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The dust exposure of the longwall shearer operator is usually determined by his position relative to the cutting drums. The dust generated during cutting may travel up-wind, against the primary airflow, and be carried out into the walkway where it can contaminate the intake air for as much as 10 feet outby the shearer operator's controls. Thus, both head and tail drum operators are exposed to un-acceptably high levels of air-borne respirable dust. One Solution The latest generation of long-wall shearers has features that make the use of radio remote or umbilical (hard wire) remote control relatively easy to implement. Remote control can enable shearer operators to control machines from positions that are less dusty than normal control stations. With either type, the head-drum operator can now control the shearer from a position up to 20 feet on the intake-air side of the shearer, while the tail-drum operator's station is now located across from the head drum.

Jan 1, 1984

By L. J. Froisland

The Bureau of Mines conducted a 4-year research program at Uravan, Colo., on a 2-1/2-acre reclamation plot on the slope of a uranium tailings pile that had been covered with mine waste rock. The purpose of this study was to determine the effects of plant species, type of irrigation, type of fertilizers, and use of dust control chemicals on plant growth and surface coverage. Best grass coverage, nearly 100 percent with 240 plants per square foot, was developed in a section that was seeded with crested wheatgrass, fertilized with sewage sludge, and sprinkler irrigated. For comparison, a section that had been treated with commercial fertilizers developed 3.1 crested wheatgrass plants per square foot and 24 percent coverage without irrigation, and 8 plants per square foot and 75 percent coverage with irrigation. Results of spraying a dust control chemical were inconclusive. Russian-thistle invaded all test sections and ranged in density from 0.6 to 7.3 plants per square foot.

Jan 1, 1982

By J. R. Thoenen

This circular is part 6 of the third paper (entitled "Excavation") of a series summarizing the technical problems involved in the production and preparation of sand and gravel. Part 1 discussed the use of power shovels, draglines, and excavator cranes; part 2, power scrapers, slackline cableway excavators, and hydraulic monitors; part 3, hydraulic, clamshall, ladder, and diaper dredges; part 4, haulage equipment, particularly industrial cars with locomotive or hoist as the motive power; part 5, conveyor belt, motor truck, pump and pipe line, towboat and barges, and aerial-trams haulage. This circular discusses the application of these various types of equipment to the different types of sand and gravel deposits and contains a reference bibliography. It completes the discussion of excavating problems.

Jan 1, 1936

By G. S. Scott

In the course of tire investigation into the causes, behavior, and control of mine fires, which the Bureau of Mines is now conducting, come attention was given to the subject of spontaneous heating. It is self-evident that the temperature of a pile of broken coal will rise if the rate of generation of heat exceeds the rate of heat dissipation and will fall if the opposite is the cane. Factors that affect the rate of generation of heat are:

Jan 1, 1941

By D. Harrington

The coal-mining industry of the United States finds difficulty not only in making ends meet financially but also in operating with anything like reasonable safety. The record to date has not been particularly good as to either finance or safety, but at least in some phases or safety there are indications of better times to come. During the fiscal year ending June 30, 1929, only 139 lives were lost in explosions in our mines as against 342 lost during the fiscal year ended June 30, 1928; this decrease in such fatalities is definitely a matter for satisfaction. During the fiscal year July 1, 1928, to June 30, 1929, the attention of the safety division of the U. S. Bureau of Mines was directed to 38 mine explosions in the United States. Two explosions were in non-coal mines, one in a semianthracite mine, two in anthracite mines, and 33 in bituminous mines. These were not all major explosions - that is, explosions in which five or more lives were lost; in some of the explosions no lives were lost, while in others fewer than five fatalities resulted. Table 1 gives data on the explosions, showing the number of mines using open or closed lights and the number of explosions with resulting deaths, by causes, for each State.

Jan 1, 1929

By Robert P. Vinson, Fred N. Kissell, Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

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 Robert E. Barieau

General expressions for evaluating practically all the thermodynamic properties of a fluid from a single equation of state are derived. Most of the formulas are expressed in terms of the compressibility factor, with this factor being an explicit function of the temperature and the molal density. Similar expressions are given using reduced variables.

