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By Robert A. Jankowski, Ellsworth R. Spencer, Jay F. Colinet

Longwall mining is the most productive method of under- ground coal mining in the United States (U.S.), and record levels of production have been reached in recent years. These ever-improving production levels have the potential to generate significantly higher quantities of respirable dust. Consequently, the longwall industry continues to struggle with controlling dust liberation and maintaining compliance with the federally-mandated respirable dust standard. In response, longwall operators have increased the application of primary dust controls, airflow and water flow, in an effort to improve respirable dust control and reduce worker exposure. Pittsburgh Research Center (PRC) personnel conducted dust surveys at 13 longwalls operating throughout the U.S. and collected information to: identify current operating practices on these longwalls, identify the types of dust controls in use, document the levels at which these controls are being applied, and measure the respirable dust levels present. This data was analyzed to quantify the dust levels generated by the major sources on the longwall section and to evaluate the relative effectiveness of the control technologies in use.

By J. J. Forbes

The rapid increase in the quantity of coal being mined by stripping methods is one reason for the increased interest evinced by safety and other agencies in the hazards that are inherent in this Method of mining. The coal-mining laws of some States contain general provisions governing the mining of coal by open-cut methods, but none contains a complete list of specific safety regulations or laws for-the safe operation of such mines. The cool-mining laws of one State empower the head of the coal-mining inspection organization to proscribe regulations for coal-stripping operations and gave him the authority and power to enforce the rules and regulations promulgated by him.

Jan 1, 1944

By d&apos, Kathleen J. Amico

This summary appears in Minerals Year-book volumes I-II, and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The sections of this chapter and the area chapters in volume III contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operations at or near mines.

Jan 1, 1967

By Michael S. Wieland

Recognizing the dynamic nature and possible range of toxic concentrations in the impending fume cloud prior to undertaking explosive blasting can reduce potential hazards and mitigate related incidents. The scaled cloud model was formulated to predict the relevant (major) toxic components in fume clouds released by nonideal mining explosives used for surface blasting. Natural turbulence unceasingly disperses the toxic molecules, widening (inflating) the fume cloud while diluting the concentrations, ultimately rendering nonhazardous conditions. The threshold cloud size depends upon the type and quantity of total explosives used and the cloud's thermodynamic condition. Though the scaled theory works for fume clouds with irregular (odd) shape, an equivalent upright cylindrical form is useful for rendering simple riskhazard scenarios. The cylinder's projection downward on the underlying terrain yields a circular 'shadow' marking the region threatened, thereby permitting a rough estimation of the potential hazards, were the cloud to settle down there. Wind causes the cloud to drift while it expands, so the shadow travels while it grows, until the risk hazard process is truncated at the nonhazardous threshold. The overall relative fume toxicity (RFT) is taken from the traditional Russian RFT rule, which utilizes only the two fume components that tend to dominate the resultant toxicity: carbon monoxide (CO) and total nitrogen oxides (NOx). Tabulated constants that characterize the fume spectrum in the cloud model were resolved for ammonium nitrate (94%) with fuel oil (6%), ANFO-94/6, using a refined thermodynamic work-principle. Comparable results were found with the reduction factor technique, when test results from the underground fume chamber were readjusted to reflect nominal field shooting conditions.

By J. H. Perry

The Bureau of Mines is conducting research to determine the effectiveness of long holes in degasifying an area of the Upper Split of the Lower Sunnyside coalbed at Kaiser Steel Co.'s Sunnyside No.1 mine. These holes were drilled from the two outside entries of a section that was closed to mining because of excessive methane emissions. Two holes drilled to 430 and 450 feet produced initial gas flows of 160,000 and 127,000 cfd, respectively. Sixteen days after the completion of the second hole, the total gas production declined to just over 144,000 cfd. In 9 months of degasification, over 35 MMcf of commercial-quality gas has been removed from the coalbed. The combined gas flows declined to 106,000 cfd in the 9-month period. The two holes have reduced face emissions by about 40 pet.

Jan 1, 1978

By Isaac A. Zlochower, Michael J. Sapko, Ronald S. Conti

This paper describes a U.S. Bureau of Mines investigation of large-scale coal dust explosions in an experimental mine using a high speed electro pneumatic mechanism for the rapid grab-sampling of gases and dusts. This technique enables the monitoring of pyrolysis and charring in fuel dust particles, and the collection of gaseous combustion products, in both large and small-scale explosions. Data obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Test facility show the following: Rapid sampling appears to "freeze" the burned gas compositions at the flame temperature values. Gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen. The particles collected in the flame zone show signs of extensive pyrolysis and charring. Measurements of gas concentrations and particle flame temperatures suggest that char burning may have occurred in the flame zone.

