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By Kefton H. Teague

Olivine is a mineral containing a mixture of forsterite (Mg,SiO,) and fayalite (Fe,SiO,) in solid solution. The name "olivine" was first applied by Werner in 1790 (Hunter, 1941) because of the olive-green color of the mineral. Uses The principal use of olivine is in various foundry applications. Perhaps the largest tonnage is utilized as a special foundry sand for mold-making in brass, aluminum, and magnesium foundries (Schaller, 1957, 1958; Snyder, 1957). Olivine was first used as an industrial mineral in the early 1930s for a refractory material (Anon., 1970; Hunter, 1941). As a refractory raw material, olivine was first introduced in the United States as handcobbed, selected, shaped blocks of crude olivine. This use met with limited success. More recently, finely ground olivine blended with MgO and pressed into bricks, which are then fired, have found use in glass tank furnaces and open-hearth furnaces. Ramming or gunning mixes for basic furnace linings also utilize olivine. Olivine has been used in ladle linings with varied success. In Europe, substantial tonnages of olivine are utilized in refractory brick for night storage heaters (Anon., 1970). A limited amount of olivine has been used in the past as a fertilizer (magnesium source) and has been fused with rock phosphate to produce a magnesium phosphate as a plant food. The relatively high magnesia (MgO) content of olivine also attracted attention to it as a potential source of both magnesium compounds and as a source of metallic magnesium (Bengston, 1956; Hunter, 1941). Industries using olivine have not standardized specifications. Normally, producers supply a product which meets individual customer requirements. Such requirements involve type and amount of impurities, grain size of product, refractory characteristics, etc. Geology Olivine occurs commonly as accessories in basic igneous and basic metamorphic rocks. Economic deposits are of magmatic origin and are restricted to essentially the dunite variety of periodotite. Dunites are medium to coarse- grained crystalline rocks, generally reddish brown on weathered outcrop, and are composed primarily of olivine.

Jan 1, 1975

By R. S. Kinasevich, D. D. Crabtree, D. W. Fuerstenau, T. P. Meloy, A. L. Mular

The effect of such variables as feed size, particle shape, cleavage, and hardness on the relative proportion of impact, abrasion, and chipping events in a tumbling mill is demonstrated. The concept of an average event, which is a combination of the three comminution mechanisms, is introduced. It is postulated that the average event in a particular mill determines not only the size distribution but also the energy-size reduction relationship for the comminution process. Fragmentation of particles in tumbling mills appears to result from a combination of impact, abrasion, and chipping grinding.' The relative rates of size reduction attributable to any of the basic grinding mechanisms must depend upon a number of variables, such as feed size, particle shape, hardness, and the number and kind of particles in the mill. The purpose of this paper is to show experimentally how these variables in the properties of materials affect the size distributions obtained by grinding the material's in a laboratory tumbling mill. The resulting size distributions will be intetpreted in terms of a combination of three comminution mechanisms. METHODS AND MATERIALS In this study, minerals of widely differing properties were ground either separately or as mixtures in laboratory mills using rods or balls for grinding media. The materials used include quartz, Tuolomne, limestone (99.8% CaCO3), barite, corundum, galena, pyrite, glass beads, and crushed glass. The mill used was 8 in. in diam. and 9-1/4 in. long. For the ball milling tests, 17.6 kg of steel balls (36: 7/8 in. balls, 178: 1 in. balls, and 44: 1-1/8 to 1-1/4 in. balls) were used. For the rod milling experiments, 17.6 kg of steel rods 9-1/16 in. long (25: 5/8 in., 10: 3/4 in., and 5: 7/8 in. in diam.) were used. In each test, 1 kg of solids were ground wet at 60% solids at 77 rpm. In all cases except where otherwise specified, the feed to the mill was 4 x 8 mesh material. Size distributions of the ground products were determined by a wet-dry sieving procedure with Tyler series sieves. Size distributions of mixed products containing limestone were determined by dissolving the limestone with acid and sizing the residue. EXPERIMENTAL RESULTS AND DISCUSSION If the size distribution of the product from a tumbling mill depends upon the relative proportion of impact and attrition (abrasion and chipping) events, altering the grinding conditions may change these proportions and consequently alter the size distribution of the product. Data to illustrate this point can be taken from Gaudin's classic 1926 paper.2 In one series of experiments, Gaudin ground quartz of different initial sizes for four hours in a laboratory ball mill with 7/8-in. balls. In Fig. 1, his data are reproduced as the cumulative fraction finer than the stated size for the following initial feed sizes: 13.3 x 9.4 mm, 6.7 x 4.7 mm, 2.6 x 1.6 mm, and 0.83 x 0.59 mm. As the feed size was decreased, a dramatic change in the shape of the size distribution curves took place, even though the amount of minus 100-mesh

