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By L. D. Lash

The key to successful liquid-liquid extraction is the solvent. First, and most important, it must be highly selective for the metal desired and yet reject other metal ions present; second, the ideal sol- vent is completely insoluble in the aqueous feed liquor; third, it has rapid phase separation and will not form emulsions; and, fourth, low cost is desirable, since losses occur even though the solvent is recycled. For this application a solvent known as DDPA (dodecyl phosphoric acid) was chosen since it closely met these requirements. DDPA is a long-chain alkyl phosphate developed for AEC by Oak Ridge National Laboratories, Dow Chemical Co., and the U. S. Bureau of Mines. The long chain contributes to low solubility in the aqueous phase and to high extracting power from acidic sulfate solutions, whereas the alkyl phosphates generally exhibit high selectivity for uranium solutions.

Jan 11, 1958

By H. D. Williams, R. A. Scriven

The distribution of elevation angle of finite plane facets distributed symmetrically about a given axis is derived in terms of the angular distribution of lines which these facets produce in a plane section parallel to the axis. It is assumed that the facets are not markedly elongated in preferential directions. The theory is intended for application to the angular distribution in polycrystalline metals of slip planes and of particular grain boundaries on which certain phenomena such as cavitation can occuv. Illustrative examples are given in closed form and simple numerical techniques are de-ueloped for practical application. The results are applied to the distribution of cavitated boundaries in a copper specimen after fatigue at 400°C and it is found that voids form on the boundaries that exper~enced maximum shear stress. When investigating the distribution of elevation angle between a given axis and planes symmetrically distributed about this axis the angular distribution observed in a plane section parallel to the axis is not necessarily the same as the required distribution. Consequently a technique for processing the results obtained by sectioning methods is required. An example where such a technique would find application is in the problem of intercrystalline void formation during uniaxial tensile creep. Two theories have been proposed to explain this cavitation in terms of the normal and the shear components of stress, respectively. Hull and Rimmer (1959) postulate that the growth of intercrystalline voids is controlled by the rate of supply of vacancies from the grain boundary, the local vacancy concentration being proportional to the normal stress on the boundary. Gifkins (1956) considers that slip arising within a grain causes a ledge to be formed at the grain boundary which is subsequently opened up into a cavity by grain boundary sliding. It might be possible to differentiate between these mechanisms by determining the angular distribution of grain boundaries containing cavities since the former theory predicts a predominance of cavitated facets normal to the stress direction whereas the latter should favor an angle of 45 deg to this direction. In a similar manner an indication may be obtained of the type of mechanism responsible for intercrystalline cavitation during high-temperature fatigue. Davies and Wilshire (1962) have analyzed the slip-plane distribution in a nickel specimen but the problem was not treated in any detail nor was any account taken of the finite extent of the planes being sectioned. Hilliard (1962) has given a very general account of how anisotropy in the microstruciure can be related to measurements taken in one or more plane sections by expressing both the measured and the true angular distributions as expansions in spherical harmonics.* The present analysis is con-

Jan 1, 1965

CFD (Computational Fluid Dynamic) models have been developed and validated for a pulsed column with disk-doughnut internals, as used for solvent extraction. First a single phase model was developed to simulate the turbulent oscillating flow around the internals of the column. This model was successfully validated using detailed PIV measurements of velocity taken at eight different phases through the pulse cycle. Second, the CFD model was extended to allow for a continuous aqueous phase and a dispersed organic phase (kerosene) flowing counter-currently. The model was a two-fluid model that accounts for droplet breakup and coalescence, and solves for droplet size distribution using a population balance model incorporated into the CFX4 package. PDIA (Particle Droplet Image Analysis) measurements were taken on a pilot scale solvent extraction pulsed column to determine droplet size distribution for calibration and validation of the CFD model. The measurements were made under pulsing intensities ranging from 10 mm/s to 32.5 mm/s.

