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Papers presented at a U.S. Bureau of Mines (USBM) technology transfer seminar describe the causes of violent material failure in U.S. mines, measurement techniques for monitoring events that result in violent failure, and mitigation techniques for controlling failure. Specific factors contributing to violent failure are identified on the basis of geotechnical monitoring in 16 U.S. hard-rock and coal mines and on statistical analyses of 172 coal bump events. New monitoring and analysis techniques developed as tools for assessing violent failure; geotomographic methods that provide new capabilities for the study of material failure and stress changes over large areas; and seismic methods for determining source locations, calculating energy release, and determining source mechanisms are described. Fair correlations have been established among seismic parameters, elastic stresses, face support load, and violent events. USBM studies have identified the advantages using both yielding and stable pillars for coal bump control. A computer program has been developed as an aid for selecting room-and-pillar layouts. The practical aspects of implementing a destressing program is outlined for coal mines, while the importance of mine orientation and timely support installation in controlling buckling-type failure is identified for hard-rock mines.

Jan 1, 1995

By G. A. Wancheck

Shear tests were performed on several prepared samples of granular and powdery bulk materials to investigate the following parameters: Particle size and distribution, particle movement, moisture content, consolidation of material, bulk density, void ratio, porosity, volume change, and strain rate. A series of shear tests was performed with weight-percent-ratios of minus 0.185-inch tertiary sand and 1-1/2-by l/2-inch tertiary gravel mixtures, and weight-percent-ratios of minus 200-mesh limestone (rock dust) and minus 200-mesh bituminous float coal dust. A comparison was made for shear test results obtained with rectangular and circular shear cells utilizing the large and small direct shear testers. Specifically, the shear results obtained include the angle of internal friction or shear strength of the tested material under known consolidating pressures, and the kinematic angle of friction or coefficient of friction between the interface of a bulk material and a sample wall material. The experimental procedure, tests, and results are given for each parameter investigated.

Jan 1, 1973

By Harry A. Schrecengost

The Bureau of Mines has found considerable lack of uniformity in style and content of record books used for reporting the results of examinations made by coal-mine officials. These books range from elaborate forms designed for specific examining and operating procedures at certain large mines to simple composition books, tablets, and pocket-style notebooks at other mines. Examination of thousands of these record books discloses that the reports of many examinations are so brief and so poorly worded that they cannot be understood readily. The contents, in some instances, appear to be deliberately ambiguous. The value of keeping accurate accounts of safety inspections in coal mines is often underestimated. Well-kept records reflect managerial attitude and indicate well-governed operations as well as training of official personnel to conform to considered policy and regulations and if necessary, may serve as documentary evidence to protect the mine officials and the operators.

Jan 1, 1962

By E. P. Carman

This report is the 20th in a series summarizing Bureau of Mines research and technologic work on coal and related investigations; it is the second4/ to be issued on a calendar-year basis. Previous reports related largely to publications by Bureau authors during the reporting period. This one discusses the publications issued during 1955 and in addition describes briefly the work in progress during the year. Further details on the published work may be found by referring to the publications cited in the footnotes. The Bureau continues to direct its research and technologic work on coal toward safer and more efficient mining, improved preparation, and more effective utilization, with the ultimate twin goals of promoting conservation and insuring that coal will make its maximum contribution to the Nation's industrial capacity. Significant advances toward these goals were made in 1955.

Jan 1, 1957

By Chas. F. Jackson

The mining literature is replete with descriptions of methods and costs of operation at producing mines. To day the mine manager can find published information bearing upon almost any problem with which he may be faced. From this literature he can familiarize himself with methods employed by otter operators for coping with problems similar to his own, under more or less parallel conditions. Transaction of mining societies, publications of the U. S. Bureau of Mines, technical journals, and handbooks all afford valuable information dealing with operating methods and costs, Very little has been published, however, regarding methods and costs of equipping and developing new properties and bringing them to tae productive stage. There may be some question in the minds of many as to the value of papers on this subject, due to the great variety of conditions encountered. No two prospects are alike. Obviously, it is impossible to forecast what expenditure will be required to develop a mine from a raw prospect or even to predict whether the prospect can be developed into a productive mine.

