Search Documents

By Larry R. Powell

As part of the Bureau of Mines effort to establish a comprehensive subsidence data base for subsidence technology development, subsidence and related data are being compiled for various mining, geological, and environmental situations. This publication presents data for a longwall mining operation in the Northern Appalachian Coal Region. Vertical displacements and relative face positions are tabulated for 110 subsidence monuments. Measurements were taken twelve times during the eight months it took to mine the panel. Brief physiographic and geological descriptions of the mining site are presented along with a general account of the mining and subsidence monitoring methods.

Jan 1, 1981

By J. M. Mutamansky

"Coal mine dust research throughout the world has been stimulated by the recognition of its importance in the development of coal miners' diseases, particularly coal workers' pneumoconiosis (CWP). A historical look at the problem and the present state of knowledge in this area of importance to the worldwide coal industry is presented. A summary of progress made in this area is provided and some research ideas for the future are discussed.1. INTRODUCTIONI thank Dr. Yong Won John, President of the Korean Institute of Mineral and Mining Engineers, for his invitation to address the International Symposium on Coal Mining and Safety. This presents me with an interesting opportunity to take a broad look at the research in coal mine dust and where we are going. From this broad perspective, we can all view the progress and problems that are apparent in the present state of knowledge of coal mine dust. One important element in the review of coal mine dust research and its role in miners' diseases is that of its history. The existence of diseases attributed to the mine atmosphere is often traced back to Pliny the younger in the first century A.D. His work on natural history mentioned observed human effects attributed to mine fumes and vapors. However, the subject of the effects of dust in the mine was not mentioned in published literature until 1556 when Agricola discussed the ailments of miners in his day (Seaton 1975).For many centuries, many medical ailments of the lungs were often categorized together and distinct diseases were often not recognized until more modern times. The ability to distinguish different lung diseases was limited until the discovery of X-rays in 1986. Nonetheless, Zenker in 1866 applied the term pneumonokoniosis to any disease where dust gathers in the lymphatic depots of the lungs. This term was changed to pneumoconiosis in 1932. While pneumoconiosis was defined in the 1800s, scant attention was paid to control of miners' diseases until recent decades. The first attempt to control disease through control of the mine atmosphere has been attributed to the South Africans who instituted a silica control in 1910 (Drinker and Hatch 1954)."

Jan 1, 1989

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 Seth C. Schaefer

As part of the Bureau of Mines, U.S. Department of the Interior, effort to provide thermodynamic data for the advancement of minerals technology, the Gibbs energy of formation of sphalerite (zinc sulfide) was investigated with a high-temperature galvanic cell employing stabilized zirconia as the electrolyte. In the temperature range 948 to 1,210 K, potential measurements were obtained for the cell Pt, ZnS + ZnO, S02 = 1 atm // Zr02 // Cu20 + Cu, Pt, with the overall cell reaction ZnS(c) + 3 Cu20(c) = ZnO(c) + 6 Cu(c) + S02(g). (1) These results, combined with the best available values of ?Gf° for ZnO, S02, and Cu20 from the literature, give the Gibbs energy of formation of zinc sulfide for the reaction Zn(l,v) + 1/2 S2(g) = ZnS© (2) ?Gf° = -64.223 + 24.02 X 10-3T ± 0.650 kcal/mole (3) (948-1,180 K; standard states - pure liquid zinc and S2 gas at 1 atm), and ?Gf° = -92.720 + 48.17 X 10-3 ± 0.650 kcal/mole (1,180-1,210 K; standard states - pure zinc vapor and S2 gas at 1 atm). A third law analysis yields for the formation reaction Zn(1) + 1/2 S2(g) = ZnS(c), (5) a standard enthalpy of formation as follows: ?Hf298.15 = -63.64 ± 0.700 kcal/mole.

