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By Albert W. Deurbrouck

The percentage of coal cleaned mechanically has increased greatly in the past 30 years. This technological change in preparation methods, accompanied by mechanical innovations in most phases of coal mining, has enabled the industry to supply quality coals at competitive prices. The Bureau of Mines has contributed to this progress by conducting research on coal-preparation problems, by evaluating the performance of domestic-and foreign-made preparation equipment, and by recording advances as they occur in industrial coal-cleaning practices. The Bureau's work in this field is recorded in the more than 150 technical and scientific publications listed in this volume. These reports, published by the Bureau over the past half century, document the Nation's progress in a vitally important phase of fuel technology.

Jan 1, 1961

Provide an unobstructive means of measuring small changes in distance from roof to floor or from rib to rib of a mine opening and the rate of closure in order to help operators of under-ground mines detect hazardous ground conditions. Approach A small ultrasonic measurement system was developed to detect g round movement and define closure rates. How the System Works The system contains two parts: a transducer and a readout device. The small ultrasonic transducer, similar to an audio speaker diaphram, is plucked with an ultrasonic frequency every six seconds. This frequency wave is sent through the air and reflected back to the transducer off any surface at which the transducer is pointed. The amount of time needed by the ultrasonic wave to make this round trip is accurately measured using a precise oscillator / timer and is converted into a measure of distance. The accurate 6-second time interval is used to convert any subsequent changes in the reading to a rate of change in feet per minute. Two readings are then displayed alternately on the readout instrument.

Jan 1, 1984

By J. E. Murphy

The u.s. Bureau of Mines investigated electrode designs for electrowinning lead metal from a LiCl-KCl-PbCI2 electrolyte at 4500 C. The major objective of this investigation was to decrease the energy requirement for lead electrowinning. Electrolysis was performed in a bench-scale cell using several graphite electrode assemblies. Such parameters as electrode spacing, current density, and chlorine gas removal from the anode were investigated in the bench-scale tests. An optimum electrode assembly, termed the sawtooth design, was scaled up and operated at 3,000 and 4,000 A. The sawtooth electrodes operating at 3,000 A produced lead for 0.66 kW·h/kg. The electrodes were constructed by cutting large triangular grooves in the electrode surfaces. The electrodes were placed together such that the triangular peaks of one electrode projected into the triangular valleys of the other electrode. Chlorine did not build up on the anode with the sawtooth electrodes.

Jan 1, 1991

By Maria I. De Rosa, Charles D. Litton

The National Institute for Occupational Safety and Health (NIOSH/PRL) conducted a series of large-scale experiments to evaluate the effectiveness of optical flame detectors, photoelectric smoke detectors, and combined ionization and photo­electric smoke detectors for rapidly detecting mining equipment cab fires. The detec­tor alarm times were then used to trigger the discharge of a fire inerting system inside the cab to suppress cab material fires. This paper discusses the types of fire detectors tested, the experiments that Were conducted, and the results that were obtained. Con-" elusions are that rapid detection of equipment cab fires can be achieved to trigger the discharge of a fire inerting system inside the cab to protect the operator in the cab.

By John G. Parker

Important quantities of gold, silver, platinum-group metals, selenium, tellurium, and arsenic are recovered in the processing of copper concentrates. The objective of this Bureau of Mines study was to determine the occurrence of these elements in copper ores and to trace their distribution during subsequent processing steps. The study describes the important areas supplying concentrates, precipitates, and unrefined copper to the copper smelting and refining industry in a composite of the years 1971-74. The relative importance of these areas as a source of the respective byproducts is assessed. The lack of certain quantitative and assay data, recycling of dusts and slags, and the addition of scrap to the feed often complicates calculations and estimations of the byproducts in the smelter-refinery throughputs. Such volatile or low-boiling point elements as arsenic, selenium, and tellurium may be lost in gaseous and other emissions in various processing stages, or they may be concentrated in slags and residues for which samples were not available. The effects of antipollution legislation to improve control of sulfurous and other emissions that may affect recovery of certain byproducts was noted. A section on newer technology illustrating hydro-metallurgical techniques that may affect the recovery of minor metals is included.

