800&apos;C.; 0.9 at 600°C.; 0.35 at room temperature. (c) For copper-silicon (Fig. 3) : 6.8 ± 0.1. per cent. at 800° C.; 3 per cent. at 400° C. and probably below 2 per cent. at room temperature if sufficiently long annealed. (d) For copper-cobalt silicide: 3.3 at 1000° C.; 2.4 at 900° C.; 1.6 at 800° C.; 0.7 at 600° C.; 0.3 at 300° C. (e) For copper-nickel silicide (Fig. 4): 8.2 at 1000° C.; 5.5 at 900° C.; 3.6 at 800° C.; 1.6 at 600° C.; 0.7 at 300° C.

Jan 1, 1927

By Warnie Flint

According to statistics that have been compiled by the National Safety Council, U.S. Bureau of Mines, American Medical Association, and other agencies, accidental injuries cause more deaths than all the leading diseases. There isn&apos;t anyone who is immune to an accident. Probably the best way to describe an accident is to say that it is an unexpected happening. The automobile driver isn&apos;t expecting a terrifying crash, the electrician isn&apos;t expected to be electrocuted, nor is the coal miner expecting the roof to fall on him. All personal injuries will not result in death. There is a multitude of victims who are living proof of what accidents can mean to an individual. These are the victims who are blind, paralytic, missing arms, legs, etc. In most instances the earning power of these individuals is gone, and they are utterly dependent upon family or welfare. For many years there seemed to be an attitude that prevailed upon industrial America that accidents were inevitable, and that so many fatalities and injuries should be expected. This, of course, was utter nonsense. Since the birth of such organizations as The National Safety Council, American Society of Safety Engineers, and the U.S. Bureau of Mines, much progress has been made in reducing accidents. The enactment of compensation laws greatly contributed to the progress that has been made. Does this mean that all accidents can be prevented? Unfortunately, it doesn&apos;t. Human psychology indicates that men will work unsafely or perform unsafe acts for the following reasons: 1) Lack of knowledge or skill. 2) Conflicting motivations, such as: (a) to be more comfortable, (b) to save time or effort, (c) to be accepted by a group 3) Physical or mental condition.

Jan 1, 1973

By P. L. Rittenhouse, M. L. Picklesimer

A rapid and seniquantitative method of determining prefered orientation on large numbers of. Zircaloy-2 specimens was desired. knoop microhardness measurerrzetzls were irvestigated as a solldtion to this pro6lem. The variation of Knoop microhardness measurerlerzts on selected planes as a function of &apos;irzdenle axis relutilje lo cryslallograplzic or fabrication divectals were used to corzstrrcl a polar coordinate hardness contour map. With use of an empirical relationslip between the single-crystal hardnesses and those of the polycrystalline material conentional pole figures could be constructed which compare favorably also obtained. To determine preferred oriention qualitatively from hardness data requires a minimum of twelve measurements per plane on three, preferattention to grain size, specimen prepartion, and in-rreinetzt, and analjlsis is of the order of- 45 to 60 rrin. THE design of structures from Zr alloys requires consideration of preferred orientation and the resulting anisotropy of mechanical properties. Rapid and semi-quantitative methods of evaluating anisotropy and of determining preferred orientation are needed for quality control and for examining the large number of test specimens required in development programs. The variation of Knoop microhardness with indenter orientation has been studied in single crystals of several hcp metals including titanium.&apos; beryllium,&apos; magneium, and zinc.4 The maximum hardness observed on any crystallographic plane other than the basal plane invariably occurred when the long axis of the Knoop indenter was either parallel or perpendicular to the projection of the [ OOOI.] direction on the plane of examination. When the major slip mode was (0001)(i2i0j the maximum hardness occurred at the parallel positio! but when the operating slip system was {10i0) (i210) the hardness was a maximum perpendicular to the [0001] projection. A minimum hardness was always observed at a rotation of 90 deg from the maximum. It follows that the orientation of the projection of the [0001] can be determined on any non-basal plane by making hardness measurements at a number of indenter orientations. The determination of the orientation of the [0001] projection on two non-parallel, preferably orthogonal, surfaces of the specimen will allow location of the [0001] direction in the specimen. It seems possible that such measurements could be used to examine, at least qualitatively, the preferred orientation existing in polycrystalline hcp materials. An investigation of the microhardness anisotropy in Zircaloy-2 was undertaken to ascertain whether these measurements could be used for this task. EXPERIMENTAL PROCEDURE Single crystals of Zircaloy-2 were grown by an a-8-a annealing sequence using electron-beam heating.= The orientation of the crystals was determined by a conventional back-reflection Laue technique. The crystals were then mounted on a goniometer head and the desired crystallographic faces were milled and chemically polished. Polycrystalline Zircaloy-2 specimens were prepared from fabricated sheets or plates. Inverse pole figures for these materials were obtained using the X-ray diffraction techniaue described by Jetter, McHargue, and illiams.&apos; A Wolpert-Greis Micro-Reflex hardness-testing machine was used to make the Knoop microhardness measurements. The single-crystal and polycrystalline specimens were loaded to 0.5 and 2.0 kg, respectively. Determination of the scatter of hardness numbers as a function of applied load for several indenter orientations on several specimen surfaces showed that the loads selected were the lightest consistent with minimum scatter. Heavier loads did not appreciably decrease the scatter and produced hardness impressions too large to be conveniently measured with the equipment used. Seven crystallographic planes of the single crystals were examined, while six planes of examination were used in studying Zircaloy-2 polycrystals. The specimens were rotated 10 to 15 deg after each measurement and from four to eight impressions were made at each angle of rotation. RESULTS The two angles which were used to relate crystallographic directions and planes in the hcp cell to the planes of examination of the single crystals are shown in Fig. 1. 8 is the angle between the c axis. [0001]. and the normal, N, to the plane of examination. a is the angle between the long diagonal of the Knoop indenter and the projection of the c axis on the plane of examination. For exampIe, if P = 90 deg and a = 0 deg, the plane of examination is of the family

