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By Paul W. Jeran, Michael A. Trevits, William P. Diamond

In this U.S. Bureau of Mines study, production trends have been analyzed for 82 gob gas ventholes on 7 longwall panels in the Lower Kittanning Coalbed, Pennsylvania. Cumulative production from individual holes was found to vary considerably, ranging from 0.03 x 106 to 10.1 x 106 m3. Peak production rates were generally about 0.03 x 106 to 0.06 x 106 m3/d, but rates over 0.10 x 1@ m3/d were observed. The variability of gas production from individual holes can be attributed to several factors, including completion practices and problems, the extent of fracture development in the strata above the extracted panel, water production, and location on the panel. Of particular significance is hole location. Holes on the ends of the panels, where overburden strata are in tension because of the support of the surrounding pillars, were generally the highest and longest producers. This observation led to the experimental placement of gob gas ventholes in the zone of tension along the margin of a panel, instead of in the traditional centerline location, which is in compression. Analysis of 7 months of gas production data indicates that the experimental near-margin holes produced 77 pct more gas than did centerline holes on the same panel.

Jan 1, 1994

Identify abnormal low-frequency blast vibrations. Develop blast design procedures for such adverse vibration cases, including the selection of delay times based on ground conditions, vibration frequency, and structural response. The Problem Research by the Bureau of Mines and others has demonstrated how structural response and the potential for cracking and other damage depends on blast vibration frequency in addition to particle velocity amplitude. The Bureau has published recommended criteria for blasting near low-rise residential-type structures; criteria that specified frequency-dependent amplitudes. The typical vibration frequency from surface mine and quarry blasting is 20 hertz (Hz). Sites have been found, however, that regularly produce ground-roll-type waves with frequencies as low as 4 Hz. The most serious cases arc those where vibration frequencies fall in the natural frequency range for structures of 4 to 12 Hz. Such vibrations have a higher potential for causing, damage to residential structures, particularly at the low end of this frequency range, because of the resulting high strains these frequencies produce in structural materials.

Jan 1, 1990

By J. S. Browning

The physical properties and specific gravity ranges of various liquids and salt solutions used for laboratory sink-float separations of rocks or minerals are presented. The test equipment and techniques employed by the Bureau of Mines in making sink-and-float separations of particles as coarse as 3 inches to as fine as 400 mesh are described. Also discussed are methods of recovering and reclaiming the liquids or salts from the minerals and wash solutions, as well as the hazards encountered and precautions to be followed while working with the materials. The laboratory use of various liquids for separating minerals of different specific gravities has been recognized for many years. During this time, laboratory sink-float procedures have proven their utility as a rapid and moderately accurate means for determining the mineral content of ores, test products, and plant products in certain nonmetallic concentrating operations, such as those producing mica, spodumene, kyanite, and so forth. These procedures also have been used as analytical tools for determining the mineral content and associations of other metallic and nonmetallic ores.

Jan 1, 1961

By Thys B. Johnson

A three-dimensional dynamic programing method is presented for determining the optimal ultimate open pit limit. The method given is based on the block concept and is an extention of the two-dimensional Lerchs-Grossmann approach. The three-dimensional technique presented herein is fast and simple and may be used for an initial open pit evaluation when only limited data are available or as a more refined model when the entire deposit is well delineated. The method is illustrated by simple numerical examples and is also presented in algorithmic form. A computer program was written in Fortran IV which implements the three-dimensional algorithm and some computational aspects are discussed.

Jan 1, 1971

By Joan T. May

Anhydrous methods were tested for the extraction of beryllium from low-grade source materials. The purpose of the investigations was to find new extraction processes that are applicable to domestic ores. Beryl, helvite, and phenacite materials containing from 0.1 to 2.8 percent BeO were used as starting materials for direct halogenation tests and pretreatment followed by halogenation. The results of the investigations showed that direct fluorination and carbide-chlorination are two practicable methods that can be applied to low-grade concentrates. Treatment of concentrate-carbon mixtures with anhydrous hydrogen fluoride extracted 99 percent of the beryllium in the concentrate; the soluble fluoride product, converted to an oxide, contained 70 percent BeO. Chlorination of beryllium-silicon carbide, prepared from low-grade concentrates, extracted beryllium into the volatile chloride product.

Jan 1, 1962

By Oliver Bowles

Sandstone, a widely distributed siliceous sedimentary rock, is the third most popular building stone in the United States. It is formed by the breaking down of preexisting rocks by weathering, subsequent segregation of the detrital quartz grains into discrete deposits by the sorting action of water or wind, and finally cementation of the quartz sand into a coherent rock. The homogeneity and resistance to weathering of the resultant sandstone make it suitable for exterior construction. Its excellent wearing properties explain its popularity for flagging and stair treads. However, quarrying and dressing methods and costs are adversely affected by the abrasiveness and hardness of sandstone especially as compared to limestone.

