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By E. V. Potter

"INTRODUCTION The oscillator and amplifier system described in this paper was developed specifically for driving sound generators of the type developed by H. W. St. Clair and described by him in an article 3/ published several years ago in the Review of Scientific Instruments.Nevertheless, with little or no alteration it can be used to drive any vibrating system in which the vibrating member must be driven at its resonant frequency; the only restrictions are that the driving mechanism be electrical in nature and that the vibrating member be accessible so that some type of pick-up can be coupled to it. Operation of the automatic frequency-control element in the oscillator, however, depends entirely on the operating characteristics of the vibrating member; therefore, in order to completely explain the operation of the circuit, it will be necessary to describe the construction and operation of the vibrator used with it. Only the essential features and characteristics of the vibrator will be described in this article, and the reader is referred to St. Clair's 4/ report for further details."

May 1, 1943

By Philip C. Tully

This bibliography contains 2,072 citations to technical and scientific literature about helium and alpha-particles abstracted by 12 abstract service publications during 1962. Citations are listed by 16 major subject classifications with several subclassifications to minimize areas of literature search. Automatic data processing was used to reduce the time and labor required to compile the bibliography.

Jan 1, 1969

By J. B. Zadra

Tungsten metal, chemically equivalent to commercial grade, is produced by electrolysis of impure tungsten compounds or scheelite in an alkali, phosphate or borate electrolyte. A preliminary investigation of fused-bath electrolysis shows the effect of electrolyte composition, temperature, and current density on current efficiency, yield, crystal structure, and purity of product. Experiments show that tungsten can be electrowon from scheelite in a fused alkali, phosphate, or borate bath with similar results. Studies on electrolyte composition show that the addition of sodium chloride is essential to both electrolytes in treating scheelite. Although its main function is to react with or flux the CaO, it also increases the bath fluidity. Temperature studies revealed optimum ranges between 900° and 1,100° C.; 900° C. proved satisfactory for tungsten trioxide, and 950° to 1,050° C. for scheelite. Current efficiencies were satisfactory for all current densities ranging from 10 to 57 a./dm.2. Yields were 400 to 650 g./kw.-hr. over the same current-density range. Crystal size and purity of the product are functions of temperature, current density, and amount of impurities in the electrolyte. Deposited crystals vary in shape from spherical grains to clusters of dendritic hexagonal needles, and in size from smaller than 35 to 570 microns. The purity of the tungsten metal produced ranges from 99.7 to 99.94 percent.

Jan 1, 1959

By T. D. Hackett

Multislice mining methods were analyzed by the U.S. Bureau of Mines to determine their application to western United States thick coal seams; ground control, geology, and costs were considered. Multislice mining is used in widely varying seam conditions worldwide, including flat seams too thick to mine in a single pass, pitching thick seams, and seams containing a rock parting. Longwall multislice methods predominate, but room-and-pillar variants also exist. The initial use of the method in western seams is planned at a deep Colorado mine where a rock parting will be used to separate two slices mined by longwall. Ground control and spontaneous combustion are major hazards associated with multislice mining. A well-consolidated upper slice gob can reduce ground control problems and provide a seal against spontaneous combustion. Geologic analysis indicates that the consolidation of the gob depends on the composition of the upper slice roof, the presence of water, and sufficient overburden pressure. A geologically competent intermediate rock parting can also reduce ground control problems and seal against spontaneous combustion. To compete in western coal markets, the cost of multislice mining must be within the range of normal longwall costs. Analysis indicates that multislice operating costs should be within this range, and that multislice mining costs decrease as panel width increases. Relatively wide (600 to 800 ft) panels also provide increased coal recovery.

Jan 1, 1990

By Sean Gallagher, Gene Wilson, Christopher Mark, Craig S. Compton, Gregory M. Molinda

Falls of small pieces of rock from between roof bolts continue to cause fatalities and to injure hundreds of coal miners each year. Roof screen is the most effective way to prevent these incidents, but some mines are reluctant to use it because they believe installing screen can be awkward, expensive and time-consuming. The most common type of roof bolting machine used in mines today is the dual boom, outside-controlled roof bolter. Mines who install roof screen using these machines have developed some machine modifications and techniques to ease roof screen installation. This paper describes some successful techniques and machine modifications that are being used in productive mines to assist with roof screen installation. Since the material handling involved with roof screen installation can expose miners to an increased risk of musculoskeletal injuries, the National Institute for Occupational Safety and Health (NIOSH) ergonomists, designed machine modifications and implemented a series of tests to evaluate roof screen handling procedures for outside-controlled, dual boom roof bolting machines. Roof screen installation can also have a positive economic impact on a mine by reducing the cost of injuries, workers’ compensation, required spot or re-bolting, and clean-up of long term travel and belt entries.