Jan 1, 1967

By J. S. Seawright

Haulage is a costly feature in the operation of an open pit mine, whether it be iron, copper, or limestone. The National Iron Co. has adapted an old underground method to the open pit inclined skip haulage to bring the ore from the pit bottom to the crusher or beneficiation plant. The Rockover skip has been placed in operation where limited areas have retarded or eliminated use of long rail or road slopes. Deep and narrow orebodies subject to rapid increase in depth that discourage use of conveyor belts and necessary crushing plants are ideal for this system. The skip haulage method was developed to combine the desirable features of conveyor, truck, and rail haulage and at the same time avoid the draw- backs. The skip was designed to follow the natural angle of repose of the pit wall and can vary from 25° to 45°. Open-pit skips now in operation show that the installation is successful and provide the

Jun 1, 1955

By Dale S. Preece

INTRODUCTION In 1975 Congress passed the Energy Conservation Act to establish a U. S. Strategic Petroleum Reserve (SPR) with a capacity of 750 million barrels of crude oil. The most economic storage medium was determined to be salt caverns leached in salt domes in Louisiana and Texas. Salt caverns existed at several sites when the reserve was created. These were obtained by the U. S. Department of Energy (DOE) and used to initiate SPR oil storage. In order to meet the storage capacity approved by Congress, new caverns also had to be leached. To support the resulting design effort, finite element computer programs have been used to determine the creep closure and structural stability of salt caverns Using site specific material properties including creep models, elastic moduli and fracture data, the finite element analyses have replaced earlier empirical approaches to cavern design. This report presents results of such finite element analyses to determine the best cavern roof shape and the minimum pillar to diameter ratio, P/D. These numerical predictions indicate that the current cavern design is safe. FINITE ELEMENT AND MATERIAL MODELING The finite element program used in this study has existed for approximately four years. Its theoritical basis (Key, et al, 1980) and application are well documented It was originally developed to predict the creep around mined openings In bedded rock salt for the Waste Isolation Pilot Plant (WIPP) The program was tested by modeling the creep of salt around a drift and by comparing the results with the predictions of eight other structural computer codes (Morgan, et al, 1981) Since then the program has had continual use for calculations to support the WIPP (Miller, et al, 1982) For about two years the

Jan 1, 1984

By David S. Cahn

Pilot-plant and laboratory tests were made on blends of steel plant flue dust and portland cement to determine whether the flue dust could be pelletized for use as a source of iron in dry process cement manufacture. Strength and setting time results showed that an acceptable agglomerate can be made with a Type II portland cement binder. Abrasion-resistant and well-sized pellets were made in a horizontal drum, using a simulated closed circuit, with a binder content of 7.5% and a moisture content below 15%. Pellet quality was found to be relatively insensitive to changes in binder concentration above 5%. Simulations of stockpiling and weathering indicate that little difficulty would be encountered with use of the flue dust pellets in cement plants.

