Search Documents

By J. M. Stuve

Provisional values for the heat of formation of europium trichloride and europium sesquioxide were determined by solution calorimetry utilizing europium metal of more than 99-percent purity. The resulting values for the heats of formation of Eu203 (cubic) and EuCls (hexagonal) were -386,970 ±l,200 cal/mole and -218,740 ±650 cal/mole, respectively, measured at 298.15° K.

Jan 1, 1965

By W. M. Myers

The U. S. Bureau of Mines conducted an investigation to determine the cause of the deterioration of Portland cement during storage and transportation , and to discover a means of preventing it . All available printed sources of information on this subject have been examined and a bibliography has been compiled . The subject has also been discussed with the leaders in the cement industry ; the present report is the result of their cooperation , and is based principally on information thus obtained . Deterioration of Portland cement during storage over any considerable period of time has long been noted ; closely related to it is deterioration of cement during transportation, which involves not only the time factor of storage but also exposure to varied climatic conditions . Deterioration in both cases is due to hydration of the cement by absorption of moisture from a humid atmosphere , or by exposure to actual rain-fall . After hydration cement possesses no cohesive power ; the degree of deterioration is directly proportional to the degree of hydration . The amount of deterioration of Portland cement during storage has been accurately determined in an investigation by the Structural Materials Research Laboratory , in cooperation with the Portland Cement Association . Cement stored in a shed in cloth sacks retained 80 per cent of its original strength after three months storage ; 71 per cent after six months ; 61 per cent after one year ; and 40 per cent after two years . The deterioration of Portland cement during storage and transportation was noted particularly in France during the World War . Information concerning cement used by the American Expeditionary Forces was furnished by Lt. Col. H. S. Spackman and Major E. C. Eckel , U. S. R. , who had charge of practically all matters concerning cement used by the A. E. F. The cement used by the A. E. F. came from the following sources : 42,000 tons was French , Swiss , and Spanish cements ; 120,000 tons was English cement ; 55,000 tons made in plants operated by the A.E.F .; 500 tons ( Not over) from America . Deterioration was most marked in cement from the first source .

Jun 1, 1922

By Jerry W. Ramsey

The Bureau of Mines studied two Pennsylvania anthracites using low-temperature carbon dioxide adsorption. A modified form of the Brunauer-Emmett-Teller equation was used to calculate specific surface areas. Two mesh sizes of each anthracite were used to determine how gamma irradiation at 106 and 108 rads, both in vacuum and in the presence of air, affected the carbon dioxide surface areas. Results show that anthracites have a system of pores that are essentially all interconnected rather than isolated; that anthracites differ from one another in specific surface, which may correlate with density; and that irradiation in vacuum has no discernible effect on specific surface of anthracite, but irradiation in air does produce changes in specific surface.

Jan 1, 1966

By P. G. Pigott

This investigation by the Bureau of Mines demonstrated that building bricks can be produced by the steam-curing process from various types of industrial mineral wastes. Wastes, utilized to produce bricks, consisted of copper mill tailings, roofing granule fines, asbestos fines, and zinc mill tailings. Bonding of the wastes with either Ca(OH)2 or portland cement resulted in building bricks that met ASTM specification C73-67 for grade SW and MW bricks when evaluated in accordance with ASTM designation C67-66 on sampling and testing of brick. An economic evaluation of the process indicates the total operating cost per 1,000 bricks is about $36.