Jan 1, 1964

By C. A. Queener, W. L. Mitchell

In recent years bismuth telluride has received considerable attention, primarily due to its value as a thermoelectric material. Since there seems to be little dependence of thermoelectric effect upon crystal orientation1 many of those who have previously worked with this material have been unconcerned with knowing its crystallographic angles to any degree of accuracy. However, when one studies deformation modes, lattice stresses, or the aniso-tropy of mechanical properties of a material, knowledge of the interplanar angles and their relationships as depicted in a stereographic projection becomes essential. Lange2 originally published crystallographic data which described the structure of bismuth telluride as rhombohedral with the space group A more recent work by Francombe3 presented data which corroborated and refined the original findings of Lange. In addition, Francombe established that there is no coexistence of rhombohedral and hexagonal lattices in bismuth telluride as was suggested by Vasenin and Konovalov,4 and that the structure can be treated as a pseu do hexagonal structure with an axial ratio, c/a, of 6.95 for convenience of presentation and study. The interplanar angles and standard projections for several unalloyed hexagonal metals have been previously published,5-9 but the present work appears to be unique in that it presents data for a rhombohedral compound in pseudohexagonal form. As a pseudohexagonal structure, this material has an extremely large axial ratio as compared to the usual range of approximately 1.5 to 1.9 for the hexagonal metals. Since the interplanar angles are a function only of c/a, the angular relations between various planes for Bi,Te3 will be grossly different

Jan 1, 1965

By Niels Hansen

The substructure formed by drawing at room temperature in aluminum (99.5 and 99.998 pct purity) and in recrystallized aluminum aluminum-oxide products containing from 0.2 to 4.7 wt pct of aluminum -oxide was examined by transmission electron microscopy, and the flow stress of the drawn materials was measured by tensile testing at room temperature. A sub-grain structure was present after a reduction in area by drawing of 10 to 20 pct, and the subgrain size was observed to decrease with increasing deformation. The tensile data show that the increase in flow stress (0.2 pct offset) by drawing from 10 to 95 pct depends on the reduction in area, not on the composition of the materials. Dispersion strengthening and subgrain bowzdary strengtlzening contribute to the flow stress, and these strengthening processes have been found to be linearly additive. The flow stress (0) can be related to the subgrain size &) by the Petclz relation = uo + k . t, where go is dependent on the composition of the products and k is approximately the same far all materials. THE microstructure of dispersion-strengthened aluminum aluminum-oxide products consists of small oxide plates distributed in an aluminum matrix. The matrix structure depends on the manufacturing history, and in hot-worked as well as cold-worked products the matrix is divided by subgrain (or dislocation) boundaries. For hot-extruded products it has been shown1 that dispersion strengthening and subgrain boundary strengthening are linearly additive, and the flow stress (0.2 pct offset.) at room temperature has been related to the subgrain size (ts) by a Petch equation,2,3 s = so + k . ts-1/2, where s0, increases with increasing oxide content. For cold-worked products containing subgrains no systematic work has been reported, and it was the aim of the present study to examine the microstructure and the relationship between the flow stress and the subgrain size for such products. The behavior of' aluminum aluminum-oxide products depends on the purity of the aluminum matrix, and aluminum of the matrix purity (99.5 pct) was included in the investigation. The literature contains few data about the behavior of this impure aluminum, and aluminum of a higher purity (99.998 pct) was therefore also examined. As regards the relationship between the flow stress and the subgrain size in cold-worked dispersion-strengthened products, no systematic work has been reported. For aged cold-worked structures containing fine precipitates (Fe-Mo carbide) a Petch relation has been found,4 and it has been shown that the k value NlELS HANSEN is Head, Metallurgy Department, Danish Atomic Energy Commission, Research Establishment Riso, Denmark. Manuscriot submitted January 9, 1969. IMD is approximately the same as in iron, whereas the s0 value is higher owing to the presence of the precipi-tates. Investigations of metals such as tungsten,' ferrous metals,4,6 and molybdenum7 cold drawn or swaged at room temperature have shown that the flow stress can be related to the subgrain size by a Petch relation when ts is taken as the subgrain size perpendicular to the direction of deformation. For aluminum no work has been reported on the relationship between the flow stress and the subgrain size after deformation at room temperature, whereas for aluminum tensile strained at different temperatures in the range -183" to 375°C a Petch relation has been found by taking ts equal to the subgrain size.' In the present study two aluminum materials (99.998 and 99.5 pct) and three aluminum aluminum-oxide products (containing 0.2, 1.0, and 4.7 wt pct oxide) were drawn at room temperature to reductions in area from about 10 to about 95 pct. The structures were studied by transmission electron microscopy, and the flow stress (0.2 pct offset) was measured at room temperature. EXPERIMENTAL Materials. The materials are given in Table I together with the chemical analysis. The three aluminum aluminum-oxide products were manufactured from aluminum powder that had been compacted and Table I. Chemical Analysis of Materials Al203 Fe SI Material wt pct wt pct wt pct 99.998 pct* - 0.0004 0.0012 Aluminum 99.5 pctt - 0.36 0.16 Aluminum AlMD13† 0.2 0.16 0.12 Aluminum- -Oxide AlMD105† 1.0 0.26 0.18 Products SAPISML960s† 4.7 0.22 0.19 *Other impurities: O.0004 pct max each of Cu and Zn (supplier's analysis). †Other impurities: 0.03 pct max Cu. 0.02 pct max each of Mn, Mg, Zn, Ti. Table 11. Mean Diameter of Aluminum-Oxide Particles in Extruded and in Cold--Drawn Aluminum Aluminum-Oxide Products Mean Diam. of A1203-Plates* Material State A AlMD105 Extruded 540 Cold Drawn 97 pct 510 SAP ISML 960 Extruded 770 Cold Drawn 95 pct 820 *The standard deviation of the mean is approx. 5 ±pct.