Jan 1, 1972

By Augustus J. Bowie

THE discovery of the auriferous cement gravel deposits in and near Deadwood Gulch, Lawrence County, Dakota Territory, in 1876, created a mining excitement, and rush to the Black Hills. Numerous ten and twenty-stamp mills were built on Deadwood Gulch ; Central City and the town of Deadwood sprang into existence, and became the centres of the mining industry of the Hills. Gold quartz deposits were subsequently discovered and located on a so-called mineral belt, extending from Whitewood Creek on the south, to Deadwood Gulch on the north. A northerly group of these quartz locations was purchased in December, 1877, by parties in San Francisco,, who formed a company, incorporated under the name of the Father de Smet Consolidated Gold Mining Company. This company immediately commenced the work of exploration. The deposits were proved to be extensive, and easily mined, but it was found that the ore, on an average, would not. yield more than $10.00 per ton* of 2000 pounds. At this time the cost of supplies and materials in the Hills was high. Miners&apos; wages were $3.50 per diem, and custom mills charged $6:00. per ton. The successful working of mines on "the belt" necessitated cheap milling. The ores being of so low grade,† this could be accomplished only with large and economically running mills. To insure the greatest possible economy, the Father,& Smet mill * Up to December 31st, 1879; the de Smet mine had produced bullion of the value of $718,211.68 from 76,155 tons of ore, being an average value of $9.41 per ton. During the year ending December 31st, 1879, the mine produced 46,344 tons, which yielded $425,360.42, or $9.18 per ton. The total gross cost of working for the corresponding period, including deadwork, exchange, legal expenses, fete., wits $219,914.82. The yield of the mine for the year 1880 (Engineering and Mining Journal, February 5th, 1881), was $600,011, with total expenses of mining and milling, of $313,108. † The first 4083 tons extracted from the de Smet mine, were selected, yielding $62,783.97. The next 25,728 tons produced $230,067.24. The total 29,811 tons were weighed, and worked at custom mills. The yield of the first 409 tons from tine Golden Terra Mine was $11.44 per-ton.

Jan 1, 1882

ASIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has three major awards to make annually and one special prize for excellence in technical papers, as follows: The Robert W. Hunt Medal and- Prize, The J. E. Johnson, Jr., Award, the James Douglas Medal, and The Lewisohn Platinum Prize to senior members. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert. W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes; first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best on al paper or papers on iron and steel. The scope of the term "iron and steel" shall determined by the sub-committee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt&apos;s main contributions to the industry have been in the improvement of production and quality of material. 3. A sub-committee of three to five, including the Chairman of the Iron and Steel Committee, shall be appointed by the Iron and Steel Committee annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October Meeting, and the award be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of the Institute. 5. The recipient of the award shall be designated "The Hunt Medallist." This prize is administered by the Iron and Steel Committee. J. E. JOHNSON, JR., AWARD This award is made from&apos; the income of a. fund of $3000 donated by Mrs. Margaret Hilles Johnson in memory of her husband, J. E. Johnson, Jr., who was a prominent engineer, author of two valuable volumes on iron blast-furnace construction and practise, vice-chairman of the Institute&apos;s Iron and Steel Committee, and a frequent contributor of papers. to the Institute&apos;s Transactions. This prize is administered by the Iron and Steel Committee. The intent of the donor is to encourage young men in creative work in branches of the metallurgy or manufacture of pig iron with which the professional activities of Mr. Johnson were chiefly concerned. The control of the fund and distribution of the awards having been vested in the Board of Directors of the Institute, this Board has made the following regulations concerning it:

Jan 1, 1925

By Louis P. Gignac

INTRODUCTION The selection of trackless equipment for underground mining can be a complex engineering problem due to the wide range of equipment sizes and operating modes. Computer simulation is particularly useful in estimating the performance of different systems for specific rock- handling problems. A hybrid simulator, incorporating some of the features of deterministic and stochastic simulation, was developed in order to handle not only queuing delays at loading and dumping points, but a1 so traffic interferences. Any number of vehicles can operate in any one of four basic modes (LHD, LAF, FEL, HFC) in parallel or in series. If the units use common roadways, loading and dumping points, certain operating delays will occur and be registered by the simulator and thus give a better evaluation of the marginal productivity of each additional unit. Based on a typical layout of drawpoints and ore passes for the sub-level stoping method, productivity and operating costs of different rock-handling systems will be examined. 1 . COMPUTER SIMULATION Numerous applications of computer simulations are reported in the 1iterature for various mining problems. Depending on the complexity of the system to be studied, simulation models were conceived with different degrees of sophistication. Three different types of simulators are generally recognized: stochastic, deterministic, and hybrid. Stochastic or Monte Carl o simulation randomly generates items, transactions, or events from some population defined by a frequency distribution and produces some expected future situations. Because this type of simulation is governed by the input of probability distributions, it requires a detailed knowledge of the system to be simulated; it implies expensive and time-consuming studies and reports to gene- rate this input information. A major short- coming of stochastic techniques is in new equipment evaluation, where the lack of data is unavoidable, and in new system design where the conditions are outside the range of the known historical behavior of the equipment. However, probabilistic simulation is almost essential for the study of cyclic queues and traffic problems. Deterministic simulation studies a system by generating performances on the basis of the mechanical capabilities of the vehicles and the physical limitations of the mining scheme. It is based on the engineering principle that the engine converts its energy into a rimpull at the wheels, which is in turn opposed by the rolling resistance and the grade of the ground; the machine is accelerated or decelerated until the tractive and resistive forces are in equilibrium, at which point it moves at constant speed. The information required by this technique, such as rimpull charts and equipment weight, is readily available from equipment suppliers. However, equipment performance at the mining site is also dictated by human and environmental conditions and changes with time and usage. For this reason, deterministic simulation generally overestimates the system capabilities; these must then be adjusted by efficiency factors based on observation and experience. Recently, hybrid simulation models, using both stochastic and deterministic techniques, have been built with some of the events generated stochasticly and others being deterministic. This compromising approach originated at the Pennsylvania State University. O&apos;Nei1 (1966) designed a simulator for truck-and- shovel operations that allows for transportation from multiple faces to mu1tiple destinations. Each truck performs according to its mechanical capabilities while its loading and dumping time and its load fluctuate according to specific probability distributions. A major advance in the simulation of mining systems is due to Sanford&apos;s model (1969) of underground coal mining operations. The originality of the model is in the use of an Executive System Control which sets up the initial system, de- fines the operation conditions , and instructs continuously four sub-assemblies representing shuttle cars, trains, continuous miners , and conveyors, which in turn generate a feed-back of their movement to the Executive Control System for further instructions. The model has enough flexibility to simulate simultaneous and sequential jobs that characterize any dynamic system. Sanford&apos;s early work evolved slowly to what is known today as the Under- ground Materials Handling Simulator for coal mining (Manula, 1974).

Jan 1, 1981

By W. Joseph Schlitt

The types of copper leaching and recovery operations in the United States are reviewed, along with characteristics and trends in the industry. The contribution of the various leach operations to total mine output is discussed in order to provide a perspective on the relative importance of copper leaching as a method of production.

Jan 1, 1980

By Joseph Chalmers, J. S. Desmond, R. Van A. Mills

[Because of the limited space in this volume and the fact that a description covering the oil recovery buildings and equipment (see page 4, Technical Publication No. 144) will be given in a forthcomnig U. S. Bureau of Mines publication, and because the paper was published in detail as Technical Publication No. 144, and is available as a separate at the Institute, it is impossible to include here more than the following brief extract.] Problems Being Studied The selection of the first problems to be studied was based largely upon the following very practical questions asked by several of the largest operators in the Mid-Continent field. 1. What are the causes for the formation of excessive amounts of bad thick oil on properties that are being repressured with compressed air and how can this trouble be prevented? 2. Why, in some areas, does the oxygen in the air injected into an oil sand during repressuring operations apparently change to carbon dioxide? Is carbon dioxide formed by the oxidation of some of the oil in the sand&apos;? How can the formation of inert or low B.t.u. casinghead gas, loaded with nitrogen, carbon dioxide and oxygen, be prevented? 3. What percentage of the oil originally present in an oil sand can be recovered by the ordinary methods of operation when the gas originally dissolved in the oil is the main propulsive agent? 4. What percentage of the amount of oil produced by ordinary methods can be recovered under average conditions by repressuring a so-called depleted oil sand? 5. What are the relative propulsive efficiencies of compressed air and natural gas in repressuring operations? 6. What are the practical advantages of pressure maintenance and early repressuring as compared with late repressuring?