Jan 1, 1974

By A. W. Khair, L. D. Gehl

"This paper describes the study of bit wear characteristics on three types of rock namely Tennessee sandstone, Berea sandstone and Indiana limestone. High content of quartz with quartz cement in Tennessee sandstone causes removal of material from the bit body and dam2ge to the tip of the bit resulting into excessive weight and height loss as compared to other two types of rock. The drum speed and water spray pressure do not contribute significant effect on bit wear. The polycrystalline compact diamond (PCD) tipped bits are more wear resistant than the ordinary tungsten carbide (WC) tipped bits, but, due to wider body of PCD bits, the wear rate increases particularly at greater depth of cut. INTRODUCTIONThe impact of bit-rock interaction during the cutting process in underground coal mines has always attracted the-interests of mining operators, researchers and the manufacturers. Coal cutting bears directly on airborne coal dust generation which causes ""black lung"" in coal workers. On the other hand, rock cutting generates frictional sparks causing face ignitions. The bit wear not only produces airborne rcspirable coal dust , but also affects the productivity, safety and economy. Hun and Evans (J) concluded that the point attack bits have greater ignition potential than the conventional wedge shaped bits. The results of a study (2) suggested that after 7% of weight loss, the bit should be replaced. In a survey study (3), it was found that the bit consumption of bit had an effect on the productivity and utilization of the continuous miners. The mining industry is yet to receive a solution which could provide them with optimum operating parameters for coal cutting machines in underground C9al mines.The study was, therefore, taken up to determine wear characteristics as influenced by the rock propenies and varying operating parameters. For the purpose of this study, three types of rock, Tennessee sandstone, Berea sandstone and Indiana limestone were used. The machine operating parameters included (i) drum speed, (ii) water spray pressure and (iii) bit type. Besides studying the wear characteristics, the effects of these parameters on the required cutting force, specific energy consumption, acoustic emission generation and bit temperature rise were also studied. Also, the preliminary experiments were performed to compare the bit wear between PCD and WC tipped bits."

Dec 1, 1995

By Michael J. Magyar

This report contains a cost estimate of the Bureau of Mines process for dewatering Alaskan placer effluent streams with polyethylene oxide (PEO). In this process effluent slurry is withdrawn from the placer plant pond system after a primary settling stage. A dilute PEO solution is injected into the slurry line to flocculate the fine, suspended solids. The flocculated solids are dewatered on a stationary screen. Clarified water is returned to the placer operation or discharged, while the 35 percent solids waste is pumped back into the mine cut. Cost estimates are presented for dewatering plants processing 1,000 gallons per minute of effluent slurry at three representative turbidity levels. Both the placer and the dewatering plants operate on the same 1-shift-per-day, 6-day-per-week schedule for the 100-day Alaskan operating season. Estimated fixed capital costs for these plants processing placer with effluent turbidities of 1,000, 3,000, and 5,000 nephelometric turbidity units (NTU) are approximately $29,000, $31,000, and $34,000, respectively, on a fourth quarter 1986 basis. Operating costs are estimated to be $0.34, $0.37, and $0.40 per thousand gallons of effluent slurry.

Jan 1, 1987

By L. C. IlsLey

"According to accident statistics, issued from time to time by the Department of the Interior, Bureau of Mines covering fatalities in coal mines, between the years 1870 and 1921 there were 4,897 deaths caused by explosives. The legislatures and safety commissions of the various mining States have Elected and formulated many excellent regulations in regard to the handling and use of explosives in an endeavor to keep this class of accidents as low as possible. An analysis or comparison of the explosive, regulations issued by over thirty States would make a very long paper, however, by subdividing according to phases and issuing several papers it is believed that the material will be more readily available. The first phase was treated in Serial No. 2405 of the Bureau of Mines (""State and Federal Electrical Shot-Firing Regulations,"" issued in October 1922) which gave a compilation of such regulations as apply strictly to electric shot-firing. The second phase under consideration is ""Who may set off blasts in coal mines.""In some States, the person who does the firing must be an ""authorized shotfirer,"" while in other States he must have proved his ability to do this work, and again in other States he is ""any person."" The present paper covers rules and regulations relating to this phase of shotfiring, and those States having similar regulations have been grouped as follows."

Jun 1, 1923

By A. E. Raddatz

The Bureau of Mines has determined the electrochemical rate of anodic dissolution of vanadium metal in a VC12-VC13-NaC1 electrolyte at 860' C for the purpose of elucidating the reaction mechanism. Rate measurements were carried out with the help of specially designed equipment capable of continuously recording the weight loss experienced by a cylindrical vanadium anode immersed in the molten salt electrolyte while a constant current is maintained through it. The rate is expressed as a function of current density and VC13 concentration, and the reaction is interpreted in terms of an adsorption mechanism. Multiple regression analysis of the data gave the following rate equation: Rate x 104 (g.cm-2.sec-1) = -0.38 + 2.64 current density (amp-cm-2) + 0.69 log, (mole-percent VC13).