Jan 1, 1970

By R. P. E. Hermsdorf

THE electrolytic refining of metals for the removal of undesirable impurities has become a recognized necessity in the nonferrous field. Copper, lead, zinc, nickel, silver and gold have been produced in this manner for years. The United States Metals Refining Co., realizing that considerable quantities of lead and tin could be made available to the trade if a satisfactory method of purification of these metals could be established, decided to investigate the possibilities of electrolytic solder. In cooperation with Dr. Edward F. Kern, of the School of Mines at Columbia University, the company developed a process of electrolytic refining of lead-tin alloys using a tin-lead fluosilicate electrolyte. A pilot plant was installed in November, 1927, and the commercial unit was put in October, 1929. Since that time thousands of tons of electrolytic solder have been produced in this plant and consumed by all branches of industry that use solder.

Jan 1, 1936

By J. S. Diller

In 1827, chromite was discovered near Baltimore by Isaac Tyson, Jr., who initiated the mining of chrome ore an:! later (1845) .the manufacture of chromium compounds in this country. From 1828 to about 1860 the United States, supplanting Russia, supplied chromite for most of the world. Chrome deposits were found also in California, and the Tyson Company shipped ore to Philadelphia by way of Cape Horn. In 1848, J. Lawrence Smith, an American in the employ of the Porte, discovered large bodies of chromite in Asia Minor. They were developed in 1865 and became the chief source of the world's supply for a number of years. The discovery of the large high-grade bodies in New Caledonia, and later in Rhodesia, with other foreign sources, gives at present an abundant supply for all demands. For a number of years before the great war, the United States produced only a few hundred tons of chromite annually, for local use, but during the war the demand for domestic ore resulted in a production of more than 82,000 long tons of crude ore in 1918, and it was demonstrated that the United States has reserve deposits equal to a war demand of several years' duration. Now that the war is over, the country is conserving its domestic supplies by employing higher-grade but cheaper ore from foreign countries. ChromiUm-bearing Minerals Oxides: Chromite-—chromic iron ore................ FeO.Cr2O3 Picotite—chromic iron ore................. (MgFe)O.(Al,Cr) Chromates: Crocoite—lead chromate................... PbCrO4 Phoenicochroite—basic lead ohromite........ 3PbO.2CrO3 Vauquelinite—phospho-chromate of lead..... 2(PbCu)CrOd.(PbCu)3P2O8 Sulfates: Redingtonite—hydrous chromium sulfate.... Knoxvillitel—hydrous basic sulfate of chromium.............................. Daubreelite-—iron-chromium sulfide (known in meteorites only)...................... FeS.Cr2S3

