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By A. J. Barry

Recent developments in mechanizing longwall it mining in Europe have aroused considerable interest among American coal-mine operators because this method provides an opportunity to improve safety, production, efficiency, and recovery. The success of longwall mining in Europe has depended to a large degree on development of effective roof-control systems. One of the major contributing factors in designing these systems is development off improved supports, which combine high load-bearing capacities with controlled yield characteristics, to use in the face areas. Other factors that relate to successful longwall mining involve knowledge of the structural properties of the strata above end below the coal bed being mined, movements of these strata induced by mining, and effects of the strata movements on the strata itself, as well as on the support system used. Extensive studies of the above factors relating to long-wall mining have been made in coal-mining countries abroad, and corresponding studies (1, 2, 3, 4, 5)3/ of room-and-pillar operations have been made in this country. Although descriptions and results of experiments of mechanized longwall operations in the United States have been published (6, 7, 8), this is the first instrumented study of roof behavior on a longwall operation. In view of the possible widespread application of this method of mining to American coal mines, where underground mining conditions are different from those found in European mines, an investigation was conducted at a mechanized longwall operation inn the Lancashire No. 15 mine, Barnes & Tucker Co., Cambric County, Bakerton, Pa., to study the factors that affect roof control. This report describes this investigation and discusses the results. ACKNOWLEDGMENTS This investigation was made under a cooperative agreement between the Bureau of Mines and the Barnes & Tucker Co., Barnesboro, Pa., end was conducted in the Lancashire No. 15 mine located at Bakerton, Cambria County, Pa. The authors acknowledge the cooperation given by Richard Z. Todhunter, Sr., president, Richard T. Todhunter, Jr., general manager, and other mine officials and employees of the Barnes & Tucker Co. Mr. Edward Thomas, chief, Roof Control Section, Bureau of Mines, Washington, D. C., and Dr. Leonard Obert, chief, Applied Physics Branch. College Park, Md., collaborated in the planning and promulgation of the program investigation.

Jan 1, 1954

By Albert S. Konselman

This paper describes the mining methods and operating costs for 1938 at the South Burns shaft, situated in the Cripple Creek district, Colorado. The shaft is operated by Golden Conqueror Mines, Inc., through which portions of the properties of the Acacia Cold Mining Co., The Free Coinage Gold Mining Co., and The United Gold Mines Co. are worked under lease. During 1938, 30,773.61 dry tons of ore averaging $9.59 in gold per ton was mined. Of this, 10,138.439 tons averaging $10.65 per ton was produced on company account, and 20,635.171 tons averaging $9.05 per ton was produced by "split-check" lessees.

Jan 1, 1940

By David L. Bickel

Stress-relief techniques and instrumentation have been developed through many years of research in the Bureau of Mines and successfully used to determine the in situ state of stress in rock. This report describes the Bureau's three-component borehole deformation gauge and the drilling equipment and accessories used with it. Operation and calibration procedures for the deformation gauge are discussed in detail, along with site selection and overcoring procedures. Information and references included in this publication provide a guide to the Bureau's cover-coring method for determining rock stress.

Jan 1, 1985

By F. N. Kissell, C. D. Litton

This study ranks the factors impacting survival during a coal mine fire. It bas already been established that reducing time delays is the most important factor in saving lives. Consequently every event during afire is measured in terms d its duration, and the effectiveness d any action taken to improve survival is measured in terms d the time it saves. By ranking actions according to time saved these authors found that a comhination d actions was most effective. This combination was: • installing lifelines. • moderately decreasing air leakage and • decreasing the fire growth rate. Changing ventilation leakage alone was much less effective, as was altering the CO (carbon monoxide), sensor alarm threshold. These results confirm an earlier fault-tree study on escape from mine fires. The fault-tree study bad shown that, with the exception d delays, single factor changes have minimal impact. Significant reductions in fire fatalities only take place with multiple factor changes.

By H. D. Baylor

This is the first of a series of papers describing mining methods and costs at cement plant quarries throughout the United States and deals directly with those methods employed and costs obtained at the quarry of the Louisville Cement Co. located at Speed, Ind. ACKNOWLEDGMENTS The author wishes to acknowledge the assistance of Mr. J. M. Buohheit, superintendent of quarries, and Mr. H. E. Schoonover, quarry engineer, in furnishing data and in compiling this report.