Jan 1, 1978

To suppress the natural bacterial action in acid mine drainage (AMD), the major contributor to acid formation. Approach Recycle partially-treated affluent back to the source of AMD within a mine, or to the coal or coal-waste stockpile. This effectively eliminates any further biologically-promoted AMD by inhibiting catalyzed weathering or oxidation by acid-forming bacteria. How it Works AMO-type effluents can be largely reduced by "recycling" the acidic outflow back to the source of AMD within a mine or to the Input side of a waste pile to percolate through the reactive pyrite and bacteria mixture. The bacteria in the cell thrive on the oxidation of ferrous to ferric iron through the electron transfer, Fe2 +[=]Fe3 + + e. Its reaction product [s, therefore, essentially ferric iron. While small quantities of Fe3 + will not interfere with the exponential multiplication of the bacteria

Jan 1, 1982

This report summarizes the results of several field tests conducted by Collins for the Bureau of Mines under contract SO122076 and contract H0232056. The field projects represent a part of Collins continuing effort on a broad study of coal mine communications. These experiments analyze the propagation characteristics of radio signals in a working coal mine environment. The intent of the program is to provide basic propagation loss characteristics by which we may evaluate various approaches to an integrated mine communications system. The goal of such a system is to satisfy both operational and emergency communications needs in the mine. Field testing was conducted during the last week of November 1972, at a coal mine operated by Inland Steel Company, near Sesser, Ill, and in the Robena No. 1 Mine, Waynesburg, Pa, on 12 March 1974. The tests included uhf propagation losses and noise (200 MHz to 1 GHz) in the Sesser, I11 mine location and vlf propagation loss and noise (1 to 200 kHz) in both of the above locations. The basic experimental parameters were frequency, polarization, antenna type/orientation, and distance. The following reports treat the various aspects of the test programs in detail. Since different antenna configurations were used in the two mines, each report contains its own experimental predictions drawn from its corresponding test activities. A test equipment list and block diagrams of typical experimental setups for the tests of section 2 are contained in appendix A.

Jan 1, 1974

By W. W. Adams

luring the past two years the Bureau of ?,lines has been receiving from 100 to 150 coal mines in various States a report of each accident causing death, permanent total disability, permanent partial disability, or temporary disability lasting beyond the remainder of the day or shift on which the accident occurred. For each 100 accidents in these groups, there are perhaps from 35 to 45 accidents that do not disable the employee beyond the remainder of the day, and of these fraction-of-a-day accidents the Bureau has compiled no statistics. Information revealed by the reports is to the effect that falls of roof and coal in bituminous coal mines are responsible for 28 per cent of the temporary injuries to underground workers and 33 per cent of the days lost from all temporary injuries underground; they also indicate that falls caused 59 per cent of the deaths from all causes underground. Figures compiled by R. N. Hosler, of the Pennsylvania. Mine Rating Bureau, and covering accidents in bituminous; minis in that State, chow that 61 per cent of the deaths underground during the years 1917-1921 wore due to falls. Neither of these percentage figures includes deaths in major explosions; figures for all bituminous mines in the United States during the five years 1920-1024, inclusive of deaths in major explosions, show that 52 per cent of the deaths underground and in shafts were due to falls of roof and coal.

Jan 1, 1925

In the last few decades, a considerable amount of effort was directed at accurately determining the coal pillar strength to use for safely designing coal mines. The outcome of this early work was the well known Obert-Duvall, Holland-Gaddy, Bieniawski, and Salamon-Munro equations for coal pillar strength. All of these equations were developed for, and were calibrated with, pillars in a large room-and-pillar area such that the loading could be determined using the "tributary-area" theory. In order to account for the abutment loads associated with full-extraction mining, the empirical methods have typically adopted a simple conceptualization of the abutment load through use of an "abutment angle." Short of a complete numerical or analytical analysis of the coal seam and surrounding strata, very little work has been Fretted toward refining the empirical analysis of pillar loading. It appears that the vast majority of the research has been directed at determining the pillar strength, the numerator of the safety factor equation, when the denominator of the safety factor equation, the pillar loading, plays an equally important role in pillar design. This paper will address the deficit of pillar loading research by exploring the accuracy of the empirical abutment load calculations using insight provided by an elastic overburden model, a laminated overburden model and field observations. Ultimately, it is determined that a constant abutment angle probably over-predicts the abutment load as the mining depth increases.