Jan 1, 2007

By J. B. Mawdsley

From the view point of the mining engineer, the square-set method of stoping as practised at Butte, Montana, is one ?of the outstanding features of well conducted mining operations in that camp. The following information was obtained in the course of two months underground work in the Granite Mountain mine, during the summer of 1920, which is one of the properties of the North Butte Mining Company, situated on the well known Speculator vein. Most of the information was derived from personal observation and from discussions with various miners and with members of the staff. Geology The copper mining area of the Butte district is some two miles long by one and a half miles wide, a mineralized area in a great batholith of monzonite granite, locally known as the Boulder batholith. This extensive body of granite is traversed by several series of mineralized fault-fissures which differ in strike but generally dip steeply. Geologists agree that following the formation of the fissures, alkaline solutions ascended and decomposed the felspathic portions of the granite in the immediate vicinity of the fissure walls, and that these alkaline solutions were followed by cupiferous solutions which filled the fissures and replaced the granite next to the walls. A zone of oxidized ore, varying in thickness from 10 to 400 feet, overlies a sulphide zone containing chalcocite, enargite, bornite and chalcopyrite, with a small amount of quartz gangue. The veins are from 3 to 100 feet in width and contain, on the average, 3 per cent of copper, 2 ounces of silver, and 15 cents in gold per ton.

Jan 1, 1925

By O. P. Arora, J. B. Darby, Paul A. Beck

LAVES and Wallbaum' reported that the phases occurring at the compositions TiFe, TiRu, and TiOs, which are stable over a wide range of temperatures and are separated from neighboring phases by wide two phase fields, have a CsC1-type ordered structure. For TiRu and TiOs, this was recently confirmed by C. B. Jordan.2 Recent results of Greenfield and Beck3 show that solid solutions with ruthenium of the body-centered-cubic elements vanadium and tantalum (and presumably also of colum-bium) in group Va of the periodic table undergo CsC1-type ordering. Although detailed phase diagrams for these systems are not yet available, it would appear that these ordered structures are separated from the neighboring body-centered-cubic solid solutions by relatively narrow two phase fields.

Jan 1, 1957

By W. G. Diamond

Lightweight aggregates have become increasingly important to the construction industry. From 1953 to 1960, the quantity of the aggregates used in concrete block, precast and prestressed concrete, and monolithic structures increased about 92 percent. The present study was conducted in Bureau of Mines Area IV which encompasses the South-Central States of Arkansas, Kansas, Louisiana, Mississippi, Missouri, Oklahoma, and Texas. This is an administrative area and does not delimit a market area or imply an economic unit. Because of the increasing importance of metropolitan areas in evaluating economic growth, significant data showing relationships between growth of the metropolitan areas and the lightweight aggregate industry are included.

Jan 1, 1964

By Mark A. Williams

Topography and geology greatly impact the decision of how to plan and operate a surface mine. To extract coal, five primary surface mrning methods are practiced in the United States. These include contour strip. mountamtop removal, area, modified area, and open pit mining methods. The first four approaches are commonly associated with coal mining while open pit techniques, although used in the mining of coal, are more commonly applied to the mining of hard rock, metals, and aggregates. Various sub-routines of the primary surface mining methods are likewrse applied rn the industry.

Jan 1, 1991

By D. W. Smith

THE beta solid solution phases of the systems copper-zinc, copper-aluminum, copper-tin and silver-zinc are structurally analogous.1 R. F. Mehl and 0. T. Marzke2 have shown that the a phase upon segregating from the 0 phase in the system copper-zinc takes the form of needles lying parallel to a [111.] direction or some similar direction, such as [556], of the parent solid solution, and that the a phase upon segregating from the ß phase in the system copper-aluminum also takes the form of needles. By analogy they assume that in this case also the segregate needles lie parallel to the [111] or [556] direction in the ß lattice. The purpose of this investigation is to determine whether the structures resulting from segregation of the a phases from the respective 0 phases of the systems copper-tin and silver-zinc are analogous to those obtained by Mehl and Marzke in the systems copper-zinc and copper-aluminum.

