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By C. W. Davis

This report follows the same general scheme as did its predecessors; it begins with a dissertation on some phase of ore-testing, continues with results of investigations of ore-treatment methods and of metallurgically important analytical processes, and concludes with an exposition of tests made by established methods on typical ores selected as representative of certain mining districts. One of the first things that is done after an ore has been received is to look at it under the microscope. Microscopic examination serves as an important complement to chemical analysis in interpreting the percentage composition in terms of minerals. If it has been found difficult to treat an ore, the reasons for this action and indicated methods to overcome the difficulties may be ascertainedd by testing with a microscope. For example, failures in selective flotation have been traced to intimate mineral association and changes in mineral surfaces through incipient oxidation. The importance of surface stains or tarnishes and the presence of adhering slime particles have been found to be responsible for the difficulty experienced in the treatment of certain gold ores.

Jan 1, 1938

By Lloyd A. Morley

This final report concludes the documentation under Grant G0155003 and details research not covered under foregoing report volumes. The first chapter lists all other reports. The following chapters are divided into three major research tasks: Continuous Safety Monitoring Systems, Battery and Battery-charging Safety, and Mine Power System Transients. The monitoring chapter discusses the prediction of power-system failures. The battery chapter details work on battery-box stresses, battery chargers, and the elimination of electrocutions. The final chapter covers transient instrumentation, distribution transients sources and suppression, and utilization transients on mine power systems.

Jan 1, 1981

By T. A. Clancy

Since many new mineral processing systems under development can impose severe corrosive conditions on construction materials, the Bureau of Mines reviewed and assessed the literature on corrosion resistance of ceramic materials. Corrosive conditions were categorized as: (1) acids and aqueous solutions, (2) glass and slag/metal melts, and (3) gases. Information on the corrosion resistance of ceramic materials, generally, is disseminated by many sources, each of which is interested in specific corrosive environments. Based on this survey, it was noted that (I) the development of standardized tests is needed to study solution-type corrosion of ceramics, (2) slag/melt corrosion data are the most comprehensive of the available data, and (3) better definition of corrosion mechanisms In gaseous environments is needed.

Jan 1, 1980

By R. V. Higgins

A numerical method is presented to calculate the isopressure (isobar) lines and streamlines for an oilfield from the pressure distribution. A knowledge of these lines is useful in the study of the flow of fluids in underground reservoirs, especially for those containing gaseous and/or liquid hydrocarbons. This work was done primarily to enable determination of the shape factors needed in the calculation of petroleum reservoir performance. However, it has application for the flow of water in aquifers, or electricity or heat in odd-shaped geometry. Techniques previously developed were used to calculate the pressure distribution. From this pressure distribution, the isopressure lines were calculated accurately by the method presented in this paper. Then by successively projecting orthogonal lines from one isopressure line to another, the streamlines are determined. From the coordinates of the isopressures and the streamlines, the shape factors can then be determined by a published method. Computer methods are presented to calculate the streamlines and isopressures for any well-spacing pattern existing within a field with multiple wells. The method reproduces the flow net for several well configurations having extensive geometrical variations. Such information provides the petroleum engineer with data from which he can compute oil recoveries for different patterns and thereby maximize the recovery of hydrocarbons from the reservoir.

Jan 1, 1972

By Christopher Mark

Roof bolt system design means the selection of the type, length, capacity, and pattern of bolts for a particular application. Despite research efforts dating back 50 years, no design methodology has found wide acceptance. This paper begins by identifying four mechanisms that roof bolts use to reinforce the ground. It argues that the reinforcement mechanism is determined by the roof geology and stress level, not by the type of bolt. Next, the attributes of roof bolts are discussed in the light of recent research, including anchorage mechanism, installed tension, length, capacity, timing of installation, and installation quality. Several significant areas of controversy are identified. Design methods from around the world are discussed, including those based on empirical research, numerical modeling, and roof monitoring. Finally, some simple guidelines for preliminary design of roof bolt systems are proposed based on statistical analysis of roof support performance at 37 U.S. mines.

Jan 10, 2000

By Charles E. Green

This study was conducted to identify, evaluate, and develop procedures to minimize or eliminate safety hazards associated with the electrokinetic dewatering process, such as toxic and volatile gas emissions, electrical shock, accidental detonation of explosives, electrochemical corrosion of metal appurtenances, and possibly others. The identification, evaluation, and procedure development were based on pertinent literature, existing safety regulations, interviews with mine personnel, physical and mechanical properties of the electrokinetic dewatering process, and physical characteristics of the material to be dewatered. The electrokinetic dewatering process was described in detail. Potential safety hazards were identified and evaluated. Procedures and/or safety regulations were developed to minimize or eliminate the potential hazards. It was recommended that the electrokinetic dewatering process when used in deep metal mines be properly monitored to obtain additional information on other potential hazards that possibly exist.