Jan 1, 1963

Objective To improve seats on mine shuttle cars with ergonomic design and by reducing shock impact transmitted through the mine vehicle seat to the vehicle operator. Background Operators of underground mobile equipment, particularly shuttle cars, are often exposed to significant levels of shock and whole-body vibration. Past studies have reported that as many as one-third of underground equipment operators could be exposed to adverse levels of shock and whole-body vibration. Moreover, seats on mining equipment, historically, are inadequate relative to the ergonomic needs of the equipment operator. In the extreme, amine vehicle seat has sometimes consisted of blocks of wood or a bent steel plate bolted to the machine frame. Also, the lack of sufficient vertical clearance in some underground mines is an impediment to providing adequate shock isolation systems on mine equipment seats. Approach The NIOSH Pittsburgh Research Center (PRC) is conducting research with viscoelastic foams to improve seats on mine shuttle cars. Viscoelastic foams were used in an ergonomically designed seat to reduce the amount of shock transmitted through the mine vehicle seat to the vehicle operator. Data on selected viscoelastic foams were analyzed from laboratory shock tests at PRC. Using information from the analysis, two ergonomic seats incorporating selected foam were constructed for in-mine testing on a shuttle car (Joy 21SC) in eastern Kentucky. The shuttle car operated in a 35-in-thick coal seam with an approximate mining height of 43 in. Operational data were recorded on the ergonomic and original seats. Further, the shuttle car operator was asked to compare these seats. Results When comparing the original seat (figure 1) with the ergonomic seat (figure 2), the shuttle car operator described the ergonomic seat as generally “much better” than the original seat. The operator explained. “It’s just easy to adjust. And it’s got the lower lumbar support. And the pad is thicker. It’s just much better all the way around.” He added, “It does support you more and [there is] less shock when you hit a hole...I liked the lower lumbar support. That’s where most of your shock is at, in your lower back.” The operational data supported the operator’s comments. In the full-load case, significant improvements in isolation were achieved(down to 15 Hz) with the ergonomic seat. Additional laboratory testing of seven viscoelastic foams was done to further improve the level of isolation from shock and better characterize the material properties of each foam. Data from this testing were used in an analytical model of the seat pan isolation system. Results showed that two of the viscoelastic foams, SUN-MATE EXTRA-SOFT and PUDGEE, gave the most effective shock isolation of the seven materials tested. A composite of EXTRA-SOFT and PUDGEE foams improved the isolation characteristics of the seat pan to approximately 4 Hz. Similarly, EXTRA-SOFT by itself provided isolation to 5 Hz. These results will be validated with future in-mine measurements. Cooperative Research Opportunity NIOSH is seeking cooperators to assist in further research and development of this technology. Additional information on cooperative reseach may be obtained by contacting Jacqueline H. Jansky, Technology Transfer Officer, NIOSH Pittsburgh Research Center, P.O. Box 18070, Cochrans Mill Rd., Pittsburgh, PA 15236-0070, phone: (412) 892-6615, fax: (412) 892-6678, e-mail:jgj7@cdc.gov

May 1, 1997

By R. P. Vinson, Abdurrahman Cetinbas, Joseph Cervik, M. G. Zabetakis

The periphery of longwall panels in the Pocahontas No. 3 coalbed is characterized by a zone of reduced permeability that inhibits the natural drainage of methane. A residual gas pressure of 105 psig was measured after 1 year in an isolated block of coal measuring 340 by 1,100 feet. The buildup of gas pressure within such large blocks causes methane problems during plowing operations. However, natural drainage holes drilled during development have been found to reduce the gas content of the coal in this coalbed by over 90 percent. The effect of water infusion on dust during plowing operations was investigated using existing methane drainage holes. These holes were cleaned of debris and a pipe was grouted into the hole for water infusion of the panel. Both total and respirable dust levels were reduced by 40 to 79 percent. Water infusion of the panel proved more effective than did the use of a plow-mounted spray sys tem.

Jan 1, 1974

By H. B. Carroll

The Bureau of Mines investigated the adaptability of the Meteorology Research Inc.2 (MRI) nephelometer and the Sinclair-Phoenix smoke meter for use in routine, analytical, smog-chamber experiments and to compare their responses to aerosol during these experiments. Both instruments' sampling systems were modified--smaller size sample input systems were studied using the nephelometer and a secondary sample system was added to the smoke meter to allow measurement of Aitken or condensate nuclei. Both instruments were easily adapted for use with small smog chambers and both displayed good precision and sensitivity to aerosol. A correlation was shown to exist between the two instruments' responses to aerosol. This correlation makes it possible to report the Sinclair-Phoenix measurements in visibility and/or mass units if desired.