Jan 1, 1978

By John C. Machisak

DATA ON INJURY experience at quarries and related plants of the United States are presented in this publication under the following general sections: A) General injury experience: Tables 1-4: Contain current data on number of injuries, injury-frequency rates, work location, accident agency, degree of injury, and related employment data. (B) Injury experience at different kinds of quarries: Tables 5-6: Current data on number of injuries, injury-frequency rates, work location, accident agency, degree of injury, and related employment data. (C) Injury experience by States: Tables 7-19: Current data on the number of injuries, injury-frequency rates, accident agency, degree of injury, and related employment data. (D) Selected injury data: Tables 20-30: Current data on various selected factors of operating conditions at different kinds of quarries, including employment size-groups, length of shifts, comparative severity of injuries, and injury data and related employment experience at dimension-stone and crushed and broken stone quarries, and underground quarries. (E) Mining methods and historical injury experience: Tables 31-32; Employment data and injury experience in the quarrying industries of the United States, by mining method and work location, 1953-58; and historical injury experience and employment data in the quarrying industry, 1911-58.

Jan 1, 1962

By G. L. Oldright

In an earlier series of 15 Reports of Investigations on Smelting in the Lead Blast Furnace, experimental data were given on the operations of a custom smelter, a smelter treating rich lead products, and a smelter treating highly zinciferous charges. Five "reports" were written on each of the three types of operation, which were later compared in a summary written for the Institute. Developments in each of these types of operation in lead smelting since the last of the above reports was written have continued and have followed modifications necessitated by changes in the nature of the products received for smelting. The sintering-blast furnace-smelting plants have improved their sintering operation .and have made "2-pass" sintering a more standard operation; the richer lead feeds are diluted when marginal precious metal ores are not available to prevent fusion of the sinter cakes and to permit air to contact the sulfides. Means have been devised to make it easier to remove metallic lead from the wind boxes, but no attempts have been observed to use the D & L somewhat as an ore hearth to make more metallic lead. Except in those cases where zinc-rich lead blast-furnace slags were to be retreated in a "slag-fuming furnace," the sintering and the blast-furnace operations were so carried out that a relatively "clean," lead-poor, final slag was discarded.

Jan 1, 1949

These proceedings consist of papers presented at two Bureau of Mines Technology Transfer Seminars for the purpose of disseminating recent advances in mining technology related to coal mine fire and explosion prevention. Primary, although not exclusive, emphasis is placed on underground coal mining. The papers address research accomplishments ranging from methods for detecting mine fires to remote sealing systems for extinguishing coal mine fires. Each paper represents the current state-of-the-art in the respective research categories. Presentations include research occurring from both Bureau in-house and contract efforts.

Jan 1, 1978

WHY IS IT that smoke-abatement efforts do not bring more satisfactory results? The main reason is an incorrect estimate of the kind and size of the job. When an industrial community realizes that keeping the air clean is a project of similar magnitude to keeping streets clean, providing clean water, removing city waste, or guarding the moral atmosphere, then there maybe a real hope of success. We usually think of the project in too small terms. It is thought of as is the dog catcher or the boiler inspector--a matter of a man or two, a job or two, a small appropriation of variable and uncertain amount, to be abolished in a fit of economy and reestablished under pressure of a vigorous minority. Even so, it is surprising how much is obtained for the effort; but the community is rarely satisfied, for the job is bigger than it was conceived to be. Continuous, never-ceasing effort is required to clean up a smoky city. A few months of relaxation and the situation slips back some years of effort.

Jan 1, 1938

By Choon Kooi Quan

Water availability is essential for mining and minerals processing. To provide government and industry with recent data for water use planning and management, the Bureau of Mines canvassed a number of U.S. producers of nonfuel minerals to determine their water use in 1984. Data were analyzed and compared with previously published data in order to examine historical trends in water utilization in the nonfuel minerals industry and to estimate water requirements in the year 2000. Total water use in the domestic nonfuel minerals industry during 1984 was estimated at 2,267 billion gal, of which 571 billion gal was new water and 1,696 billion gal recirculated water. The largest users of water were the phosphate rock, iron ore, copper, sand and gravel, and crushed stone industries, together accounting for almost 90% of total used. More than one-half of all water was used in Florida, Michigan, and Minnesota. In the year 2000, total water use will amount to an estimated 2,679 billion gal, of which 810 billion gal will be new water and 1,869 billion gal recirculated water. Most of this water would be used in producing the foregoing suite of minerals,