Jan 1, 1932

By Murali M. Gadde

Welded wire mesh is the most commonly used skin control technique in the United States underground coal mines. Currently, selection of the mesh is based on trial and error rather than any rigorous design methodology. Several factors affect a wire mesh?s performance including the amount of rock material to be supported and how the load is distributed, wire gauge, aperture size, grade of steel, weld strength, bolting pattern and sheet size. Although the best way to choose the mesh is to conduct full-scale physical load tests, because of the limitations on the number of variables that can be considered in such tests and the requirement of an elaborate test set-up, it may not always be possible to use this option. An alternative would be to use numerical modeling to study the load-deformation behavior of a wire mesh. In addition to providing a very detailed stress, strain distribution in the entire mesh, the advantage of this approach is the ease with which parametric studies can be conducted. In this paper it is shown that the load-deformation curves generated by nonlinear numerical models match closely with laboratory derived ones. Then, based on parametric studies, design guidelines are developed to choose the mesh appropriate for different loading conditions. The modeling studies also bring forth the limitations of the current lab studies. For example, under some conditions it was noticed that the small sheet size considered in lab tests would produce higher mesh deformations than a full-size one used in actual practice.

Jan 1, 2006

By Frank M. Monroe, James R. Cost

The solubility of nitrogen in vanadium is determined from 275" to 575°C by measuring the height of the nitrogen internal friction peak of equilibrated V-N alloys. The proportionality constant at 275°C between the internal friction peak height (Q- 1) and the atom percent nitrogen in solution is found to be 0.095 per at. pct for nitrogen concentrations up to 0.8 at. pct. The heat of solution of the nitride in vanadium is 5500 cal per mole. The solubility of nitrogen in the Group V metals is discussed. LITTLE work has been performed on the vanadium-nitrogen terminal solid solution. Hahn1 found the solubility for nitrogen to be very small and reported the existence of a hexagonal phase of composition near that of V2N at the solubility limit. Rostoker and Yamarnoto2 reported the solubility to be at least 3.5 at. pct at the melting point and to be less than this value at 900°C. In addition, they reported from X-ray diffraction studies that nitrogen in solution produces tetragonality in the vanadium lattice. An X-ray study by Schonberg3 has confirmed the results of Hahn but indicated that the tetragonality observed by Rostoker and Yamamoto was due to the presence of oxygen in their specimens. Beatty4 has performed lattice parameter and hardness measurements on terminal solid solutions and found the upper limit of the solubility to be at least 0.66 at. pct N. No measurements have been made of the pressure-temperature-composition relationships (P-T-X) for the terminal solid solution. As a part of a research program on gas-metal equilibrium, an attempt was made to study the P-T-X relationships in the V-N system using both the internal friction and the gas equilibration methods which have been successful with the Nb(Cb)-N and Ta-N systems (see Ref. 5 for a review of this work). Extensive investigation, using the gas equilibration methods, showed this method not to be applicable with vanadium This was presumably due to the gettering action of vanadium sublimed on the walls of the Sieverts apparatus. Thus, the nitrogen pressure relationships with temperature and composition were not obtained. The internal friction methods were, however, found to be applicable, and the temperature-composition relationships are reported in this paper and compared with similar results for the Nb-N6 and Ta-N7 systems. The existence of a Snoek internal friction peak due to nitrogen in solution in vanadium has been clearly demonstrated. 8-10 Powers and Doyle found the peak to be at approximately 275°C for frequencies near 1 cps.8 In a subsequent paper10 they reported the proportionality constant at 275°C between the internal friction peak height (Q-1) and the concentration of ni- trogen in solution (in atom percent) as 0.06 per at. pct. The studies of Stanley and wert9 indicated qualitatively that the height of the Snoek peak decreased with aging at the peak temperature and thus suggested that internal friction methods were suitable for study of the solubility. EXPERIMENTAL METHOD The vanadium for this investigation was of particularly high purity. It was obtained from the Ames Laboratory of the U.S. Atomic Energy Commission, Ames, Iowa in the form of a 1/2-in. diam, three pass zone-refined ingot. The electrical resistivity ratio (p300ºk/p4ºk) was 160. The initial composition was determined as follows: Carbon 200 ppm Oxygen 150 ppm Chromium <50 pprn Iron 125 ppm Silicon <50 ppm Other metallic 100 pprn The initial vanadium ingot was fabricated to 30-mil wire by swaging and wire drawing without the need of intermediate annealing. Lengths of this wire were then further purified (particularly for oxygen) by outgassing at 10-6 torr at 1400°C for 4 hr. The outgassing treatment resulted in specimens with a bamboo grain structure and a lustrous appearance. Desired amounts of nitrogen were added to the outgassed wires in a Sieverts apparatus in which known amounts of nitrogen were equilibrated with the wire at 1300°C. Nitrogen concentrations were produced in the desired range from less than 1 to 10 at. pct N. Monitoring of the partial pressure of nitrogen in the Sieverts apparatus indicated that at 1300°C equilibrium between the nitrogen gas and the vanadium was obtained within 10 min. Relatively rapid cooling from the nitrogen addition temperature was obtained simply by turning off the specimen heating current and cooling to room temperature in the partial pressure of nitrogen. Internal friction measurements of wire specimens were made under forepump vacuum in a torsional pendulum at frequencies near 1 cps. The torsional pendulum was of low thermal inertia and was designed so that specimens could be heated both by a conventional tube furnace and by the joule heating of a separate current through the wire specimen." Use of a static atmosphere of helium gas as a quenching medium made it possible to cut the specimen current, rapidly cool the specimen to the measurement temperature, and make a measurement of the internal friction in less than 1 min. Because of the large solubility of vanadium for nitrogen, the internal friction peak heights were in some cases greater than Q-1 = 0.1. This high damping resulted in an estimated relative uncertainty in the damping measurements of approximately 10 pct. X-ray analyses made to identify the precipitated ni-

