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By Hazel B. Comstock

This materials survey on magnesium and magnesium compounds is one of a series of Bureau of Mines publications designed to serve the needs of Government and industry for comprehensive, up-to-data information on mineral commodities and activities. Magnesium, the world's lightest structural metal, has become a most useful material in airborne and spare vehicles, automotive equipment, machine tools, and consumer products. Use of magnesium ores in basic refractories for iron and steel furnaces has expanded as the production of iron and steel has increased, Progress in converting steel fun cares to the use of oxygen has further increased the use of magnesia and magnesite brick.

Jan 1, 1963

By Lloyd G. Fitzgerald

"The dangerous nature of explosives makes them a potential hazard wherever they are used, but they are likely to exercise their greatest harmfulness under conditions inherent in coal mining. The ease with which explosives can be detonated and the suddenness and violence with which they detonate require great care in their handling and use, if acci-dents are to be avoided. Campaigns have been waged by the manufacturers, the Federal Bureau of Mines, coal-mining companies, and other agencies to educate users of explosives in their dangers and in their proper use and care.Probably 95 percent of the explosives accidents can be attributed to poor judgment, carelessness, negligence, or chance taking. In many explosives accidents it is difficult to determine the cause definitely, as the evidence of the origin is destroyed by the blast and frequently those involved have been killed. Survivors of the accident often are of little help in determining the cause, as the accident occurs so suddenly they cannot tell what happened or prefer not to divulge the information they have because it may point to their own carelessness.A survey has indicated that about 10 percent of all fatalities in coal mines were caused by explosives accidents (excluding gas and dust explosions initiated by explosives). A list of explosives accidents by States, from 1925 to 1932, classified according to the severity of the accidents, indicated that Kentucky and Wyoming had the greatest number of fatalities resulting from explosives accidents. Records of the Bureau of Mines show that 14 coal-mine explosions occurred from January 1 to June 1, 1943. Explosives were involved in four of these explosions. Black powder caused two of the accidents and permissible explosives used in a nonpermissible manner the other two. These statistics are mentioned to show that explosives are still causing severe accidents.Elimination of the hazards associated with explosives begins on the surface. Storage magazines should have no opening, except for entrance and ventilation; ventilators should be screened effectively to prevent the admittance of sparks as well as to prevent unauthorized entrance. The interior should be kept clean and dry, and the floor should be of nonsparking material with no metal exposed. The surrounding area should be kept free of combustible material for not less than 25 feet (and preferably 50 feet) in all directions. Storage magazines should be fire-resistant and reasonably bulletproof."

Aug 1, 1944

By S. E. Khalafalla

The Bureau of Mines investigated variations in the activation energy for the carbon monoxide reduction of magnetite and ferrous oxide with respect to the state of aggregation of the oxide material. Reduction phenomena can only be satisfactorily explained by including an adsorption step in the reduction process. Summation of the values of the exothermic heat of chemisorption and the variable apparent activation energy for reduction yields a nearly constant value of about 50 kcal for either ferrous oxide or magnetite regardless of whether they are aggregated in pelletized form or coarsely crystalline particles.

Jan 1, 1965

By Bertrand L. Johnson

Pure talc is a hydrous magnesium silicate (Mg3Si4010(OH)2). Pyrophyllite, although it resemble: talc in certain physical properties and uses, is a hydrous aluminum silicate (Al2Si4010(OH)2) - like kaolin, except that kaolin has a somewhat different composition (Al2Si205(OH)4) and structure. Soapstone can be considered essentially an impure talc grid when pulverized is used for many of the same purposes as talc. Massive, compact varieties of talc often are called steatite. PROPERTIES Talc and pyrophyllite are characterizes; by their softness (hardness on Mohs' scale, 1) their greasy feel, pearly luster, white color, and perfect basal cleavage. They have similar crystal structures, and this similarity explains the close resemblance of the two minerals in physical acid chemical properties. Talc is a good electrical insulator, resists the action of most acids and alkalies, and has an exceptional heat-retaining capacity. Its specific gravity is about 2.7.