Jan 1, 1988

By Frank B. Fulkerson

A study was made of scrap iron and steel in the South Central States in order to determine trends in processing, shipment, and consumption if this important commodity. These data were derived in part from statistical sources and in part by visits to scrap yards and steel mills. Trends in the industry were reviewed. Dealers in 1963 supplied 1.8 million tons of iron and steel scrap to steel mills and foundries in the south-central area, compared with 2.1 mill ion tons in 1955. Most of the scrap was processed and shipped within 200 to 300 miles of consuming centers. Exports provide a principal outlet for dealers along the gulf coast. Most of the scrap that fills these orders is loaded onto freight cars at yards in Texas and Louisiana and is shipped to ports for direct transfer from railroad car to ship. The tonnage exported varies greatly from year to year. The largest scrap operations are in or near large cities which are heavy scrap generating areas, steel mill sites, or port cities for export of scrap. A tentative analysis indicates that the short-run supply of prepared scrap is inelastic to price changes; therefore, buyers probably are in a strong bargaining position at times of declining demand. One technological development in the iron and steel scrap industry is the use of large presses which can take complete automobiles with frames, wheels, springs, and other heavy parts still intact and reduce them to bundles. At Houston, Tex., and Kansas City, Mo., shredding plants are in operation that reduce car bodies and other light scrap into flat pieces 4 to 6 inches in size.

Jan 1, 1966

The general nature of the special constructional features that are required to provide safety from explosion hazards on machines approved as permissible by the Bureau of Mines is fairly well known to mining men who are at all interested in safety. These requirements are outlined in the schedules, under the provisions of which the investigations of such machines are conducted. Also, the method of conducting inspections and. tests of such machines has been described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine Type Electrical Equipment for Permissibility, published in 1929. A more detailed knowledge of the special safety features of a particular machine is often useful and sometimes essential for inspectors, safety engineers, maintenance men, and engineers in selecting machines for a particular application. Three bulletins that give information of this nature have been published by the bureau, viz., Bulletin 313, Permissible Storage-Battery Locomotives and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 382, Permissible Coal-Cutting Equipment.

Jan 1, 1937

By W. P. Yant

A previous report of the Bureau of Mines dealt with the toxicity of dichlorodifluoromethane5, a new refrigerant that has a remarkably low toxicity. Continued research by the Prigidaire Corporation6 and toxicological experiments performed in the Laboratory of Applied Physiology of the University of Cincinnati7 revealed another organic fluoride, dichlorotetrafluoroethane, whose toxicity also appeared to be of a very low order and whose physical-and chemical properties make it suitable for refrigeration purposes. In addition to low toxicity, safety in its use is further enhanced by its physical properties, which permit the design of equipment that operates at comparatively low pressures and hence mitigates the dangers and problems of leakage. The investigation described in this report was performed by the Bureau of Mines at the request and with the cooperation of the Frigidaire Corporation.

Jan 1, 1932

Provide improved permanent stoppings designed specifically for use in mines with large cross-sectional entries. Approach The large entry sizes in many mines, such as oil shale, salt, and limestone, make the conventional stopping construction techniques used in smaller opening mines unacceptable. The Bureau of Mines and Colorado Mining Association jointly sponsored a contract to design and test new or modified stopping concepts for these mines. The most promising concepts were then tested in an oil-shale mine having 30-foot-high by 55-foot-wide mine entry openings. All stopping designs tested were evaluated in terms of cost, air tightness, and resistance to blast damage.

Jan 1, 1987

By William G. Pariseau

A brief description of a two-dimensional elastic-plastic finite element program intended for mine stability analysis is presented that includes detailed instruction for input data preparation and how to obtain output.

