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By F. N. Kissell

The applicability of the "direct method" for determining the methane content of virgin coalbeds was tested. Preliminary results indicate that the direct method, when applied to exploration cores, can be successfully used to estimate coalbed gas content and also approximately predict the total gas emission from a prospective mine located in the coalbed at the exploration site.

Jan 1, 1973

By Bill M. Stewart, Philip W. Patton, Curtis C. Clark

Handling materials in underground mines continues to be a major safety problem. To help reduce materials-handling injuries, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are investigating those materials-handling tasks in underground mines that appear to generate a high number of injuries. Data from the Mine Safety and Health Administration for the years 1989-1999 were studied to find out if there were any trends in materials-handling accidents and if so, to determine what tasks were involved and the sources of injuries. Several underground coal and metal mines we revisited to document innovative materials-handling technologies. Considerations for safety training and mechanization needs for continued reduction in materials-handling injuries are described.

By D. A. Reynolds, J. D. Davis

"INTRODUDTION Investigations by the Bureau of Mines have shown that the carbonizing properties of splint and bright coals may differ greatly. In a study of 55 coal columns selected from representative coals of the Appalachian region, Sprunk and coworkers 10/ compared various chemical and physical properties of splint and associated bright coals. Carbonization tests in the Fischer retort at 932°F. (500°C.) showed that, except for bright coals of high oxygen content, the coke residue from bright coal was much more swollen and cellular than that from splint. ·with one exception, agglutinating values determined by the Bureau of Mines test, were lower for splint than for associated bright coal.Because sorting of coal in quantity is tedious and time-consuming, separate types have not been carbonized by the Bureau of Mines-American Gas Association (BM-AGA) test, which requires 85- to 200 pound charges. However, this method has been used to determine the carbonizing properties of samples 0f bed layers that are composed largely of either splint or bright coal.4/ In these earlier tests, which were made at high temperatures on layer samples from the Elkhorn bed, Letcher County, Ky., the splint coal yielded more coke than the bright coal, and this coke was slightly stronger than that from the bright coal. The cokes from samples with large proportions of bright coal were more cellular or porous, as were the low-temperature cokes obtained from carbonization of separated samples of bright coal in the Fischer retort."

Apr 1, 1944

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

The Bureau of Mines has developed a system using a high-speed electropneumatic mechanism for the rapid (grab) sampling of dusts and gases during an explosion. The sampling system consists of an aluminum housing that incorporates two 30-cm3 preevacuated glass vials with rubber septums. Upon actuation, the sampling probe needle is driven through the septum with a pressurized air pulse, filling the tube with gas and dust from the mine explosion. After a predetermined time, the sampling probe needle is retracted by a second high-pressure air pulse to its normal (quiescent) state, allowing the sampling tube to reseal. The onset and the duration of sampling are independently variable and controlled by a time-delay relay package. This technique enables the monitoring of pyrolysis-charring in coal particles and the generation and combustion of the pyrolysis vapors in both large- and small- scale explosions. The following results were obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Laboratory: (1) Gas sampling of the leading edge of the flame front shows the large concentration changes, characteristic of the flame front; (2) gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen; and (3) the particles collected in the flame zone show signs of extensive pyrolysis and charring.

Jan 1, 1988

By d&apos, Kathleen J. Amico

This summary appears in Minerals Yearbook volumes I-II, and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonweath 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

To separate complex mineral mixtures according to their dielectric properties. Approach Develop a laboratory-scale continuous dielectric separator to separate mineral mixtures by exploiting their difference in dielectric properties. How it Works Dielectric separation is de-fined as the separation of particles based on their dielectric properties. The uniqueness of the Bureau's continuous separator, called the ?Rotating Drum Dielectric Separator,? is that it contains a high-voltage electrode con-figuration. The drum electrode consists of a series of coaxial parallel wires mounted on the outside surface of an Insulated cylinder. The screen electrode Is a wire mesh, quarter cylinder positioned outside and coaxially with the drum electrode. The drum electrode is placed in a liquid of dielectric constant K with the liquid level just above the drum's axis. The screen electrode is completely Immersed

Jan 1, 1981

By Jacqueline A. McClaskey

The U.S. Bureau of Mines (USBM) Information and Analysis Directorate collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U. S. economy. The USBM's data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority for the USBM survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress). This act strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1994