Jan 1, 1979

By R. R. Faddick

A mineral slurry data hank has been compiled, containing slurry pipelining data on sixteen ores, concentrates, and tailings. The data bank it in the form of a computer print-out all they necessary system constants and headloss data for each mineral commodity. The purpose of the data bank was to assist in the development of a universal head loss correlation for mineral slurries, if such a thing exists. Present headloss correlations were tested and found to be inconsistent for the various mineral slurries. Consequently, a different approach was taken, that of compiling a library or Stanton diagrams relating friction factor and Reynolds numbers for a given slurry in a given pipe diameter. The advantages of the diagrams arc demonstrated and discussed. While this correlation shows excellent potential, it is necessary that additional work, both theoretical and experimental, be performed. In addition, two equations are given from which a design velocity may be obtained to minimize deposition or formation of bedload. The equations are based on data taken from the mineral slurry data bank.

Jan 1, 1972

By W. S. Landers

This report presents a detailed study of low temperature, entrained-bed carbonization of an Australian coking coal. The coal studied was high-volatile B bituminous from the Foybrook mine, an open-cut operation in the Liddell seam, New South Wales, Australia. Carbonization was conducted in an 8-inch diameter, continuous vertical reactor at several temperatures from 960° to 1,300° F. It was demonstrated that this bituminous coal can be carbonized within this temperature range to produce tar and a nonagglomerated char, without prior oxidation or char recirculation. Carbonization rates from 138 to 287 lb/hr (as-carbonized basis) were investigated. It was found that the carbonization temperature and the air-to-coal ratio must exceed minimum values to insure continuous operation. At the higher air-to-coal ratios employed, all or most of the carbonization heat was provided by internal combustion with air in the reactor. At the lower air-to-coa1 ratios, part of the heat for carbonization was supplied externally. On the moisture-and ash-free basis, the yield of tar plus light oil ranged from about 26 to 44 gallons per ton, and the char yield ranged from approximately 1,160 to 1,370 pounds per ton. The heat in the gas ranged from about 900 to 3,000 Btu/lb of moisture-and ash-free coal. Carbonization product yields correlated well with air-to-coal ratio and carbonization temperatures. The volatile matter in the char was found to be temperature dependent. At 1,300° F carbonization, the volatile matter in the char was 8.7 percent (dry basis), whereas at 9600 F carbonization, the residual volatile matter was about 16 to 18 percent (dry basis).

Jan 1, 1965

By Wilbur I. Duvall

A linear array of shot and gage holes 30 feet deep in a granite outcrop was used to compare the size and shape of radial strain pulses produced in the rock when short cylindrical charges of cast composition B were detonated axially or at one end. The axially detonated charges produced radial strain pulses that had shorter rise times and larger peak strain than the strain pulses produced by end detonated charges.

Jan 1, 1965

By Chas. F. Jackson

This paper is one of a series dealing with mining methods and costs, prepared and published under the sponsorship of the United States Bureau of Mines and made possible through the cooperation f many mining companies in the United States and foreign countries. The preparation of this paper follows a field study of top-slice mining during which the author visited and discussed with operating officials a large number of iron mines in the Lake Superior region. During this study special note was made of changes in top-slicing practice during the past decade, prior to which the author had acquired several years experience with the method through active connection with a number of mines employing top slicing.

Jan 1, 1931

By Albert L. Toenges

The fuel requirements for industrial and domestic consumers in New England, in normal times, are supplied almost entirely by fuel oil, anthracite, and bituminous coal. A shortage of these fuels occurred during the war. This shortage was caused by: (1) The diversion of oil to military uses; (2) the use of railroad and boat facilities that ordinarily would transport coal for the transportation of war material; (3) the inability of coal mines to apply the increased demand for coal which resulted from the conversion from oil to coal by domestic and industrial consumers; and (4) the increased demand of war industries for coal. Because of this Critical fuel situation, an investigation was made of possible sources of fuel nearer to points of consumption in New England.