By G. E. Rennick, F. E. Armstrong, J. Pasini, J. R. Abrams

An oil well penetrating the Pittsburgh bituminous coalbed in northern West Virginia was plugged and safely mined through 3 months later. A sensitive chemical tracer, introduced into the oil reservoir before the test, was not detected in the mine air following the plugging and during mining of the pillar and penetration of the well. Effectiveness of the plugging in preventing reservoir gas from entering the mine through the well hole was verified by continuous monitoring of the mine air for indications of sulfur hexafluoride, an inert gas detectable in amounts as minute as 112 part per billion. Expand- able cement and fly ash-gel-water slurry were utilized to seal the well above and below the coal seam. Three other wells were also plugged using various techniques.

Jul 1, 1972

By d&apos, Kathleen J. Amico

THIS SUMMARY appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operatons at or near mines.

Jan 1, 1963

By Ivette E. Torres

Many significant events that began in 1990-91 continued to have a profound impact in the world minerals economy in 1992. The dissolution of the U.S.S.R. and the formal breakup of the Council for Mutual Economic Assistance (CMEA) had significant effects far beyond the geographic boundaries of Europe and Central Eurasia. CMEA's network of economic interdependence had relied on central planning, a variety of subsidies, and barter agreements that allowed its members to function without the pressures of productivity and efficiency. In the mineral sector, many decisions had been made based on the need for military planning and technology competition with the market economy world. Because of inexpensive oil available through subsidies and technology assistance from the former U.S.S.R., industries III CMEA member countries had been able to function and maintain production to supply minerals and materials required to support the policies of the central plan. In 1992, most of the former CMEA countries decreased their output of many minerals. In some cases, the network of production that had been in place was severed. Political and economic instability, destruction of infrastructure, and new priorities were affecting other mineral industries in the area. In late 1991, 15 independent countries replaced the U.S.S.R. and in early 1991 the former CMEA countries found themselves trying to adjust to the realities of economic independence and the need to compete with former allies for survival. Although 11 of the 15 former Soviet republics joined in the Commonwealth of Independent States (CIS) in December 1991, in 1992, individual economic needs exceeded the needs of the Commonwealth III importance. As a result, new mineral trade patterns emerged as minerals were used as a source of much needed capital.

Jan 1, 1994

By E. Chin

Natural gas was Bangladesh's only significant exploited mineral. A few other minerals or mineral-based commodities were produced for local consumption. The most valuable were nitrogen fertilizer, salt, cement, and clay for brick.2 The most important mineral industry development of 1987 was the start of modest production of crude oil, the first discovered and produced in the country. PRODUCTION AND TIADE Production of natural gas from the nation's huge reserves continued to increase but was limited by the lack of residential and industrial demand. Gas reserves of 7 trillion to 16 trillion cubic feet were sufficient for far more production than the country could efficiently utilize for many years. The country's consumption-to-reserves ratio was one of the lowest of the developing nations. Mineral exports have been insignificant, comprising a small amount of nitrogen fertilizer. Nitrogenous fertilizer exports could become important when planned new capacity comes on-stream. Mineral imports were dominated by crude petroleum.

Jan 1, 1989

By Jamie Girard Dwyer, Edward McHugh, Stanley Miller, Jeffrey Whyatt

This user's guide covers the operation of a suite of three computer programs-Bplane, Bstepp, and Bwedge. These programs can be used to evaluate the potential for plane shear, step-path, and wedge failures along the crest of a slope bench. Such failures reduce the width of a catch bench and may compromise the bench's ability to catch rolling or sliding material before it reaches miners working below. The Bplane and Bwedge programs address sliding of blocks defined by continuous planar joints. The Bstepp program examines sliding of blocks defined by more complex failure surfaces that include steeply dipping cross joints and may even include breaks across small bridges of intact rock. The programs are applicable to jointed rock masses where the joints are small relative to the overall slope and form a number of sets with uniform statistical characteristics within a slope sector. The theoretical basis, application, and operation of these programs are described.