Jan 1, 1929

By Sandford S. Cole

Manganese compounds occur in many mineral forms widely distributed throughout the crust of the earth. The most important of these commercially are the oxides which are usually found as irregular masses, but in some places (notably U.S.S.R.) occur as extensive beds of varying thickness and purity. The principal sources of ore have been U.S.S.R., Ghana (the Gold Coast of Africa), India, Union of South Africa, Belgian Congo, French Morocco, Cuba, Brazil, and Mexico. New developments of ore are being conducted in Brazil, British Guiana, French Equatorial Africa, and Northern Rhodesia. The production of the United States normally meets less than 10 pct of domestic manganese consumption. Manganese ore (35 pct or more Mn) is used principally by the ferrous metallurgy industry for production of manganese metal, ferromanganese, and other manganese alloys for use in production of steel ingots and castings. Some manganese is used in the nonferrous industry as an alloying element and cleanser in aluminum alloys, aluminum bronze, constantan, manganese bronze, Monel, Everdur, nickel-chromium resistance alloys, and nickel-silver. The metallurgical uses consume about 97 pct of the total manganese ore requirements of the United States. The balance goes principally for the manufacture of dry cells and for chemicals, with limited amounts for ceramic products, plastics, welding rods and varnish. The Materials Survey on Manganese, compiled in 1952 for Materials Office National Security Resources Board by the Bureau of Mines and Geological Survey, provides an excellent review of resources, reserves, specifications, uses, mining, beneficiation, metallurgical processes and deposits, and is worth referring to for greater details. Mineralogy and Geology The more common manganese minerals with typical characteristics are listed in Table 1 in order of importance. [ ]

Jan 1, 1960

By AIME AIME

FRIEND recently remarked that the career of Scott Turner is characterized by Work and Wild -A Ducks. To these might be added Accomplishment and Persistent Fishing. All of these elements are manifestations of his character. The diversions-hunting and fishing-are in the nature of the proverbial trolley conductor&apos;s holiday, for many of Turner&apos;s years have been spent in the outdoors, often in distant lands, as in Spitzbergen, where the ducks pictured below were bagged. The election of Scott Turner to the presidency of the Institute marks the culmination of a quarter century of membership, during the last two years of which he has been vice-president. He was born at Lansing, Mich., on July 31, 1880, and received his A.B. at the University of Michigan in 1902, with a B.S. and E.M. at the Michigan College of Mines in 1904. Since then he has been granted two honorary degrees, D.Sc. from the Colorado School of Mines, and D.Eng. from the University of Michigan, but he still prefers to be called "Scott" rather than "Doctor." Government service was not a new experience for Turner when he was appointed Director of the U. S. Bureau of Mines by Secretary Hoover in 1925, for his first employment after graduation was as Field Assistant in the U. S. Geological Survey in Oregon and Idaho. This was followed by work in Tombstone, Ariz.; then his first foreign engagement in 1905-6 as superintendent of the San Pablo Gold Mining Co. in Panama. Various field experiences followed, though there was an interlude in work of a kind that few mining engineers ever experience. This was in technical journalism, for in 1906 he was

Jan 1, 1932

By M. E. Wadsworth, R. D. Groves, B. W. Madsen

Experimental results obtained from large-scale (7 ton), long-term (500 days) leaching of low-tenor copper sulfide ores were interpreted by a geometric model involving the movement of a reaction zone through the ore fragments. The postulated leaching mechanism involved mixed kinetics and included diffusion of the reacting species through the host rock and a chemical reaction at the surface of the mineral particles. Ore properties which were considered were Ore particle size and shape, grade of ore, and mineral content. Excellent agreement between the mixed kinetic model and the laboratory leaching results was obtained when -1/2-in. ore particles were not included in the leach. Also, a satisfactory prediction of copper recovery from +1/2-in. ore with a different particle size distribution was made; however, it was necessary to modify the shape factor in the model. Prediction of copper recovery from an ore sample which included the -1/2-in. fine fraction and leaching for 460 days was 56.5%, and the recovery from leaching was 47.0%. The presence of fines caused solution channeling and a deficiency of oxygen which inhibited the leaching rate. Also, compaction of fines around coarser particles interfered with circulation around the ore particles, and bulk solution transport probably was a rate controlling factor.

Jan 1, 1976