Jan 1, 1974

By M. J. Spendlove, P. P. Zapponi

"INTRODUCTION In carbothermic processes for the production of magnesium, magnesium oxide is reduced by carbon according to the following equation:(1) MgO + C = Mg(g) + CO.The reaction is virtually complete at temperatures above 2,000° C. but reverses rapidly at somewhat lower temperatures. To produce magnesium by this reaction, therefore, it is necessary to cool the gas very rapidly to a temperature at which the rate of the reverse reaction becomes negligible. Several media for quenching the gas have been proposed, among which are hydrogen, natural gas, liquid hydrocarbons, and molten metals of low melting point.The results of a preliminary investigation on the use of molten lead as the quenching medium are summarized in this report. The work was done in 1941, when the threat of war made it imperative to investigate every process that offered possibilities for rapid expansion of domestic production of magnesium. Although the results were encouraging, other processes appeared to offer better prospects for immediate wartime development, so the work was not continued. Shortly before the investigation was completed, several patents on the use of low-melting metals for absorption of magnesium vapors appeared, 4/"

Jun 1, 1947

By Roy H. Grau, John C. LaScola

"This Bureau of Mines report contains a tabulation of methane emissions during 1980 for all coal mines located in the United States with emissions greater than 0.1 MMcfd. Listed for each mine are methane emission quantity, location, and coalbed. The report also compares records of 1975 and 1980 and describes relationships between emissions in 1980 and the Bureau's coalbed gas content data on 11 mines.INTRODUCTIONMethane gas is a threat to safety in underground coal mines. Research by Government and industry has led to great gains in reducing methane gas ignitions and explosions. The development of advanced methane control techniques is necessary for the safe operation of more gassy mines and the implementation of rapid mining techniques.As part of this research, the Bureau of Mines has surveyed total methane emission data from underground bituminous coal mines in the United States and tabulated emissions from mines producing over 0.1 MMcfd of methane. This report is an update of similar studies previously described in Information Circulars 8733, 8659, and 8558 (2-4).3The data from 1980 were compiled from Mine Safety and Health Administration (MSHA) records of air quality-quantity inspections made quarterly at each mine. The inspections involve measuring airflow and collecting air samples in the main returns. From these data, an average methane emission is calculated and used to represent the daily mine emission for each quarter. The methane emissions given in this report are the averages of the four 1980 quarters and do not include mine emissions from other sources such as degasification projects. Since a previous Bureau study showed that emissions from mines emitting less than 0.1 MMcfd represented only 2 pct of all emissions, 0.1 MMcfd was chosen as a lower limit for data collection (4)."

Jan 1, 1982

By Edwin M. Thomasson

Helium shipments for 1965 exceeded the volume shipped during the previous year for the 16th successive time. Shipments from Bureau of Mines helium plants were 698.6 million cubic feet, 2 about 4.7 percent more than in 1964. Production at Bureau of Mines plants totaled 757.4 million cubic feet, and an additional 3,549.6 million cubic feet was produced by private companies participating in the helium conservation program and purchased by the Bureau of Mines and stored underground for future use. The Bureau of Mines continued to sell helium at $35 per thousand cubic feet, the price established in 1961. Production and sales of helium increased from the one private plant operating entirely outside the Government's helium program. A second private plant was virtually complete at yearend, although actual production had not commenced.

Jan 1, 1967

Apply state-of-the-art monitoring and computer systems technology to remotely monitor geostructural data and evaluate ground conditions in near real-time. Background Recently, the coal mining industry has progressed dramatically from a labor-intensive industry to highly mechanized and automated systems achieving significantly higher production rates. In underground longwall coal mines, production and face advance rates have increased by almost tenfold in the last 15 to 20 years. With increasingly high advance rates, geologic anomalies which affect rock mass quality are encountered more frequently, far exceeding the current rate at which ground control information can be processed and analyzed. As a result, mine operators find themselves with insufficient time or resources to cope with the rapidly changing ground conditions. To keep up with the technological advancement in mining and the associated ground control problems, the Bureau of Mines is conducting a multi-phase research pro¬gram to implement a computer-assisted Ground Control Management System (GCMS). Research is ongoing at present, but when completed the system will be designed to 1) monitor and evaluate data on rock properties, geologic conditions, and rock mechanics data from underground sensors in near real-time; 2) interpret the analyses to evaluate the interaction between various critical ground control parameters; 3) assess the structural integrity of the mine; and 4) determine failure modes and provide recommendations for control measures, design modifica¬tions, and alternative support procedures. The system will be expanded into its full capability during various phases of this research program.

