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By Melford H. Salsbury

The maximum net return from the sale of ores and concentrates of gold, silver, copper, lead, and zinc accrues to the producer when these mine products are marketed to the best advantage. Data are presented that the producer, especially the small mine operator, can use to survey available markets and make a preliminary estimate of the net return to be expected from an ore, on the basis of typical mill, smelter, and freight schedules. A review of the industry is presented by States in which recent production statistics are given, marketing facilities are discussed, and locations of principal mining districts, custom mills, and smelters are shown. Explanations of treatment processes, ore types, treatment charges, payments for metals, and deductions are given. Published rail and truck freight rates for mine products, based on marketing patterns developed over many years, are listed and explained.

Jan 1, 1964

By R. A. Cummings

Certain roof shales in coal mines deteriorate upon exposure to the atmosphere, causing difficulties in the mining operations and adding to the cost. This report presents the results of both field investigations, in a West Virginia mine, and laboratory studies on the effects of atmospheric moisture on roof shales. Based on these observations, a conceptual procedure is presented on how shale deterioration might be predicted during exploration, and guidelines are given as to how air tempering or conditioning chambers may be designed to reduce moisture effects. Recommendations for further studies are included. An annotated bibliography of the literature constitutes the second volume.

Jan 1, 1981

By Will H. Coghill, G. Dale Cole

"INTRODUCTION This paper describes a method for the rational sorting of particles by means of a laboratory batch jig. Its purpose is to show that a material can be reliably appraised for gravity concentration without the drudgery of sink-float fractionations.Development of the batch- jig method of testing was incidental to a study of the Birmingham, Ala., red-iron ores now being conducted by the Bureau of Mines in cooperation with the University of Alabama and the ore-producing companies.APPLICATIONOres and coal are commonly tested for their gravity-concentration characteristics by specific-gravity dissections in heavy liquids. The heavy liquid most commonly used for coal is zinc chloride and for ores they are benzene, carbon tetrachloride, acetylene tetrabromide, methylene iodide, and thallium malonate formate. The last is poisonous and corrosive to the skin but is essential for separations in the 3.3 to 4.4 specific gravity range. The last two of these liquids are expensive, and several of them are hard to obtain now.Although it is not suggested that heavy-liquid dissections be eliminated entirely, sometimes a more reliable evaluation of coal and ore can be obtained by other and more simple means. For example, sink-float data were unsatisfactory as a guide to commercial gravity concentration of a red-iron ore because they did not take into account the difference in particle shape of the hematite and gangue and the differences in true and apparent specific gravity of the hematite grains, some of which were porous. For this ore, the batch-jig method of testing herein discussed proved advantageous. Not Only did the batch-jig data give a truer picture of the concentration problem, but only about one-tenth the time of the conventional sink-float tests was required."

Jul 1, 1944

By R. P. Walters, M. J. Lynch, D. R. Flinn

The Bureau of Mines evaluated tthhee feasibility of substituting platinum- coated metals for bulk platinum shapes as a means for conserving platinum . Platinum coatings were prepared using four different methods of electrodeposition , then tested and evaluated . In order for platinum coatings to be useful in process environments , they must be thick , adherent , stress - free , and pore - free . The Bureau evaluated direct - current , current reversal , cathode shielding , and pulsed- current plating techniques for producing a pore-free platinum electrodeposit from a molten cyanide bath . Aqueous corrosion tests of Fe - 10Cr substrates coated with approximately 25 μm of platinum showed that pulse plating yielded the most corrosion- resistant and , hence , the most pore -free coatings . The morphology of coating cross sections was in all cases columnar . The average grain size of pulse -plated deposits was independent of thickness , while all other plating techniques produced grains that increased in size as the coatings became thicker . It is believed that the constant grain size in the pulse - plated deposits resulted from better mass transport during the electrodeposition .

Jan 1, 1965

By A. J. Strazisar

The Bureau of Mines conducted a laboratory investigation to study the effectiveness of low-pressure steam and water spray in suppressing respirable dust at the tips of a saw-type cutting wheel. Suppression efficiencies were found to be proportional to the amount of the water or steam applied at the cutter tips. For equivalent water output rates, a maximum efficiency of approximately 80 percent was reached for both steam and water spray. Results from the steam and water spray tests showed an increase in suppression efficiency with an increase in particle size of 1 to 8 micrometers. The data indicate no advantages for using steam as a dust suppressant.

