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By S. J. Page, R. A. Jankowski, J. A. Organiscak

The U.S. Bureau of Mines investigated the relationship of bituminous coal seam parameters and the amount of airborne respirable dust generated at longwalls. Dust and coal samples were obtained from 20 longwalls operating in geographically representative coalfields throughout the United States. Statistical analyses of coal seam parameters and airborne respirable dust measurements indicate a likely causal relationship between seam type and respirable dust. Low-ash, high-volatile coal seams were associated with higher airborne respirable dust levels. A negative linear correlation (significant at the 95-pct confidence level) was observed between the seam's ash content and airborne respirable dust, explaining up to 18 pct (R2 = 0.18) of headgate dust level variation and up to 15 pct of tailgate dust level variation. Volatile matter was found to have a positive linear correlation with tailgate dust level, explaining 16 pct of the variation. Further data examination indicates that these relationships with dust are most likely nonlinear, because of improved R2 values over the linear correlations. However, a notable portion of longwall dust production is influenced by other operational parameters, so additional research under more controlled conditions is needed to determine the seam's causative functions.

Jan 1, 1992

Because surface mining removes the original plant cover from the land and exposes the soil, special care is needed. Until the mined land is stabilized by revegetation, snowmelt and rainfall can pick up sediment and erode mined lands much faster than undisturbed areas. Sediment control is an important aspect of protecting the environment during mining and reclamation because without it, large amounts of sediment can clog streams, increase the risk of flooding, damage irrigation systems, harm aquatic habitat, and limit the use of water for other purposes. Stream quality can be affected many miles downstream from the mine. Before SMCRA was implemented many streams were degraded by uncontrolled sediment from mining. Sediment is controlled through careful planning and a design that incorporates a variety of measures that work together to reduce soil erosion at the mine. Disturbed areas are graded, and some areas terraced, to achieve stable slopes, reduce runoff water velocity, increase infiltration, and divert runoff into drainage channels so that it flows away from unvegetated, erodible areas. Grading along the slope contour and scarify in gun vegetated slopes with bulldozer track marks help prevent erosion by slowing down the flow of water. Runoff from haul roads is controlled by culverts and roadside ditches. Sedimentation ponds or other forms of sediment control are required at all mines to minimize the amount of sediment leaving the site.

Jan 1, 1992

By C. Özgen Karacan

The methane emission rate into an underground mine environment from overburden strata during longwall mining is impacted by reservoir and geomechanical characteristics of the coal measure rocks in the overlying strata, as well as the presence of any coal seam. The reservoir characteristics and how they change during mining potentially affect the performance of gob gas ventholes, which consequently impacts the efficiency of methane control in the mining environment. This study presents reservoir and elastic properties of coal measure rocks in the Lower Monongahela Group in Greene County, southwestern Pennsylvania, of the Northern Appalachian Basin. Since the source of methane in this region from underground mining is located between the Sewickley coal and the Pittsburgh coal, a specific emphasis was given to this interval. Core analyses were performed in the laboratory to determine rock porosity and permeability. Geophysical logging data (gamma, density, sonic) obtained from two exploration boreholes were used for evaluating formation boundaries, shale contents, log porosities, and geomechanical properties of formations. Permeability was also calculated using density-log data and empirical equations and compared with laboratory measurements and slug tests performed in isolated intervals of boreholes. The results presented in this study can be used as data sources for reservoir studies related to the production and control of methane.