By J. H. East, D. Harrington

"INTRODUCTION Considerable interest has been shown in the prospective use of Diesel-powered haulage equipment in both coal and non-coal mines. Foreign technical magazines have devoted considerable space to discussions of the use of Diesel locomotives in European mines and some mention of it has been made in technical papers in the United States. The Bureau of Mines has extensively tested the gases produced in the exhaust of the Diesel engine under various atmospheres and conditions of use; it has established a schedule of tests for permissibility of Diesel engines for use in underground coal mines, including, gassy or dusty mines.This publication provides information as to the successful use of Diesel-powered equipment underground workings in the United States and Europe, briefly discusses the characteristics of some of the toxic gases found in the exhaust of Diesel engines, and points out that Diesel-powered equipment can be used with reasonable safety in underground minus if necessary and entirely feasible precautions are taken."

Apr 1, 1947

By Wilson Blake

Rock preconditioning in advance of mining was shown to be an effective means of rock-burst control based on the results of a field demonstration carried out on the 7700 level of the Hecla Mining Company's Star mine. Mining through the preconditioned zone was characterized by greatly reduced rates of released seismic energy and no bumping or rock bursting occurred within the preconditioned zone. Mining above the preconditioned zone was characterized by greatly increased rates of released seismic energy and rock bursting, particularly where the vein became very narrow in waste zones. This increased incidence of rock bursting points out the need for stope preconditioning to be carried out on an entire stope block basis. The data obtained from the monitoring of the mining above the preconditioned zone on the 7700 level will be extremely useful in evaluating any future stope block preconditioning experiments on the lower levels or the Star mine.

Jan 1, 1980

By McHenry Mosier

The object of this investigation is to determine the field for the use of detachable bits in metal mines of the United States by correlating the data developed through the experience of mines using these bits. Most of the metal-mining districts in the Middle Western and Eastern States already have been visited. The purpose of the present circular is to define the problem and to discuss the factors that must be considered in order to determine, under different operating conditions, the advantages and disadvantages of this type of bit. Some of the data obtained to date are presented to emphasize points made in the discussion. It is hoped that, as the study progresses, a great many data on drilling will become available. It is evident that since in some cases these data will be confidential they cannot, therefore, be published except as they may be included in average figures covering several different mines. Some data already secured are of this nature, Although considerable information on drilling operations has been gathered at different mines, there were only a few instances in which there were available complete data on all the factors entering into the total cost of drilling with detachable bits and with conventional bits on regular drill steel.

Jan 1, 1936

By D. R. Wilburn

The Bureau of Mines investigated the potential availability of magnesium from 45 properties in market economy countries (MEC's). The 38 significant deposits evaluated have demonstrated resources of approximately 29 billion short tons (st) magnesium-bearing material containing 416 million short tons (MMst) magnesium oxide (MgO). Using data it gathered, the Bureau determined the magnesium production potential for each property including a 15-pct rate of return on invested capital. Total and annual availability assessments for the next 30 yr were completed for magnesium (Mg) metal, deadburned MgO, and caustic calcined MgO. At a January 1984 market price of $1.34/Ib Mg metal, the properties evaluated could economically produce an estimated 13 MMst Mg metal. At a market price of $400/st nonmetal magnesium product, these properties could economically produce 109 MMst deadburned MgO and 43 MMst caustic MgO. These properties could produce approximately 301,000 st Mg metal, 3.0 MMst deadburned MgO, and 430,000 st caustic MgO annually at current full production levels and 1984 market prices until at least the year 2000. Total 1984 MEC production assessed in this study was 153,000 st Mg metal and 4.3 MMst nonmetallic MgO products.

