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By N. N. Moebs

The atmosphere in part of an air-sealed coal mine was monitored continuously through a drill hole for oxygen content to determine the effectiveness of sealing a mine against the entrance of air and the major force that caused the phenomenon of mine breathing through the overburden. The differential pressure across the seal and the barometric pressure on the outside also were recorded. A general correlation, obtained between the oxygen level, differential pressure, and barometric pressure, indicates that changes in air pressure are the cause for periodic replenishment of the oxygen in the mine. Mine effluent quality was determined by conditions in many sections of the mine and could not be related to the oxygen level at the drill hole.

Jan 1, 1972

By P. C. Good

To meet a growing need for thorium metal of high purity and amenability to fabrication, the Bureau of Mines devised a method for preparing thorium metal by the reduction of thorium tetrachloride. Thorium tetrachloride was prepared by chlorinating calcined thorium oxalate with carbon tetrachloride. The crude thorium tetrachloride, containing oxygen-bearing compounds, was purified by a double vacuum distillation at 800 to 900° C., and thorium metal was made in the form of a dense sponge by the reaction of metallic sodium or magnesium with thorium tetrachloride at 800° C. Vacuum arc melting was used to consolidate the sponge metal to ingot form for evaluation of its physical and chemical properties.

Jan 1, 1960

By Steven J. Schatzel

Prior research has suggested that the source of respirable silica dust in underground coal mines is typically the immediate top or bottom lithology adjacent to the mined seam, not mineral matter bound within the mined coal bed. Geochemical analyses were applied in an effort to identify the specific source rock of respirable quartz dust in coal mines. The analyses also demonstrate the compositional changes that take place in the generation of the respirable dust fraction from parent rock material. All six mine sites were mining coal with relatively low mineral matter content, although two mines were operating in the Fire Clay coal bed which contains a persistent tonstein. Interpretations of Ca, Mg, Mn, Na, and K concentrations strongly suggest that the top strata above the mined seam is the primary source of mineral dust produced during mining. One site indicates a mixed or bottom source, possibly due to site specific conditions. Respirable dust compositional analyses suggest a direct relationship between the quantity of mineral Si and the quantity of quartz Si. A similar relationship was not found in either the top or bottom rocks adjacent to the mined seam. An apparent loss of elemental Al was noted in the respirable dust fraction when compared to potential parent rock sources. Elemental Al is present in top and bottom rock strata within illite, kaolinite, feldspar, and chlorite. A possible explanation for loss of Al in the respirable dust samples is the removal of clays and possibly chlorite minerals. It is expected that removal of this portion of the Al bearing mineral matter occurs during rock abrasion and dust transport prior to dust capture on the samplers.

Jan 1, 2009

By Frank E. Chase, Deno M. Pappas, Christopher Mark

Multiple seam interactions are a major ground control hazard in many U.S. underground coal mines. The two most common types are: • Undermining, where stress concentrations caused by previous full extraction in an overlying seam is the primary concern, and; • Overmining, where previous full extraction in an underlying seam can result in stress concentrations and rock damage from subsidence. The National Institute for Occupational Safety and Health (NIOSH) has completed a major study aimed at helping to identify the location and likely severity of these interactions. In the course of field visits to mines throughout the U.S., more than 300 multiple seam case histories were assembled into the largest data base of multiple seam case histories ever collected. These data were analyzed with the multivariate statistical technique of logistic regression. The study also employed LaM2D to estimate the multiple seam stresses, ALPS and ARMPS to determine pillar stability factors, and the CMRR to measure roof quality. The study resulted in the development of a computer program, called Analysis of Multiple Seam Stability (AMSS), which can help mine planners to evaluate each potential interaction and take steps to reduce the risk of ground control failure. AMSS first evaluates pillar design by calculating the single seam Stability Factor (SFSS) using ALPS or ARMPS. It also automatically generates a LaM2D analysis that provides the additional multiple seam stress so that the final, multiple seam SFMS can be determined. The second part of the AMSS procedure builds upon the statistical findings that overmining is much more difficult than undermining, isolated remnant pillars cause more problems than gob-solid boundaries, and weaker roof significantly increases the risk of multiple seam interactions. AMSS quantifies these effects and predicts the outcome in terms of three levels of risk: GREEN (where a major multiple seam interaction is considered unlikely), YELLOW (where adding a pattern of cable bolts or other equivalent supplemental support could greatly reduce the probability of a major interaction.), or RED (a major interaction should be considered likely, and it may be desirable to avoid the area entirely).