Jan 1, 1933

By K. Hanna

This U.S. Bureau of Mines report describes a rock mechanics instrumentation program conducted in a shallow underground coal mine in central Illinois. This research program was designed to provide a basic understanding of the structural behavior of entry intersections. A wide variety of instruments and measurement techniques including hydraulic borehole pressure cells, multiple-point borehole extensometers, roof bolt compression pads, and overcoring were employed to monitor roof stresses, pillar loading, strata movement, floor heave, and bolt loading before, during, and after intersection development. A summary of intersection design theories, failure modes, and support techniques is included and instrumentation installation procedures and analysis methods are presented. The study identified two critical parameters that affect intersection stability: in situ horizontal stresses and geological discontinuities. Important design parameters for improving intersection stability are roof span and intersection geometry.

Jan 1, 1991

By Forrest T. Moyer

In 1969, the number of fatal injuries in the coal mining industry was lower than in any previous year and the number of nonfatal injuries was lower than in any preceding year except 1968. Fatal injuries in 1969 totaled 203 with frequency rates of 0.85 per million man-hours of worktime and 0.36 per million tons of coal These rates were new annual lows. Nonfatal injuries totaled 9,917 with frequency rates of 41.76 per million man-hours and 17.42 per million tons. The severity rate for fatal and nonfatal injuries combined was 7,359 days lost or charged per million man-hours. The average severity was 173 days lost or charged per injury. These statistics represent the injury experience of an average of 133,302 employees per day working an average of 225 days in 5,955 coal mines for a total of 237-5 million man-hours worked and a coal output of 565 2 million tons

Jan 1, 1973

Research 86 highlights significant studies conducted during the past fiscal year at Bureau facilities and offices. Readers who want more information about the projects and studies summarized here can contact the researchers whose names and locations appear with each summary. General information on Bureau of Mines programs is available from the Office of Technical Information 2401 E Street, NW., Washington, DC 20241. A listing of principal officials, a location map of field facilities, and a selected bibliography of publications and patents issued on Bureau developments during the past 3 years are provided.

Jan 1, 1986

By E. J. Gleim

Many people consider the mining of coal to be an extremely hazardous occupation; but it should be remembered that most large industries have to meet special conditions which, if not dealt with properly, might become hazards to life and property. Mining men may not always be fully aware that some practices and certain equipment that is incorrectly designed or maintained can lead to dangerous conditions. In endeavoring to help the coal-mining industry to prevent accidents and disasters, the Bureau of Mines has engaged in a program of education on conditions and practices that must be avoided. An effective way to teach safety is by visual demonstration. For example, it is generally known that certain kinds of electrical flashes have ignited explosive atmospheres in mines, but actually to see and hear explosions caused by electrical sparks of different size and character under laboratory control is likely to teach a much more emphatic and lasting lesson than would be learned by merely reading about them. The interest manifested by those who witness the demonstrations seems to prove that this is true. The purpose of the demonstrations is not to discourage the use of electricity in mines, but rather to indicate what types of equipment (including some generally regarded as harmless) can ignite gas and what safeguards have been developed to prevent such ignitions. It is hoped that this information will improve the ability of mining men to cope with underground hazards.

Jan 1, 1937

By F. P. Haver

Primary lead is produced in the United States by the pyrometallurgical smelting of lead sulfide (galena, PbS) concentrates, which poses sulfur dioxide and lead air pollution control problems. The Federal Bureau of Mines has investigated an alternative hydrometallurgy procedure that does not generate gaseous sulfur oxides and diminishes the potential for the escape of lead into the atmosphere. The procedure involves leaching galena flotation concentrates with ferric chloride (FeC13) solution to obtain lead chloride (PbC12) and elemental sulfur as expressed by the following chemical reaction: PbS + 2FeC13 ? PbC12 + 2FeCl2 + S°. At 100° C, over 99 pct of the PbS in the concentrate is converted to PbCl2 in less than 15 min. The leach solution, composed of brine (NaCl) containing slightly more than the theoretical required amount of FeC13, dissolves the PbC12 as it is formed, leaving a residue of elemental sulfur plus gangue. High-purity PbC12 (>99.9 pct) crystallizes from the leach filtrate on cooling and is electrolyzed in a low-temperature, fused-salt cell to obtain corroding-grade metal (>99.94 pct Pb). Spent leach solution (FeC12) is regenerated for further use by reaction with the chlorine obtained in the electrolysis of lead chloride. Other values, such as Ag, Cu, Zn, and S°, are recovered by additional treatment of either the leach solution or leach residue.