Jan 1, 1939

By J. K. Whyatt

The U.S. Bureau of Mines has been conducting a series of rock mechanics investigations at the Lucky Friday Mine in the Coeur d'Alene Mining District of northern Idaho. In the present study, the energy release rate (ERR) index was used to evaluate three underhand stope backfill parameters-cement content, density, and placement gap-to determine their influence on rock bursts. This index provides a relative measure of the likelihood of rock bursting for a given rock mass. It is known that the elastic idealization of the rock mass inherent in this method causes underestimation of stope closure and hence underestimation of the influence of backfill on rock bursting. However, this evaluation still showed that (1) changing from present practice to one in which backfill was omitted altogether would increase the ERR by 42 pct and (2) perfect placement of backfill would reduce the ERR below present practice levels by 28 pct. The easiest step toward perfect placement would be elimination of the placement gap, which accounted for half of the difference in ERR between present practice and ideal placement conditions. There was no indication that increasing initial fill strength through increased cement content would affect the ERR.

Jan 1, 2010

This document is Volume II of a two-volume report on underground and surface coal mine fires occurring between 1950 and 1977. Volume I discusses the methods of data acquisition, data analysis procedures, results and conclusions. This volume contains (1) a master list of all fire incidents obtained from MSHA reports, (2) an annotated bibliography of all MSHA reports, journal articles on selected incidents, and non-reportable fires (appendix), and (3) indexes to be used in accessing incidents in the master list and annotated bibliography. These three types of information provide the reader with a complete summary of coal mine fires during the period from 1950 through 1977 and a convenient means to locate incidents of specific interest. The body of this volume is organized around two tables and a series of indexes. The two tables are master lists of underground and surface fire incidents. They are followed by 14 indexes keyed to the master list and annotated bibliography. The appendix contains three different parts: o The annotated bibliography of MSHA fire reports (one section each for underground and surface mine fires) o The annotated bibliography of journal articles about selected fires from the MSHA bibliography o A listing of non-reportable fires (one section each for underground and surface mine fires) Descriptions of the contents and use of each of the three major components of this volume (i.e., master list, indexes, and appendix) are presented in Section 2.0.

Jan 1, 1979

By D. E. Wolfson

As part of its overall program of coal-carbonization research, the Bureau of Mines is studying the coking properties of coals from various fields of this country. Few of the coals included in this survey are used for the manufacture of metallurgical coke, although some well-known coking coals necessarily are tested to provide comparative data, particularly on blending properties. The overall objectives of the study were given in detail in a previous report.3/ The inherent suitability of coal for metallurgical purposes, as distinguished from economic considerations, depends primarily on (1) the available reserves, (2) chemical composition, (3) preparation characteristics, and (4) carbonization behavior. These items are considered in selecting coal for carbonization tests.

Jan 1, 1956

By K. E. Tame

The Bureau of Mines is studying possible modifications in conventional ore-processing methods that will confine and permit controlled disposal of radioactive liquid wastes. Stream and ground water pollution from radio-active nuclides, principally radium 226 and thorium 230, in liquid wastes from uranium mills can be minimized by reusing the waste solution within the mill. Such reuse of waste solution in an acid leach-resin-in-pulp flowsheet was investigated in the laboratory. The process consists of acid leaching for dissolution of the uranium, sand-slime separation and countercurrent decantation washing for recovery of a pregnant slime slurry, and the use of ion-exchange resin for recovery of uranium from the slurry. Reuse of clarified barren effluent for washing in the simulated mill circuit was carried through 55 cycles. Dissolution of uranium from the ore averaged 97.5 percent. Washing efficiency of 99.9 percent was attained when using 4.35 volume tons4 of combined barren effluent and makeup water per ton of ore. Absorption of uranium from the pregnant slime slurry by an ion-exchange resin averaged over 99.9 percent.

Jan 1, 1962

By J. J. Sammarco

Light emitting diodes (LEDs) are emerging as viable replacements for incandescent-based cap lamps used in mining. The photometric and energy characteristics of these light sources differ in important ways. The present paper describes the performance of LED and incandescent sources in cap lamps in terms of correlated color temperature, color rendering, light output, electric power, ambient temperature and airflow, and light source aging. Importantly, these characteristics can influence a miner?s ability to spot mining hazards thus impacting safety. Secondly, some of these characteristics interact with the operating life of the cap lamp?s battery power, such that differences between LED and incandescent sources can be magnified toward the end of a 10­hour battery discharge cycle. Empirically, we have determined that after 8 hours at an ambient temperature of 25 °C, the average light output of an incandescent cap lamp can decrease to about 69% of its initial value when powered by a lead-acid battery and it can decrease to about 65% of its initial value when powered by a nickel-hydride battery. An LED-based cap lamp using a constant current drive circuit can maintain about 96% of its initial value when powered by a nickel-hydride battery. Real-world tests addressing the effects of ambient temperature and airflow on the light output of an LED and incandescent cap lamp were conducted in the NIOSH Safety Research Coal Mine (SRCM). The LED cap lamp yielded a vertical average illuminance improvement of approximately 9.5% and the INC cap lamp yielded a vertical average illuminance degradation o f approximately 4%. The differences between LED and incandescent cap lamps were further quantified by the calculation of ?mesopic luminance? data that indicated for the same photopic luminance (i.e., as measured using a conventional light meter) the LED cap lamp could be up to 38 % more efficient than the incandescent cap lamp with a lead-acid battery at the end of the 10-hour driving cycle. Lastly, accelerated life tests were used to empirically determine light output depreciation as the incandescent light source age approached its useful life. There was about a 35% decrease in light output. This is quite considerable, especially given that the light output will decrease an additional 30% to 45% over the period of a 10-hour shift. The implications of the differences between LED and incandescent sources are discussed. This information is crucial in determining how visual performance could be affected for real-world conditions where batteries discharge during the work shift and as the light source ages. To date, only idealized conditions have been used for LED and incandescent cap lamp visual performance research.