Jan 1, 1970

By Z. Kowalski

In the defunct Gorka quarry, there are situated both a waste disposal site of an area of 6.7 ha and containing approximately 1 million ton of high aluminium wastes and a pond of an area of roughly 3 ha, up to 15 m deep, with about 400000 m3 of polluted water. The reservoir is fed with the filtrates arriving from the disposal site mentioned, at a rate ~130 m3/day. An alarming phenomenon is the subsidence of the pond bottom and the infiltration of solutions into the Triassic and Jurassic water resources, assessed at ~40 m3/ day. The basic problem related to the effluents in the Gorka pond is their high alkalinity (pH 12-13.4) and variable pollutants whose level increases appreciably with the pond?s depth. The solution offered provides pumping out and treatment of about 500000m3 of effluents retained in the Gorka reservoir in an about yearly time. Effluents would be treated in a reverse osmosis plant, according to a process so far verified on a quarter-commercial scale. The treatment process by-product would be discharged into the Ropa stream. The brine solution (containing about 25% NaCl), whose amount may reach up to100000m3, might be supplied to the Debiensko Mine which produces technological salt from salt-bearing mine waters. Similarly, there would be provided an intake of underflows of infiltrates (by means of deep wells, and possibly girdling ditches) arriving from the high aluminum site, and such effluents would be subject to ongoing dilution in water courses. It would be possible to test the system of underflows reaching the Gorka reservoir by means of geochemical identification, previously performed. The next stage following the pumping, would be the utilization of approx. 50 000m3 of bottom slurry. Highly alkaline slurries would be utilized in the production of self-solidifying mixtures. Slurries would be pumped out and temporarily dumped on drying beds, located nearby the Gorka reservoir, and later on used successively for making self-solidifying mixtures in a plant similar to a concrete making seat. Those mixtures would be applied for sealing the bottom of the Gorka reservoir and the necessary part of the edges of the defunct quarry. An alternative solution is the utilization of slurries in the facilities of the Trzebionka Mining Works and the application of self-solidifying mixtures, made in the Trzebionka Works, for sealing the reservoir bottom.