Jan 1, 1930

By Margaret R. Egan

The Bureau of Mines experimentally burned Pittsburgh Seam coal and other combustible materials found in mines in order to obtain a better knowledge of their emission products. These experiments were conducted in the Bureau's intermediate-scale fire tunnel, which simulates environ-mental conditions in underground mines. Smoke characteristics, gas concentrations, mass loss, and ventilation were measured. From these values, heat-release rates, particle sizes, obscuration rates, combustion yields, and production constants were calculated. This information was sought as part of a comprehensive study of combustible materials that will ultimately advance the design of more efficient fire detection and suppression systems. The coal combustion measurements presented in this report, together with previous analyses of wood and transformer fluid fires form a data base by which future studies of other mine combustibles can be compared.

Jan 1, 1987

By Sathit Tandanand

This Bureau of Mines report describes the method of obtaining a strength index for rock drillability, particularly for percussion drills. The original Protodyakonov method has been slightly modified, essentially to eliminate uncertainties in the measurement of the volume of fines, and to avoid conjecture in selecting the representative value as the strength coefficient. A theoretical consideration of the relevant parameters in the method was extended from a comminution theory, and hence the meaningful value was obtained experimentally by plotting the ratio of the number of drops and the volume of fines against the number of drops. The minimum ratio of the number of drops to the volume of fines in the plot was selected as the coefficient of rock strength. The modified method of obtaining the strength coefficient preserves the original Protodyakonov test apparatus and the merit of simplicity of the test procedure. The modified coefficient of rock strength shows its usefulness in predicting penetration rates with greater reliability than other mechanical properties. Consequently, the drillability curves were drawn using the modified coefficient of rock strength as the parameter for penetration rate prediction in the field.

Jan 1, 1975

By F. R. Lee

This publication lists permissible equipment approved by the Bureau of Mines during 1967 and 1968 (calendar years), except breathing apparatus and explosives. The purpose of this publication is to inform the public about approved equipment for use in underground mines.

Jan 1, 1970

By Thomas O. Llewellyn

This U.S. Bureau of Mines (USBM) report presents a concise review on sources, processes, supply, and historical use patterns of domestic cadmium. It also covers a preliminary estimated cadmium material flow for the year 1989. This preliminary study contains information on cadmium and cadmium-bearing products in the United States. The data in this report were obtained from both published and/or unpublished sources of information. However, in order to estimate the fate of cadmium in each operation or application stage, some assumptions, judgments, and correlations were made by the USBM in an attempt to determine the material flows losses.

Jan 1, 1994

By R. D. Dey, V. Castranova, J. M. Antonini, J. A. Blackford Jr.

Alveolar macrophages (AM) exposed to cytokines or bacterial lipopolysaccharide (LPS) produce the free radical nitric oxide (NO·) by an inducible nitric oxide synthase (iNOS). They also release reactive oxygen free radicals following exposure to silica dust. The purpose of the present study was to determine whether NO· is produced by rat AM and/or recruited leukocytes following the intratracheal (IT) instillation of silica. Male Sprague-Dawley rats (175 to 225 g) were IT instilled with either silica dust (10 mg/100 g body wt) or LPS (0.25 mg/100 g body wt). After 24 h, bronchoalveolar lavage cells (BALC) and lavaged lung tissue were assayed for iNOS mRNA. Cell counts of BALC and iNOS-dependent (Nw-nitro-Larginine methyl ester [L-NAME]-inhibitable) chemiluminescence generated by AM were also determined. Northern blot analysis demonstrated that the steady-state levels of BALC iNOS mRNA were significantly increased by 3-fold following IT silica and by 7-fold following IT LPS. Partially enriched fractions of either AM or leukocytes from silica-treated rats both exhibited significantly elevated iNOS mRNA in Northern analysis. iNOS-dependent chemiluminescence was significantly increased in AM by 36-fold following IT silica and by 89-fold following IT LPS. Differential counts of BALC showed that AM numbers did not change in any of the treatments; however, red blood cells increased by 30-fold following IT silica and by 23-fold following IT LPS. Total leukocytes (polymorphonuclear leukocytes plus lymphocytes) increased by 58-fold following IT silica and by 274-fold following IT LPS. The results demonstrate that AM and neutrophils iNOS steady-state mRNA levels, AM iNOS-dependent chemiluminescence, and lavagable red blood cells and leukocytes all increased following IT silica. These findings suggest that NO· production in rat AM and neutrophils is increased in response to silica. NO· has the ability to then combine with superoxide and form a highly reactive toxic species, peroxynitrite, which may be responsible in part for silica-induced lung damage.