By S. E. Khalafalla

The Bureau of Mines investigated the metallothermic reduction of copper oxide as a function of temperature, reactant proportions, form of reductant, and gaseous environment, using iron and steel scrap reductants. The reaction proceeded rapidly with powdered iron at temperatures above 560° C, attaining over 95 percent copper metallization within 3 hours. The importance of inter-reactant contacts on the extent of the reaction was evident from the variable, but usually lesser, degree of metallization obtained with iron from tin cans and automobile steel scrap. Reduction decreased as the molar ratio of copper to iron increased between 1 and 3. The most favorable gaseous environment for the reaction was a static helium atmosphere containing about 0.6 percent water vapor. Ferrothermic extraction of copper from its oxides appears to be essentially a "solid-state cementation" process. While ordinary cementation processes must be preceded by leaching, the ferrothermic method avoids this generally slow step and also the water pollution caused by the leaching agents. Sulfidic copper concentrates could likewise be reduced with metallic iron following their complete oxidative roasting.

Jan 1, 1969

By Thomas J. Peters

In 1988, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 5,640-acre Soda Mountain Wilderness Study Area (OR-011-017), in order to evaluate its identified mineral resources. The study area is located in Jackson County, OR, about 30 miles south-east of Medford. The study area covers most of the south-facing slope of 6,071-ft Soda Mountain. Geologically, the area is underlain by Oligocene to Pliocene basaltic andesite flows and less extensive intrusive rocks of the western Cascade Mountains. In addition, there is a 3/4-mile-diameter area of kaolinized and silicified rhyolite tuff, which appears to have intruded the andesite, and is host to epithermal gold mineralization.

Jan 1, 1989

By M. J. Friedel, D. F. Scott, T. J. Williams

In an effort aimed at monitoring mining-induced stress changes that may influence ground failure, the US Bureau of Mines conducted a series of active 3-D seismic tomographic surveys at the Homestake (Lead, South Dakota) and Lucky Friday (Mullan, Idaho) mines. Existing rock bolts were used to mount geophones and as strike points for introducing seismic energy using a 3.6 kg sledge hammer. Travel time measurements were recorded spanning up to 160 m between drifts at several levels. The tomographic uncertainty was minimized by computing iso-velocity surfaces of constant probability based on statistics from multiple reconstructions and a threshold criteria. Periodic imaging using tomographic velocity surfaces demonstrated that temporal and spatial changes in the local stress field occurred in response to ground failure and stope advancement at a gold and silver mine, respectively. Keywords: Temporal imaging; Mine-induced stress; Seismic tomography; Geophysics

Sep 9, 1996

By M. C. Irani, Maurice Deul, M. G. Zabetakis, T. G. Bobick

This survey was conducted to determine the magnitude of the methane emission and control problem in U.S. bituminous coal mines. The resultant data indicate that the emission rate for any given coalbed depends primarily on the coal production rate and on mine depth, as well as on the nature of the coalbed and the surrounding strata. An excellent correlation was found between (1) the methane emission rate and (2) the product of coal production rate and mine depth for the mines in the Pittsburgh, Pocahontas Nos. 3 and 4, and the Illinois Nos. 5 and 6 coalbeds. The highest total emission rates found in U.S. bituminous coal mines were as follows, in million cubic feet per day: Monongalia County, W. Va., 39; Marion County, W. Va., 30.4; McDowell County, W. Va., 13.1; Washington County, Pa., 11.9; Greene County, Pa., 11.4; Buchanan County, Va., 21.6; Jefferson County, Ala., 10.3; and Franklin County, Ill., 6.6.

