Search Documents

By J. W. Howland

A demonstration of dozer blades, designed for recontouring area-mined spoil and shown effective at Kansas and East Texas surface mine sites, was conducted at a Northeast Arizona surface coal mine to determine their effectiveness in different climate and soil conditions. The specialized tools were: 48-ft angle blade (on side-by-side tractor), 24-ft grading bar, modified 24-ft "U" blade (on side-by-side tractor), and a 13-ft deep "U" blade. Interest in the increased dirt-handling capacity of a previously built 22-ft blade, resulted in the design of a new Centerflow Blade of good versatility, able to maintain increased flow in otherwise difficult-to-move spoil. The demonstration involved 263 acres and showed a reduction of 50% in reclamation costs and 20% in fuel requirements for this mine site over conventional equipment. This savings resulted from improved technology, trained operators, and rigorous application of supervisory and monitoring techniques. Procedures and results of the demonstration are presented and analyzed here, along with guidelines for application of findings.

Jan 1, 1982

By R. W. Stahl

Burning coal-mine refuse banks were surveyed in 15 States. The following characteristics were tabulated for 495 hanks: County; name, population, and distance of nearest town; size and status of bank; status and stage of fire; and topography. Ways of controlling fires were reviewed, the compacting and sealing method proving most satisfactory. Means for preventing refuse-bank fires by proper construction of banks are described.

Jan 1, 1964

By N. T. Lowe

This Bureau of Mines publication presents salient deposit information in abstract form on 119 principal mineral deposits in the State of Nevada. Commodity coverage addresses 17 critical and strategic commodities that appear to have commercial production potential in the State. The core of the deposits described is taken from those properties evaluated d under the Bureau of Mines Minerals Availability Program (MAP); additional deposits are included to provide a more complete coverage. Institutional and infrastructural factors affecting mineral development are also discussed.

Jan 1, 1985

By R. Stefanko

This Final Report covers the work performed for Contract No. H0377043, "Cables for Face Equipment" from August 1, 1977 to April 1, 1981. It reports the findings in three areas of research: cable protection, circuit-breakers, and high-voltage cable couplers. Laboratory and analytical studies have been conducted in the three areas to determine proper circuit-breaker settings, cable sizes, and coupler performance. Also, an extensive field-monitoring program was established to relate in-mine epxerience to laboratory findings. Further, various pieces of equipment was designed for laboratory testing, particularly in the area of cable reeling and unreeling.

Jan 1, 1981

Productivity in underground metal and nonmetal mines is contingent upon work methods, mine layout, and ore handling techniques. One of the most important factors impacting productivity is the efficient movement of men, materials and supplies from the surface into and throughout the mine. Various transportation systems such as man-trains, service shafts, rubber-tired diesel equipment, etc. are currently used to transport men and supplies in underground mines. In many underground mines, it is not uncommon for a worker to spend 25% of his eight-hour working day traveling from the surface to his work area and returning to the surface.

Jan 1, 1975

By Henry C. Meeves

The Bureau of Mines, between 1956 and 1963, examined 18 major pegmatite districts in Arizona, Colorado, New Mexico, South Dakota, Utah, and Wyoming to evaluate their content of beryllium, a material in short domestic supply that has become increasingly important to modern industry. This examination report includes the salient statistics on the production of pegmatite minerals other than quartz and feldspar; and brief descriptions of 170 specific pegmatite deposits.

Jan 1, 1966

By R. L. Balmer

This information circular, which describes the methods and costs of sinking a small underground shaft with steel supports at the Keystone mine of American Smelting and Refining Co., near Crested Butte, Colo., is one of a series being prepared by the Bureau of Mines on current shaft-sinking practices in various mining districts of the United States. Preparations for sinking a combined exploration, development, and production shaft from the lowest level of the Keystone mine began early in 1957. This vertical, three-compartment, 6-1/4-by 16-foot rectangular shaft was to be sunk in separate stages or lifts so as to correspond with the progress of an associated lateral exploration and development program. The first section of the shaft was collared and sunk to a depth of 209 feet between September 1957 and April 1958. Because of the depressed base-metal market, the mine was shut down as soon as the initial phase of the exploration and development program had been completed and before any deeper sinking could be attempted.