Dec 1, 1995

By R. R. Wells, K. C. Vincent, A. O. Ipsen

"INTRODUCTION The Philipsburg Mining District, Granite County, Mont., has been the largest producing area for battery-grade manganese (70 percent MnO2) in the United States since the First World War. Two companies, the Trout Mining Division of the American. Machine & Meals Co., and the Moorlight Mining Co., have intermittently mined and milled 120 to 250 tons of 25-percent manganese ore per day for the production of concentrates of this grade.Investigation of the district by engineers of the Federal Geological Survey and Bureau of Mines indicated that further exploration and develop¬ment would make available additional oxide and carbonate manganese ores for milling and production of metallurgical-grade manganese. If the battery-grade producers converted their plants to the production of metallurgical-grade concentrates, their production also could be increased through greater recoveries.Until February 1, 1944, the Metals Reserve Company, through its agent, the Sunshine Mining Co., purchased milling-grade manganese oxide and carbonate are for stock-piling at Philipsburg. After that time, only carbonate ore was purchased. Based upon the assumption that the stock pile was a true cross-section sample of the producing area, metallurgical studies were made on representative samples from the Metals Reserve stock piles. Testing also was conducted on two other samples of Philipsburg oxide manganese ore obtained by engineers of the Bureau of Mines from the Little Dandy claim of the Donlan group and from the Marie mine. All ore samples tested were found to be amenable to concentration by ore-dressing methods for the production of concentrates that when sintered met Metals Reserve Company specifications for metallurgical-grade manganese."

Nov 1, 1947

By G. W. Birge

Carbonizing properties of the principal coal beds of Butler County, Pa., are described in this report by the Bureau of Mines. Eight samples, representing the Upper Freeport, Lower Freeport, Upper Kittanning, Middle Kittanning, Lower Kittanning, Clarion, and Brookville beds, were carbonized at 900° C. by the Bureau of Mines-American Gas Association (BM-AGA) method. Butler County coals rank as high-volatile A bituminous and are generally characterized by high sulfur content compared with Appalachian coals used for industrial coking. If cleaned, the Brookville and one sample of Upper Freeport coal would be acceptable as the major component of metallurgical coking blends. The other Butler County coals tested would be unsuitable for this purpose because of either excessive sulfur or poor coking properties.

Jan 1, 1962

By Herbert R. Babitzke

As part of a project to develop refractory metal alloys suitable for high-temperature structural applications, the Bureau of Mines applied solid solution and precipitation-hardening techniques to columbium and tantalum alloys. Thirty-three alloys were evaluated to determine their formability, strength, and oxidation resistance. Three alloys had tensile strengths near 40,000 psi at 1,200° C: Cb-1N-5W-5V-10Hf (No.4), Cb-15Hf-5W-0.5B (No. 31), and Cb-15Hf-SW-IB (No. 32). Oxidation resistance of the high-strength alloys was good. Alloy4 gained only 34 mg/cm2 at 1,200° C, and 21 mg/cm2 at 1,000° C in 2 hours. Hot forming was done without any protection from oxidation.

Jan 1, 1968

By F. S. LOTT

The number of petroleum refineries in the United States decreased from 399 on January 1, 1947, to 390 on January 1, 1948. On the latter date two additional refineries were under construction , a large one in New Jersey and a small one in Texas . This Crude oil charging capacity, based on complete facilities only , increased in 1947 from 5,569,482 barrels to 6,034,252 barrels per day , owing to material gains reported in all of the larger refining districts . great increase in effective capacity is only in part the result of the completion of major new units for crude-oil processing . Much of it is due to rearrangement and minor additions to existing facilities to permit more efficient and complete utilization . Recent experience has apparently demonstrated that many processing units are capable , with greater emphasis upon maintenance and precise controls , of sustained operations at higher volumes than were indicated in their old rated capacities . This situation doubtless has caused some upward revision in capacity data .