Jan 1, 1973

By Richard A. Busch

Inadequate engineering design criteria for coal refuse embankments has allowed hazardous impoundment structures in coal mining areas to be created. A necessary first step to develop adequate design criteria is the determina¬tion of basic, respresentative physical property data on the materials that constitute typical refuse embankments. An extensive field and laboratory program was undertaken by the Federal Bureau of Mines. Much physical property data was generated. Additonal petrographic analysis and large scale triaxial compression testing was performed by others. The data presented here should aid in establishing design parameters for coal refuse embankments

Jan 1, 1974

By M. D. Schlesinger

Experimental data for coal hydrogenation are presented to show that when a vehicle oil produced from coal is present, coal is hydrogenated to the same high conversion whether molybdenum catalyst is impregnated on the coal or intimately mixed with the slurry. Differences in product distribution could be related to the severity of operating conditions. No minimum mixing time was established, but 2 hours was sufficient. Longer periods of mixing, to 14.75 hours, had no effect on the results. The hydrogenation conditions were in the pressure range of 8,500 to 10,000 p,s,i. at 400° to 500° C. Most of the experiments were made in duplicate. The results were obtained with molybdenum concentrations of 0.01, 0.1, and 1 percent. Al the mentioned pressure range and a time at temperature of 15 to 60 minutes, coal conversions higher than 98 percent were obtained.

Jan 1, 1962

By Ronald T. Mayerle

A mineral survey of portions of two contiguous WSAs (Wilderness Study Areas) along the South Fork Owyhee River in southwestern Idaho and north-central Nevada was done by the U.S. Bureau of dines in 1984. The portions of the WSAs, known as study areas, have a combined area of 47,610 acres. The Idaho study area consists of 42,430 acres of the 42,510-acre South Fork Owyhee River WSA (ID-16-53). The Nevada study area consists of 5,180 acres of the 7,840-acre South Fork Owyhee River WSA (NV-010-103A). The Idaho study area is within the Boise District of the Bureau of Land Management, and the Nevada study area is within the Elko District. In the Nevada study area, no claims or hard rock mineral occurrences are known.

Jan 1, 1986

By A. Wahab Khair, N. P. Reddy

"Abstract. This paper attempts to characterize coal breakage due to the action of a continuous miner. Coal blocks with an approximate dimension of 45.7 cm x 38.1 cm x 15.2 cm (18 in. x 15 in. x 6 in.) were first subjected to confining pressures equivalent to in-situ conditions. Then the blocks were cut along the face/butt cleat direction by the cutting head of a specially designed unique automated rotary coal cutting simulator (ARCCS), simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-sit and operating parameters a number of other para¬meters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment, the coal fragments were collected in bags using a vacuum cleaner. These fragments were then sieved for size distribution analysis.INTRODUCTIONThe Federal Coal Mine Health and Safety Act of 1969 was enacted to emphasize to coal operators that the airborne respirable dust should not exceed 2 mg/m3, thus reducing the incidence of coal workers pneumoconiosis.Dust control techniques such as conventional water sprays and dust collectors are only partially effective and require additional equipment expenditures. A more authentic approach would be to reduce respirable dust at the source the continuous mining machine cutting head, where the fragmentation process occurs. Improving the fragmentation process by characterizing the coal breakage will not only reduce respirable dust at the face, but it will also decrease the amount of respirable dust that is liberated during the secondary handling.Fragmentation of coal can be expressed as a function of three major groups of parameters; namely, 1) coal properties, 2) in-situ conditions and 3) operating parameters. This paper deals with the characterization of coal breakage along both face/butt cleat direction as a function of machine operating parameters such as rate of advance, angle of attack, bit configuration, bit lacing (spacing and pattern) and bit speed at various equivalent in-situ pressures."

Mar 1, 1989

By Constantine C. Popoff

Several limestone deposits in western Washington were examined by the Bureau of Mines in 1946. This report presents data obtained from the investigation of limestone deposits in the vicinity of Arlington, Snohomish County, Wash. The work consisted of surface surveys and sampling. Samples were taken where complete, or nearly complete, sections of limestone were exposed or where individual beds were exposed at a number of separate .localities. Areas were cleaned by blasting prior to sampling. Channel samples were cut where practical; otherwise chip samples taken. Twenty-one samples were taken. The locations of the samples and the analyses are shown on maps accompanying this report.