Jan 3, 2007

By P. D. Bergman

To assess the efficacy and economics of producing power from coal, four open-cycle magnetohydrodynamic (MHD) processing schemes were selected for study. Each involved a different mode of coal combustion and level of gas cleanliness. The options considered were: (1) coal burned in a slagging combustor; (2) suspension gasification with slag removal prior to combustion; (3) parallel cyclone combustors, one operating fuel rich and the other operating with excess air; and (4) suspension gasification by the hot exhaust gases from the MHO duct with ash removed prior to combustion. Option 1 has the highest ash content in the combustion plasma and as a result would have the greatest operational difficulties associated with it. Options 2 and 4 have the cleanest MHD combustion plasma. For coal priced at $4/ton, the power generating cost of option 4,11.78 mills/Kw-hr, is the highest, with Option 1, at 9.04 mills/kW-hr the lowest. These costs may be compared with a conventional power cost of 9.92 mills/kW-hr for the late seventies. Capital costs of three of the four options were competitive with those of conventional thermal power plants employing stack gas S02 cleanup systems. Option 2 has the most favorable combination of operating characteristics and power cost. It was concluded that a clean, high-temperature working fluid can probably be produced from coal without leading to depressed system efficiencies and exorbitant capital costs.

Jan 1, 1973

By Joan C. Biordi

The Bureau of Mines used molecular beam-mass spectrometry to determine the microstructure of a 10.1% CH4-2l.2% 02-67.6% Ar-1.1% CF3Br inhibited flame and its uninhibited analog, both stabilized at 32 torr on a cooled flat-flame burner. Composition profiles of atomic, radical, and stable species and temperature profiles for both flames were obtained and compared. Kinetic analyses of the profiles yielded values for the rate coefficients of several elementary methane flame reactions and information on the reactions of formation and decay of the observed halocarbon species. CF3Br is judged to decay by thermal decomposition as well as by abstraction reactions, and the fluorocarbon chemistry occurring in the inhibited flame is due primarily to CF2 radical reactions. Rate coefficients and mechanisms for reactions of the inhibitor-related species are given.

Jan 1, 1978

By Michael J. Sapko, Eugene M. Bazala, Eric S. Weiss, Kenneth L. Cashdollar

The data presented in this report are the results, to date, of an ongoing Pittsburgh Research Center Disaster5Prevention research program on the explosion hazards associated with blasting operations in noncoal mines. Laboratory and experimental mine tests have shown that oil shale and sulfide ore dusts can be ignited given the proper predispersed dust concentrations, particle size, and kerogen or sulfur content. Methane (CH) gas may also4be present in deep oil shale formations and can pose a significant added hazard to underground blasting operations. The most common explosive used for blasting in oil shale had been ANFO, a combination of ammonium nitrate and fuel oil; blasting in sulfide ore had used ANFO and/or dynamites. Tests conducted at the cannon gallery at Lake Lynn Laboratory near Fair chance, Fayette County, PA, provided a means of evaluating the relative incendivity characteristics of new and existing explosive products. Three explosives—a pumpable emulsion-ANFO blend, a packaged water gel, and an emulsion blasting agent—exhibited low-incendive qualities compared with other more highly incendive products such as ANFO and some dynamites. Based on the data collected during numerous full-scale blasts in oil shale and sulfide ore mines, the low-incendive products significantly reduced or eliminated the ignition hazards while at the same time providing effective fragmentation of the rock. Based on the positive results from the gallery and field testing, low-incendive explosives, coupled with good blasting procedures, show promise in reducing dust and/or gas ignitions associated with blasting operations in oil shale and sulfide ore mining applications.

By R. V. Ramani, V. T. Burgos, J. A. McClay

Introduction The Cost program was developed to provide the planning engineer with a tool to evaluate the cost implications of the technical mine design decisions. Direct costing methods are employed, where feasible, to provide greater detail and accuracy in the primary cost centers. Options have been provided in the cost computation, economic analysis, and output data subsystems to increase the flexibility of the system. Computer Program The program is written in Fortran IV for use in the IBM System 360/370 computers. i. Main - The main routine reads and stores input data from three sources, user input, Cost Data Library, and data transfer from the Master Design Simulator. Data is trans¬ferred to the appropriate subroutines, as they are called, by means of labeled common blocks. ii. Subroutine CSTCOM - is a data modification routine which computes the peripheral charges related to labor and supervisory costs. iii. Subroutine MANPWR - interrogates section data to determine the total labor and supervisory costs for each cost center. iv. Subroutine CAPCST - computes the total capital investment for each cost center, including the economic life and salvage value of each element. Capital costs are determined by user selection of quantities and models of equipment. Equipment costs are stored in the Cost Data Library for retriev-