Jan 1, 1948

By E. A. Sondreal

The Bureau of Mines investigated the use of lignite char for producing carbon disulfide; CS2 production rates were as high as when wood charcoal was used as raw material. The maximum space velocity for CS2 produced in the bench-scale study was 9,280 hour-1, reacting sulfur and lignite char at 792° C. The reaction temperature and the temperature at which the char was carbonized were the two most important factors in determining CS2 production rates. Increasing the carbonization temperature in nitrogen from 400° to 900° C advanced the temperature at which carbon disulfide was first produced from 550° to 850° C. The average activation energy for reacting chars with sulfur was 44,000 cal/g mole. The reaction was first order with respect to the partial pressure of sulfur. Increasing the rate of sulfur admission caused a decrease in rate of production at otherwise similar conditions. Rates were not affected by either char size or sodium carbonate catalysis. High space velocities at moderate temperatures using inexpensive lignite chars could offer an economic advantage in the manufacture of carbon disulfide provided that yields were attractive.

Jan 1, 1967

The low production rates associated with the underground metal mining industry have received considerable attention during the last decade. A number of significant technological advancements, in the form of new equipment, have taken place to improve the economics of ore production. Unfortunately, an extremely important factor in the equation -- the operator protection and safety -- continues to receive a low priority. The underground metal mining industry has one of the poorest industrial safety records in the United States. Equipment operators are constantly being placed in hazardous situations. Even one fatality is one too many. All of us bear the responsibility to eliminate it. This project is one of the important steps currently being undertaken by the U.S. Bureau of Mines to improve the operational safety of seven major pieces of ore handling equipment commonly used in underground metal and non-metal mines. The objectives of this study are; (a) to identify the existing hazards associated with the operation of the specific equipment, and (b) to recommend practical solutions that will minimize these hazards and reduce operator injuries. These recommendations are to be in the areas of equipment design improvements, additional operator protection and warning devices, equipment operating procedures and any modifications to the existing safety regulations.

Jan 1, 1975

This Bureau of Mines report is devoted to descriptions of systems that provide in-mine wired telephone service. Although they may incorporate other features, each system described functions to allow one telephone to selectively access another telephone. Except for the paper on Conventional Telephone Equipment, the equipment described is newly developed and specifically designed to satisfy the requirements of underground mine communications.

Jan 1, 1977

By Ott F. Heizer

This paper describing the practice at the tungsten concentrator of the Nevada-Massachusetts Co., Inc., at Mill City, Nev., is one of a series being prepared by the Bureau of Mines on milling practices, methods, and costs in the United States. The ore, which contains about 1.10 per cent of scheelite (CaW04), is concentrated on tables and by means of a magnetic separator and roasters. A product containing 70.43 tungsten trioxide is shipped. The plant was designed for a capacity of 100 tons per 24 hours, but at present 142 tons of ore are milled per day. The author acknowledges the assistance of William O. Vanderburg, associate mining engineer, U. S. Bureau of Mines, in preparing this paper.

Jan 1, 1930

By K. E. Stanfield

One of the initial projects under the oil-shale research and development phase of the Synthetic Liquid Fuels Act, Public- Law 290, 78th Congress, approved April 5, 1944, was a survey of oil shales of the United States for the selection of a site for an oil-shale demonstration plant. The oil shales were assayed by the conventional Bureau of Mines retort method proposed by Karrick and described by Guthrie in a more recent publication. From previous experience and that had in making these assays, it became evident that the assay method should be modified or replaced by a more satisfactory one. There are several outstanding objections to the Bureau of Mines oil-shale assay method: (1) the oil yields are frequently smaller than those obtained by other types of assay equipment and by commercial retorts; (2) the assayed oil yield represents only a portion of the organic matter in the shale, which under more favorable conditions, may, Jae converted, more completely into oil; (3) the retorting procedure is controlled mainly by trial-and-error methods; and (4) the assay requires approximately 6 hours for completion.