Aug 1, 1948

By Sidney Katell

This study estimates capital investment, operating costs, and selling prices for four underground bituminous mines producing coal with annual production ranging from 1.06 to 4.99 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of December 6, 1974, under the Bituminous Wage Agreement of 1974, and costs for material and equipment are based on 1975 indexes. Initial capital investment ranges from $23,629,500 for the 1; 06- million-ton-per-year (MM tpy) mine to $79,907,500 for the 4.99-MM-tpy mine. Total capital investment ranges from $35,336,500 to $1 18,863,500 for the same mines. Corresponding selling prices for the coal range from $13.57 to $11.36 per ton, assuming a 15-percent discounted cash flow rate of return after Federal income taxes.

Jan 1, 1975

By Henry Kreisinger, J. F. Barkley

This book is one of a series of publications being issued by the Bureau of Mines for the purpose of disseminating information in regard to the methods by which the fuels in this' country may be used most efficiently. A knowledge of the temperature of the gases in boiler settings and in other commercial apparatus using heat tends to develop improved designs of apparatus and better methods of operation, thus reducing waste of fuel. The following pages present, for the benefit of those designing, operating, and testing such apparatus, information as to the accuracy of temperature measurements made under certain conditions and the corrections that can be safely applied.

Jan 1, 1918

By Wallace W. Roepke

Research to evaluate the lubricity effects achieved by spraying water on the cutting bit of a mining machine or spraying water on the coal during cutting has shown that neither practice affects cutting forces, as had been believed. However, when water was supplied to the cutting zone axially through the bit at 3,000 to 5,000 psi pressure, tangent'ial cutting forces were reduced an average of 30 pct at a I-in depth of cut while normal bit forces were reduced an average of 65 pct. Lower normal forces mean reduced bit wear, faster advance with greater depth of cut, and fewer coal fines.

Jan 1, 1985

By R. V. Ramani

This volume is the second of a four-volume final report on research carried out under a contract from the U.S. Bureau of Mines on the development of a computer simulation model for surface mine reclamation planning. The other volumes are titled as follows: Volume I: Ore Reserve Estimation, Volume III: Mine Coordinate Generator System, and Volume IV: User's Manual for OPMHS/2. The dragline model described in this report simulates the movement of the dragline bucket across the digging face, the swing load, the dump, and swing back. It is programmed to handle chopdown, key cut, main cut, and rehandling operations. Provisions have been made for simulating equipment and mining delays. Any mining method can be specified in terms of numbered blocks, the dragline positions for the mining block and the dumping location for the block. Accounting procedures permit the calculation of production rates, rehandle volume, dig and delay times. The model can be used to study the effects of varying mining conditions, cut width, and spoiling sequence with special reference to toxic spoil, overburden and bench removal procedures. The basic input data for the model include machine parameters, the geology and material characteristics, the mining parameter, and the delay characteristics of the equipment.

Jan 1, 1985

By W. A. Haley

The purpose of this investigation was to develop and improve mining methods for mining thin coal beds, to increase productivity, and to increase the recovery of coal. German coal planers and a modified longwall system of mining were introduced into American mines and are bringing about increased productivity and better recovery as compared with the conventional methods displaced. Since the first installation, 4 additional planers have been purchased by coal companies and over 1-1/2 mil¬lion tons of coal has been mined by them, using the modified longwall mining method. INTRODUCTION Except from 1932 to 1934, the growth of mechanical loading in underground bituminous-coal and lignite mines in the United States has increased steadily. The amount of coal loaded mechanically in underground mines has increased from 0.3 percent in 1923 to 79.6 percent of the total underground production in 1953.3/ The use of new and improved mining machines and auxiliary equipment, together with new techniques in mining methods, usually has resulted in increased productivity.

Jan 1, 1957

By George T. Motock

In Germany the extraction of lithium and its salts has been handled mainly by units of the two major concerns - Metallgesellschaft A, G. and Deutsche Gold und Silber Scheide Anstalt, both with headquarters in Frankfurt. Zinnwaldite, which belongs to the mica group, is the major source of the lithium-containing raw material in Germany. Lepidolite and amblygonite also are used when available, but they are imported, as there are no major deposits of these two minerals in Germany.

Jan 1, 1946