Jan 1, 1972

By Ted C. Briggs

Twenty-two compressibility runs were made with helium over the temperature range -5° to 80° C and at pressures to 800 atmospheres. A Burnett apparatus was used. Data from the runs were fitted to a fourth degree polynomial equation of state in the pressure and a weighting factor of Pr-3/4 was used. All data for a particular isotherm were treated simultaneously. A temperature function was found to represent the parameters B and C. Compressibility factors determined by this investigation are believed to be accurate to better than 0.05 percent.

Jan 1, 1970

By Lloyd A. Morley, Robert Stefanko

Before going directly to the analysis, it would be good to summar¬ize explosion-proof container approval methods. Both Magison (52) and Short (84) state that in general practice, the systems are certified for: 1. a rugged enclosure able to withstand an internal explosion but not allow explosively hot gases to escape, and 2. maximum surface temperature, with equipment operating inside, that will not ignite the surrounding atmosphere. Also, testing insures that any material in contact with the container surface will not be ignited by a hot spot. Associated with the first practice, the enclosures are inspected for: 1. a safe flange gap width, 2. a pressure increase during ignition, and 3. an hydrostatic pressure withstand level. The hydrostatic pressure level is almost always determined by a meas¬ured ignition-pressure test and is usually applied to prove the mechan¬ical design to some safety factor. Consequently, explosion-proof enclosure testing includes temper¬ature, permissible flame gap, and pressure. Specifications and prev¬ious research also can be similarly separated even though some interre¬lation exists between the flame gap size and internal enclosure pressure during an explosion. The Schedule 2G Sections applicable to these subjects are: 1. 18.2 Definitions; 2. 18.6 Applications;

Jan 1, 1974

By George S. Koch

Several methods of calculating ore grades by diamond-drill sampling in the Homestake mine, Lead, S. Dak., have been evaluated by statistical analyses of assay data. The natural distribution of gold particles, partly masked through sampling and assaying procedures, is probably lognormal. As a consequence of the gold particles being clustered rather than randomly distributed within the ore bodies, (1) more mine samples are needed to obtain a specified precision of mean grade than the number predicted by the standard-error-of-the-mean law; (2) the variance of gold values is not inversely proportional to sample volume, and, therefore, small-diameter drill core yields samples nearly as good as larger diameter core; and (3) sampling at 5-foot intervals provides nearly as good results as sampling at shorter intervals.

Jan 1, 1971

By Ronald D. Hill, Elmore C. Grim

Sediment is one of America's greatest pollutants. More than a billion tons of sediment reach the major streams of the United States annually(l). Damages are reflected in the reduced carrying capacity of streams, clogged reservoirs, destroyed habitat for fish and other aquatic life, filled navigation channels, increased flood crests, degraded facilities for water-based recreation, increased industrial and domestic water treatment costs, premature aging of lakes by enrichment of the water with silt-carried fertilizer that promotes algae growth, destroy crops, and reduce productivity of flood plain soils. Erosion and sedimentation are natural processes that are usually gentle actions releasing controlled amounts of silt from watersheds to receiving streams. Surface mining activities accelerate these natural processes and short duration, high intensity storms can become a violent force moving thousands of tons of soil in a brief period of time. Cover is a very important factor. With the removal of ground cover, water moves across the denuded area on its own terms picking up soil particles as it flows and leaving gullies behind. The susceptibility of strip-mined land to erosion depends on: 1.Physical characteristics of the overburden 2. Degree of slope 3. Length of slope 4. Climate 5. Amount and rate of rainfall 6. Type and percent of vegetative ground cover. By development of erosion and sedimentation control plans before disturbance of the area, many of the detrimental effects of strip mining can be prevented.