Jan 1, 1976

By R. R. Wells, G. M. Potter, R. Havens, W. W. Agey

"INTRODUCTION As part of the program of investigating possible domestic sources of manganese, ore-dressing studies were conducted at Salt Lake City, Utah, on five samples of manganese oxide ore obtained by mining engineers of the Bureau of Mines from the Havasu Lake District, California and Arizona.Two lots of radically different ores were procured from the Arizona Manganese claims 30 miles above Parker Dam, Mohave County, Ariz. One of the original 11 claims has been flooded by Havasu Lake, formed by Parker Dam. The claims are owned by R. H. Thompson, Parker Lumber Co., Parker, Ariz. The 2-ton lot of high-grade ""TA"" ore represented ore occurring as pyrolusite and psilomelane accompanied by a black calcite gangue in lenses along a series of fault planes in granite. A half-ton lot of low-grade ""TB"" ore was taken from a large lense of reddish iron-bearing material outcropping on another section of the property.A 2-ton lot of ore was taken from the Jones property, 8-1/2 miles southwest of Powell, Mohave County, Ariz. At the time of the investigation, the property was leased by J. H. Jones, of Oatman, Arix., from the owners, the Atchison, Topeka, & Santa Fe Railroad Co. The ore body was described as a re¬placement in a sandstone formation in a region that has been faulted extensively."

Dec 1, 1947

By Robert A. Harrow

This report documents the results of the development and installation of an illumination system for an underground coal mine Shortwall Mining Section. Also presented are the techniques used for the above ground test and evaluation of the lighting system prior to installation underground which resulted in the issuance of a Statement of Test and Evaluation (STE) from the Mine Safety and Health Administration, Technical Support, Beckley, West Virginia.

Jan 1, 1979

By G. S. Scott

In the course of the Bureau of Mines investigation relative to the causes, behavior, and control f anthracite-mine fires, attention was directed toward the correlation between the temperature of oxidation and the gaseous oxidation products in the range of temperatures between 100° and 350°C4/ These tests, made on a high-grade anthracite to determine the amount of oxygen consumed and the amounts of carbon dioxide, carbon monoxide, hydrogen and methane evolved when air was passed through samples of the anthracite at various elevated temperatures, showed that the gases evolved and their relative proportions vary with temperature, constitute a means for determining the probable temperature of the anthracite, and thus permit detection of incipient heating before a dangerous fire hazard exists. As the relationships mentioned are affected somewhat by the amount of previous oxidation of the coal, it was deemed desirable to know to what extent they might vary owing to this cause. It was also considered desirable to have a means for estimating the extent of oxidation from the gas analysis, as this would permit a more accurate estimate of probable temperature. Finally, it seemed desirable to know how much the composition of coal might vary over an extended period of oxidation, since this was previously suggested5/ as a possible means for estimating the probable maximum oxidation temperature to which a sample of coal had been subjected.

Jan 1, 1940

By W. W. Adams

Rock dust, as a preventive or limiting factor in explosions of gas and coal dust in bituminous-coal mines, was used in larger quantities in 1939 than in any other year except 1937 since annual figures first became available in 1930, Reports from mining companies to the Bureau of Mines revealed that 144,430,000 pounds of rock dust was applied to underground nine workings in mines that produced 126,635,677 short tons of coal during the year. This quantity of rock dust applied averaged 1.14 pounds for each ton of coal produced. Rock dusted mines were the source of 39.7 percent of the total production of bituminous coal from underground mines; 33.2 percent of the total number of underground workers were employed at rock-dusted mines, and 35.8 percent of the total number of man-hours worked underground at all bituminous-coal mines in the United States during 19719 can be accredited to mines so treated. Rock dust was employed chiefly in the larger mines, which numbered only 431 out of 6,016 underground mines in operation in 1935, according to reports from mining companies. The mines in which rock dust was used had an average of 288 underground employees per mine, whereas mines in which rock dust was not used averaged only 62 underground employees per mine.

Jan 1, 1940

By W. W. Adams

Rock dust, as a preventive or limiting factor in explosions of gas and coal dust in bituminous-coal mines, was used in larger quantities in 1939 than in any other year except 1937 since annual figures first became available in 1930, Reports from mining companies to the Bureau of Mines revealed that 144,430,000 pounds of rock dust was applied to underground mine workings in mines that produced 126,635,677 short tons of coal during the year. This quantity of rock dust applied averaged 1.14 pounds for each ton of coal produced. Rock dusted mines were the source of 39.7 percent of the total production of bituminous coal from underground mines; 33.2 percent of the total number of underground workers were employed at rock-dusted mines, and 35.9 percent of the total number of man-hours worked underground at all bituminous-coal mines in the United States during 19719 can be accredited to mines so treated.