Jan 1, 1962

By G. L. Mowrey, S. D. Maksimovic

An important element of the U.S. Bureau of Mines (USBM) mining research program is the development and evaluation of reliable coal interface detection (CID) systems. Commercially available CID sensors based on natural gamma radiation (NGR) are only applicable if the immediate roof is composed of shaley material. The USBM has made numerous underground and laboratory measurements using several NGR systems approved for installation on mining machines by the Mine Safety and Health Administration. In addition, two small handheld NGR instruments were used to make comparative measurements. Underground NGR measurements in 10 different coal seams, potassium-uranium-thorium radiometric analyses on samples from 16 seams, and chemical analyses of coal and rock for correlation with NGR counts were made. Laboratory test results on the effect of air gap and sample thickness, size, and weight on the NGR measurements, as well as general results of the various NGR systems, are discussed.

Jan 1, 1995

By Ann G. Kim

Fires that occur in abandoned coal mines, waste banks, and in coal outcrops constitute a serious health, safety, and environmental hazard. Toxic fumes, the deterioration of air quality, and subsidence constitute the greatest hazards from these fires. Although tires on abandoned mined land (AML) occur in every coal-producing state, the severity of the problem varies. Methods to extinguish or control AML fires, including excavation, fire barriers, and sealing, are generally expensive and have a relatively low probability of success This U.S. Bureau of Mines report includes information from a variety of sources, i.e., agencies of the Federal Government, State agencies, research reports, conference proceedings, product information, and technical literature. This information has been collated into a comprehensive discussion of AML fire problems. Data on past fire control projects and on the estimated extent of the current problem have been compiled. Factors affecting the occurrence, propagation, and extinguishment of AML fires are discussed. Conventional fire control methods are described, and their probable effectiveness is evaluated. Information on the hazards of AML fires and safety considerations is included. The status of current technology, recent improvements in fire control methods, and areas of current research are discussed.

Jan 1, 1993

By Allen McComas, Frank Chase, Phyllip Worley

Longwall mining has gained the reputation as being the safest extraction method in underground coal mines. However, one of the most difficult tasks associated with longwall mining is moving the face once a panel is completed. Based on Mine Safety and Health Administration (MSHA) fatality reports since 1996, longwall face recovery operations have claimed the lives of 5 U.S. miners and have resulted in numerous injuries. Recovery operations can be hazardous because they involve moving large pieces of equipment in very confined spaces. They are also conducted in highly stressed ground conditions due to front abutment loads generated by panel extraction. Shield removal is the most hazardous operation during face recovery because miners are constantly exposed to the unpredictable gob edge. To protect the miners, one or more walking shields, cribbing and/or other supplemental roof and standing supports are typically employed as breaker line supports as each shield is removed. At the Harris No. 1 Mine in southern WV, mobile roof supports (MRS’s) have been used in lieu of traditional walking shields on 17 face moves since 1997. MRS’s are shield-like support units mounted on crawler tracks and are commonly used during room-and-pillar retreat mining operations. For longwall recovery, the two biggest advantages that MRS’s have over traditional walking shields are that they are remotely controlled and are highly maneuverable. MRS’s have contributed to safer shield recovery and shorter move times at the Harris No. 1 Mine. This paper will address both the safety and the operational issues associated with MRS usage during shield recovery. It will also discuss new developments, including the use of the inherently safer battery powered MRS’s, which have been recently certified by the Mine Safety and Health Administration.

By Virgil Marple

In the summer of 1979 the University of Minnesota Mobile Laboratory (UMML), designed for the analysis of airborne particles and gases was used to study fugitive dust from an open pit coal mine. The analysis consisted of determining the particle size distribution and concentration of dust from various mining operations, such as blasting, draglines, loading, roadways and bottom scrapers. For some operations the particles size distribution and concentrations were determined at varying distrances. Details of the dust concentration within the plumes as the plume passed the UMML were measured with an optical particle counter. For line sources, such as roadways this enabled the calculation of the particle flux at the sampling location. In addition to the standard instruments associated with the UMML, the applicability of some new instruments were investigated. These included a uniform deposit cascade impactor and a flux meter. Finally, a technique in identifying plume origins which utilized elemental X-ray flourescence analysis of filter samples was shown to be effective.