Jan 1, 1974

By A. L. Engel

This publication describes further research by the Federal Bureau of Mines in beneficiating domestic manganese ores. The ores selected for treatment were typical of many manganese deposits in California and Nevada in that they have not been economical to mine because they are low grade or contaminated with siliceous minerals and are not amenable to physical concentration.3 4/ It would be desirable to develop a simple treatment method resulting in nearly complete extraction of manganese from these ores and applicable to small-scale operations. Sulfation reduction appeared to be such a method. The studies reported in this publication were directed toward sawdust or lignin-sulfonates as reducing agents. Sawdust, as waste from lumbering, and lignin-sulfonates, byproducts of woodpulp papermaking, are comparatively cheap and may be available in areas where manganese ores are found. Sugar, oils, and coal were also tried as reducing agents.

Jan 1, 1960

By H. D. Jacobs

The Bureau of Mines developed a concentration method to upgrade and utilize marginal natural or direct-shipping iron ores and fine-grained lean iron ores. Presently these ores receive little beneficiation and accordingly have low iron-silica (Fe-Si02) ratios. Ore samples were roasted with equal weights of solid reductant at 1,100° C for 1 hour to metallize the iron and for an additional hour at 1,200° C to promote grain growth. Concentration was effected by crushing and screening techniques and/or wet magnetic separation. Sized concentrates (minus 4 plus 35 mesh) derived from crushing-screening processes contained from 80 to 85 percent iron that was 90 percent metallized. Iron-silica ratios as high as 12:1 and iron recoveries from 75 to 94 percent were obtained. The sized concentrates were judged suitable for use as blast furnace feed. Minus 200-mesh metallized concentrates derived from roasted minus I-inch plus 8-mesh ore fractions and magnetically concentrated contained 90 percent Fe and 4 percent or less Si02, chemically qualifying them as feed for electric furnaces. Roasting minus 8-mesh ore with hydrogen, then magnetically concentrating it, produced iron concentrates containing 57 percent to 67 percent Fe and 3.6 percent to 8.4 percent Si02. The concentrates having Fe-Si02 ratios ranging from 8:1 to 12:1 were considered adequate for use as blast furnace feed. Overall iron recoveries for the 12 ores tested ranged from 56 percent to 94 percent with an average iron recovery of 86 percent.

Jan 1, 1969

By D. H. Chambers

Digestion studies were undertaken to develop a method for the rapid dissolution of high-temperature ferroalloy scrap. Laboratory tests showed: (1) dissolution of alloy scrap with ferric ion as the leaching agent was a moderately rapid method of digestion; (2) the dissolution process can be considered as a typical reaction of a metal with chlorine gas, although evidence was obtained to show dissolution as a two-step process, one step as the reduction of ferric ion by the soluble alloy constituents and the other as the oxidation of ferrous ion with chlorine gas; and (3) the attack of ferric ion on the alloy was a function of alloy composition, ferric to ferrous ion ratio, and area of contact between leach solution and alloy. The exceedingly complex nature of alloy compositions and dissolution products generally precluded satisfactory analytical determinations. Results of moderate accuracy were obtained using complex modifications of standard analytical and spectrographic techniques.

Jan 1, 1968

By Kenneth L. Cashddollar, Terry G. Montgomery, Eric S. Weiss, John E. Going

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research on dust explosions by studying post-explosion dust samples. The samples were collected after full-scale explosions at the PRI, Lake Lynn Experimental Mine and after laboratory explosions in the PRL 20-L chamber and the Fike 1-m3 chamber. The dusts studied included both high and low volatile bituminous coals. Low temperature ashing for 24 hr at 515°C was used to measure the incombustible content of the dust before and after the explosions. The data showed that the post-explosion incombustible content was always as high as or higher than the initial incombustible content. The MSHA alcohol coking test -was used to determine the amount of coked dust in the post-explosion samples. The results showed that almost all coal dust that was suspended within the explosion flame produced significant amounts of coke. Measurements of floor dust concentrations after LLEM explosions were compared to the initial dust loadings to determine the transport distance of dust during an explosion. All of these data will be useful in future forensic investigations of accidental dust explosions in coal mines or elsewhere.