By E. C. Westman

Three-dimensional velocity tomograms were generated on a daily basis to image mining-induced changes to the overburden above a longwall mine. The hypothesis was that a coherent redistribution of seismic velocity, due to the development of high-stress zones, could be imaged at the mine scale. Seam depth was 360 m and source location depth varied from 100 to 1000 m. Sixteen geophones were distributed over a 600 by 600 m square area on the surface above the mine. More than 12,500 events were recorded over an 18 day period. The recorded seismicity provided input for the local-earthquake tomography code, SIMULPS. Eighteen tomograms were generated and high-velocity regions correlated well with high abutment stresses. Additionally, the high-velocity regions were observed to redistribute as the longwall face retreated. These results indicate that velocity tomography can be used to provide a better understanding of temporal changes within a rock mass, and can potentially be used to produce a better understanding of the mechanisms that lead to unanticipated ground failures.

Jan 1, 2008

By Frank B. Fulkerson

Mining began in Pend Oreille and Stevens Counties about 1885, Lead and zinc have been the principal products, and the area has supplied nearly all the output of these metals in the State. Fend Oreille County's output of lead and zinc from 1902 to 1956 was 110,700 and 229,600 tons, respectively. The Stevens County total was 54,100 tons of lead and 87,600 tons of zinc. Copper ore was produced mainly from the United Copper mine, Chewelah district, from 1912 to 1920; the principal gold mine was the First Thought, Orient district, which was active from 1904 to 1942. Approximately 225 mines and prospects produced; most of the ventures were on a small scale. The total value of gold, silver, copper, lead, and zinc produced from 1902 to 1956 was $75.2 million in Pend Oreille County and $39.4 million in Stevens County. INTRODUCTION In compiling the figures for this report, use was made of Bureau of Mines permanent records of nine production, the annual tabulations of producing mines, and the Minerals Yearbook. Requests to publish individual data, obtained from the annual production canvass, were made to the latest recorded operators of all mines in the area. Response to this request was good; therefore, it was possible to make the tables nearly complete. In a few instances the producer requested that the production data remain confidential, and in others it was not possible to reach the mine operator at his last known address. The district and county tables combine statistics for all mines, including those mines whose output could not be published separately.

Jan 1, 1958

By Rodney D. Rosenkranz

Energy consumption in domes tic copper production has increased nearly 60 percent in the last 10 years, reaching approximately 175 trillion Btu in 1973. Energy required to produce 1 pound of copper rose from nearly 41,000 Btu in 1963 to nearly 50,000 Btu in 1973. Production from lower grade ores and strict pollution control regulations have contributed to this increase. Each stage of copper production has been analyzed to determine total energy consumed, energy mix required, cost of the energy, and recent or proposed changes in operations which may affect the consumption of energy by the copper industry. Data have been gathered from a recent Bureau of Mines canvass of the industry, from visits to copper operations, and from conversations with copper industry officials.

Jan 1, 1976

By W. F. Marshall

This Bureau of Mines report discusses tests conducted with four different catalytic reactor designs to determine the influences of exhaust treatment systems on emissions from diesel engines. Although there was significant differences in oxidation efficiencies at light to intermediate engine loads, all four catalysts were very effective in reducing emissions at heavy loads. Compositional determinations included carbon monoxide, carbon dioxide, unburned hydrocarbons, oxides of nitrogen, aldehydes, sulfur dioxide, sulfates, and particulate loading. Particulate size, exhaust odor intensity, and the character of the unburned hydrocarbon component were also determined.

Jan 1, 1978

By F. R. Cattoir

The Federal Bureau of Mines refined chromium from an aqueous electrolytic process in molten sodium chloride-chromium chloride electrolytes. Oxygen and nitrogen contents were reduced by a factor of 10 to 40, but most other impurities were little changed. The product usually contained a little more iron than the feed. Since iron was entering the bath from the iron pot and the graphite liner at a nearly constant rate, contamination of the chromium deposits by it was more serious at low currents and deposition rates. A few runs in an iron cell with a nickel liner yielded chromium containing one half as much iron as the feed, but up to 1.5 pct. nickel. In all cases the anode feed lay in the bottom of the container, which itself was used as the anode connection. With a 12-in. cell, variations in applied voltage from 0.05 to 1.5, in current from less than 10 to over 100 a., and in initial cathode current densities from less than 100 to over 2,000 a./sq.ft. had little or no effect upon the analysis of the metal produced) except for iron content. Changes in bath analysis from 3 to 11 pct. chromium were also without effect. These changes did bring about large differences in the physical forms of the crystals obtained. The thick heavy crystals produced at low voltage and current contained voids which made them difficult to leach free of chlorides. Easiest to leach were the thin leaf-like crystals obtained at around 1 v.