Jan 1, 2009

By Michael J. Jorgensen, Pranathi B. Aedla, N. K. Kittusamy

Risk factors associated with the development of muscu­loskeletal discomfort and disorders during the operation of heavy mobile equipment include whole-body vibration and awkward and sustained joint postures of the shoulders, neck, and trunk. Cab design may influence awkward postures of the joints, and task duration may influence duration of exposure to awkward and static postures and whole-body vibration. To reduce exposure to risk factors related to the interface between cab design and task, it may be necessary for manufacturers to address cab design. This study assessed the repeatability of a cab design checklist developed to evaluate various design characteristics that can influence exposure to risk factors for musculoskeletal discomfort. The ability of the cab design checklist to identify posture-related deficiencies of design was also assessed. The checklist was used by two administrators across 10 pieces of heavy construction equipment. Video analysis was performed to quantify postures of the neck, shoulder, and trunk; correlation analysis was used to determine whether specific questions from the checklist were associated with the identification of awkward postures. The repeatability assessment resulted in kappa coefficients ranging from 0.52 to 1.0 (good-to-excellent reproducibility) across each piece of equipment, and an overall kappa coefficient of 0.77 (excellent reproducibility) when considering all equipment together. Results from the correlation analysis showed that shoulder flexion posture was correlated with scores from the cab design checklist. However, results of the cab design checklist were not significantly correlated with shoulder abduction or awkward postures of the neck and trunk. Results suggest that the cab design checklist may be useful for identifying cab design characteristics that need further improvement and for identifying design characteristics that increase shoulder flexion. The strength of the repeatability assessment suggests that outcomes of the cab design checklist administered by different individuals may be consistent, independent of the type of equipment being assessed.

By C. A. Herbert

During the fiscal year ended September 30, 1932, there were 27 fatalities in the coal mines of Indiana. Four of this number occurred in small mines employing less than 10 men, over which the State Inspection Department has no jurisdiction. In addition to these coal mine fatalities, an explosives accident in a clay mine resulted fatally to one man. Tables 1 and 2, which follow, list the fatalities as to cause and occupation. Table 1. - Fatal accidents by cause, fiscal year ended September 30, 1932 [ ]

Jan 1, 1933

By R. A. Welsh

The Bureau of Mines has developed a photoelectric concentrator apparatus which is capable of collecting incremental products from the discharge of wet concentrating tables. The instrument uses photoelectric cells as sensors to differentiate between two products which have differences in color or reflectivity. The photocells provide a signal that controls a mobile splitting device that separates the products. Tests conducted on a wet table demonstrated the ability of the apparatus to separate a product containing 81.5 percent pyrite from a lower-grade product containing only 68.8 percent pyrite. The photoelectric concentrator should have a broad application for collecting concentrates with visible color or reflectivity differences from wet concentrating tables.

Jan 1, 1972

By G. A. Apell

Completion of 18 churn-drill holes totaling 2,218 feet and 3 diamond-drill holes aggregating 421.5 feet of drilling in the M.C. mine area, near Truman, Wis., provided information indicating the existence and trend of a zone of zinc mineralization extending for 1,000 feet west of the old M. C. shaft.

Jan 1, 1949

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining the potential for reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/ lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978

By James P. May

Operating mine haulage trucks near the crest of stockpiles and waste dumps is a potentially hazardous practice often resulting in a localized slope failure and a dump point accident. The U.S. Bureau of Mines has developed a computer code (INSLOPE3) based on the kinematic method of limit analysis which determines an admissible truck weight (upper bound value) for varying distances from the slope edge. The program considers the material strength parameters, slope geometry, and inertial forces induced by vehicle braking. The program can be utilized to assist in the determination of safe operating distances for a haulage truck from a slope edge, the development of safe vehicle operating procedures, and the admissible weight for a static concentrated loading near the crest of an otherwise stable slope. This report provides information on the use of INSLOPE3, interpretation of the results for mining applications, and instructions for acquiring a copy of the software.

