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By Lance R. Barron

Over the past decade, the U.S. Bureau of Mines (USBM) has studied longwall gate road stability at four mines in the Book Cliffs and Wasatch Plateau Coalfields of Utah. These operations are characterized by multiple-seam mining, abruptly varying cover depths to 914 m (3;000 ft), and massive rigid, sandstone units in the main roof or floor. Such conditions encourage severe bumping, roof instability, and occasional floor heave problems.' Various gate road configurations have been employed to alleviate' these problems. Although the mines have comparable basic conditions, the lithologies and qualities of the immediate roof, floor; and seam ate different in each mine and often vary in a single mine. Gate road systems that mitigate hazards in one mine may prove inappropriate in another or for different areas of the same mine. This report relates the geology of the coalfields; describes the location, geologic setting, specific mining conditions, operating history, and the USBM field study and results or conclusions for each mine; summarizes the relative performance of the gate road systems; and emphasizes the need for site-specific geotechnical data to evaluate gate road conditions and performance.

Jan 1, 1994

By S. H. Ash

Unusual mining conditions prevail in the State of Washington because the majority of the coal seams lie on extra steep dips, and the roof and floor of the seams are of such a character as to require an excessive amount of timber- ing. The seams as a rule give off a considerable amount of methane, which makes good ventilation imperative. Due to physical conditions, supervision is costly and travel about the workings is difficult. Because of the facts stated, the accident rate has been above the average, and for some time considerable thought has been given the idea of making promotion of safety in and about the mines a responsibility to be shared equally by the employees and the management. With this idea in mind the legislature of the State of Washington, turing March, 1927, passed laws providing that safety committees be selected to function at the coal mines of the State and at the same time recognizing the fact that first-aid education is an integral part of any safety movement; legislation was passed making it mandatory to have all persons in and about the ines trained in first-aid administration. The provisions of the State mining law3 are as follows: "In every mine a general safety committee shall be selected, composed of the mine superintendent or manager of mines, one man selected by the employees or any association of employees in or around said mine, and a third member selected by these two. "The general safety committee shall elect one of the members to act as chairman and one to act as secretary. The duties of the chairman shall be to preside at all meetings of the general safety committee, enforce its rules and regulations and see that its business is conducted in a prompt and business-like manner. The secretary shall keep an accurate written record of the proceedings of all meetings, conduct its correspondence and post notices of regular and special meetings and other matters pertaining to safety. The duties of the general safety committee shall be to investigate all serious and fatal accidents; make bi-monthly.

Jun 1, 1930

By John C. Holtz

"The Federal Bureau of Mines serves the mining industry by approving equipment that is designed to prevent explosion, fire, shock, or toxic hazards in mines when such equipment is used and maintained in a proper manner, through research, consultation, testing, and inspection, the Bureau studies machinery and component parts submitted by manufacturers and others. Before receiving the Bureau's approval as permissible for safe use in mines, equipment must pass exacting tests and must meet strict requirements established through research and experience and listed in the Bureau's various permissibility schedules. An important phase of the Bureau's research is the testing of diesel engines.Mobile diesel-powered equipment can be used safely in underground noncoal mines and tunnels when mechanical ventilation is provided to dilute and remove the exhaust gas and to replenish oxygen in the underground atmosphere. Safe ventilation is determined by suitable tests of each engine used in a diesel machine. This ventilation cannot be predicted safely, accurately, and economically from any general empirical relationship.In determining safe ventilation, the quantities of carbon dioxide, carbon monoxide, and oxides of nitrogen generated by a diesel engine must be ascertained. These quantities are related to the displacement of the engine, its speed of operation, the design of the combustion chamber, and the fuel:air ratio needed to produce useful power. At overrich fuel:air ratios, all diesel engines generate excessive quantities of toxic carbon monoxide and smoke. The results of engine tests are used to determine a maximum fuel-injection rate at or below which carbon monoxide can be controlled by a reasonable ventilation and smoke is essentially eliminated. Toxic oxides of nitrogen are related to fuel:air ratio and the design of the combustion chamber. Their concentration in the exhaust cannot be controlled by engine adjustments, and each engine appears to have individual characteristics concerning formation of these oxides. Production of oxides of nitrogen frequently is the most important factor in determining safe ventilation."