Jan 1, 1960

By John Nagy

The Bureau of Mines adapted thermal theories explaining combustion of gases to correlate parameters affecting ignition of dust dispersions. The dust dispersions were ignited in a Godbert-Greenwald furnace at atmospheric pressure. Ignition temperature and the concentrations of fuel, admixed inert powder, and atmospheric oxygen were related mathematically. Values for these parameters obtained in laboratory experiments for cornstarch agreed with theory. The developed equation permits extrapolation; the predicted upper igni-tion limits correspond with limited experimental data from laboratory and large-scale tests. Explanation of the effect of fineness of dust on ignition parameters is attempted by introducing a surface-area constant to modify the activation energy. Arguments are presented to show that the ignition process is a solid-gas phase reaction rather than an ignition of prevolatilized gases.

Jan 1, 1966

By Liming Yuan

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Jan 1, 2009

By Jeffrey H. Welsh

The Bureau of Mines studied the use of computerized, continuous, remote monitoring systems for safety from power system faults in underground coal mines. In this report the need to improve protection against power system faults is documented, and types of faults are identified. The relationship between mine safety regulations and computerized, continuous, remote monitoring is analyzed.

Jan 1, 1983

By Eugene Fry

The Huber-Rydalch manganese property is in the Erickson mining district of Tooele County, Utah. The district covers the southern part of Simpson Mountains, a block rising abruptly above the surrounding desert floor (fig. 1). The Ruber-Rydalch deposits and other deposits in the Simpson Mountains manganese area were examined by Bureau of Mines engineers during 1940 and 1942 under the strategic minerals program. J. T. Pardee visited the district briefly in 1918. A. E. Granger and A. F. Shride, of the Federal Geological Survey, mapped the geology of the area in 1942 and 1943. The manganese deposits occur as veinlike masses in brecciated fault zones that traverse Cambrian and pre-Cambrian quartzite, quartzite conglomerate, and phyllite. The deposits now exposed near the surface represent the oxidized portions of primary mineralization originally containing rhodochrosite and rhodonite associated with quartz and calcite and small quantities of pyrite, galena, sphalerite, and chalcopyrite. The oxide ore is composed of manganite, pyrolusite, psilomelans, and wad in a gangue of quartz, calcite, and brecciated quartzite.

Jan 1, 1949

By A. L. Engel

In previous reports5/ of ore-testing studies, teats made by established methods on typical ores selected as representative of certain mining districts have been described in considerable detail. In addition to established test procedures, such as screen analysis, Chemical analyses, microscopical examination of ores and products, sink-and-float separation, gravity concentration, floatation, and magnetic separation with or without roasting, it was sometimes necessary to apply other methods, such as leaching, in instances where physical separations were not feasible.

Jan 1, 1940

By Travis Q. Lyday

The other South Pacific islands included in this chapter extend from Papua New Guinea, east of the Indonesian Province of Irian Jaya on the island of New Guinea, to Fiji, straddling the 180° meridian. A number of islands have been omitted from this chapter owing to the fact that their only mineral production remained insignificant to the economy of the respective country or territory. These islands include the French overseas territories of French Polynesia and Wallis and Futuna Islands; the independent states of Kiribati, Tonga, Tuvalu, and Vanuatu; the New Zealand freely associated state of the Cook Islands; and the New Zealand dependency of Niue. The mineral production that did exist in these islands was limited to construction materials such as coral reef limestone, crushed stone, and sand and gravel in minor quantities used solely for domestic consumption. FIJI Fiji, an archipelago in Melanesia consisting of 300 islands ranging from tiny coral atolls, cays, and rugged coral limestone islets to the larger mountainous, volcanic islands of Kadavu, Taveuni, Vanua Levu, and Viti Levu, straddles the 180° meridian about 1,800 kilometers south of the Equator. Fiji has been an independent member of the British Commonwealth of Nations since October 10, 1970.

Jan 1, 1988

By Frank E. Cash

Data on the accident experience of the pebble-phosphate industry in Florida for 1930 and 1940 are combined in this report with statistics for the 9-year period 1930-38, inclusive, which were published in Information Circulars 69173/, 69684/, and 71005/. The periodic compilation and publication of such data enable the pebble-phosphate industry, as well as other industries, to consider the relative hazards, compare experience, and thereby help to prevent accidents. ACKOWLEDGMENTS Accident data were furnished by the following operating companies: Amalgamated Phosphate Co., Brewster; American Agricultural Chemical Co., Pierce; Coronet Phosphate Co., Plant City; International Agricultural Corporation, Mulberry; Phosphate Mining Co., Nichols; southern Phosphate Corporation, Bartow; and Swift & Co., Fertilizer Works, Bartow.