Jan 1, 2008

By T. J. Ballard, Austin B. Clayton

"INTRODUCTION The Conrad Hill mine was first opened as a gold mine about 1832 and has been operated at various times since then.The Bureau of Mines, as part of the strategic minerals program, mapped and sampled the accessible mine workings.The: work failed to reveal appreciable copper values or evidence of additional ore deposits.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the and that they make the greatest possible contribution to national security and economy. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The field work embodied in this report was under the direction of Austin B. Clayton. The final report was prepared by T. J. Ballard uncle,- the general supervision of Mitchell H. Kline, chief, Raleigh, N. C., Branch, Mining Division. Analyses of samples and beneficiation tests were made by the Metallurgical Division. ACCESS AND OWNERSHIPThe property is 6 miles southeast of Lexington, N. C., and can be reached by U. S. Highway 64, turning off at Hedrick Grove Church, and is 1 mile north from the highway on the county road. The mine is in Davidson County at approximately 35° 47' latitude and 80° 10' longitude (fig. 1).The property comprises 471 acres and is owned (1943) by the McKeeMining Co., 512 Fifth Avenue, New York City. The property was optioned to Woodrow McKay of Lexington, N. C., in 1943, who in turn subleased the property to the Robert G. Lassiter interests of Raleigh, N. C."

May 1, 1948

By D. J. Parker

Owing to its flexibility, convenience, economy, ands availability, electric power is peculiarly adapted to the needs of the coal -mining industry. Because of such obvious advantages, the application of electricity has in recent years become more and more extensive and is now a most important factor in the Nation's coal prediction. With the introduction of this type of power into coal mines certain new, specific, and well-recognized hazards resulted. The question arises, therefore: Has the industry met these hazards squarely and. effectively? With respect to some individual companies, the answer happily is in the affirmative; with respect to the industry as a whole, there is much room for improvement.

Jan 1, 1933

By Raghoottma S. Pandurangi, Mohindar S. Seehra

"The interaction of amorphous 1ilica particles with several hydrogen bonding agents (H2O, C2H5OH, C7H2NO) was investigated by monitoring the changes in the bulk and surface IR vibrational modes of silica using photoacoustic spectroscopy. It is argued that the intensity of the silanol band at 3747 cm-1 provides (an inverse) quantitative measure of the interaction or surface groups, along with the shift in the broad hydroxyl band, the interaction following the order C7H2NO > C2H5OH > H2O. Index Headings: Silica; Surface vibrational modes; Photoacoustic spectroscopy; Hydrogen bonding agents.INTRODUCTIONThe use of m spectroscopy to study the adsorption on solid surfaces is well documented in the literature.1 2 For example, hydroxylation of a clean silica surface results in the formation of the free silanol group Si-OH, with a sharp IR band near 3747 cm-1• Further hydroxylation produces a broad band near 3500 cm-1, which is believed to result from various hydrogen-bonded silanol bands leading to a multilayered surface structure of few nm.3-5 Earlier studies had indicated a relationship between the surface silanol band and various chemical activities of silica such as cytotoxicity, 7- 9 catalysis, 10-12 and others.13 Recent studies from our group14-in which the intensity of the silanol band and cytotoxicity of silica, heat-treated at various temperatures up to 1095°C, were investigated have provided a strong correlation between cytotoxicity and intensity of the silanol band.Coating of silica by PVPNO (polyvinyl-2-pyridine N-oxide with the empirical formula C7H8NO), a strong hydrogen bonding agent, is known to reduce the cytotoxicity of silica, presumably by chemically blocking the silanol groups from phospholipids.15 This interaction of the hydrogen bonding agents with the silica can be studied by m spectroscopy, and Knozinger16 and Rouxlet and Semples11 have used transmission m spectroscopy to study the effect of various chemicals on the surface IR modes of silica. However, one of the major disadvantages of transmission IR spectroscopy is that the sample preparation (grinding and mixing with KBr and pelletizing) usually distorts the surface modes (see, e.g., Ref. 14) and there is always a doubt about the effect of the sample preparation on the measured properties. In recent years, photoacoustic (PA) spectroscopy has become the technique of choice for studying the IR spectra of samples in their natural state, since no sample preparation is necessary.18•19 Moreover, according to a recent paper, 20 the relative intensity of the surface modes in PA spectroscopy of silica particles is much higher than that in transmission FT-IR spectroscopy. Consequently PA spectroscopy is ideal for studying the surface chemistry. In this work, we have used PA spectroscopy to investigate the interaction of three hydrogen bonding agents (C7H8NO, C2H50H, and H20) with the silica surface by monitoring changes in the surface m modes. Our results show that the surface IR modes get perturbed to a larger extent than the bulk IR modes in interaction with the hydrogen bonding agents. Moreover, whereas in the earlier studies, the shift of the broad silanol band near 3500 cm-1 was used as a measure of the interaction with hydrogen bonding agents,16•17 here we show that the relative decrease in the intensity of the sharp silanol band near 3747 cm-1 also serves as a quantitative parameter for the relative surface coverage and surface modification. Details of this work are given below."