Jan 1, 1920

By F. V. Lenel

Two years ago in Chicago a seminar was held on the theory of sintering of pure metal powders. As an introduction to this seminar D,.. Rhines1 gave an excellent survey of the literature on this subject, His method of presentatioll was to summarize the experimental observations on sintering and from them to develop a composite theory of sintering in which he combined all the important contributions to the theory into one organic whole. In contrast to the mechanism of sintering of pure metal powders, which, of course, al\vays takes place in the solid phase, sintering j,, the presence of a liquid phase, cannot be treated as one unified mechanism, such as the sintering mechanism of pure metals. The reason is that there are really several mechanisms depending upon the type of alloy system which is sintered and the field of its con. stitutional diagram ill which the sintering takes place, Two mechanisms have heen investigated and will be reviewed in this paper. Ill the first lnechanism the liquid is presellt during the entire time while the compacts are at the sintering temperature, In other words they are sintered between the liquidus and the solidus of the alloy system and are ~e~erogelleous during the entire sintering cycle. The second mechallism applies to alloys in which the liquid phase is formed during the sintering process, but disappears before the sintering process is completed through diffusion and formation of a solid solution. These alloys are therefore homogeneous at the end of the sintering cycle. This second mechanism is more complicated because of the two stages of sintering, the liquid and the solid, as they may be called. It is therefore not surprising that the few detailed investigations of sintering in the presence of a liquid phase have been concerned with heterogeneous sintered alloys, namely the tungsten-nickel-sinter ing which is the so-called "heavy alloy," and the cemented carbides. The mechanism of sintering of these systems is characterized by the fact that theoretical or near theoretical density is attained during sintering, while simultaneously a distinct grain growth takes place through solution of the smallest grains of the solid phase in the liquid phase and reprecipitation on the larger grains. In the first part of the survey this sintering mechanism which is called for short the heavy alloy mechanism is treated in detail. In the second part Of the survey experimental observations for the sintering of homogeneous sintered alloys where the liquid phase disappears before the completion of sintering are discussed. Much less systematic work has been done on these alloys to which the conlmercially important Porous bronzes and the iron-nickel-aluminum permanent magnet alloys belong. Emphasis will be laid throughout this survey upon the microstructural and density changes during sintcring because the Sintering mechanism can usually be described directly by these changes. Other

Jan 1, 1949

By P. A. Larssen, P. R. Gage, R. W. Bartlett

The kinetics of formation of intermediate sili-cide compounds from MoSi2/Mo and WSi2/W couples were studied using a cylindrical sample configuration. Concentration profiles of the constituent metals were deter mined from electron-microprobe analysis of cross-sectioned samples after isotlzernzal diffusion annealing. These data also yielded hand widths of phases. Growth of intermediate phases depends on diffusionin them and obeys a parabolic rate law. The rates of formation of the intermediate phases decrease in the order Mo5Si3 > W5Si3 > Mo3Si. Crowth rates. for the isomorphous phases Mo5Si3 and W5Si3 had the same activation energy. 43 kcal per mole. SILICIDE coatings employed to protect refractory metals from high-temperature oxidation are usually formed by a diffusion process requiring concurrent transfer of silicon to the refractory metal surface. For a simple binary system and a coating thickness of one or two mils, the coatings on molybdenum and tungsten are primarily the disilicides WSi2 and MoSi2, respectively. During use of the coated re- fractory-metal system at high temperatures, in the absence of the silicon source, further diffusion causes growth of lower silicide compounds and depletion of the disilicides. Recent investigations have shown that the lower silicides are less effective than the disilicides in forming a glassy oxide film which impedes oxidation.' Consequently, failure of coatings at high temperatures may coincide with complete conversion of the disilicide phase. The purpose of this part of the study is to investigate the growth kinetics of the intermediate compounds in the W-Si and Mo-Si systems. There are three intermetallic compounds in the Mo-Si system: MoSi2 with a tetragonal structure