Jan 1, 1941

This pamphlet and the enclosed video describe a safe, effective and economical method for removing dust from work clothes. Background Information Dusty work clothes can increase a worker’s exposure to respirable dust. Respirable dust is usually considered to be particles having an aerodynamic diameter of 10 microns or less and able to enter and deposit in the gas-exchange region of the human lung. A former U.S. Bureau of Mines report documented a 10-fold increase in worker dust exposure on a number of separate occasions from dusty work clothes.* It was found that once clothes become contaminated, they are a continual dust source until cleaned. The only MSHA approved method to clean work clothes requires a HEPA-filter vacuuming system which is very time consuming and difficult to perform effectively. Therefore, most workers use a single air hose (not MSHA approved) which can elevate dust levels for the worker, co-workers, and the work environment. A substantial amount of engineering technology has been developed that, when applied, can significantly lower respirable dust exposures of workers at mineral processing plants. But even with these improvements, some workers continue to exceed their permissible exposure limit. Elevated exposures increase the potential for developing debilitating or fatal lung diseases. ?e clothes cleaning method described within is an example of a continuing effort to reduce the potential for developing these lung diseases. Information about engineering research by the former U.S. Bureau of Mines and NIOSH can be found online at www.cdc.gov/niosh. ?is website can also be used for obtaining NIOSH information about health hazards associated with crystalline silica.

By H. N. Dunning

A comprehensive production research program, now in progress at the Petroleum Experiment Station of the Bureau of Mines at Bartlesville, Okla., includes studies of the displacement of petroleum from sand by detergent solutions. An earlier report (12)2/ presented the results of an extensive research program to determine the value of detergents as floodwater additives. This report presents later results of the detergent-testing program (13, 17). Although water-flooding methods and controls are constantly being improved to increase the production of oil from secondary-recovery operations, considerable crude oil commonly remains.in place after a water flood has been terminated. Therefore, the possibility of improving the efficiency of a waterflood by the use of detergents is of increasing interest. The effects of many substances on the efficiency of water flooding have been investigated in laboratory studies (5, 11, 13, 17, 19, 24). Of the various sub-stances tested, only surface-active agents were consistently effective in removing oil from sand. Results of laboratory studies presented in earlier reports (9, 11, 12, 13) show that many detergent solutions effectively displace petroleum from sand surfaces under varying conditions encountered in centrifuging, manual and mechanical agitation, ultrasonic vibration, and imbibition.

Jan 1, 1957

By Charles Prasky

The Bureau of Mines investigated the conversion of nonmagnetic iron minerals to magnetic form through reduction Toasting operations. The primary objective was to obtain a concentrate that could be used as a direct shipping material for blast furnace consumption. Crude iron materials from the Steep Rock Lakes, Ontario, area were prepared into a blend of 8 parts siliceous ore, 3 parts pyritic ore, and 1 part tailings. Experimental work included laboratory reduction roasting tests, two continuous 10-day campaigns, and one 12-hour test all in a 34-inch by 36¬-foot rotary kiln. The objective of the project was achieved in producing an iron concentrate containing about 66 percent iron with over 90 percent iron recovery. Desirable operating conditions were developed in the kiln but optimum process variables were not completely established.

Jan 1, 1969

By Alton B. Cook

In the Scurry Reef field, Scurry County, Tex., a study was made to determine the physical properties of the oil in all parts of the reservoir by a new method developed for this study. The method involved correlation of data from a survey 1 of the gravity of the produced oil, from measurements of gas-oil ratios on key wells selected to give representative data for the entire reservoir, and from laboratory analyses of reservoir oil samples. A field survey was made of the API gravities of the produced oil by testing oil samples from 107 key wells. Precise gas-oil-ratio tests were made on 45 key wells that were producing under comparable separator-operating conditions. Subsurface-oil samples were obtained from seven wells, selected to provide reservoir oils ranging approximately from a minimum to a maximum in saturation pressure. The physical properties of the subsurface-oil samples were determined, and correlations were made of these laboratory data with the field gas-oil-ratio test data. These correlations were then used to estimate physical properties of the oil throughout the reservoir. A logical procedure of determining the variations in physical properties of reservoir oils in most fields is to obtain and analyze subsurface-oil samples from enough key wells to provide an ample coverage of the field. Under this procedure, data from a large number of samples would be needed to provide the desired information on the Scurry Reef field, as it is one of the largest known in the United States.

Jan 1, 1955