Jan 1, 1972

By R. Hogg

"The basic population balance models for agglomeration processes are reviewed and procedures are described for extending their applicability to systems with size-dependent rate constants and to the formation and growth of porous agglomerates from rigid, solid-particles. Simplified procedures for the further extension of the models to include simultaneous agglomerate growth and breakage are also described.INTRODUCTION The association of small particles into clusters or agglomerates is a significant factor in many facets of particle processing. Agglomeration processes are widely used to facilitate handling, storage and utilization of fine powders. Processes such as coagulation or flocculation are used to aid solid-fluid separation in dispersed particulate systems. Agglomeration also occurs as an accompaniment, often unwanted, to other particulate processing operations such as fine grinding, mixing and blending, transport and flow.Reliable agglomeration models are needed for improved understanding of the processes in general and of the complex role of numerous, interacting variables as well as for direct application to the design and control of industrial processes such as flocculation, granulation and pelletization. Ideally, the models should account for the primary forces responsible for agglomerate formation and growth, the effects of external forces on process dynamics, the development of agglomerate structure and its role in the process itself, and the effects of concurrent processes such as structure modification (e.g. compaction) and agglomerate breakage or degradation."

Jan 1, 1989

By T. F. Mitchell, J. V. Batty, R. R. Wells, R. Havens

"INTRODUCTION )ne of the most important wartime activities of the Bureau of Mines was the search for new sources of minerals necessary to the prosecution of the war. As a part of the investigation of strategic mineral deposits in the United States under the Strategic Minerals Act (Public 117, 76th Cong., 1st Sess., Ch. 190), examining engineers of the Bureau of Mines investigated and sampled various deposits of chrome ore in California, Idaho, Montana, Oregon, and Washington, and those deposits that warranted further study were explored by diamond drilling, trenching, and drifting, as re¬quired. During these investigations, samples were submitted to the Ore Dressing Section of the Salt Lake City Station for metallurgical testing. This paper gives data summarizing results obtained from laboratory ore-dressing studies of the chrome ores submitted.Although the deposits range widely in geographical location, the mineral occurrence of all of them is strikingly similar. Chromium, in all of the ores tested, is present as impure chromite or chromium spinel. Although pure chromite (FeCr204 or FeO.Cr203) contains 68 percent chromic oxide, the iron may be replaced in varying amounts of magnesium, and the chromium may be replaced similarly by aluminum and ferric iron. In studying concentration methods as applied to chrome ores, the composition of the chrome mineral is of fundamental importance, because it is manifestly impossible to produce a high-chrome concentrate from a low-chrome chromite by any mechanical process.In all but one of the ores, the gangue material consists of olivine or altered olivine minerals such as serpentine, antigorite, and chrysotile. The exception, the Antelope or from Montana, has a gangue chiefly composed of actinolite, chlorite, and talc."

Jun 1, 1947

By M. L. Williams

In recent years the use of visual aids has expanded the? field of safety education. This is a modern adaptation of a method employed in ancient times, when simple paintings and drawings were the only means of recording current events. In its present application, visual aid employs sound and silent motion pictures, stripfilms, lantern slides, descriptive posters, and color. According to Roberts,3/ "Visual education is a method of imparting information which is based on the psychological principle that one has a better conception of the thing he sees than of the thing he reads about or hears discussed." Dent4/ further defines visual aid as "all the materials used to facilitate the understanding of' the written or spoken word."

Jan 1, 1951

By M. H. Kline

The Great Gossan Lead in Carroll County, Va., is one of the largest undeveloped sulfide ore bodies known in the eastern United States. It extends for 16.7 miles along the western slope of the Blue Ridge Mountains (fig. 1). The various known segments of the deposit, extending from the southwest end to the northeast, are: The Great Outburst or Iron Ridge segment, Chestnut Creek, Copperas Hill, Sarah Ellen, Wild Cat, Cranberry, Dalton Hill and offset segment to the south of the Cranberry, Little Reed Island, Little Vine, and the Betty Baker at the northeast end. All of these segments have been explored or mined to various extents in the past for the iron gossan and secondary copper ore. The Great Outburst or Iron Ridge segment is now being mined by the General Chemical Division of the Allied Chemical & Dye Corp. for the sulfur and iron content of the primary ore. These deposits are becoming increasingly of Interest as a. large potential source of iron and sulfur owing to their proximity to Birmingham, where the burned cinder sells at a premium, and to the acid markets of the region.