Jan 1, 1940

By W. L. Barry

A review of the practices of analyzing for precious metals at the Reno Research Center, U.S. Bureau of mines, is presented. A general description of fire assaying, the physical layout of a fire assay laboratory, and the use of fire assaying in combination with atomic absorption, induction coupled plasma, and emission spectroscopy is reviewed. The combination of techniques significantly decreases the detection limits for precious metal analyses and simplifies the analysis of the platinum-group metals. Methods of protecting personnel from ingestion of lead are also discussed.

Jan 1, 1982

By R. V. Higgins

The results of two separate but related studies are given. In the first study, four equations were tested; the object was to determine which would produce a curve that would best fit data points that represent a trend of declining oil production in 90 California fields. Two conventional equations (the Arps and semilog) and two novel equations (extreme-c and double semilog) were tested. The curves were first fitted to the initial 9 years of the 15-year production data and then extrapolated for 6 years to determine how well the extrapolated curve would fit the data points. The generated curves were also extrapolated beyond the last data point to predict rates of future production. The results of the first study showed that no equation was clearly superior to the others in all respects. The semilog equation resulted in the best fit to production data for the first 9 years, but the Arps and extreme-c equations produced a better fit for the extrapolated data for the period of 9 to 15 years. The Arps and extreme-c also gave more realistic production rates when extended to the point where cumulative production equaled reserves. A second study was made to determine if the least-squares technique applied to the Arps equation would result in more accurate extrapolations. The merits of the logarithmic and the nonlogarithmic forms of the Arps hyperbolic equation were also tested. For the logarithmic expression, it was found that one of the constants of the Arps equation reached a value so small or so large that the equation was not applicable to the data of 40 of the 90 California fields. The nonlogarithmic form of the Arps equation was applicable to neither the same 40 fields nor to a few additional ones. When the data and the Arps equation were compatible, the use of the least-squares technique as compared with other methods improved the extrapolation accuracy somewhat.

Jan 1, 1971

By H. E. Powell

Basic data were recorded on the decompositions that take place during thermal decomposition of siderite (FeC03). Both the naturally occurring and a synthetically prepared mineral were studied by differential thermal, thermo-gravimetric, X-ray-diffraction, and chemical (including gas) analyses. Thermal decomposition was studied in the media of dry air, moist air, dry carbon dioxide, dry helium, and dry carbon monoxide and at atmospheric and at reduced pressures. Results showed the thermal decomposition of FeC03 to be an extremely complex process, dependent on environmental factors and side reactions that cannot now be completely controlled. Therefore, full understanding of the reaction involved must depend on additional research with advanced evaluation techniques.

Jan 1, 1965

By W. H. Goghill

Numerous investigators have studied grinding. Each has contributed his bit to a literature that is difficult to correlate. Too many of the results have been transformed into curves with so many "inflection points" and "counterflexures" that they obscure the issue. Some of the investigators have neglected the very essence of the problem, namely the power and the amount of material to which a known amount of work was applied. The purpose of this paper is to show the ease with which results can be interpreted when these quantities are duly recognized. Some grinding tests will be given for illustration. Grinding studies are of two kinds: (1) Study of the character of the ore and (2) study of the performance of the machines. Several ores may be crushed by a given machine, or several machines may be used on a given ore. The illustrations given in this report cover both objectives.

Jan 1, 1934

By Virgil A. Marple

It was the purpose of this contract to conduct research in several different areas of instrumentation used to determine the quantity of respirable dust in the mining atmosphere. One area of research was in evaluation of instruments including several respirable dust monitors, several types of photometers, and a QCM cascade impactor. An instrument evaluation chamber was developed to aid in evaluating the instruments in a dust atmosphere. Another area of research was investigations into new instrumentation concepts, such as a virtual impactor/photometer instrument, a new optical device which can be used as either an optical particle counter or photometer, a new personal respirable sampler, which employs an impactor instead of a cyclone as a preclassifier, and the development of a new cascade impactor, which deposits the particles uniformly on the impaction plate. Another area of research included the use of many of these instruments in two field studies, including a silica sand plant and a tungsten mine.

Jan 1, 1981