Jan 1, 1967

By K. A. Johnson

Marshall and Bird have published the results of a cooperative investigation by the Bureau of Mines in which they developed a procedure for measuring the agglutinating value of coal.4 As stated in their paper, the procedure outlined was suggested by the early worn of Richters5 and Campredon,6 whose procedures were hurriedly modified to meet the need of an investigation then in progress. Since the publicatien of that paper, further work has been done in an attempt to show how the variables involved affect the concordance of the results, in order that such results may be obtained in different laboratories. Briefly, Marshall and Bird's method for determining the agglutinating value of coal consists in carbonizing an intimate mixture of 10 parts by weight of sand and 1 part by weight of coal in a porcelain crucible at a uniform temperature of 950° C. in a, vertical, cylindrical, electrically-heated furnace. After carbonization, the resultant buttons are crushed in a testing machine and the breaking strengths recorded in grams. The agglutinating value reported is the average breaking strength of 10 buttons. The coal for the test is prepared by crushing to pass a 100-mesh screen. The sand used as a diluent is sized between 40 and 50 mesh sieves with openings of 0.381 icon and 0.279 millimeters, respectively.

Jan 1, 1930

By Robert A. Jankowski

Through laboratory and underground studies, the Bureau of Mines has evaluated the use of passive barriers (dust shields) to help confine dust generated by longwall shearers to the face area. Laboratory studies focused first on selection of the optimum barrier design, which proved to be a simple, gobside barrier (made of conveyor belting), coupled with a headgate splitter arm, which was found necessary to prevent the dust cloud from entering the walkway at the headgate end of the shearer when cutting tail to head. Further laboratory testing was done to determine whether using passive barriers in combination with different water-spray dust-reduction methods, including the shearer-clearer system developed by the Bureau, would improve dust reduction over that from using the water sprays alone. It was found that the combination of gobs ide passive barriers plus the full shearer-clearer system was most effective, and surmised that this would be especially useful in thicker seams. However, underground testing revealed that the shearer-clearer system alone was 35 pct more effective in reducing dust contamination than when used with the gobside passive barriers, and far more effective than using passive barriers with a conventional water spray system. For such an effective system as the shearer-clearer; the reduction in avail-able space over the top of the machine actually impeded system performance; this was shom1 in both eastern and western mines. But when used with comparatively inefficient water spray systems, the passive barriers, used in combination with a headgate splitter arm, provide consider-able help in reducing dust levels in the walkway.

Jan 1, 1986

By D. R. Mathews

Electrorefined vanadium was evaluated with respect to tensile properties and the effects of interstitial contaminants in the temperature range of 77° to 273° K. The yield strength of 18,500 psi and hardness of 63 diamond pyra-mid hardness (DPH) of electrorefined vanadium are approximately equal to that of iodide crystal bar vanadium. The ductile-brittle transition temperature was found to be below 77° K, but with 0.175 weight-percent oxygen or 0.10 weight-percent nitrogen, it increased to between 123° and 190° K. With carbon content up to 0.11 weight-percent, the transition temperature remained below 77° K. The yield strength of the interstitial-containing alloys can be expressed by: au = 7.5 + 480 (pct N) + 290 (pct 0) + 280 (pct C), where au is the upper yield stress in 1,000 psi at 273° K. Profuse deformation twinning occurred in the alloys tested at 77° K. However, twinning could be suppressed by dissolved oxygen or nitrogen in excess of 0.15 and 0.086 weight-percent, respectively. Carbon, even though present in excess of the solubility limit, did not affect twinning.