Jan 1, 1991

By J. L. Stauffer, L. J. Gaydos, L. M. Demers, D. C. Kuhn

"Eicosanoids and cytokines produced by alveolar macrophages (AM) are key mediators of pulmonary inflammation and fibrosis. In order to determine if eicosanoid production and cytokine production are altered in AM obtained from coal miners, we compared production of prostaglandin E2 (PCE2), thromboxane A2 (TXA2), leukotriene B4 (LTB4), interleukin-1 beta (IL-1B ), and tumor necrosis factor alpha (TNfa.) by cultured AM from normal human subjects and coal miners. The recovery of AM from miners' lungs by bronchoalveolar lavage was significantly greater than that from control subjects. Mean eicosanoid and cytokine production by AM from active miners was also increased compared to AM from control subjects, but this increase was not statistically significant. AM from control subjects produced significantly more TXA2 and TNFa. when exposed to lipopolysaccharide than did AM from miners. The cyclooxygenase inhibitor suprofen reduced PGE1 and TXA1 production and TNF0t. release but had no effect on LTB4 production or IL-1B release by miners' AM. The lipoxygenase inhibitor nordihydroguaiaretic acid attenuated TNFa release, as well as that of LTB4, but had no effect on IL-1B release. Inhibition of thromboxane synthase by UK 38,485 also reduced TNFa release by active miners ' AM but had no effect on PGE1, LTB, production, or IL-1 f3 release. The results of these studies suggest that occupational inhalation of coal dust may increase total lung eicosanoid and cytokine levels and reduce the reactivity of AM to bacterial endotoxin. Furthermore, coal dust-induced changes in both eicosanoid and cytokine release may be subject to pharmacological modulation.The alveolar macrophage (AM) is a primary defensive cell in the lung and is one of the first cell types to encounter inhaled mineral dust. The response of the AM to invading foreign material is designed to enhance the defensive capacity of the lung. However, in the case of occupational inhalation of mineral dust particles, this response may be inappropriate, resulting not in the defense of the lung but in chronic inflammation and fibrosis (Rom et al., 1987; Takemura et al., 1989). The reaction of the AM to chronic mineral dust exposure may involve the exaggerated release of paracrine mediators of lung function, including eicosanoids (oxygenated derivatives of arachidonic acid) and peptides, including cytokines and growth factors (Sibille & Reynolds, 1990). Eicosanoids are involved in bronchial and vascular smooth muscle reactivity, vascular permeability, fibroblast growth, and the recruitment of additional immune cells to the alveolar space (Barnard et al., 1992; Elias et al., 1985; Scott et al., 1982). AM-derived cytokines such as interleukin-1 beta (IL-1 B) and tumor necrosis factor alpha (TN Fa) have a variety of biological activities including the regulation of fibroblast growth and proliferation (Becker et al., 1989; Libby et al., 1989; Schmidt et al., 1984). Interestingly, in vitro studies with macrophages suggest that the production of cytokines may be linked to eicosanoid production, in particular that prostaglandin E2 (PGE2) may down-regulate IL-1 f3 and TN Foe production by the AM (Bonta et al., 1989; Kunkel et al., 1986; Monick et al., 1987)."

Dec 1, 1996

By W. N. Poundstone, W. M. Merritts, B. A. Light

A joint investigation by the Bureau of Mines and the Christopher Coal Co. at the Humphrey No. 7 mine, operating in the Pittsburgh coalbed in northern West Virginia, was undertaken to gain more insight concerning the hazardous emission of methane gas in mining. This report describes the equipment, procedure, and results. Horizontal bleeder holes drilled in the faces drained large quantities of methane, eliminating downtime of mining equipment. Also, larger quantities of methane were removed by forcing 14 to 25 g,.p.m. water at 25 to 200 p.s.i. 5 pressure into the bleeder holes. In one infusion test a fluorescein dye was added to the infusion water; in later mining operations, the infusion water was traced for a distance of 1,500 feet. With vacuum pump applied to the horizontal hole the gas-flow rate increased, and the methane content decreased. Tests indicated that methane and water infused in bleeder holes traveled along the bedding planes of the Pittsburgh coalbed at a faster rate than across the planes. Methane associated with coalbeds is produced by the slow decomposition of carbonaceous material in the absence of air and the presence of water. It is lighter than air and, depending on its concentration, forms an inflammable or explosive mixture with air. It is believed that methane is entrapped in and around the pores of the coal and adjacent strata--often under great pressure. In many cases where the strata have been disturbed by geologic movements the