Jan 1, 1986

MR. RIGG: Gentlemen, I would like to welcome you all to the symposium this morning. My name is Jack Rigg, and I m a special assistant to Hollis Dole, Assistant Secretary of the Interior for Mineral Resources. Hollis is not in town this morning, and I am here to pinch-hit for him. The first order of business this morning is remarks by the Honorable Russell Train, Under Secretary of the Department of Interior. Mr. Train. MR. TRAIN: Thank you, Mr. Rigg. Lest you think that Hollis Dole is not interested in this symposium, let me just say that fie is flying back from Australia just to be here. He is heading up a United States delegation in Australia meeting on resource problems in the Pacific. And I believe he will be here about noon.

Jan 1, 1970

By Robert H. Peters

The objective of the project descibed in this report was to design and field test a model health and safety program at a coal mining company and a gold mining company. The model program was implemented primarily by providing training on loss control, accident investigation, and the operation of mobile equipment; and by providing technical assistance to help solve health and safety problems. Data were obtained from company records on occupational injuries, illnesses, accidents, and "near misses"; and through direct observation of employees performing a large number of randomly selected jobs. At the coal mine, employees were observed five times over a 15-month period. At the gold mine, employees were observed six times over a 16-month period. During the study, the percentage of sampled jobs containing one or more safety deficiencies decreased from 74.3 pct to 36.6 pct at the coal mine and from 86.4 pct to 19.1 pct at the gold mine. Work on this project was performed by Woodward Associates, Inc., under a Bureau of Mines contract.

Jan 1, 1986

By J. A. Kost

A survey of 80 coal producers was conducted to determine the extent and scope of respirable dust control research for underground coal mines and the current methods employed to control respirable dust. Results of the survey showed that proper face ventilation and an adequate water spray system are sufficient to comply with mandatory standards in room and pillar mining. Difficulties still exist with longwall equipment, auger miners and buring machines. In these cases, known dust control techniques are not sufficient to obtain compliance. Present state-of-the-art face ventilation and water systems were discussed in addition to the sampling program.

Jan 1, 1980

By D. E. FOCG, A. E. Wells

When the United States entered the World War governmental agencies found little definite knowledge available as to the exact capacity of each sulphuric acid plant in the United States to manufacture acid under the stress of a great emergency. It is true that on account of the demand for acid for the manufacture of munitions for the Allies, prior to the entrance of this country into the war, most of the acid plants near industrial centers in the Eastern and Northern States were running at or nearly their maximum capacity, but, . for various reasons, many plants in these States and plants in other districts were not. For a number of years statistics as to the production of acid by the plants of the country were compiled by the United States Geological Survey, but obviously such figures did not give information as to the maximum capacities that might be available for meeting the he.a vy war ·requirements, or as to the steps that would have to be taken to bt-ing these capacities into use. During the summer and early fall of 1917 various attempts were made to obtain the desired information, but no satisfactory or complete data were obtained. Late in 1917, under the authority granted to the Bureau of Mines by the explosives act, the Director of the Bureau of Mines directed A. E. Wells, metallurgist of the bureau, to uiake a complete survey of the situation. Mr. Wells personally conferred with officials of the acid companies and visited most of the acid plants in the North that are east of the Mississippi River. The information obtained through this personal survey, together with that obtained through the ready cooperation of the subcommittee on ncids, and the subcommittee on fertilizers of the Committee on Chemicals of the Council of National Defense, enabled the preparation of a report containing the desired data concerning the sulphuric acid industry. This report was made immediately available to the War Industries Board and to those offices in the War and Navy Depart- ments that were most directly concerned in planning the explosives program and in obtaining the necessary supplies to produce the explosives. Beginning with this survey and report, the sulphuric acid section of the war minerals investigations of the Bureau of Mines took an active part in all matters pertaining to the sulphuric acid industry during the remainder of the war. Mr. Wells, the chief of the section, was appointed an associate chief of the sulphur, pyrite, and sulphuric acid sections of the War Industries Board. .Also, by this direct contact with the War Industries Board, the data obtained by Messrs. R. R. Hornor, H. A. Buehler, a.nd 0. Lindstrom, who were in charge, for the bureau, of the investigations concerning the supplies of pyrite and sulphur, were constantly made available to all interested Government agencies. D. E. Fogg, of New York City, was appointed chemical engineer to the sulphuric acid section to make special investigations relating to the acid industry, especially the possible utilization, in an emergency, of those sources of raw material.not then being used. Mr. E. E. Corbett, of Brooklyn, N. Y., was appointed chemical engineer to make investigations concerned primarily ,vith the conservation of acid. Direct and intimate contact with the industry was had through the close cooperation with the committee on acids of the Chemical Alliance, this committee during the greater part of 1918 occupying rooms with the acid section of the bureau. With the ending of the war and the close o:f the active work of the acid section of the bureau, the suggestion was made by many interested parties that a bulletin be prepared giving some qf the fun. damental and most important facts regarding the sulphuric acid industry, including a discussion of the technical :features of the manufacture of acid. During the war the bureau received -a vast number of inquiries in regard to various phases of the industry, a.nd this fact also made such a bulletin seem desirable. Therefore, the present bulletin was prepared to cover the main facts in regard to the industry in this country, including a discussion of the supplies of sulphur-bearing raw materials, the situation of the acid plants, the principal points in regard to manufacturing processes, and the uses of the acid. No attempt has been ma.de to discuss at length the manufacturing processes, as details differ more or less at the different plants and in general are carefully guarded by the acid ·companies. A great deal of the data given in this bulletin may be found in various pub]ications, but this is the first publication in which such data have been assembled and made readily available. Most of the data were obtained directly from observation and from cooperating acid companies or from individuals who had been or are now engaged in acid manufacturing and were liberal and generous in making their information available for publication. Care has been exercised to publish no data that were obtained as confidential by the bureau's representatives. The average acid manufacturer may be already more or less acquainted with most of the information presented in this bulletin, yet it is believed that the bulletin will be of value to those who wish to obtain a. general review of the present condition, both the economic and technical, of the sulphuric acid industry in the United States.