Jan 1, 2006

By N. J. Grant, K. M. Zwilsky, J. T. Blucher

DISPERSION strengthening has been studied in a number of metal-metal oxide systems. To date those pure metals available as fine particles (less than about 5 p) have received most of the attention whereas solid solution alloys, generally unavailable as fine powders, have not been examined in detail. The present work was undertaken as a preliminary study to evaluate combined effects of solid solution and dispersion strengthening. The technique used was that of dry mixing of elemental powders with the oxide, followed by a diffusion treatment to obtain the solid solution. The average particle size of the powders used was: Ni, 3.2 p (1nco B); Mo, 1.3 p (Fansteel Metallurgical Corp.); and y alumina, 0.027 \i (G. L. Cabot, Inc.). The particle size of the metal powders was determined by Fisher subsieve measurements while the size of the alumina was calculated from a surface area determination. Prior diffusion studies on small compacts pressed from mixtures of nickel and molybdenum powders with and without 7.5 vol pct A1203 indicated that diffusion was complete after sintering for 100 hr at 1800" , or 50 hr at 2250", or 20 hr at 2550° F. The progress of diffusion was followed by microstructural examination and micro-hardness measurements. Two observations made during the diffusion experiments were: 1) That diffusion proceeded faster in the presence of alumina, confirming similar findings by Seith and Loepman on "SAP&apos;&apos;;4 2) That diffusion at temperatures above 1800°F resulted in coarsening of the alumina in agreement with results of other authors reporting on the growth of alumina in nickel above 1800"F. Similar experiments in the Ni-Cr system using 6 and 20 p Cr powders of 0.7 and 0.025 pct 0, respectively, did not result in significant solid solution formation even after long time exposures at 2550° F. It must be concluded that chromium oxide films around individual particles interfere with normal diffusion. A nickel alloy containing 5 wt pct Mo and 7.5 vol pct alumina was fabricated by dry mixing of powders, isostatically compacting at 30,000 psi, diffusing for 120 hr in dry hydrogen at 1800" F, and extruding at 1950"~ with a 30 to 1 reduction of area ratio. The resulting structure, presented in Fig. 1

Jan 1, 1963

By S. P. Banerjee

There has been a phenomenal increase in production of coal from opencast mines in India. At the same time environmental problems caused by mining are receiving greater atttention. Deterioration in ambient air quality due to increased concentration of suspended particulate matter (SPM) in and around an opencast project is a major problem. Some measured values of SPM level around opencast mines in diff coalfields show that in many cases the TLV of 500 ug/m^3 is exceeded. The impact of dust emission from a mining project on surrounding areas are estimated by using computer models for air pollution dispersal but such treatment suffers from errors in predicting the dust load and failure to take into account the terraced nature of the opencast mine site. The haul roads have been identified as the most prolific source of dust and some recent trials on haul road dust consolidation in Indian mines are mentioned in the paper. Statistics regarding pneumoconiosis cases in Indian coal mines for the last decade are presented to show an increase in reported cases and a gist of the recently amended regulations on the subject of precaution against dust is mentioned.

Jan 1, 1991

By Kennedy G. L

Experience is reporled in the operation of the pilot Lurgi carbonization plant at Morwell, afler it had been reconstructed to obtain better control of the heating of the briquettes in order to produce a strong char suitable for use as a metallurgical fuel. The theoretical Ideal Heating Cycle, which had been designed from earlier laboratory research, was closely approached in the carbonizer, and up to 97 per cent of the whole dried briquettes entering the carbonizer were recovered unbroken in the char.The strength of the char produced in the pilot plant was limited by the performance of the drier where the cracking and breakage of the briquettes was more severe. Theoretical studies have indicated that this limitation could be removed by using a hot briquette feed to the pilot plant. Experience indicates that with a hot briquette feed to the drier and with ideal heating in the carbonizer, hard char could be produced from Yallourn briquettes in continuous operation.The project has been terminated for economic reasons...