Jan 1, 1980

By Edward W. Parsons

The transverse force developed by expansion-shell rock-bolt anchors on the wall of a drill hole as the bolt is tensioned was measured by the Bureau of Mines using a device specially designed and fabricated for attachment to a universal testing machine. Load cells equipped with electrical-resistance strain gages provided the data from which the transverse force, in pounds, was calculated. Seven different expansion-shell anchors were tested, and the ratio of transverse force to bolt-tension load was found to range between 0.98 and 1.94 to 1.0. The drag load appeared to be the major cause of the transverse-force variation, but the relative effects of individual factors that affected the ratio between the transverse force and the bolt tension were not determined.

Jan 1, 1968

By R. E. Hershey

1. Reserves were estimated for three coal beds: Lantana, Sewanee, and Richland. 2. Known measured and indicated reserves for all beds, based on a minimum thickness of 14 inches and on 1,800 tons per acre-foot of coal in place, are estimated at 34 million short tons as of Januray 1, 1954. Of this total, 15 million short tons represents coal 28 inches and more thick. Areas in the beds were omitted from the estimate because available data relative to the bed characteristics were insufficient to permit making an estimate conforming with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves determined by this investigation.

Jan 1, 1956

By M. A. Schellhardt

In recent years development of instruments and equipment for determining subsurface pressures and temperatures in. gas and oil wells has made it feasible to obtain information that eras not available in the past on many gas-production problems. The material presented in this report illustrates particularly the value of subsurface-temperature data in the study of subsurface leakage from gas wells. An abnormal decline in the shut-in pressure of the Lone Star Gasoline Co. A. Jones No. 1 gas well in the southern part of the Buffalo (Tex.) field was observed during an interval when a negligible volume of gas bras being withdrawn from the reservoir. Wellhead-pressure readings indicated that the shut-in pressure of the well declined from 2,295 pounds per square inch gage on February 3, 1937, to 1,445 on February 12, 1935. Tests conducted by engineers of the Lone Star Gas Co. suggested that the subnormal pressure gaged on February 12, 1938, probably was not caused by a head of liquid in the well.

Jan 1, 1940

By R. P. Maloney

Since mining operations began in 1900, Government geologists and mining men have periodically recorded the presence of the minerals of mercury and antimony in the extensive gold placer deposits near Flat in the Iditarod district of the Yukon River region, Alaska. No serious effort was made to recover the cinnabar contained in the gold placer gravels, and there is no evidence that veins of cinnabar and stibnite exposed in the placer operations (as reported by the Geological Survey) were ever explored or developed. A large monzonitic intrusive, which is the dominant geologic feature of the immediate area, is believed to be the lode source of the valuable minerals in the placer deposits. In contact with the monzonite are argillite and quartzite, metamorphic products from the Cretaceous shales and sandstones.

Jan 1, 1962

By J. S. Miller

The Bureau of Mines conducted surface tests to determine the feasibility of using liquid explosives for underground rock fracturing. The effects of configuration, confinement, length, critical layer thickness, and fracture-propping sand on detonation and explosive propagation velocity of desensitized nitroglycerin were studied, using polymethyl methacrylate and glass-plate reservoirs through lengths from 3 to 12 ft, with explosive-layer thicknesses from 0.1875 to 0.0312 in and in aluminum tubes 8 ft long with diameters from 2.000 to 0.125 in. Interval and continuous detonation velocity data were obtained. Under the test conditions detonation velocity was dependent upon explosive confinement and fracture-propping sand. The detonation velocity of a confined nitroglycerin explosion in aluminum tubes can be reduced by as much as 85 percent, when the tube contains fracture-propping sand. The shape of the reservoir, whether triangular or rectangular, has little effect on the detonation velocity or explosive propagation. The critical or minimum explosive-layer thickness between glass plates, capable of supporting propagation, was 0.0312 in. The presence of a fracture-propping sand in the sheetlike layers increased the critical explosive layer thickness to 0.0625 in. In nitroglycerin-filled and nitroglycerin-sand filled tubes, the minimum tube diameters successfully tested were 0.125 in and 0.375 in, respectively.