Jan 1, 1975

Over and above the technical support arid consulting work described in the preceding Parts of this Volume, ADL staff also provided a wide range of additional technical assistance to the Bureau on an ad hoc basis over the course of the contract, and particularly in 1973. Some of these assignments were on tasks that temporarily assumed a high priority at PMSRC, requiring a fast response, while others were more suited to conventional schedules but on communication and location topics less directly related to those in the preceding Parts. Chapter I briefly describes some of the diverse short-term assignments while Chapters I1through V treat assignments on the other topics. I SHORT-TEXM ASSIGNMENTS A sampling of short-term, fast-response assignments undertaken on mine communications and miner location for PMSRC during 1973 are given below. These assignments included technical reviews, discussions and recommendations related to the theory, experimental data, designs, and hardware implementation of experimental CW and pulse miner location EM transmitters; preparation of technical performance specifications for a miniaturized preproduction prototype CW electromagnetic location transmitter; review of specifications for a seismic signal detection experimental study; participation in technical discussions and experiments with PMSRC and equipment suppliers regarding the UHF radio/radiax-cable communications installation in the Bruceton mine; participation in an informal conference to discuss mine communication and monitoring needs and preferences with representatives of the Bureau, mine operators, and equipment manufacturers; participation in technical discussions with representatives of a U.S. mine operator and CERCHAR* concerning the characterization of faults on trolley lines and means of improving their rapid detection;** recommendation of simple signal, noise, and ground fault measurements on mine phone lines; review of an inexpensive automatic telephone dialer; preliminary discussions regarding the feasibility of adapting and assembling a collection of available telephone industry carrier equipment for installation and test in an operating coal mine; evaluation of a proposed call alert mine paging system; review of hardware designs and future experiments for a mine communication sled; design critique of a proposed six-channel narrow-band FM voice modem for carrier communication on the mine phone line; preparation of technical performance

Jan 1, 1974

By David R. Hanson

Experimental work performed by the Bureau of Mines in a laboratory environment has shown that the formation of failure zones within certain rock types is accompanied by the emission of significant amounts of radiofrequency (RF) electromagnetic (EM) energy. This radiation was detected using nonresonant, "electrically short," broad-band antennas. Rock types for which emission was observed include granite, quartzite, and taconite; sandstone and marble did not emit measurable radiation. Amplitude spectra of the radiation showed the energy to be concentrated between 10 and 40 kilohertz. These data indicate that emission is directional, but this has not yet been proven. In addition, amplitude of RF emission increases with increasing crack size. Since emission was observed only for brittle quartz-bearing rocks, it appears the formation of piezoelectric fields is a necessary condition for RF radiation. Plausible mechanisms for emission include rapid decay of piezoelectric fields accompanying the sudden stress release at failure and/or the acceleration of an "exoelectron plasma" through the intense local piezoelectric fields. Since emission appears to increase with the scale of failure, and since antennas do not need to be coupled directly to rock surfaces as with conventional geophones, the possibility of developing a portable system to monitor seismically active areas exists.

Jan 1, 1981

By J. P. Barkley

"The accompanying tabulation gives the results of a series of operating tests on two types of small stokers. One was an inclined, natural-draft, moving-grate, overfeed ""hand-stoker"" fired and manipulated by hand; the other was. a horizontal, forced-draft, stationary-grate, underfeed, mechanical unit-stoker operated by an electric motor. These were installed as shown by the accompanying sketches (figs. 1 and 2) under horizontal return tubular boilers of a nominal rating of 150 bl.h.p. each.The steam load carried by these boilers was a rather typical heating load. It was fairly constant and of about 30 bl.h.p. throughout the summer months, with small variation between day and night. During the winter months the daily variations were dependent upon the outside temperature. The boilers were banked a considerable part of the night.As noted in the table, two kinds of coal were used. The size of one kind was run-of-mine and the other 11/4 inch nut and clack. These coals from two different mines of the New River district both caked considerably during burning, the nut and slack more than the other. Analyses of the coal were as follows:"

Jun 1, 1929

By A. C. Fieldner

The Bureau of Mines has recently conducted a study of results obtained in analyzing similar samples of coal and coke by 25 laboratories throughout then country, in comparison with results obtained in the Bureau's coal laboratory at Pittsburgh. The purpose of this work was primarily to obtain a comparison of the methods of coal analysis used by the laboratories of the American Gas Association. Therefore, four standard samples of coal end one of coke ware prepared in the Bureau of Mines coal laboratory at Pittsburgh, and portions sent to each laboratory. At the same time, a like number of standard samples were submitted to 12 commercial laboratories rot affiliated with the Association, for the purpose of comparing their analyses with the results is obtained by the U. S. Bureau of Mines and the American Gas Association. Tire comparison is based on the average of 24 analyses by the Bureau of Mines on each kind of coal, and the accompanying curves show the deviation from this average analysis, together with deviations from the check limits of the American Society for Testing Materials.

Jan 1, 1923

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Jan 1, 2012