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

MINE VENTILATION NETWORK ANALYSIS

Jan 1, 1977

By John W. Adams, W. D. Bensema, Motohisa Kanda

Two different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating coal mine, Robena No. 4, located near Waynesburg, Pennsylvania. One technique measures noise over the entire electromagnetic spectrum of interest for brief tine periods. With present instrumentation, the spectrum can be covered from 40 Hz to 400 kHz. It is recorded using broad-band analog magnetic tape, and the noise data are later transformed to give spectral plots. The other technique records noise envelopes at several discrete frequencies for a sufficient amount of tine to provide amplitude probability distributions. The specific measured results are given in a number of spectral plots and amplitude probability distribution plots. The general results are that at frequencies below 10 kHz, power line noise within the mine is severe. Impulsive noise is severe near arcing trolleys, and at lower frequencies near any transmission line. Carrier trolley phone signals and harmonics are strong throughout the mine whenever the trolley phone is in operation. Additional information beyond that included in this report may be obtained from the authors, who are with the Electromagnetics Division of the National Bureau of Standards.

Jan 4, 1974

By Jon C. Volkwein

Advances in mining technology have enabled deeper seams of coal to be mined from the surface. Highwall mining is frequently used to mine areas at the perimeters of a surface mine when removal of the overburden becomes uneconomical or threatens environmentally sensitive surface features. At the same time, advances in materials and technology have enabled highwall mining of coal that create blind headings over 300 meters in length. Deeper surface mining and deeper highwall penetration depths have lead to more frequent encounters with methane gas. While this coal is remotely mined from the surface, underground ignitions of methane have propagated to the surface and injured miners. Methods described in this paper show how this hazard can be correctly monitored and controlled for auger type highwall mining machines. Research indicates that small quantities of gas liberated during mining migrate to the face, creating higher gas concentrations than would otherwise be expected. Using the same principles that cause the gas to migrate to the face, researchers have shown that inert gas introduced at the collar of the hole can inert the entire hole, thus ensuring safe conditions for mining.

By Lloyd M. Kniffin

[This paper is one of series being prepared by the United States Bureau of Mines on mining methods, practices, and costs in the various mining districts of the United States. It describes the mine of the Hanover Bessemer Iron & Copper Co. at Fierro, Grant County, N. M., which is the only operating iron mine in the southwestern part of the United States. This mine is in a district noted for the great variety of ores that it produces. Within a small area, as shown is Figure 1, there are noteworthy deposits of nearly all the common metals. The ore occurs in lenticular masses dipping at about 50°. An underhand stoping method has been developed that requires but a very small amount of handling of ore. As the ore is very irregular in iron content and also in the distribution of the impurities--chiefly sulphur, silica, and magnesia--a method has to be used that will permit selective mining and will also allow ore and waste to be taken out separately as conditions change. A magnetic cobbing plant raises the grade of the ore shipped about 10 per cent.]

Jan 1, 1930

By John Paul Gries

This Bureau of Mines study outlines the history of 11 major metal ore deposits or districts that are relatively new discoveries. The oldest operation is the White Pine mine, where major exploration was initiated in 1929. Discovery (delineation of ore bodies) dates range from 1948 to 1976. All but two of the deposits, Quartz Hill in Alaska and Flambeau in Wisconsin, are or shortly will be in major production.

Jan 1, 1979

By J. R. White, S. W. Lambert, C. M. McCulloch

Examination of several coalbeds in Walker County, Ala., Cambria, Greene, and Fayette Counties, Pa., and Raleigh and Wyoming Counties, W. Va., indicates that cleat orientations are similar throughout a vertical sequence of strata. Studies of cleat orientation were carried out in underground mines that are operating in separate coalbeds vertically above one another. The data show that over a vertical separation of 100 to 400 feet, the average difference in coal cleat orientation between mines is 04° for the face and 08" for the butt cleat. Variations of coal cleat direction between coalbeds examined in strip-mined areas show similar values. Cleat orientations measured at outcrops agree well with the directions measured underground, suggesting that the amount of vertical separation between coalbeds has little effect on the resulting differences in cleat directions. The largest variation of cleat directions between adjacent coalbeds occurs where a large horizontal distance separates two sample locations. Cleat orientations for deeper coalbeds are most reliable where the data are taken from directly above.