Jan 1, 1991

By Steven J. Schatzel, William P. Diamond

Coalbed gas content measurements are commonly used in mine safety as well as coalbed methane resource assessment and recovery applications. Gas content determination techniques generally fall into two categories: (1) direct methods which actually measure the volume of gas released from a coal sample sealed into a desorption canister and (2) indirect methods based on empirical correlations, or laboratory derived sorption isotherm gas storage capacity data. Direct gas content determination techniques may be further. subdivided into quick-crushing and extended desorption methods. The quick-crushing methods are primarily used in mine safety applications outside the United States, but have also been used for resource recovery applications. Quick-crushing methods rely on crushing the coal sample soon after collection to release all the desorbable gas, thus significantly shortening the amount of time required for desorption measurements. However, some data useful for resource recovery applications are lost. Extended desorption techniques are most commonly used for resource assessment and recovery applications where information on desorption rates is useful for reservoir modeling, and for fundamental coalbed methane research. Extended desorption methods allow the gases in the coal sample to desorb under controlled laboratory conditions until a defined low desorption rate cutoff point is reached. The sample may then be crushed to measure the amount of gas remaining within the sample. Direct method techniques for gas content measurement are the focus of this paper.

By Jeffery M. Listak, Ernest A. Curth

"It took only 9 years from the first appearance of roof shields on the U.S. longwall mining scene to the present predominance of shield faces. An apparent consequence is the welcome downward trend in accidents related to failures in longwall ground control. The report addresses load prediction, the effects of shield geometry on support loads, factors contributing to ground control, and related techniques. The Bureau of Mines took an active part in the evolution of longwall mining, including developing one of the first shield faces in 1975, the first lemniscatetype shields in 1976, the Mine Roof Simulator completed in 1980, the first shields in steeply pitching coalbeds in 1981, and the first multilift working of a thick coalbed in 1982. The information offered in this state-of-the-art report will assist in establishing criteria for roof support selection. INTRODUCTIONIn terms of roof support technology, the introduction of shields in the seventies and eighties was a major step forward. Table 1 indicates the predominance of shield faces on the U.S. longwall mining scene and its apparent consequence, a welcome downward trend of ground-control related accidents.The rapid progress of longwall technology began in 1975 and is highlighted by a development leading from the caliper shield to the modern lemniscate type. Shields have been gaining preference over chocks since their advent to longwall mining in 1975. Safety and productivity factors favoring shields over chocks are--1. A sheltered working space requiring minimum cleanup work.2. Structural stability that allows advancing without delay even with brushing roof contact and, by controlling all lateral loads, removing the requirement for cumbersome leg restraint and restoration devices.3. Wide hydraulic range of mining height.The development of roof shields in the Federal Republic of Germany preceded and paralleled their rapid adoption by U.S. miners. In 1983, 87 pct of the total production in Germany came from shield faces (1).2 In Great Britain, the National Coal Board introduced the first shield support system in 1977 to initiate Advanced Mining Technology (ATM) and Heavy Duty Mechanization (HDM) programs; as of mid-1982, 44 shield faces were operating, or 7.5 pct of a total of 581 faces CJ_)."

Jan 1, 1985

By Ronald D. Hill, Elmore C. Grim

The United States is richly endowed with mineral resources. However, mineral recovery by its very nature, involves a destructive process, Figures 1 and 2. In the past, mining practices were all too often conducted with the purpose of removing minerals by the simplest and cheapest method possible, without plans for the preservation of land, water, and air, and with too little consideration for the rights of others. A mining company is in business to make a profit, but every company, regardless of the nature of its business, has moral obligations to reduce its undesirable effects on the environment and to safeguard the rights of others. The problem of environmental degradation caused by surface mining is widespread and serious. Minerals in some form occur in each of the 50 States and several States are extensively mined. Data on the acreage disturbed in the United States, by commodity and State are presented in Table 1. Thirty-one States have laws regulating surface mining, (Table 2). Briefly reviewed in Appendix A-1 are the basic provisions of State laws governing surface mining. It can be seen that these laws vary considerably from State to State owing largely to the mining conditions within that State. Of the 24 coal-producing States, only three (Alaska, Arizona, and Utah) do not regulate strip mining. Even the states that are often cited as models of comprehensive regulations still have problems minimizing environmental damages. Uncontrolled surface mining presents a situation as critical to the well-being of the society as any it has ever faced. Many mining activities have imposed huge social costs on the public at large. These costs are long-range and are in the form of stream pollution, floods, landslides, loss of fish and wildlife habitats, unreclaimed land, erosion, and the impairment of natural beauty. In a 1965 Department of Interior study,(1)it was estimated that of the 25,000 miles (1+0,225 kilometers) of contour bench in Appalachia, approximately 1,700 miles (2735 kilometers) are affected by massive landslides. Additionally, 1+800 miles (7723 kilometers) of streams and 29,000 surface acres (11,716 hectares) of impoundments and reservoirs have been seriously affected by coal strip mining operations in the United States.

