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By F. P. Haver

The Bureau of Mines is developing a leach-electrolysis procedure to produce Special High Grade (SHG) zinc from sulfide concentrate without the generation of sulfur oxide gases. Chlorine-oxygen leaching of the concentrate yields zinc chloride (ZnCI2) which, after purification, is electrolyzed in a fused-salt cell to obtain molten zinc metal and chlorine gas for recycle. This paper describes a laboratory-scale investigation made to develop a procedure for electrowinning zinc metal from ZnC12. Zinc chloride by itself is not a suitable electrolyte because it fumes badly above its melting point and is a poor conductor of electricity. Other salts therefore must be added to prevent fuming and improve the conductivity. Optimum results were obtained with a KC1-LiCl-ZnCl2 bath at 500° C, using a current density of 5 amp/in2 and an electrode spacing of 0.5 inch. Under these conditions, SHG zinc was produced at a current efficiency of 94.3 pct and an energy requirement of 1.16 kwhr/lb. Fused-salt electrowinning eliminates the need to handle and melt cathodes and increases the production of metal per unit cell volume through the use of higher current densities than are possible with aqueous electrolysis.

Jan 1, 1976

By W. J. Fullerton

This paper is one of a series prepared for the United States Bureau of Mines discussing the methods used in crushing and grinding materials for cement manufacture, and deal particularly with the methods used at the Howes Cave plant of the North American Cement Corporation. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that publication of total production costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1932

By F. E. Cash

Much has been written concerning accidents in coal mines; the fact that accidents cost the employer and employee money is generally well known, but how much accidents actually cost is vague, even in the minds of many operators. Unquestionably there are hazards in coal mining, but many of them can be eliminated; and from the prevention of accidents there can be realized a material saving in dollars and cents as well as in human suffering. In presenting the frequency, severity, and cost of accidents in some Tennessee coal mines, it is hoped that other mines in Tennessee, as well as mines in other States, will by a comparison of the data with their own ex¬ perience be enabled eventually to reduce the number of' their accidents.

Dec 1, 1932

By Foster Fraas

This Bureau of Mines report describes a method for separating minerals at magnetic susceptibilities within the diamagnetic susceptibility range. The maximum feed rate varies directly with the square root of the lower limit of permissible susceptibility, while the lower limit of permissible susceptibility varies inversely as the square of the magnetic field strength. Minerals may be separated at particle sizes smaller than possible on conventional dry-type magnetic separators.

Jan 1, 1969

By G. W. Birge, D. E. Wolfson, J. H. Lynch

This report presents all available 900 ° C BM- AGA carbonization and related data for coals from the principal beds of the southwest Virginia field in a form which permits ready comparison of product yields and properties of coals and cokes . Thirty- one channel samples from Buchanan , Dickenson , Russell , Tazewell , and Wise Counties were carbonized at 900 ° C in an 18 - inch - diameter retort . Blending properties of 10 of the coals were studied , and expansion of most of the coals and blends was measured in the Bureau of Mines sole - heated oven . Ash Most of the samples were chemically suitable for metallurgical use in coking blends , and their coking properties generally were satisfactory . content exceeded 10 percent in only three samples , and none of the coals contained more than 1.5 percent sulfur . Dry , mineral - matter - free fixed - carbon content of the coals ranged from 62.1 to 77.5 percent . Expansion behavior varied widely , ranging from 16.8 percent expansion to 27.6 percent contraction .

Jan 1, 1964

By J. E. Hamak

This publication contains analyses and related source data for 151 natural gas samples from 19 States. Of the total samples, 138 were collected calendar year 1989. The remainder were collected earlier, but releases to were not received until 1989. All samples were obtained and analyzed as part of U.S. Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by mass spectrometer and chromatograph.

Jan 1, 1990

By Ann G. Kim, Thomas R. Justin, John F. Miller

The U.S. Bureau of Mines applied its mine fire diagnostic method to an abandoned anthracite mine fire site in Carbondale, Lackawanna County, PA. The technique to locate fires in abandoned coal mines and coal refuse piles includes the determination of hydrocarbon concentrations in mine gases, the imposition of an underground gas flow direction, and use of a surface mapping method, to define heated and cold zones in underground coal strata. The heated zones at Carbondale were characterized by elevated methane concentrations. The results of 25 communication tests were analyzed to define 2 large (approximately 100 by 250 ft) and 5 small, isolated heated zones. An approximate correlation existed between the location of the heated zones and areas of anomalous snow melt. The correlation between the results of the diagnostic test and subsurface temperatures was not significant.

Jan 1, 1992

By R. L. Grayson, S. S. Peng

"Abstract. Sampling of respirable dust and analyses of samples have been partially completed for a longwall panel. Physical and compositional properties which have been characterized include:l. Respirable mass concentration, 2. Mineral composition,3. Particle size distribution by mineral,4. Particle shape distribution by mineral,5. Particle angularity distribution by mineral, and6. Respirable size distribution.Analytical techniques used in the characterization of samples are described, and results are reported with emphasis placed on relationships between the various characteristics and worker locations. Details of existing mining conditions, equipment arrangements, dust control methods and operating system parameters are presented.INTRODUCTIONThrough the work of many researchers worldwide, the health of coal miners in modern societies is now protected from dangerous exposure to respirable coal mine dust. A vast amount of research culminated in the exposure-response model of Jacobsen, et al. (1971) whi3h has been used to establish the 2mg/m exposure limit in the United States. According to the model, exposure to respirable dust for 35 years at this level or less would prevent the occurrence of a clinically significant case of coal workers' pneumoconiosis (CWP). The exposure limit, of course, must be adjusted whenever greater than five percent free silica exists in the respirable dust.The Jacobsen model was built around a mass concentration exposure, which showed the highest correlation with incidence and progression of CWP. As Morgan; et al. (1973) noted, howev.er, the quantity of respirable dust inhaled is not the only significant factor. It is noted that although mass of respirable dust correlates highest with the incidence of CWP, it is not a causal factor. Indeed, the insidious processes causing the disease occur on the cell-particle scale, requiring microscopic investigation."