Jan 1, 1962

By Raja V. Rarnani, Robert L. Frantz

"The more than 75 research projects funded throughout the first 10 years of the Dust Center's operation have resulted in numerous cumulative findings fulfilling the goals of the Center. These project descriptions present the methodologies and project-to-project relationships leading to their various accomplishments and demonstrate the mesh between project objectives and Center goals.To develop equipment for collecting respirable dust samples.To develop experimental methods for particle-by-particle characterization of morphology, size, and chemistry.To develop experimental methods for overall respirable dust sample characterization of size distribution, chemistry, and crystallography.The project directly addresses the Center's goals to enhance the understanding of the scientific and engineering characteristics of fine and respirable mineral particles found in mining and milling atmospheres and to establish the relationship between natural and cultural factors (mine geology, mineralogy, mining and milling methods, equipment, and control measures) in the generation of fine particles. The project also aims to contribute to the development of control mechanisms for reducing ambient respirable dust concentrations and worker exposures.The work on this project is related to similar work on Coal Mine Dust Characterization (Project No. 2701/MN1) and Characterization of Dust Particles (Project No. 4203/PS3).Airborne dust sampling was performed at the following locations: 1) a sand and gravel quarry in Southern New Hampshire, 2) a welding facility, 3) a ceramic powder facility, 4) a metal powder facility, and 5) the air in Cambridge, Massachusetts. A portable sampling box incorporating two Sierra personal cascade impactors was designed and produced. At a 2-LPM flow rate, the effective cut-off diameters of the Sierra impactors were 10.0, 6.0, 3.5, 2.0, 0.9, and 0.5 mm, respectively, for each stage, and the air passed through a PVC filter after the last stage. In addition, the sampling box contained a total respirable dust filter. The substrates were weighed carefully before and after collection, and the weight increases were recorded. All films, foils, and filters were put in the balance chamber for more than 8 hours to stabilize the temperature and humidity before weighing. A Cash 21 microbalance (±0.001 mg) was used to weigh the Mylar films, SS films, and filters."

Jan 1, 1995

By David A. Benjamin

At the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied prospects, claims, and mineralized sites in a 43,053-acre portion of the 51,262-acre Desatoya Mountains Wilderness Study Area (NV-030-l10) in 1985. The study area, located 50 miles east of Fallon, NV, is underlain by alluvial deposits of Quaternary age and volcanic and volcanic-derived sedimentary rock of Tertiary age. No mines or recent exploration activity were identified within the area studied. The Gold Basin area, located 1/2 mile to the south has produced 982 ounces of gold and 10,086 ounces of silver. The Cold Springs area, located 1/2 mile to the west, has recently been explored for gold-silver. Mineralization at these two areas apparently did not extend into the study area, but future mining at these areas would likely impact it.

Jan 1, 1986

By John C. Machisak

THIS PUBLICATION presents injury experience and employment data for the nonmetal mining industry in the United States for 1960. Data for the mines and mills are presented separately, as shown in the list of tables. The Bureau of Mines is authorized to send questionnaires to the nonmetal mining industry for their voluntary submission of injury and employment data. As the information submitted contributes largely to the promotion of safety in the industry, special effort has been made to ma e these questionnaires as complete as possible.

Jan 1, 1963

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 Vernon C. Allison

The explosibility of coal dust has long been recognized by competent investigators as constituting one of the dangers of mining coal and in the use of pulverized coal as a fuel in industrial plants. The Bureau of Mines has carried on extensive series of experiments dealing with this subject, and has not only developed methods for the practical prevention of this danger, but in the, course of these experiments has developed a standard method of determining the relative explosibility of coal dusts and other organic dusts.3 Oil shale contains compounds 'of carbon and hydrogen that are either of a petroleum nature and are strongly ,adsorbed upon the incombustible part of the shale, or else are present in the shale as a compound ("kerogen") which has the property of changing into petroleum-like products when acted upon by heat. The oil shales may contain varying amounts of the organic matter, ranging from a trace to more than 66 per cent, depending upon their richness; therefore, it is important to know whether the dusts formed in mining and handling these oil shales are explosive when mixed with air and if so, to indicate remedial measures. This paper gives the results of explosibility tests of several pulverized oil shale's, selected as being typical of those which in the future may be used in commercial shale-oil production test on a sample of typical Colorado oil shale has been., published in an earlier paper.4