Jan 1, 1949

By D. Harrington

Metal-mine fires in the United States are not of frequent occurrence and relatively for of those that do occur result in loss of life, although many cause heavy property loss or are costly to extinguish. Over a span of years, however, more lives are lost in metal Trines from fires than from any other of the untoward occurrences which afflict metal mining, such as electrical storms, floods, cave-ins, magazine explosions, or strikes. In perhaps more than 90 per cent of the fires. in metal mines' there is no loss of life; hence, the general public, even the general mining public, seldom hears of these fires, though the property loss frequently reaches hundreds of thousands of dollars; on the other end, in some instances the property damage from an underground metal-mine, fire has been negligible and the loss of life comparatively high. In any comprehensive study of metal-mine fires, ventilation is certain to be found a vital factor. The influence of ventilation on fires and the influence of fires on ventilation are of vital importance. In metal-mine fires very few persons meet death from actual contact Pith heat or flame; nearly all fatalities are duo to asphyxiation or suffocation. A well-planned, well-installed, and well-operated mechanical ventilation system is unquestionably one of the best available present-day protections from loss of life and property in case of fire in a metal mine; that this is true is attested by the usual helplessness of mining officials in trying to handled underground fires in a mine that has not had the foresight to install mechanical equipment to control underground air flow. On the other hand, the establishment of high-velocity air currents without sufficient day by day attention to such details as the method of coursing, or controlling, or confining them most certainly tends to increase dangers from fires rather than to aid in the avoidance or elimination of these dangers; the truth of this latter statement is shown by the fact that the greatest, loss of life in metal-mine fires during the past 20 years has been in relatively well-ventilated workings, and in every case the life loss has been due to some more or less trivial or easily remedied defect in the Ventilating system - usually a defect that has had some reference to doors used or supposed to be used to deflect or control air currents.

Jan 1, 1933

By Edward L. Burwell

The Bureau of Mines conducted laboratory experiments to determine the change during retorting in the apparent permeability and the degree of compaction of beds of broken oil shale. Grades of oil shale studied ranged from 20.6 to 46.7 gallons of oil per ton (gpt), and the simulated overburden pressures applied to the shale were from 300 to 900 psi. Linear regression analysis of the data produced equations describing the response of the oil shale. Oil shales of approximately 20 gpt experience only minor apparent permeability reductions under test conditions, but richer shales (30 to 50 gpt) lose essentially all permeability. The permeability reductions were accompanied by corresponding decreases in bed height that ranged up to 37 percent of the original bed height.

Jan 1, 1974

By Michael S. Wieland

This report investigates whether it is tractable and thereupon reasonable to remove the booster influences when ranking the toxic fumes of non-cap-sensitive mining explosives. The hazard potential is represented by relative fume toxicity RFT, the resultant influence computed from a formulated rule with a restricted set (tally) of fume components and multiplying constants. The RFT result is compared to the rule criterion that represents the worst case tolerable toxicity stipulated by regulations or otherwise. The typical nonstoichiometric booster composition can render notable unwanted influence on the RFT ranking results. Historically, the remedy was to shoot the booster separately and reduce the trial concentrations by the relevant subtractions. Unreal negative concentration results were noted on rare occasions, revealing the faulty nature of the reduction procedure. With thermodynamic reaction chemistry codes TDRC, on the other hand, the booster ingredients can be retained in or removed from the reactant tabulation, yielding reduction factors taken as the concentration ratios for the two circumstances. The underlying presumption regarding reduction factors is that the ratios of component concentrations with and without the booster ingredients when resolved theoretically ought to equal those rendered experimentally, when tractable. Upon rearranging the presumed relationship, the unadjusted fume concentrations divided by theoretical reduction factors yield the wanted readjusted fume concentrations, thereby removing the booster influence without generating unreal negative concentrations. The work principle from thermodynamics restricted by the constraint of zero-net interaction loss is utilized in conjunction with the TDRC to resolve the wanted (Z-state) fume spectrum. This circumvents the recognized difficulty with traditional hydrodynamic detonation theory that is related to the nonideal reaction characteristics of typical mining explosives. The tacit characteristic of the Z-state resolved from the non-trajectory work principle is that it can not be remedied or tampered with, unlike the traditional trajectory techniques where the reaction products can be readjusted by changing formula representations, nullifying specific reactions or otherwise manipulating the thermodynamic trajectory process. Though the work principle theory is an unfinished formulation, the Z-state results prove worthy enough for rendering trends and comparisons and reaching otherwise useful conclusions. Further refinements should yield more reliable fume spectra and indicate explosive composition readjustments that would reduce toxic effects within underground mines and the wider world environment.

By Robert W. Geehan

The Bureau of Mines developed, by core drilling, the property of Nevada Scheelite, Inc., from October 5, 1943, to February 24, 1944. Claims of the corporation are near Rawhide in the northern portion of Mineral County, Nev. The purpose of the work was to determine possible reserves in the lateral and vertical extensions of a tactite zone which was being mined for scheelite. Production from this zone to January 1, 1944, was said to be 64,500 tons, with a recovery of 50,618 units of tungsten trioxide. The development work was done by the Bureau of Mines in cooperation with the U. S. Geological Survey and comprised a study of the geology, mapping the areas, and exploring the deposit by diamond drilling, trenching and sampling. Eleven holes were drilled for a total footage of 2,365 feet of holes.

Jan 1, 1950