Jan 1, 1949

By Michael V. Markel

This report summarizes work performed under USBM Contract No. J0100047 revealing the performance characteristics of a composite-type resilient screen deck. The ability of the composite to perform or compete with steel in noise attenuation and longevity was of interest. Tests were conducted at the River King Preparation Plant of Peabody Coal Company. This facility was chosen because it provided parallel process flow and met standard coal cleaning requirements. Comparisons could be made between the adjacent resilient and steel screen decks under similar operating conditions. Noise reductions of 1-6 dBA were realized in the near field. Although the test period did not determine resilient screen life, indications are favorable for their longevity.

Jan 1, 1981

By Lex B. Golden

The purpose of this investigation was to evaluate the corrosion properties of certain alloys of titanium and to compare them with those of unalloyed titanium. Such information should make it possible to determine the desirability of substituting these alloys for commercially pure titanium in certain applications. Titanium-manganese, titanium-chromium-iron, and titanium-vanadium-iron alloys, with 2 types of unalloyed titanium, I consolidated by arc melting and the other by powder-metallurgy techniques, were included in the study. Tests were carried out in sulfuric, hydrochloric, phosphoric, nitric, and mixed acids and in chloride solutions. All solutions were saturated with air.

Jan 1, 1957

By J. C. Gerdeen

A new analytical model for the shear stiffness at a joint of the fully-grouted resin roofbolt is developed using the Theory of Elasticity and an analogy to a beam on an elastic foundation, Gerdeen [2]. The model developed in this study treats the elastic foundation modulus of the resin as being composed of both an elastic rock and an elastic resin. All previous attempts have neglected the elasticity of the rock and treated only the resin. A three dimensional finite element model of the bolt-resin-rock system is developed also and comparisons are made between the predictions made by it and the analytical solution. It is found that the agreement between the two representations ranges between 1.2% and 10.5%, with the greater differences being observed for systems of very large or very small bolt diameters and resin annulus thicknesses. Since such configurations are not the rule in practice parameter studies are performed using the analytical solution with the finite element solution being used as a check. For a 0.75 in. bolt, a resin annulus thickness of 0.1375 in., a resin with E = 7 x 105 psi and -1) = 0.210, and a rock of modulus E = 6.8 x 106 psi and V = 0.159 the shear stiffness is found to be 1.220 x 106 lb,/in, from the analytical solution and 1.245 x 106 lb,/in, from the finite element model. Applying the finite element model to the problem of the axial stiffness of the fully-grouted resin roofbolt a value of 6.002 x 106 lb./in. is obtained which proves to be at least 50% higher than any of the now existing analytical predictions.

Jan 1, 1976

Wires leading to or from underground facilities can develop hazardous voltages because of lightning exposure. The locations of many mine portals are particularly susceptible to lightning effects. The application of protective devices to limit this potential danger is necessary.

Jan 1, 1975

By Victor R. Spironello

The Bureau of Mines has conducted studies of the slags related to ferrous technology to evaluate experimentally acceptable substitutes for the auxiliary flux, mineral fluorspar, in steelmaking operations. Comparative heats were made in a 1/4-ton, pilot-scale, basic oxygen furnace (BOF) to evaluate a waste material known as "used potlining." Used pot lining is recovered from alumina reduction cells after its useful life and contains significant levels of fluorine and sodium in various compounds. This material in both lump and pelletized form provided adequately fluid slags, based on observations made during BOF operation. No adverse effects were found on furnace performance, metal and slag chemsitry, the strength of the steel produced, or the environment. Fluorine recovery in the slag was about the same as that obtained when using fluorspar, as were the losses to the scrubber water and solids. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag. The sodium recovered in the slag apparently also contributed to fluidity, since the fluorine input was at about two-thirds that of the fluorspar. Used potlining was determined experimentally to be a satisfactory substitute for fluorspar in basic oxygen steelmaking.