Jan 1, 1976

By R. W. Smith

The Bureau of Mines has been engaged in a systematic evaluation of the thermodynamic properties of combustion gases. These studies were designed to provide basic thermodynamic information of high accuracy, facilitating the theoretical study of flame and combustion phenomena.4 This report is the fifth of a series5/ presenting results of the study for particular fuel-oxidant systems. These calculations have as their objective the constant pressure flame temperature of acetylene-air for a range of pressures.

Jan 1, 1954

By Joseph W. Martin

The Bureau of Mines investigated the backscattering of low-energy gamma rays as a method for rapidly determining the incombustible content of coal mine dust. In this method, 60-kev gamma rays from americium-24l penetrate the dust and are reflected by elements in the dust to a thin crystal scintillation detector. The number of backscattered gamma rays is proportional to the incombustible content. Tests of 40 dry, mine-dust samples containing 50 to 100 percent inert material show an average error of 2 percent. Calibration of the apparatus is necessary for each rock dust to account for variable composition. Results for samples containing more than 6 percent moisture are subject to error, but the values are lower than values obtained by chemical analysis, and thus fall on the safe side. Development of a small portable meter based on the backscatter principle appears feasible. Such a meter would find application within coal mines to check the effectiveness of rock dusting procedures.

Jan 1, 1968

By Frank E. Williams

This Bureau of Mines report deals with the urbanization of Tucson, Ariz., a southwestern city with an arid environment. Zoning regulations concerning known aggregate sources are described, and information relating to projected needs for the urban area is furnished. History of growth is outlined not only for the local aggregate industry, but also for the entire urban area. Past conditions are pointed out and background material for future conditions is provided.

Jan 1, 1967

By I. N. Beall

The present survey indicates 'that the average volatility of motor gasoline now being marketed throughout the country falls well within the limits of Federal Specifications. As would be expected, there is a slight decrease in volatility as compared with the gasoline marketed last wine:., but on the average the gasoline sold today is about the same as that sold last summer. During the past five years the Bureau of Mines has made semi-annual surveys of the gasoline marketed in the United States. To obtain a sample of each gasoline sold is obviously impracticable, but the cities in which samples have been collected have been so chosen as to be representative of the more important marketing territories. It is believed, therefore, that the samples obtained are indicative of the quality of gasoline marketed throughout the country.

Jan 1, 1925

By Manuel Gomez

A computerized, interpolative mapping technique based on the moving average method was shown to be adequate to estimate the between-drill-hole values of coal-seam variables. The forecasting of the spatial distribution of coal properties along the seam was of three kinds: (1) Estimation of the variable of interest on a regional basis from widely spaced sample points, (2) prediction of coal properties for product control from closely spaced data, and (3) prediction of coal properties for specified benches, or layers of the coal seam, from closely spaced sample points. Estimates obtained with the computerized, interpolative mapping procedure were useful in the delineation of seam thickness, elevation, and overburden and in the estimation of sulfur and ash concentrations during the early phases of exploration. This grid interpolation technique was found adequate to adjust between-drill-hole values for trends resulting from the combined effect of several variables on a measured response. This information, coupled with statistical and geologic data that can be obtained in the exploration phase of mining, enlarges the information base available for coal-mine development planning, energy forecasts, and environmental control associated with fossil fuel power generation.

Jan 1, 1972

By J. D. Marchant

Solid-state electrotransport of impurities in cerium, lanthanum, and praseodymium, using a pulsed current, was investigated. The results were compared with those of using a steady current. Impurities that showed appreciable movement with the pulsed current, but not with the steady current, were as follows: Molybdenum and oxygen in cerium, aluminum, iron, and molybdenum in lanthanum. The use of a pulsed current enhances the practical application of solid-state electrotransport to remove a wider variety of impurities from the host metals.

Jan 1, 1971

By Earl L. Phillips

The Bureau of Mines conducted laboratory tests on samples of pozzolaniccement concrete to develop a low- strength backfill . Results show that support costs can be lowered by replacing a portion of the portland cement in mine backfill with pozzolan ( fly ash ) and lime . Unconfined compression tests on various ratios of fly ash to cement in 84 samples produced compressivestrength curves that can be used to estimate the best backfill mix for any mine .

Jan 1, 1964