Jan 1, 1920

By Gerald T. Homce, James C. Cawley

Electrical arcing injuries are the most common form of electrical injury in mining. MSHA data show that 381 "non-contact electric arc burn" injuries occurred in the mining industry from 1996 - 2005. A more detailed study of data from 1990-2001 showed that five types of apparatus - circuit breakers, conductors, nonpowered hand tools, electrical meters and test leads, and connectors and plugs were involved in two-thirds of the lost workday injuries. Many of the protections from electrical arcing injury available to workers in other industries stem from the application of National Fire Protection Association Standard 70E - Standard for Electrical Safety in the Workplace (NFPA 70E). NFPA 70E is a generally accepted industry guideline document, but excludes underground mining from its scope. Many of its practices and procedures, however, can be applied in the mining workplace to supplement the existing electrical safety requirements of Title 30 Code of Federal Regulations. This paper describes how NFPA 70E can be applied to mining workplaces after an analysis of the mine power system electrical arcing hazards has been completed (and Hazard/Risk Categories determined) using the tables from NFPA 70E or the calculation method as described in IEEE 1584. NFPA 70E can then be used to determine the levels and types of personal protective equipment (PPE) needed to protect miners against burn injuries. Appropriate lockout and tagout (LOTO) procedures for use in the mining industry are also described. Suggestions for better selection of electrically-rated hand tools are included. Recommendations for electrical meter selection and use based on transient withstand capability are also discussed.

By E. J. Babcock, W. W. Odell

The Bureau of Mines since its establishment has always taken an active interest in the utilization of lignite and in the development of the lignite dep'osits of the United States. Extensive lignite fields occur in the west central States, notably in North Dakota, Montana, Wyoming, Colorado, and Texas; there are smaller areas in several other States, some of which are widely separated. The total area of the deposits and the total amount of lignite in these several districts are so enormous that the economic value is seldom recognized. To the people of ·the west and west central regions, however, the larger utilization of lignite, in whatever form it may be, is of fundamental importance, and any new methods or uses that promise to open these great lignite fields for more general and more efficient use deserve careful study. Although these lignite deposits underlie areas of thousands of square miles, their development and general utilization has been rather slow. This is no doubt partly because many of the districts are not thickly settled or highly developed in manufacturing industries, but is largely because lignites, from their peculiar physical and chemical characteristics, are low-grade fuels. Most of the lignites in these areas are imperfectly developed coals; many have a more or less woody structure; some belong to the brown-coal type; and others are darker, denser, and more homogeneous, approaching subbituminous coal. The people living in the regions in which these vast deposits occur, especially in the west central part of the United States, are vitally interested in every effort toward bettering lignite as fuel and aiding its wider utilization.