Jan 1, 1964

By J. Marvin Weller, M. King Hubbert

Preliminary investigations were undertaken with a Megger Ground Tester in 1931 by Hubbert to determine whether the faults in Hardin County, Illinois, could be located by earth-resistivity surveys. The results of these investigations, which were in part presented before this Institute in 1932,1 were sufficiently promising to warrant a more extensive field program in the same general area the following summer. During the second season an apparatus of the Gish-Rooney type was employed because of its greater sensitivity and to avoid the troublesome correction for resistance of potential electrodes necessitated by the use of a Megger instrument. The discussion of earth-resistivity traverses which constitute the main part of this paper is based entirely upon the results of the second season's work. All of the traverses were made with a constant electrode spacing of a equal to 100 ft., and the four-electrode technique was employed. Successive stations in these traverses were spaced at intervals of 100 ft. and the line of electrodes was carried parallel to the line of traverse. The graphs of resistivity profiles presented here (Figs. 1 to 3) are plotted with resistivities in ohm-centimeters as ordinates and with distance divided into stations at 100-ft. intervals as abscissas. After the traverses were run by Hubbert the results were computed, the profiles plotted, and tentative interpretations were made by him. These curves and interpretations were then taken into the field by Wellcr, who made a careful geological examination along the lines of traverse for the purpose of checking and supplementing Hubbert's interpretations. Weller then constructed a geologic cross-section extending along the line of each traverse. The accompanying diagrams graphically illustrate the correlation that can be made between earth resistivity and geology in this area.

Jan 1, 1934

By M. E. Wadsworth, T. L. MacKay

Sintered UO, samples were leached in sulfuric acid solutions of various concentrations. A pressurized system was used so that it was possible to investigate the kinetics of the reaction to 270°C with oxygen overpressures as high as 900 psi. The rate was observed to be a function of the concentration of hydrogen ions and directly proportional to the partial pressure of oxygen. Evidences are presented which indicate that a UO2 surface site reacts with a molecule of water to form a hydroxyl complex which in turn can dissociate with the characteristics of a weak acid. A rate determining step has been proposed which involves the reaction between an oxygen molecule and the hydroxyl complex on the surface of UO,. ThE 2 principal methods for uranium dissolution are carbonate and acid leaching. The sulfuric acid leach is the more popular and is used for the treatment of the majority of the ores of Africa, Canada, and the United States. Low recoveries in basic leach circuits led investigators at the University of British columbia1 to study leaching of uranium ores in pressurized vessels. Early in the study of dissolution of uranium it was found that only uranium in the hexava-lent state could be leached in acid or basic circuits. Therefore, the use of oxygen over-pressure in an autoclave offered an interesting approach to solving the low recovery problems of carbonate leaching. UO, was used in this study because it could be obtained in high purity and also because it is representative of the most refractory of the primary uranium minerals. A pressurized system was used to provide a means whereby important temperature and pressure parameters could be varied for the evaluation of the kinetic processes. The mechanism for the dissolution of UO2 should be similar for any of the uraninite type minerals. At the present all of the kinetic studies that have been conducted have been in carbonate media. Peters and Halpern2 carried out a kinetic study of the leaching of pitchblende. Their specimens were pitchblende ores selected on the basis of high grade and homogeneity. Pearson and wadsworth3 conducted a kinetic study of the dissolution of UO2 in carbonate solutions with results very similar to those obtained by Peters and Halpern. EXPERIMENTAL The UO2 as received* was found by spectroscopic *Mallinckrodt reagent, supplied by the Atomic Energy Commission. analysis to have a purity of 99.94 pct 0.03. It was ground in a mechanical agate mortar and screened through a 400-mesh sieve. Thin flat disks of UO2 were prepared by pressing the sized powder in a specially constructed die at a total pressure of approximately 25 tons per sq in. The pressed disks were approximately 0.25 cm thick, 1.6 cm diam, and 3.5 g in weight. As pressed, the samples were approximately 65 pct of theoretical density. It was essential that a binder such as poly-vinyl alcohol be added before pressing to prevent formation of cracks when fired. It was found by trial and error that pressed disks sintered close to 1870°C in a hydrogen atmosphere, reach densities between 91 and 91.5 pct of the theoretical density. At this density the samples had no measurable porosity based upon a 2-hr emersion in boiling water. An X-ray examination of these sintered UO2 disks showed them to be identical with the original UO2 received. Reaction of UO2 with the alundum furnace core was prevented by placing molybdenum between the samples and the core according to the method of Corwin and Eyerly.4 Leaching studies were carried out in a specially designed autoclave, the details of which have been presented e1sewhere.6 The main features of the equipment as applied to a kinetic study are: 1) solution samples may be removed during the course of a single run; and 2) temperature and agitation are carefully controlled. Two-ml samples removed from the autoclave during the course of a run were analyzed for U3O8 content with a Beckman model DK-2 spectrophotometer by the method of