Jan 1, 1982

By R. Hogg

"The basic population balance models for agglomeration processes are reviewed and procedures are described for extending their applicability to systems with size-dependent rate constants and to the formation and growth of porous agglomerates from rigid, solid particles. Simplified procedures for the further extension of the models to include simultaneous agglomerate growth and breakage arc also described. IntroductionThe association of small particles into clusters or agglomerates is a significant factor in many facets of particle processing. Agglomeration processes are widely used to facilitate handling, storage and utilization of fine powders. Processes such as coagulation or flocculation are used to aid solid-fluid separation in dispersed particulate systems. Agglomeration also occurs as an accompaniment, often unwanted, to other particulate processing operations such as fine grinding, mixing and blending, transport and flow.Reliable agglomeration models are needed for improved understanding of the processes in general and of the complex role of numerous, interacting variables as well as for direct application to the design and control of industrial processes such as flocculation, granulation and pelletization. Ideally, the models should account for the primary forces responsible for agglomerate ·formation and growth, the effects of external forces on process dynamics, the development of agglomerate structure and its role in the process itself, and the effects of concurrent processes such as structure modification (e.g. compaction) and agglomerate breakage or degradation.In its most general form, the process of agglomeration involves taking discrete, independent particles, bringing them into contact with one another, promoting (or allowing) interparticle adhesion to occur and then causing structure rearrangement, usually under the action of external forces. The relative importance of these steps varies with the nature of the particulate system being agglomerated and with the kinds of agglomerates being produced. Coagulation or flocculation of particles dispersed in fluids is generally dominated by the contact and adhesion steps. In the granulation of powders, on the other hand, particles are already in contact so that structure rearrangement is the principal step."

Mar 1, 1992

By R. L. Crosby

The effect of indium on the solid solubility of calcium and of silicon in magnesium was studied using metallographic, X-ray diffraction, and electrical resistivity techniques. The addition of 2 weight-percent or more of indium reduced the solid solubility of calcium in magnesium by forming a compound containing indium and calcium. Indium additions have no perceptible effect on the solid solubility of silicon in magnesium.

Jan 1, 1963

By Earl F. Hastings

The Pilgrim mine, operated by the Pioneer Gold Mining Co., is 9-1/2 miles west of Chloride in the Pilgrim mining district on the eastern slope of the Black Mountains, or River Range, Mohave County, Ariz. In March 1937, 100 tons of gold ore per day were being mined and milled at the property by a total force of 5i men. Climatic conditions allow year-round operations. Due to present activity in the county there is an ample supply of labor for the requirements of the mine. The Pilgrim is the only producing property within s radius of 6 miles; recently, however, the South Pilgrim Mining Co. has launched a development campaign on claims that adjoin the Pioneer Co. property to the south.

Jan 1, 1937

By R. E. Campbell

Uranium metal of improved purity was prepared by electrorefining commercial magnesium-reduced uranium in a molten sodium chloride-uranium trichloride electrolyte. The best operating conditions for the preparation of refined metal were established as follows: an electrolyte containing 8.7 to 13.3 weight-percent uranium; initial cathode current densities from 300 to 1,500 amp/sq ft; and a molten salt temperature of 860° C. Ingots produced from electrorefined uranium crystals prepared with these operating conditions were substantially free of metallic impurities. The only impurities in the refined and consolidated metal were present in low or undetectable amounts.

Jan 1, 1965

By E. D. Eastman

"The factors that determine the efficiency of reduction of iron oxides by gaseous reducing agents may be considered in two classes; those which effect the equilibrium between the reacting substances end their products, and those which affect the rete of reaction. Both sets are of prectical importance, the former as influencing the maximum possible efficiency and the latter as determining what fraction of the maximum yield may be readily or profitably obtained. In addition, the thermal changes attending the reduction greatly affect the chance of successful industrial application of any such process, and knowledge of them is necessary for the intelligent design of apparatus and control of the reaction. Some aspects of each of these three divisions of the problem are discussed below.I. The Maximum Reducing Power of Fuel Gases on the Oxides of IronsThe gases that heve been considered specifically in this work are coal gas, water gas and producer gas, typical analyses” of which are given in Table 1 Of the various hydrocarbons represented in Table 1, (several being grouped or averaged as C2R4), methane is the only gas assumed to be capable of existence at appreciable pressures under the conditions of interest here. The equilibria in the several systems which may ensue when one of the above gases is allowed to react with the iron oxides, may therefore be represented in the most general case by equations of the type of the following arbitrarily chosen ones:"

Jun 1, 1923

By R. H. Dickson

This paper, which describes the milling practice of the Verde Central Mines, Inc., is one of a series on milling methods and costs being prepared by the United States Bureau of Mines. GENERAL DESCRIPTION The Verde Central concentrator is located in Walnut Gulch, about 1 mile west of Jerome, Ariz., and on the Jerome-Prescott highway. It is about 1,000 feet distant from the main shaft of the Verde Central mine and treats ore from this mine only. The mill is connected with the main shaft of the mine by a 24-inch gave railway, over which the ore is hauled in 5-cubic yard capacity, rocker, side-dump cars, by a 3-ton Brookville gasoline locomotive.

Jan 1, 1931