Jan 1, 1965

By William A. Beck

Bauxite was discovered in the Springvale district in 1916. About 16, 000 tons was mined in the period 1916 to 1922, but no bauxite mining has been done since that time. The Bureau of Mines explored for bauxite in the district from September 5 to November 18, 1943. During the life of the project, the Bureau of Mines obtained mineral exploration agreements covering a total of 11,330 acres from 50 property owners. A total of 388 holes were drilled on five of these properties and 164 samples were taken and analyzed. The Springvale bauxite district includes an area of about 30 square miles in the northwestern part of Randolph County, Ga. The village of Springvale is in the west central part of the district, and Cuthbert is 8 miles southeast of it (fig. 1).

Jan 1, 1949

By V. R. Spironello

The Bureau of Mines is involved in research directed toward the utilization of municipal solid waste. One of the primary objectives is the recycling of the magnetic fraction of municipal solid waste (raw refuse). This is consistent with one of the Bureau's goals, which is to minimize the requirements for mineral commodities by maximizing metals recovery from secondary domestic resources, In this investigation, cupola trials were made using combinations of refuse scrap with shredded automobile scrap under basic and acid slag practices. Furnace operating information and the behavior of alloying and tramp elements was obtained. The research showed that it is possible to utilize up to 60 percent refuse scrap in the cupola under basic practice and 30 percent under acid practice, Aluminum in refuse scrap, present in bimetallic cans, increased the recoveries of silicon and manganese charged to the cupola. Increased use of refuse scrap provided iron of lower sulfur. The alumina resulting from oxidation increased the slag volume. The aluminum and tin contents of the iron increased with increasing levels of refuse scrap in the charge. Lead was not a problem with respect to contamination of the iron. In basic practice, operation of the cupola was satisfactory since all slags were adequately fluid. In acid practice, operation became troublesome above the 45-percent level. Under both practices, the cupola iron melting rate decreased. Particulates in scrubber water and stack condensate samples contained lead, zinc, and tin, and the dust load increased. The tensile and transverse strengths of the iron produced under both practices are reported.

Jan 1, 1980

By Henry R. Ensminger

Brazil's gross domestic product (GDP) grew only slightly in 1988 to $277 billion at current prices.2 The growth rate was the smallest registered since 1983, when the rate was minus 2.8%. The economy's performance was strongly influenced by a 2% to 3% decrease in industrial production and civil construction. The mineral industry, however, countered the downward trend in the industrial sector and grew a modest 1.4%. In November, Brazil adopted a new Constitution that placed significant restrictions on foreign investment in the mineral industries. Under certain provisions of the new Constitution, foreign companies were prohibited from establishing new mining ventures in Brazil as sole or majority owners. They could now enter the mineral industry only as minority shareholders with Brazilian partners. Foreign companies already established in Brazil had a 4-year grace period to find majority Brazilian partners, or to establish vertically integrated processing operations (mining, processing, smelting, and refining). The new Constitution also prohibited foreign risk contracts for petroleum exploration.

Jan 1, 1990

By Margaret R. Egan

A series of experiments were undertaken by the Bureau of Mines to determine the emission products of several types of conveyor belting and other combustible materials found in mines. These experiments were conducted under intermediate-scale, simulated mine conditions to determine smoke characteristics and gas concentrations. From these determinations, heat-release rates, particle sizes, obscuration rates, combustion yields, and production constants were calculated. Three types of belts were investigated: chloroprene, also known as neoprene (NP); polyvinyl chloride (PVC); and styrene-butadiene rubber (SBR). The belts were designated as ignitable or self-extinguishing depending on the length of the burning time and the subsequent combustion products. Under these experimental conditions, the SBR belts were the easiest to ignite. The PVC and NP belts tended to self- extinguish within a few minutes after ignition, but were still capable of maintaining a brief flaming period. These conveyor belt combustion results are compared with previous analyses of wood, transformer fluid, and coal fires. Together they form a data base by which findings from future experiments with other mine combustibles can be compared.