Jan 1, 1959

By Robert Glass Cleland

THE OUTBREAK of World War II found Phelps Dodge, thanks to both foresight and good fortune, in a position to increase production of its mines and factories to meet the insatiable military and domestic needs of the times, far beyond all previous records. With the timely completion of the expansion program at Morenci, the company's copper output rose to approximately 447 million pounds in 1942 and to over 478 mil- lion pounds the next year, compared to some 300 million pounds in 1939. To meet the civil and military needs for fabricated cop- per products, the Phelps Dodge Copper Products Corporation carried out an expansion program comparable in size to that of the Phelps Dodge mining operations. It built new plants, enlarged and reorganized those already in operation, multiplied the number of technical experts on its staff, adopted new methods and new machines for the new prod-

Jan 1, 1952

By J. J. De Witte, J. G. Cazort

The Paranam plant in Surinam (formerly Dutch Guiana) was built during 1939-40 to supply crushed and dried bauxite for the growing U.S. aluminum industry, supplementing production from the Suriname Aluminum Co.'s Moengo works, which began operation in 1922. A subsidiary of Aluminum Company of America, Suralco's total annual production from these two plants averages 2.55 million dry metric tons of various grades of bauxite. Starting in 1941 with bauxite from mines on the west side of the Suriname River, annual production at the Paranam plant has varied from a low of approximately 450,000 tons to more than 1 million tons in 1949. High production rates during World War II and the late 1940's rapidly depleted these reserves, and in 1950 plans were made to mine the known deposits on the east bank of the river, about five miles downstream from the original Paranam plant.

Jan 11, 1960

By Edwin S. Smith

Current research in the phenomenon of liquefaction has indicated some of the in situ material properties which should be considered in the planning of waste deposits. Practical experience in tailings disposal, however, must be combined with the results of theoretical and laboratory studies to develop the most economical and safe techniques against liquefaction failure. One of the many responsibilities of mining engineers and mill superintendents is providing for the safe and economic disposal of wastes (or tailings) that remain after a mineral has been extracted from an ore. The cost of disposal of these tailings exerts a considerable influence on the minimum grade of ore extracted from the mine. It varies to a great extent with each project and is dependent on many diverse factors, such as the local topographical, meteorological and seismological conditions together with the applicable water pollution laws of the area. The process used to extract a mineral from an ore determines the physical characteristics of the tailings and, thus, is one of the more important factors to be considered in the planning of disposal facilities. Today's trends in ore-processing operations complicate the problems of waste disposal: recently developed extraction methods result in the production of finer tailings, the use of lower grade ores produces greater volumes of wastes, and the enhanced land values in the vicinity of industrial plants preclude the former practice of spreading wastes laterally and force the expansion of waste deposits upwards to greater heights. The frequent occurrence of stability problems in waste deposits indicates that many mining organizations may not be employing current soil mechanics concepts and practices. One of the most spectacular, and often most disastrous, types of tailings dike failure is that resulting from liquefaction of the fine particles combined with a breach of the main retaining dike. TAILINGS DISPOSAL Since the many variations in site conditions, ore bodies and extraction processes dictate the general disposal procedures and mill superintendents incorporate special facilities to provide the most economical disposal method consistent with accepted safety standards, it is only natural that there are almost as many different disposal techniques as there are disposal areas. Methods used in the construction of retaining dikes include: (1) transporting granular material from an adjacent borrow pit and (2) mechanically segregating the total effluent and allowing the coarse fraction to form a retaining dike by hydraulic deposition. The location of a plant and the surrounding topography exert the greatest influence on the layout of tailings disposal facilities. Most of the above-ground waste deposits can be classified as side-hill, (Fig. 1,) cross-valley, (Fig. 2,) or stockpile deposits. Side-hill disposal areas are probably the most common type of layout because of the natural advantage of gravity flow, without the disadvantage of river diversion usually needed for tailings ponds formed behind cross-valley dikes. Stockpiles, which are placed on relatively level ground, require four retaining dikes and the effluent generally has to be pumped up into the disposal area. Changing production techniques or developments adjacent to disposal areas have produced variations or partial combinations of these three categories. In a series of articles, Lenhart describes many of the problems encountered in the disposal of tailings and certain innovations used to overcome them. He discusses weaknesses in design and layout and shows that disposal techniques are often learned the