Jan 1, 1990

By Hugo E. Camargo

In an effort to reduce Noise Induced Hearing Loss (NIHL) in the mining industry, the National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop noise controls for mining equipment whose operators exceed the Permissible Exposure Level (PEL). The process involves three steps: 1) Noise source identification (NSI), 2) development of noise controls, and 3) evaluation of the developed noise controls. For the first and third steps, microphone phased array measurements are typically conducted and data are processed using the conventional beamforming (CB) algorithm. However, due to the size and complexity of the machines, this task is not straight forward. Furthermore, because of the low frequency range of interest, i.e., 200 Hz to 1000 Hz, results obtained using CB may show poor resolution issues which result in inaccuracy in the noise source location. To overcome this resolution issue, two alternative approaches are explored in this paper, namely the CLEAN-SC algorithm and a variarion of an adaptive beamforming algorithm known as Robust Capon Beamformer (RCB). These algorithms were used along with the CB algorithm to process data collected from a horizontal Vibrating Screen (VS) machine used in coal preparation plants. Results with the array in the overhead position showed that despite the use of a large array, i.e., 3.5-meter diameter, the acoustic maps obtained using CB showed "hot spots" that covered various components, i.e., the screen deck, the side walls, the I-beam, the eccentric mechanisms, and the electric motor. Thus, it was not possible to identify which component was the dominant contributor to the sound radiated by the machine. The acoustic maps obtained using the RCB algorithm showed smaller "hot" spots that in general covered only one or two components. Nevertheless, the most dramatic reduction in "hot" spot size was obtained using the CLEAN-SC algorithm. This algorithm yielded acoustic maps with small and well localized "hot" spots that pinpointed dominant noise sources. However, because the CLEAN-SC algorithm yields small and localized "hot" spots, extra care needs to be used when aligning the acoustic maps with the actual pictures of the machine. In conclusion, use of the RCB and the CLEAN-SC algorithms in the low frequency range of interest helped pinpoint dominant noise sources which otherwise would be very hard to identify.

Jan 1, 2009

By Eliot J. White

The Bureau of Mines tested cores from 35 wells from 14 oil-producing zones in southern Illinois, southern Indiana, and western Kentucky to determine why rates of water injection were apparently low in some zones. Since these zones contain only minor amounts of clay minerals, it is concluded that permeability reduction results from movement of dislodged silica particles and other material, including the clays, that lines the pores. Both single-phase and two-phase permeability measurements, however, indicated that most samples had only low to moderate water sensitivity, so that permeability reduction due to such particle movement should usually not be of practical significance. The effective permeability to water was considerably lower than the effective permeability to oil during two-phase flow measurements, as is typical of most reservoir rocks. It can be concluded, therefore, that relatively high injection pressures will be required in waterflooding thin zones or zones having low permeabilities.