Jan 1, 1923

By Bill M. Stewart

Since 1974, a large amount of data has been developed concerning the physical properties and stability characteristics of waste generated by the mining and preparation of bituminous coal. However, very little information has been developed on the properties and characteristics of anthracite waste. During this Bureau of Mines research project, coarse anthracite breaker refuse from five sites in eastern Pennsylvania was sampled and the physical properties, which indicate stability characteristics, were determined in the laboratory. Coarse anthracite breaker refuse is quite similar to coarse bituminous refuse in chemical and mineralogical composition. However, the physical properties of the anthracite waste materials tested are different from those of coarse bituminous refuse. For the coarse anthracite breaker refuse tested, the average maximum laboratory density is 113.2 lb/ft3, the average angle of internal friction (direct shear) and average cohesion are 30.2° and 2.6 psi, respectively, and the average permeability (four sites) is 1.24 x 10-2 cm/sec. Stability analyses were conducted on six theoretical anthracite waste embankments. These analyses show the effects on minimum safety factors of geometry, phreatic surface level, and physical properties.

Jan 1, 1983

This report is the 24th in a series summarizing research on coal and related investigations3 by the Bureau of Mines. The coal programs of the Bureau of Mines include a wide range of theoretical and applied studies--such as fundamental studies of coal structure and properties, the development and evaluation of new mining techniques, and work toward more effective processing and utilization of coal. The scope of these programs is indicated, in topical outline, by the table of contents. These investigations are integrated into a broad but coordinated effort to develop information on coal that will benefit the coal mining industry and the coal consumer while promoting the wise conservation and utilization of our national coal resources. Any attempt to summarize in one volume the progress in all of the program areas indicated must necessarily be limited to a brief review of developments, without detailed reporting of the data. However, while the brief discussion in each section will present only the highlights of the Bureau's work during the year, details of many of the operations or investigations described here can be found in the publications cited throughout the text. Other work, reported here for the first time, will be covered in greater detail in later publications.

Jan 1, 1962

By Allan F. Smith

The influence of hydraulic fluids on spontaneous heating in bituminous coals is determined by measurement of the temperature increases produced in coal-fluid mixtures heated to a temperature sufficient for the initiation of self-heating. Similar tests on as-received coal samples and water-coal mixtures are compared with the results obtained for the various hydraulic fluids. Three of the four coals were sampled from coalbeds known to have a history of spontaneous heating. The data provide a basis for predicting the possible effects in gob or carbonaceous refuse of coal mines.

Jan 1, 1963

By D. Harrington

Hatch (260) made the following pertinent statement regarding the present status of engineering design of dust-control equipment: Textbooks on ventilation and engineering handbooks devote little or no space to methods of control of industrial dust, and in the technical journals papers on fundamental engineering design of equipment are conspicuous by their absence. In a recent bibliography of the literature on pneumoconiosis less than 1 percent of the articles dealt with the engineering control of the disease. The science of dust control has not developed beyond the stage of trial and error, and the design of structures for the suppression of dust is based almost entirely upon empirical data together with one or two elementary formulas. The latter were derived from the generalized experience in a limited number of Industries such as woodworking, where conditions and requirements are not at all like those, for example, in a sand-pulverizing plant. Wide experience and good judgment are essential to the proper use of the scanty information that has been collected and systematized. Without attempting to minimize the importance of experience in engineering design, it is necessary to point out that most of the past experience obtained in the empirical design of dust-control equipment was not evaluated by means of quantitative studies of the actual reduction in dust , fence, past experience does not necessarily furnish the proper guide for future design. In fact, recent surveys in certain industries, employing modern methods of investigation, have shown that existing equipment is in many cases inadequate.

Jan 1, 1935

By Ralph B. Stevens

The objective of this 20-month program was to define the relationships between mine ventilation, temperature, humidity, ore properties, material's used in mine operations, etc., and the spontaneous combustion problem in underground metal mines. Tradeoff studies of availability, reliability, cost, and maintenance of spontaneous combustion protection sensors and telemetry were conducted, after which a prototype system was selected from four design alternatives. This selected system was then laboratory tested and demonstrated in an underground copper mine.

Jan 1, 1979