Jan 1, 1970

By AIME AIME

THE following Officers, Directors, and guests were present: Herbert Hoover, A. R. Ledoux, Henry S. Drinker, Edwin Ludlow, Samuel A. Taylor, Charles F: Rand, William M. Corse, Arthur S.. Dwight, Glen H. Clevenger, L. W. Francis, F. G. Cottrell, Bradley Stoughton, Percy E. Barbour, E. P. Mathewson, Dorsey A. Lyon, Archibald Douglas, A. D. Flinn, RobertLinton, James F. Kemp, William Y. Westervelt, J. W. Richards, W. L. Saunders, George Otis Smith, Thomas T. Read, J..C. Murray, Ralph Arnold. A Committee on Mine Equipment was appointed composed as follows: Graham Bright, chairman, William Kelly, Howard N. Eavenson, R. E. Hobart, and S. P. Rumsey. B. D. Saklatwalla was added to the Committee on Miscellaneous Metals and W. Spencer Hutchinson was added to the Committee on Mining Geology. A revised budget for 1921 was approved. A petition duly signed to amend Section 1., of Article III of the Constitution, increasing the initiation fees from ten dollars to twenty dollars, was approved by the Board.

Jan 1, 1920

[RALPH ADAIR Ore Dressing Consultant Bull Mtn. Rd., Asheville, N. C. Phone 4-1693 JAMES A. BARR Consulting Engineer Mt. Pleasant, Tennessee Washington, D.C. BEHRE DOLBEAR & COMPANY Consulting Mining Engineers and Geologists It Broadway New York 4, N. Y. I. R. BERENT Engineering Consultants and Contractors Mineral Exploration, Mine Evaluation, Mine Designs and Mine Management 156, Ataturk Bulvari-Ankara, Turkey BLANDFORD C. BURGESS Registered Professional Engineer Mining Consultant Monticello, Georgia GLENVILLE A. COLLINS Mining Engineer Uranium examinations Cable "Coins" 8 Howard-Canfleld Bldg. Santa Barbara, Calif. COWIN & CO. Mining Engineers and Contractors Consulting Shaft & Slope Sinking Appraisal Mine Development Reports Mine Plant Construction I-lath St. S. W. B'ham, Ala., Phone 56-5566 MILTON H. FIES Consulting Engineer Rooms 1201-2. Albama Power Co. Bldg. Birmingham, Alabama]

Jan 1, 1952

By L. F. Marek, G. W. King, A. Bogrow

THE purpose of this paper is to present the data and some interpretation of the results of a laboratory study of the reduction of iron ore and the deposition of carbon from the reducing gas mixtures in such reductions. One major object of the study was to determine the effect of gas pressures on these chemical processes. Effort was made to approximate the conditions of temperature, gas composition, linear and mass gas velocities, pressure range, and extent of reduction prevailing in commercial blast furnaces. The results show that the reduction of Fe203 proceeds by two steps, largely consecutive under the conditions used herein: reduction of Fe203 to FeO, and reduction Of FeO to Fe. Unless the gas has a CO/CO2 ratio greater than 2.1 only the first step occurs under these conditions (850°C) but the following generalizations apply to either step or to the combination. The rate of reduction of relatively fine ore particles at any time is proportional to the mass rate of supply of CO (provided some of it is thermodynamically available) the rate therefore is proportional to the linear velocity at constant pressure, or to the pressure at constant linear velocity. Thus, the rate of reduction may be increased without increase in linear velocity f the reducing gas by increasing the mass velocity of the gas and increasing the pressure correspondingly to avoid any increase in the linear velocity. The rate "constants"-i.e., the efficiency of conversion of the "available" CO supplied-is not actually constant but decreases as the reduction proceeds, and is a function only of the state of the ore; i.e., of the amount of reduction already accomplished and hence of the amount of CO passed. The particle size Of ore used in nearly all the experiments was relatively small (8 to 14-mesh). The rate of reduction in run 16 with 3 to 8-mesh ore particles is within experimental error the same as with the finer ore. Although this would indicate an absence of effect due to particle size in this range of ore particles, it is desirable to have more data on other ore sizes and on ore of different densities before arriving at any generalizations on this point. Although it is possible to extend the analysis of these results to consideration of the more detailed kinetics and mechanism of iron oxide reduction, such extension is beyond the scope of the present paper. From the experiments on carbon deposition, it was evident that if carbon deposition is increased at all by the application of pressures up to 10 psi ga., such increase appears to be less than the experimental and analytical error. It appears safe to conclude that at top pressures on the order