Jan 1, 1966

By A. C. Fieldner

This report is the fourth of a series of annual summaries of research and technologic work on coal by the Technologic Branch of the Bureau of Mines. The coal research program of the Bureau has been broadened and made more flexible to adapt it to changing conditions and needs of the coal industry, and as a result information as to the properties and composition of coal has been increased and new and improved practices in mining, preparation, and utilization of coal have been devised. The present

Jan 1, 1940

The U.S. Bureau of Mines evaluated water-jet-assisted longwall shearers in full-scale laboratory tests and underground. Both test programs showed that use of high-pressure water did little to reduce the shearer motor energy required to maintain a given cutting rate. However, three other major benefits were achieved with the use of water-jet-assisted cutting. At a pressure of 1,800 psi, respirable dust levels were reduced about 80 pct compared with the dust levels of the conventional water spray system operating at 340 psi. Operating at higher pressures required for water-jet assist also resulted in an increase in the average size of coal cut, which translates into a decrease in product fines. Finally, although no controlled measurements of bit wear as a function of water pressure were made, mine personnel reported that the shearer bits lasted longer when water-jet-assisted cutting was used.

Jan 1, 1989

By Graham W. Marks

The general positions of the absorption maxima of aqueous solutions of the violet and green isomers of chromic sulfate the visible spectral region have long been known, but, to the knowledge of the writer, no comprehensive studies have ever been made. To gain further knowledge concerning these inorganic complexes and to investigate the possibilities of developing an analytical method for determining the concentrations of the violet and green isomers in a mixture, a more complete investigation was made in the spectral range from 325 to 850 millimicrons.

Jan 1, 1951

By Northcutt Ely

This volume- summarizes mining and petroleum legislation in 18 European jurisdictions. Within these jurisdictions, primary attention is given to requirements that must be met in each country for acquisition of rights to permit development of mineral resources. Coverage includes: First, identitication of the controlling laws or statutes governing minerals acquisition and reference to the administrative authority; second, analysis; of the laws governing mines and quarries and their products; third, analysis of laws applicable to natural gas, petroleum, and related materials; and fourth, mention of laws regulating offshore operations. Where pertinent, sections dealing with historical background or administration have been added in countries where minerals are subject to control of States or Provinces, those areas are considered separately from the central government.

Jan 1, 1974

By L. H. Wullstein

Bureau of Mines research on methods for reclaiming land disturbed by the minerals sector of the economy has produced a specific procedure for effectively germinating seed of Indian ricegrass, a drought-tolerant plant valuable for reclaiming arid and semiarid sites. This report describes the procedure which consists of acid-treating the seed followed by temperature and light cycling treatments. Use of the procedure resulted in an average germination rate of 29 percent, ranging from 18 to 56 percent. Seed subjected to long cold treatment but with acid treatment yielded an average germination rate of 9.2 percent, ranging from 6.6 to 14.7 percent. Untreated seeds (controls) gave germination rates less than 0.1 percent.

Jan 1, 1979

By H. R. Hardy Jr., E. J. Kimble Jr., H. W. Shen

"The primary objective of this research project is to study the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. Secondary objectives include the investigation of the acoustic emission technique as an indirect method for coal dust characterization and remote bit wear monitoring. The results of the project will be useful in developing efficient coal cutting techniques which significantly reduce the harmful coal dust components, and in providing methods for remote monitoring of bit condition and associated coal dust character. This paper will outline recent experiments carried out on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. During the experiments acoustic emission and a variety of other mechanical parameters were monitored. · A commercially available artificial intelligence computer package, namely: JCEPAK (Intelligent Classifier Engineering Package), has been utilized to provide a powerful and objective means for AE waveform analysis. This program is able to evaluate a number of features of each AE event and to make objective comparisons between AE signals associated with different loading or cutting parameters. Finally, the paper will discuss the results obtained from a variety of coal breakage tests.INTRODUCTIONStudies to date clearly indicate that the reduction of the severity, and eventual elimination, of Coal Workers' Pneumoconiosis (CWP) depends on gaining fundamental understanding in a number of major areas. These include dust generation and entrainment, transportation, suppression, medical effects of dust and possible treatment. At present a project is underway by the authors to investigate the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. An important aspect of this on-going project is the development of acoustic emission (AE) criteria which will make it possible to carry out remote monitoring of coal cutting operations. Suitable on-line analysis of monitored AE data would allow engineers to evaluate factors such as shearer bit condition and cutting efficiency, and to quantify the particle size and shape distribution of the generated dust. The on-going AE studies are fundamental in form and were undertaken to evaluate the general feasibility of AE monitoring techniques using simplified coal cutting procedures. This paper will outline recent experiments on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. Additional information on these studies are presented elsewhere [4]."

Dec 1, 1996