Oct 1, 1959

By W. A. Stickney

The Bureau of Mines conducted beneficiation and smelting studies on siliceous offgrade manganese samples to indicate effective methods of manufacturing silicomanganese from materials that cannot be economically beneficiated to meet General Services Administration (GSA) specifications for stockpiling. Laboratory and pilot-plant flotation tests were conducted on 2 samples, 1 from the waste-tailings dump of the Domestic Manganese & Development Co , Butte, Mont., and the other from the Nettie mine in the Butte-Philipsburg area. Smelting tests were made on the combined concentrates from the pilot-plant flotation tests and on part of the tailings sample The flotation scheme found to be adequate in laboratory tests and later in the pilot-plant tests consisted of flotation by a fuel oil-tall oil emulsion in an acid circuit (pH )-1-.8 to 5.0). The oil-emulsion reagent flocculated the manganese minerals and selectively floated them from the siliceous gangue, In the pilot-plant flotation test on Butte-mill tailings 90.1 percent of the manganese was recovered in a concentrate that analyzed 32.6 percent Mn, 4.8 percent Fe and 28.1 percent Si02. In the test on Nettie mine ore 90.8 percent of the manganese was recovered in a concentrate that analyzed 36 6 percent Mn, 5.5 percent Fe, and 26-4 percent Si02.

Jan 1, 1956

By John W. Kopp

Stemming is used in blasting operations to help contain explosive gases as long as possible. Stemming can reduce airblast, improve fragmentation, and reduce the chances of hot explosive gases igniting methane and dust explosions in underground mines. Stemming is required in underground coal mines but is generally not used in underground metal and nonmetal mines. Some underground metal and nonmetal mines are classified as gassy and can require special blasting procedures such as the use of stemming to minsure the safety of miners. The types and amounts of stemming material that are desirable in underground metal and nonmetal mine blasting to ensure good or improved fragmentation while containing the hot gases are largely unknown. This Bureau of Mines research examined the effectiveness of differing lengths of stemming by measuring stemming ejection times as related to burden movement. With properly stemmed blasts, stemming is contained until some burden movement has occurred. Test blasts at two surface limestone quarries were evaluated using high-speed photography. For the conditions of these tests, a stemming length of at least 26 charge diameters was found to prevent premature stemming ejection. In tests with stemming lengths of 16 charge diameters, the stemming was effective but there was early venting of hot gases through fractures in the rock. Further testing with other rock types, hole diameters, explosive types, and stemming materials as they affect incendivity is recommended.

Jan 1, 1987

By H. D. Bemis

This paper describing the milling practice of the American Metal Co. at its Pecos con¬centrator is one of a series on milling methods and costs being prepared by the United States Bureau of Mines. ACKNOWLEDGMENT The author acknowledges the assistance rendered by Guy Martin, metallurgist, H. E. Brown and J. H. Hastings, chemists, and Thomas J. Fahey, accountant, in gathering and pre¬paring the data presented in this paper.

Jan 1, 1932

"D bed, Ky., coaL, washing characteristics RII 5140coking coal, reserves, estimate RI 5037Pa., coal, washing characteristics RI 4834, 4941D bed mine, Ky., coal, washig characteristics"

Jan 1, 1960

By E. Robert Ruhlman

["Phosphate rock" is a broad term applied to natural deposits of minerals valued chiefly for their phosphorus content. More specifically, phosphate rock may be defined as a natural rock containing one or more phosphate minerals, usually calcium phosphate, of sufficient purity and in sufficient quantity to permit its use directly, or after beneficiation, in the manufacture of phosphorus-bearing products. The grade or quality of phosphate rock is expressed either in terms of its phosphorus oxide (P20S) content or the equivalent in tricalcium phosphate (Ca3(P04)2). The trade name for tricalcium phosphate is bone phosphate of lime (B. P. L.).]

Jan 1, 1958

By Lloyd A. Morley

This eight-chapter document is the second volume of a two-volume report that presents a comprehensive outline of coal-mine electrical power systems from theory to practice. Together, the two volumes contain the vital aspects that go into planning and designing a mine power system. Building upon Volume I, the subject of protective equipment and relaying starts Volume II, first as an introduction in Chapter 8, then by a treatment of device selection in Chapter 9. Chapter 10 continues system protection in terms of transients and overvoltages. Chapter 11 describes the design of major power equipment, including power centers, switchhouses, and substations. Solid-state applications in mining are given in Chapter 12, and batteries and battery charging are discussed in Chapter 13. Chapter 14 covers electrical-equipment in hazardous locations of mining operations. The report concludes with Chapter 15, a discussion of electrical maintenance as well as some specific mine electrical problems. Information on surface and underground use is included in all these chapters. An index finishes the documentation and is cross-referenced to both report volumes.