Jan 1, 1969

By E. Rupprecht, J. Volkwein, K. Cashdollar, R. Gürtunca

The National Institute for Occupational Safety and Health (NIOSH) mining research program at the Pittsburgh Research Laboratory (PRL), includes the areas of coal mine dust control and monitoring, and explosion prevention. One very important project at PRL is development of a continuous recording person-wearable respirable dust monitor. This Personal Dust Monitor (PDM) is a respirable dust sampler and gravimetric -equivalent analysis instrument that is part of a belt-worn mine cap lamp battery unit. Prototypes were successfully tested in the laboratory and in four underground coal mines. The PDM testing demonstrated that it was convenient to wear and use, robust, and provided accurate and timely data. NOSH is also conducting research in the program area of coal mine explosion prevention, suppression, and mitigation. Aspects of this research program include: full scale explosion research, laboratory scale research, frictional ignition of methane, mine ventilation seal construction, prediction of coal mine methane emissions, mine monitoring systems, flame cutting and welding operations, spontaneous combustion, and emergency preparedness.

By W. M. Dressel

This Bureau of Mines report describes a shaft closure demonstration project in which 11 inverted pyramid-shaped plugs were used to plug abandoned open mine shafts in Galena, KS, The inverted pyramid-shaped forms, fabricated from steelplate, were designed so that the inverted base would be larger, by 4 ft on a side, than the approximate size of the shaft opening at the surface residuum-solid rock interface. After the surface openings of the shafts were trimmed with a backhoe, the steel forms, complete with reinforcing, were lowered into the openings and filled with concrete; the remaining portions of the openings above the plugs were backfilled to slightly above the surrounding surface level with waste rock and soil. Location and elevation monuments were installed for long-tern evaluation of the success of the project.

Jan 1, 1985

By H. S. Price

This report discusses the development of a mathematical model that describes the flow of methane only and methane and water in a coal bed during mining operations. Because of the complex geometry, boundary conditions and fluid properties, the model is based on a numerical solution to the equations describing flow. The goals for the development of this model and requirements to which it complies are for the most part expressly stated in Request for Proposal No. 50110752. In addition to the capabilities specified under the scope of work the model can handle an anisotropic porous medium and a source term has been added which will simulate, somewhat, the effects of desorption. This term will be pressure dependent. The effect of time on such a term is only taken care of in the change of pressure with time. This source term will have the dimensions of Mcf/day/Mcf pore volume. It will be a part of the input data to be supplied by the user and will be entered as a table of rates versus pressure. These models consider the fracture system as the main porosity. All computed results pertain to the fractures. The source term mentioned above represents the flow from the matrix porosity into the fracture. Such flow should be small compared with the flow between fractures since these models handle only one porosity structure system.

Jan 1, 2012

By F. W. Wood

The use of consumable.-electrode arc melting as a production technology is growing. One advantageous feature of this process is that it avoids ingot contamination by soluble crucible materials by employing a chilled metal crucible. Because the thermal balance under these conditions is rather delicate and does not necessarily provide a favorable environment for solidification, catastrophic imbalances can occur. The effectiveness and mechanistic roles of various factors are mostly unknown, and more intelligent insight regarding the distribution of temperature and heat is needed. Experience has provided several pertinent observations, some of which are quite superficial. The most meaningful data have resulted from studies of molten pool shapes and sizes and from measurements of heat flow through crucible walls. Overall experience, intuitively interpreted and supplemented, is sufficient nevertheless as a basis for a boundary-value treatment of the problem. A mathematical analysis based on a separation of variables, using conventional differential equation methods, provides a useful solution. For a cylindrical ingot, the temperature varies as a Bessel function of an argument proportional to the radius and as an exponential function of longitudinal position. Trial calculations using the problem solution seem to verify the general correctness of the result as compared with experience. The role and nature of solution parameters are also clarified, though not entirely resolved. It is revealed that the barrier to heat flow at the ingot-crucible surface has a prominent influence. Utility of the model embodied in the problem solution is readily demonstrated by considering a variety of contemporary questions about arc melting, and it is hoped that utility can be enhanced by improvement of the model.

Jan 1, 1968