Jan 1, 1974

By J. D. Hadden

The Bureau of Mines conducted drilling studies in the Pocahontas No. 3, the Pittsburgh, and a western coalbed to establish the gas migration characteristics for each. Gas pressures in the Pittsburgh coalbed were about 260 lb/in2 and in excess of 550 lb/in2 in the Pocahontas No. 3. Caving in drill holes prevented pressure measurements in the western coalbed. The Pittsburgh coalbed contained intersecting "clay veins" which formed gas pressure cells. Although these geological features hamper mining, they can be used to control the flow of methane into a mine working. Methane control techniques are proposed for the Pittsburgh and Pocahontas No. 3 coalbeds.

Jan 1, 1969

By Donald P. Tuchman, Robert P. Vinson, Linda J. McWilliams, Steven E. Mischler, Jon C. Volkwein

A personal dust monitor (PDM) was developed to measure respirable coal mine dust mass to provide accurate exposure data at the end of a work shift. Additionally, the new monitor continuously displays near-real-time dust exposure data during the shift. The PDM uses a tapered-element oscillating microbalance to measure the mass of dust deposited on a filter and continually displays the cumulative exposure concentration data. The accuracy and precision of the instrument was determined by comparison to gravimetric filter samplers in the laboratory and in four mines. Laboratory results with different coal types and size distributions showed that there is a 95% confidence that the individual PDM measurements were within ±25% of the reference measurements. Mine test results indicate that data taken with adjacent PDM and reference samplers are indistinguishable. The technology proved durable enough to successfully measure 108 shifts of data out of 115 attempts in the mines. Under these specific test conditions, the PDM demonstrated that it was convenient to wear, robust, provided accurate data, provided timely data that could be used to prevent overexposure, and was easy to use.

Jan 1, 2004

By J. D. Hadden, Albert Sainato

The Bureau of Mines conducted drilling studies in the Pocahontas No. 3, the Pittsburgh, and a western coalbed to establish the gas migration characteristics for each. Gas pressures in the Pittsburgh coalbed were about 260 lb/in2 and in excess of 550 lb/in2 in the Pocahontas No. 3. Caving in drill holes prevented pressure measurements in the western coalbed. The Pittsburgh coalbed contained intersecting "clay veins" which formed gas pres- sure cells. Although these geological features hamper mining, they can be used to control the flow of methane into a mine working. Methane control techniques are proposed for the Pittsburgh and Pocahontas No. 3 coalbeds.

May 1, 1969

By Thomas H. Dubaniewicz

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approximately proportional to beam diameter for beam diameters from 0.1 to 2.0 mm. Results suggest that relatively powerful beams may be used in these atmospheres without causing ignition, provided the beam diameter is controlled. Threshold ignition delay times using 91125 and 62.51 125 pm fibers were approximately proportional to the inverse square of the laser power. Ignition delays were about 45 ms or longer for laser powers up to 800 mW. Preproduction samples of a commercial optical fuse prevented ignitions under selected test conditions. A self-healing effect was observed for one sample. Comparisons are made with the results of other researchers. O 2006 Laser Institute of America. Key words: propane ignition, butane ignition, laser ignition, nonbeam hazards, fiber optic fuse

May 3, 2006

By Forrest T. Moyer

THIS CHAPTER of the Minerals Yearbook contains injury experience and related employment information for the coal-mining, coking, oil and gas, peat, and native asphalt industries in the United States for 1962. Injury experience is measured by the number of injuries sustained per million man-hours of exposure in each industry. No attempt has been made to combine these data and present rates reflecting the mineral-fuel industries because the hazards of the separate industries are not comparable. Tabulations showing the trend of injuries and employment for all mineral industries are presented in volume III of the Minerals Yearbook. COAL The injury-frequency rate for the coal-mining industry of the United States increased less than 2 percent, according to reports received by the Bureau of Mines. The number of fatal and nonfatal injuries per million man-hours in 1962 was 45.86, based on final data for anthracite mines and preliminary data for bituminous coal and lignite mines.

Jan 1, 1963