Jan 1, 1982

By Gregory J. Chekan

The U.S. Bureau of Mines is investigating longwall panel and gate road layouts to increase coal recovery and reduce multiple-seam interactive problems. This report presents design practices for longwall mining multiple seams to provide mine planners and operators with practical guidelines for designing productive longwall mines. Key aspects of mine design that control longwall interactions are examined, including sequencing of seams, design of gate road pillars, and orientation of gate roads and longwall panels. Theories that describe stress transfer between multiple scams and the mechanics of interaction are addressed in relation to geology. Common longwall designs were further investigated using a boundary element model, MULSIM/NL. The model provided insight into relative stress transfer and distribution that occurs between longwall operations in multiple seams. Findings from the model show that (1) a longwall panel should be mined from the gob to the solid coal of an overlying mine, because the stress concentrations are lower; the approach angle should be kept under 30°; and (2) when mining in descending order, superpositioning gate roads usually produces the worst stress condition. To prevent this, the overlying isolated gate roads should be positioned from the centerline toward the headgate side of the underlying panel.

Jan 1, 1993

This report, the fourth in an annual series, outlines recent trends and developments in the minerals industry. Discussed are new methods, equipment, techniques, and systems used to more effectively extract and process mineral products. Environmental considerations, health and safety standards, price controls, inflation, material shortages, and more dependence on foreign imports were problems faced by the minerals industry. Although productivity increased for most mineral commodities, the annual rate of increase has slowed in recent years, indicating a maturing technological situation. Growing concern for energy resulted in increased interest and research in alternative fuel sources. The primary concerns of metallurgists were pollution control and improved efficiency and performance of metallurgical processes, especially for reduction of energy consumption.

Jan 1, 1974

By Herbert L. Lines

This paper is one of a series on mining and milling methods and costs published by the Bureau of Mines. The Ash Peak mine of the Veta Mines, Inc., Duncan, Ariz., is of particular interest in that the only metal of commercial value in the ore is silver. The silver is concentrated by flotation; the concentrate is shipped to a smelter for treatment.

Jan 1, 1940

By J. W. Jensen

EXTENSIVE research and development was performed on the manganese-copper vibration-damping alloys to determine the relationship between the properties of the alloys and variations in composition, fabrication, Mid heat treatment. Mn-Cu alloys with unusually high specific damping capacity, 20 to 25 percent at a stress of 5,000 psi, have also the following useful properties: Tensile strength, 90,000 to 110,000 psi; yield strong, 60,000 to psi; elongation, 20 to 25 percent; hardness, 90 Rockwell B; and fatigue limit at, 28,000 to 30,000 psi. Both standard and special methods of testing were employed to obtain data on strength, modulus, hardness, resistivity, dilatation, micro-structure, crystal lattice, and damping capacity. The extensive tabular and graphical data on these properties are presented for alloys containing 50 to 85 percent as quenched d solution) and after various aging treatments. Expansion coefficients for all Mn-Cu solid solutions are graphed and a dilatometer study of contraction during aging is reported. Although high damping capacity is associated with aging to precipitate a-Mn from solid solution, with a cubic-tetragonal transformation and with the occurrence of antiferromagnetic ordering in Mn-Cu alloys, a tenable theory of the damping mechanism has not been reached.

Jan 1, 1965

By H. J. Kelly

[This investigation of the refractory properties of seven Pacific Northwest chrome ores and concentrates has shown that five of the ores and one of the concentrates are suitable for making refractories and that all may be used in combination with high-grade chromite. The specific objectives of the investigation were to determine the inherent physic al and chemical characteristics, to shapes using each of the chrome ores and concentrates, to compare the refractory qualities of the laboratory-prepared with commercial chrome refractories. As far as possible, standard tests were used as criteria.]

Jan 1, 1952

By H. Leitch

In laboratory experiments, the Bureau of Mines investigated melting, quenching, and sulfuric acid leaching of alumina from mixtures of albite and anorthite, and from anorthosites containing 26 to 32 percent alumina. Variations in pouring temperature, quenching and leaching conditions, were studied with respect to the extraction of alumina and impurities. Virtually all of the alumina was dissolved by leaching melted and quenched California anorthosite in boiling 16-percent sulfuric acid solutions for 15 to 30 minutes. The leach solutions were readily separable from the solid residue by conventional thickening and filtration techniques. Only 2 to 5 grams of SiO2, Fe2O3, or CaO dissolved per 100 grams of alumina. The quantity of SiOz in solution varied inversely with the duration of the leach and with the concentration of the H2SO4 solution used. Melted and quenched Wyoming and Minnesota anorthosites with SiO2:CaO weight ratios of 4.3 and 3.2, respectively, were less amenable to sulfuric acid leaching than California anorthosite with an SiO2:CaO weight ratio of 5.3. However, excellent results were obtained on the Wyoming and Minnesota anorthosites by the addition of SiO2 to these materials before melting, in quantities sufficient to adjust the SiO2:CaO weight ratios of the furnace charges to between 4 and 6.