Jan 1, 1966

By W. Blake, J. Whyatt

Sixty years of rock bursting in the Coeur d&apos;Alene district has taught painful lessons and led to a number of practical advances in controlling rock-burst hazards. This paper summarizes these lessons, concentrating on practical measures that have been successfully adopted to reduce hazards. These lessons are explained in the context of district mining history and current understanding of rock-burst phenomena. Overall, the paper provides the practicing mine engineer with an appreciation of rock-burst hazards and an overview of practical measures that can be used to control these hazards in the context of Coeur d&apos;Alene district experience.

Jan 1, 2003

By L. Haavanlammi

Iron is a significant component of all copper concentrates leached in the HydroCopperTM process. The metals in the concentrate are leached in a chloride solution by oxidation with cupric ions. Copper enters into the solution as a cuprous chloro¬complex. Iron dissolves at the same time in the ferrous form, but it is immediately oxidized to the ferric state. Oxidation is effected by sparging air or oxygen into the leaching reactors. Because the pH is 1 - 2.5, ferric ion precipitates as akaganeite (T<90°C) or hematite (T> 90°C). Arsenic, antimony and the main part of the bismuth co-precipitate with iron and report to the leach residue. Cupric leaching is faster than iron oxidation; thus, leaching of low-iron concentrates (secondary copper minerals) is quicker than leaching high iron concentrates (chalcopyrite). Pyrite does not dissolve during copper leaching, but is oxidized slowly at higher redox-potentials after the copper has been leached.

Jan 1, 2006

By J. L. Parks

Designs, installation procedures, and performance characteristics of martensitic cast steel concaves are reviewed. Longer wear life, fewer pieces to install, and eliminating the need to scarf joints are the principal benefits of using martensitic steel to replace austenitic 12% Mn (Hadfield&apos;s) steel, the traditional concave material for large gyratory crushers. Installation procedures that reduce the risk of breakage are described. Operating practices that affect concave performance are also discussed.

Jan 1, 1992

By Charles Albert Ashburner

The coal-fields of the United States have been variously classified as to their geographical positions. In 1887 I proposed slight changes to the classification generally used, for more convenient description of our coal-fields in my report on the statistical history of coal in the States during 1886 for the United States Geological Survey. This new classification seems to meet all practical requirements and has been generally adopted. The coal-areas are grouped in two divisions—the anthracite division and the bituminous division. The anthracite division, in a commercial sense, may be said to include the anthracite districts of Pennsylvania alone, although small amounts of anthracite are mined in Colorado and have been

Jan 1, 1890

By M. S. Klima

A 25-mm diameter dense-medium cyclone was tested to investigate the effects of geometry and operating conditions on cyclone performance when processing -150 I&apos;m coal. The emphasis was on examining those variables (e.g., flow rate and inlet velocity) which impact the separation kinetics (specifically the number of g&apos;s and the mean retention time) and the occurrence of apparent bypass. Apparent bypass, indicated by partition curve "tails", results from the short circuiting of the feed coal to one or both of the product streams and represents a loss and/or contamination of the clean coal. This paper presents the results for this series of tests.

Jan 1, 1993

By C. J. Tonkin

Compressed air is widely used on South African gold mines. However, due to recent and proposed future electricity tariff increases it is quickly becoming too expensive to produce and use. Boxfront chute systems at ore passes were focused on during this study, and a number of alternative power sources were examined. After comparing primarily costs, and secondarily safety and practicality, of a number of systems based on water and hydraulic oil, a system making use of either air or water was determined to be the most cost effective. A payback time of 8 years was calculated, which will be significantly less taking into account the avoidance of failures due to electricity and water shortages, which would not affect this system due to its ability to swap between either air or water. It was recommended that this system be installed at all boxfront chutes as soon as possible so that the company can begin to benefit from the cost savings.

Jan 1, 2013