Jan 1, 1978

This Bureau of Mines publication consists of an overview of the mine waste management research currently being conducted by the Bureau. The following papers, given at a Technology Transfer Workshop, emphasize the increasing importance of research related to the safety and environmental considerations of mine waste disposal In recent years. Current work related to legislation passed in the last 10 years and their subsequent standards includes the development of adequate monitoring systems, development of stability and seepage prediction and control techniques, control of runoff water, and control of leaching solutions. Selected topics are included here that cover coal mine waste disposal, embankment slope stability monitoring, flow failures of mine tailings impoundments, and controlled burnout of abandoned coal mine fires. The projects described provide a current documentation of problems being addressed.

Jan 1, 1981

By I. L. Nichols

The inplace cyanidation leaching of gold from placer deposits is a potential method for treating gravels too deeply buried and too low in gold content to be processed economically by conventional dredging methods. Laboratory experiments were made to evaluate those placer cyanidation factors adaptable to small-scale studies. The variables investigated included gold particle size and location in sand beds, cyanide solution flow rate, and cyanide solution strength as factors affecting gold solubility rates. The solution flow rate, in turn, was influenced by variables such as bed slope, solution head pressure, and sand size, and the effects of these factors were studied. Free gold, minus 150-mesh and finer in size, is rapidly dissolved by dilute cyanide solutions from mixtures of gold and silica sand prepared to simulate placer deposits. About 94 percent of minus 325-mesh free gold was extracted in 5 hours from silica sand mixtures, and 94 percent extraction of minus 150-mesh gold was obtained in 21 hours with 0.1 percent NaCN solutions. Moving solutions were almost twice as effective in leaching free gold from silica sand mixtures than stagnant solutions.

Jan 1, 1971

By Jacqueline H. Jansky

The Mine Safety and Health Administration (MSHA), U.S. Department of Labor, did a linear analysis for a new underground coal mine in Grant County, WV, through the interpretation of LANDSAT imagery and high-altitude, color-infrared aerial photography, to identify areas of potentially unstable roof in advance of mining. The Bureau of Mines included this mine in its ongoing study of the correlation between geologic features and linears. Three years after the analysis, after mining had progressed through the plotted linears, a cooperative Bureau-MSHA study evaluated the effectiveness of the linear plot in predicting areas of unstable roof and defined the geology associated with the linears. Adverse roof conditions at this mine include roof falls, potted-out roof, water inflow, and local areas requiring supplemental support. At the time of this study, 34 pct of the mine workings were within 200 ft of a plotted linear. Fifty percent of the adverse roof area in the mine occurred within this area. The primary geologic anomaly associated with the linears is an increased frequency of jointing. The majority of the plotted linears coincide with the prominent joint orientations. Additional features observed in the linear zones include roof rolls and a sandstone channel that cuts into the coal seam.

Jan 1, 1983

By Jerome Apt

This report presents the methods and results performed pursuant to the U. S. Bureau of Mines contract entitled "Noise Abatement in Mining Machinery," Number H0122054. 2.1 Background Until the Congress of the United States created and passed Public Law 91-173, the Federal Coal Mine Health and Safety Act of 1969, there were no directly-applicable standards for noise exposure for underground coal miners.1 Section 206 of this law, approved December 30, 1969, provided for standards of noise to be applicable to each coal mine. It is as follows:

Jan 1, 1975

By Virgil A. Marple

The objective of this contract was to conduct characterization, evaluation and/or calibration studies of instrumentation used for measuring the quantity of respirable dust in mining atmospheres. Initially, this work involved the upgrading and detailed evaluation of the aerosol test chamber and the development of impactors with respirable classification characteristics. These were used as standards in the chamber for measuring the quantity of respirable dust based on either the ACGIH or BMRC respirable dust criteria. A program was then conducted to calibrate several photometers. In addition, the mass sensitivity of the GCA RAM-1 photometer to water droplets in the respirable size range was determined. Three additional studies were also made in this program. First, an experimental study was performed to ascertain the effect of crosswind, cyclone orientation and particle size on particle sampling and penetration through the 10 mm Dorr-Oliver cyclone. Second, a theoretical study was conducted to refine the theory used to predict the particle collection characteristics of impactors. Third, filter samples with known quantities of diesel and coal particles were produced and delivered to the B. of Mines for testing a Raman scattering analysis technique to discriminate diesel particles in the presence of coal dust.

Jan 1, 1984