Jan 1, 1966

By D. J. Donaven, Manuel Gomez, W. S. Landers

Bulk density tests were made on a Western U.S. coke oven plant blend to obtain bulk density control data that would be directly transferable to plant practice . Maximum bulk density values were obtained at zero surface moisture . Increase in surface moisture to about 6 percent decreased the bulk density to a minimum value . Increase in the fine grinding of the blend , at constant surface moisture , decreased the bulk density . The effect of oil on bulk density was observed with five oils at concentrations ranging from 1/8 to 1-1 / 2 gallons per ton . Maximum bulk densities were obtained within the 1 / 2- to 1 - gallon - per - ton range . Essentially the same bulk densities were obtained with petrolatum- and nonpetrolatum- containing oils . Storage effects were observed on samples tested at selected intervals from 0 to 56 days . No significant change in bulk density took place if no surface moisture was lost during storage .

Jan 1, 1964

By C. M. Keenan

During the 7-1/2 years (January 1945-June 1952), immediately preceding enactment of the Federal Coal Mine Safety Act, 26 major disasters3/ in the coal mines of the United States caused the deaths of 491 persons. In the next 7-1/2 years under the act (July 1952-December 1959), only 12 major disasters occurred. The total killed was 148. This improvement is commendable. However, the continuing frequency of minor fires and gas and/or dust ignitions in the Nation's coal mines, many of which could have been of major consequence, are cause for serious concern to the coal-mining industry and those affiliated agencies engaged in promoting safety in the industry. The data presented in this report have been prepared to make available to the coal-mining industry and related groups an overall perspective of the disaster potential from mine fires and gas and/or dust ignitions in coal mines after 7-1/2 years under the Federal Coal Mine Safety Act. This act, effective July 16, 1952, which amended the original Federal coal-mine investigative act of May 1941, provides under Title II certain enforcible mine-safety provisions designed to prevent major disasters caused by explosions, fires, inundations, and man-trip and man-hoist accidents in coal mines that employ 15 or more individuals underground.

Jan 1, 1960

By D. Harrington

As no cure is known for silicocis after it has developed, prevention is the only effective remedy. There are two main lines of approach to the problem of dust-disease prevention in industry - the engineering, through control of dust production, and the medical, through selection of workers by examination; success probably depends upon a combination of the two. Hatch (146) considers the following measures essential to a complete, well-balanced program of control of the dust hazard in industry: 1. Selection of workers by means of physical examinations in order especially to eliminate those with tuberculosis and other disorders of the respiratory system. 2. Reduction of the duct concentration below the standard of permissible dustiness through adequate moans of dust control and good housekeeping. 3. Limiting the frequency and duration of employment in the dusty occupations, thus reducing the rate of deposition of dust in the lungs. 4. Routine measurement of the effectiveness of the dust-control program by means of periodic medical examinations and duct surveys.

Jan 1, 1935

By Robert M. Becker

Part 5, the last of this series, deals with the theoretical confirmation and application of results developed in parts 1 and 2. The bulk-sampling variances of Hassialis and Kassel and Guy are compared with those in part 2, both as to formulation and as applied to ores and coal. The results provide confirmation for much of the development in part 2. Examples are presented for determining the reliability of bulk samples with respect to various measurable characteristics. These characteristics include, for example, assays for elements or compounds and particle surface area. The bulk samples considered consist either of a given weight, a given volume, or a given number of particles. In addition to problems of sample reliability, some of these examples may also be applicable to quality control. Several possible applications of results developed in parts 1 and 2 are outlined. These include tests for random data, degree-of-mixing indices, and particle-fineness indices.

Jan 1, 1966

By R. L. King, J. Cervik, A. A. Campoli

The Bureau of Mines performed laboratory experiments to evaluate the triboelectric effect of particulate-laden gas streams on polyethylene pipe at various velocity, humidity, dust-size, and dust-load conditions. Charges in excess of 10 kV were produced on the outside and inside surfaces of laboratory pipe samples, when exposed to 40 pct relative humidity (RH) gas stream containing coal dust. However, no charges were produced in laboratory tests that duplicated the over 75 pct RH and dust-free gas streams found in working underground pipelines. Bare cop- per wire, which is wound around the polyethylene pipe in a 1-ft (31-cm) spacing and grounded, eliminated the charge on the outside surface of the pipe, but not on the inside of the pipe surface,

Jan 1, 1986