Jan 1, 1926

By Irving Hartmann

Several recent ignitions of firedamp - a mixture of methane and air - in American coal mines have been attributed to frictional heating when hard rocks were struck while cutting and drilling coal seams. Although none of these ignitions caused severe explosions, they call attention to a problem that can become increasingly significant as mechanized mining is developed further. The power in and rapid release of energy from high-speed machinery has increased the rates of advance into virgin coal creating many problems. Unforeseen faults and hard mineral inclusions may be encountered; coal brought down in this way is finer in size; more gas is released from the seam; it is frequently more difficult to provide adequate ventilation at the' face; and new roof-support problems must be solved. In particular, continuous mining machines (also known as continuous miners) greatly increase the frequency of contact between cutter bits and minerals. In view of these conditions, it may be expected that more gas ignitions will occur as a result of frictional heating unless the situation is understood and remedial measures are introduced. The problem of frictional heating is not new in coal mining. In Europe, particularly in England, it has been a concern for more than a century. During the last 15 to 20 years frictional ignitions have been a major cuase of explosions in British mines. Explanations for the greater number of such ignitions in England may be the special character of the coal measure strata, the mining methods, the rate of gas emission and possibly its composition, and less effective ventilation near the face. To reduce the ignition hazard, considerable laboratory and field research has been conducted, particularly by the Safety in Mines Research Establishment, Ministry of Fuel and Power of Great Britain. Much of the information presented in this report has been drawn from these studies.

Jan 1, 1955

By Russell A. Schreiner

In conjunction with the Geological Survey, the Bureau of Mines conducted a mineral investigation in 1981 and 1982 of the Santa Rosa Mountains Wilderness Study Area (WSA), Riverside County, California. The Bureau of Mines is responsible for the mineral survey of mines, prospects, and mineralized areas in and near the WSA. A literature search was completed to obtain information concerning mineral occurrences and mining activity that relate to the WSA. A field investigation inside, and up to 1 mi outside, the boundary of the WSA, disclosed one prospect. This prospect was surveyed by compass and tape, and five samples were taken to determine the representative mineral content. No attempt was made to expose concealed mineralization or to re-open caved workings. All five samples were analyzed by fire assay for gold and silver and by colorimetric methods for tungsten. Two of the samples were analyzed by semi quantitative spectrographic methods to determine if any unsuspected elements were present. All analyses are furnished in this report except for the semi-quantitative spectrograhic analyses. Complete sample analyses are available for public inspection at the Bureau of Mines, Intermountain Field Operations Center, Building 20, Denver Federal Center, Denver, CO 80225.

Jan 1, 1983

By E. K. Stanek

This research study was performed on a case study basis and can be divided into two parallel thrusts: electrical and thermal energy conservation. Energy consumed annually in mining and refining operations represents about 6% of the 80 quadrillion Btu's consumed nationally. In the electrical portion of the study, five areas were addressed: optimal dispatching of on-site generation, high-efficiency motors, conductor selection, power factor correction, and high efficacy lighting. In the case study mine which has a multiple unit on-site generation system, optimally dispatching units can save significant energy. The other four methods are difficult to justify on a retrofit basis due to capital costs. In the thermal portion of the study, a thermodynamic analysis was performed on the reverberatory smelting process possible areas of energy conservation were identified as radiation and convection heat losses from the furnace arch and the dumping of high energy content smelting slag. It has been shown that materials currently available can provide the means of reducing heat loss from the reverberatory furnace. It has also been shown that a significant amount of energy may be recovered from the slag. However, these are both subject to further study and validation.

Jan 1, 1982

By Robin B. McCulloch

No producing mines are in the study area. Sample results indicate the only resources in the study area are low grade phosphate deposits associated with Cuyama Phosphate Mine (fig. 1). Within the study area, are more than 21.4 million tons of inferred subeconomic phosphate rock resources which would be reserves at an 80 percent higher phosphoric acid price; weighted average grade is 4.84 percent phosphorous pentoxide (P205). About 17.6 million tons of similar grade are outside the area to the northwest. The South Cuyama Oil Field, adjacent to the study area (fig. 1), produces petroleum from the Vaqueros Formation which underlies parts of the study area. Oil and gas potential was evaluated by U.S. Geological Survey. INTRODUCTION Location, Size, and Geographic Setting The U.S. Bureau of Mines conducted a mineral survey of the Fox Mountain RARE II area (No. 5120) during the summer of 1981. The area was examined to determine the presence or absence of mineral resources and reserves, and to estimate tonnage and grade where possible.

Jan 1, 1982