Jan 1, 1947

By Charles W. Henderson

THE influence of mineral production on the development of the western United States has been profound. From 1848 to 1860, there was only gold production, the effect of silver began in 1860, and from then on both had a powerful influence. Lead production started in 1863, copper in 1863, and zinc in 1885, but was small until 1898. Gold alone was therefore the stimulus of the early settlement and exploration of the Western States.. But mineral deposits caused neither acquisition of territory nor determination of boundary lines. Arizona, California, Nevada, New Mexico, and parts of Utah, Wyoming, and Colorado were formally acquired from Mexico fourteen days after the actual date of the discovery (January 19, 1848)1.2 of gold at Sutters Mill, near the present town of Coloma, California (a discovery which, with the immediate new discoveries, aroused the world several months later) ; but the acquisition was by treaty (under negotiation for some time but signed February 2, 1848)3 in settlement of a war involving the boundaries of the grassy plains of Texas, an area at that time not known to contain any metals, and to date found to have but few metal deposits.4 The international boundary at 49º latitude for the far northwest states was determined by causes other than mineral deposits.

Jan 1, 1933

Striving to do a better job of ad- ministering the letter and spirit of the Federal Coal Mine Health and Safety Act of 1969, the Interior Department recently invited criticism-and got it. The criticisms were voiced on July 1 and 2 at the first of a series of public meetings being held by the Office of Hearings and Appeals at the Department's behest. Later meetings, at which all interested parties are invited to comment, are to be announced in the press and the Federal Register. Persons wishing to participate in the meetings should contact the Director, Office of Hearings and Appeals, 1015 Wilson Blvd., Arlington, Va. 22203. At the first Hearing, USBM Director Elburt F. Osborn outlined the progress his agency has made to date in implementing the law on three fronts: enforcement, education and research. Since the Health and Safety Act became law on December 30. 1969, he said, the Bureau's force of inspectors has grown from a mere 300 to almost 1100, while mine inspections have increased from 10,265 in 1970 to 11,021 for the first six months of 1971. On the educational front. Osborn said, the Bureau now has some 60 instructors who have trained about 50,000 miners in safety procedures since March 30. 1971. Classes at the new Federal Mine Safety Academy for both government and industry personnel begin on September 1, 1971. he added. Health and safety re- search, meanwhile, has been allot- ted $20.1 million for the 1971 Fiscal Year. Of this, $8.1 million is assigned to the Bureau and $12.3 million to contracts with universities and private companies. Admittedly, Osborn said, the mine fatality rate is still unacceptable, hut it was lower in the first half of 1971 than ever before---0.73 per million man hours and 0.31 per million tons of coal.

Jan 1, 1971

By Gary E. McIntosh

This paper will discuss a US Bureau of Mines project designed to assess and predict the impacts which surface coal mining will have on the regional shallow groundwater systems in the Powder River Basin. The primary objective will be met through the accomplishment of the following: (1) The design and establishment of a regional network for monitoring shallow groundwater systems in the basin; (2) monitoring the direction and rate of flow, water quality, and aquifer characteristics of the shallow groundwater systems; and (3) development of a regional groundwater simulation model, with appurtenant subroutines to determine local effects.

Jan 1, 1980

By Ralph M. Barnett, Albert K. Smith

During the last few years, a great deal of interest has been aroused in the use of more refined blasting techniques. It has been the effort of many mining companies to reduce powder cost, obtain better rock breakage, reduce drilling costs and provide safer working places. With the advent of new types of powder and such techniques as cushion blasting, line blasting, smoothwall or soundwall blasting, and presplitting or preshearing, these goals are approaching reality. Smoothwall blasting and presplitting have re- ceived much attention at the Climax Molybdenum Co., Climax, Colo., mine because of the large cost factor involved. An experimental program was begun in 1961, and during 1964 to the present has been used in many working areas. Some spectacular results have been achieved by the operating personnel in hard ground, but the most beneficial results have been in areas where the ground has been soft and highly fractured.

Jan 7, 1965