Jan 1, 1988

By Fred E. Fiedler

A demonstration project investigated the feasibility and effectiveness of two management interventions, Management Training and Organization Development, for improving productivity and safety in metal/non-metal mines. The management training intervention was conducted at Texasgulf Company's trona mine, using three nearby trona mines as controls. The Organization Development intervention took place in Hecla Mining Company's Lucky Friday mine, using the highly similar Star Mine as control. The two management interventions seemed about equally effective in reducing accidents and injuries, as well as MSHA citations, and the management intervention at the Texasgulf mine also appeared to have led to substantial improvement in mine productivity.

Jan 1, 1983

SCOPE AND APPLICATION The rules cover the installation and use of electrical equipment in coal mines.- For generating stations, substations, lines, and equip¬ment aboveground, reference is made to existing rules covering such locations, viz, the National Electrical Code and the National Electrical Safety Code and any existing State or municipal regulations. The purpose of the rules is to set forth methods for safe electrical installation. In preparing the rules five basic measures for safe¬guarding the use of electricity in mines have been followed, viz 1. Remove the contributory causes of accidents or danger. 2. Remove from the vicinity of electrical apparatus all elements susceptible to the influence of electricity. 3. Keep the electric current where it belongs, if possible; if not, limit the area of its activity by protective devices. 4. Use a. large factor of safety in the selection, installation, and in¬ spection of equipment. 5. Have full control of the operation of electrically driven machines. Each rule that is given is proposed as necessary or helpful to the accomplishment of one or more of these measures. DEFINITIONS OF TERMS USED Alive.-See definition of " live." Approved.-The term " approved " means accepted as suitable by a competent committee, board, or organization designated by those adopting the rules. Authorized person.-The term " authorized person " means a per¬son appointed or permitted by the official designated by the State mining laws as the one in charge of the operation of the mine to carry out certain duties incident to the generation, transformation, and distribution or use of electric energy in the mine, such person be-

Jan 1, 1926

By John P. Hager

A special inlet system has been developed for a TOF mass spectrometer that allows the equilibrated high-temperature vapors from an atmospheric-pressure flow reactor to be leaked into the ion source of the mass spectrometer without undergoing any compositional changes. Using this flow reactor - mass spectrometer system and a modified transpiration system (one that allows for the carrier stream to be equilibrated with two different condensed samples) a series of fundamental vapor transport studies were undertaken. The results of these studies are summarized as follows: 1. The vapor species in equilibrium with condensed copper (I) chloride were determined to be Cu3C13, Cu4C14, and Cu5C15. The gas mixture is fifty percent tetramer near the melting point (703°K), with the percentage of tetramer decreasing with increasing temperature. The following thermodynamic results were obtained.

Jan 1, 1977

By G. L. Oldright

This paper is the fourth of a series of preliminary papers on smelting in the lead blast furnace.4 The objects of this investigation are to determine the conditions obtaining within the blast furnace by direct experimentation and to correlate these conditions with operating factors, furnace behavior, and metallurgical losses. ACKNOWLEDGMENTS The authors wish to express their appreciation to the management of the International Smelting Co. at Tooele, Utah, for their whole-hearted cooperation in this investigation.

Jan 1, 1929

By F. Garcia, J. Cervik

Recent advances in the commercial separation of gases using membranes have renewed interest in the possibility of applying this technology to the recovery of methane ( CH4 ) from mining operations . This Bureau of Mines report briefly reviews the history of the development of membranes for gas separation , the theory of how they work , and their application to the separation of methane from air and associated problems . However , methane -air mixtures are difficult to separate with membranes because the pertinent gas couples , 02 - N2 , 02 - CH4 , and N2 -CH4 , have poor separation characteristics , as indicated by their separation factors of about 3 or less . Even if these separation factors were substantially higher , there is doubt that methane could be recovered economically from the low concentrations in mine ventilation exhaust ( 2 vol pct or less ) . The exhaust pressures are not sufficient for adequate separation . The power cost of compressing the methane recovered . these mixtures would far exceed the value of New discoveries could make separation of gob hole methane - air mixtures practical . These mixtures have much higher concentrations of methane (from 30 to 100 vol pct ) ; however , for safety reasons , be limited to gob gas with 60 vol pct CH4 or more .

Jan 1, 1988