Jan 1, 1949

By T. R. Waters, F. Li, R. L. Huston

This paper describes the development of a multi-body biomechanical model that can be used to assess the risk of low back disorders due to occupational exposure to jarring and jolting from operation of heavy mobile equipment (e.g., trucks, haulers, graders, tractors, etc.) The four-element dynamic spinal model is capable of providing estimates of the force and acceleration responses of the head/neck, upper, lower, and middle torso resulting from vibration input collected in field studies. The paper also presents a method for using the model output to assess an individual's risk of low back disorder due to a specific jarring and jolting exposure.

By Gary W. Krantz

Fibered, portland-cement-based gunite products were applied in the Bureau of Mines Lake Lynn Laboratory Experimental Mine using a variety of pneumatic guns and gunning crews, The demonstrated wet-mix (with silica fume), dry-mix, and surface bonding products were sampled by the Bureau and subjected to a suite of engineering analyses. Gunite flexural and compressive strength, rebound, permeability, porosity, dust loading, shooting rate, crew requirements, and cost factors were evaluated. Steel, fiberglass, or polypropylene fibers were contained in all but two of the gunires tested. Both Bureau and private testing laboratory analyses are provided for some products. Electron probe micro-analysis and X-ray diffraction analysis were performed on the silica fume fraction of the wet-mix gunite to characterize the dust. Aggregate size fraction distribution analyses were performed to provide strength relationships. Results indicate that all of the commercially available fibered-gunite materials tested can provide beneficial sealant, spall prevention, or roof stability control attributes for underground mining environments when applied by an experienced crew using a well-maintained gun, in accordance with product manufacturers' recommendations and when used for the designated purpose.

Jan 1, 1984

By Warren D. Longwill

The Bureau of Mines inventoried Federal lands in the State of Oregon and classified them in detail, section by section, according to their availability for mineral exploration and development as affected by legal status and agency management practices. The Bureau determined areas of the State having past mineral production and/or known metallic mineral resources and areas favorable for coal, oil, gas, and geothermal resources, and prepared maps that spatially compare the availability of Federal mineral land with these mineral areas to demonstrate the extent of restrictions to mineral entry. Oregon contains 62.1 million acres, of which 33.9 million acres or 55% is Federal mineral land. About 2.3 million acres of Federal land is favorable for selected metallic mineral deposits, of which 64% is available, 13% is restricted, and 23% is unavailable. Of the 21.1 million acres of Federal leasable land favorable for oil and gas, 68% is available, 11 % is restricted, and 21 % is unavailable. Of the 146,720 acres favorable for coal, approximately 71% is available, 13% is restricted, and 16% is unavailable. Federal leasable land favorable for geothermal resources amounts to 458,968 acres, of which 42% is available, 34% is restricted, and 24% is unavailable.

Jan 1, 1988

Provide the U.S. mining industry with a user friendly computer program to calculate stresses in underground coal mines in order to improve safety conditions for mine workers. Capabilities of MULSIM/NL MULSIM/NL (multiple seams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines. It can analyze one or two parallel seams that can have any orientation with respect to the Earth's surface. Three main new features distinguish MULSIM/NL from its predecessors: (1) non¬linear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. The multiple mining step capability enables the user to efficiently simulate a changing mine geometry. Finally, MULSIM/ NL computes energy release rate due to mining using the most recent concepts advanced by Salamon.

Jan 1, 1993

By Larry G. Stolarczyk

This report deals with information regarding a new Medium Frequency (MF) Wireless Communication System for underground mines. This new telecommunication system works on low loss electromagnetic wave propagation modes which allow it to provide quality radio communications almost anywhere in a mine. Tests show the MF system can provide improved safety and managerial control, increased productivity, better organizational team-work and reduced maintenance cost; furthermore, MF's unique design allows for easy installation at a minimum cost. This paper covers the following: 1) MF design plan, 2) Overview of mine radio communications systems, 3) Preparations needed for designing an MF system, 4) MF equipment, 5) MF installation, 6) MF design considerations, 7) MF design specifica¬tions, and 8) Recommendations dealing with MF system. Experiments in four mines are illustrated to demonstrate the success and via¬bility of the MF system. The mines range from small (500 tons/day) to large (67,000 tons/day) capacity and represent several different mining methods. The MF Wireless Communication System represents an advancement in mining communication and the groundwork for other advanced mine systems.

Jan 9, 1984

By S. A. Gustavson, H. E. Olund

This report has been prepared to review the history of the Premium Price Plan for copper, lead, and zinc, which was in operation from February 1, 1942, to June 30, 1947. It includes various charts and tables comparing costs and production data, and data on exploration premiums that were included in the Plan during the last year of its operation.

Jan 1, 1950