Mar 1, 1989

By T. Estelle Gardner, A. R. Taylor

Heat capacity measurements were made on sodium bromide ( NaBr ) and sodium iodide ( NaI) in the temperature ranges of 7 ° to 300 ° K and 56 ° to 300 ° K using an adiabatic calorimeter . Smooth values of heat capacity, entropy , enthalpy function , and free- energy function were calculated from the heat capacity data at 10° K intervals and at 273.15° and 298.15° K. Entropy and free energy of formation values at 298.15° K also were calculated for the two compounds using entropy values determined in this study and other data reported in the literature . The entropy values calculated at 298.15 ° K were 20.75 ± 0.06 entropy units (eu ) for sodium bromide and 23.55 ± 0.07 eu for sodium iodide .

Jan 1, 1964

By Welby G. Courtney

The Bureau of Mines conducted an exploratory field survey to determine the amount of airborne coal dust, the size distribution of the dust, and the rate of dust deposition in coal mine airways. The survey was taken at eight underground locations in operating coal mines. The rate of dust deposition in the airways depended upon the concentration of air-borne dust and decreased exponentially with distance from the dust source. The rate was seemingly independent of the size of the airborne dust particles. The rate of deposition, along a return, for the coal dust from a fade being mined with a continuous mining machine closely matched the rate for the rock dust from a trickle duster. A sample rock-dusting schedule for that return is presented; that is, the trickle duster should be operated for 3-112 hours after every five shifts to protect the average deposit of new float coal dust in the return, but operation after every three shifts is preferred, to protect an occasional heavier deposit.

Jan 1, 1982

By William Cochran

The mineral waste disposal system at the Grace Mine, Morgantown, Pa., was designed to minimize environmental effects while allowing much of the waste from the iron mine, mill, and concentrator to be utilized. Standard cost estimating procedures were used by the Bureau of Mines to determine waste disposal costs. Mill tailings and rock waste disposal costs were estimated at $0.151 and $0.276 per ton, respectively, for the 1965-67 production period. Total waste disposal cost was reduced about $0.015 per ton by utilizing part of the waste as aggregate. The net average cost for disposal of all mineral waste was $0.189 per ton.

Jan 1, 1969

By John Dasher

The impetus given to mineral dressing arid chemical engineering by the war has placed many persons without previous experience in positions where they are concerned with the size of solid materials they are testing. Many good textbooks cover this field in considerable detail but are more concerned with the "why" than with the "how" For beginners and those to whom size is not of primary concern, this brief circular has been prepared. Refer-

Jan 1, 1942

By B. E. Davis

Over 80 pct of domestic phosphate rock, which is the starting material for phosphorus-containing fertilizers, comes from central Florida deposits. As K-her grade deposits are depleted, lower grade phosphate ores containing 'Mg0 in the form of dolomite are encountered. Treating high MgO ores with present beneficiation technology will not yield a concentrate meeting specifications for acidulation. The Bureau of Mines conducted research on three high-MgO phosphate samples from south Florida. The sales contained, in percent, 5.4 to 10.2 P205, 1.9 to 7.6 MgO, and 35.3 to 60.1 acid insolubles. A technique of sizing, grinding, desliming, scrubbing, and redesliming was used to produce a feed suitable for continuous flotation studies, A conventional fatty acid-fuel oil rougher flotation followed by two to three cleaner stages resulted in concentrates containing, in percent, 30.7 to 31.3 P205, 0.6 to 1.3 MgO, and 2.5 to 4.8 acid insolubles. The P205 recovery from the flotation feed ranged from 55.1 to 89.7 pct.

Jan 1, 1984

Oil from shales has long been a source of fuel in foreign countries; however, in the fuel economy of the United States this source is classed as a reserve for future needs. In fad, shale oil has never been produced here in quantities necessary to establish oil-shale utilization as a sustained industry. The first known resources of stored energy that man endeavored to utilize were probably wood and water, and from these he directly obtained heat and power, respectively. With the evolution of man came the search for and the development and use of other natural fuel resources, the series progressing through the solid, liquid, and gaseous fuels until today those of one type can be converted into another, depending upon the use for which they are intended. The most important fuels are those that appear naturally in the most concentrated, conveniently obtainable, and usable forms. With the discovery of each new and more concentrated fuel there has been an appreciable increase in the importance of and number of devices for converting these fuels into energy.

Jan 1, 1938

By Lewis V. Wade

This report provides background information concerning a mine roof simulator currently being considered by the Bureau of Mines. The simulator is a mechanical device with the ability to simulate the forces and displacements associated with mine roof over an area 20 by 20 feet. The topics covered in the report include a conceptual description of the system, definition of system capabilities, discussion of how such capabilities were decided upon, description of available control modes, and a comparison between the mine roof simulator facility and similar facilities existing elsewhere.

Jan 1, 1974

By J. L. Stauffer, L. J. Gaydos, L. M. Demers, D. C. Kuhn

"Eicosanoids and cytokines produced by alveolar macrophages (AM) are key mediators of pulmonary inflammation and fibrosis. In order to determine if eicosanoid production and cytokine production are altered in AM obtained from coal miners, we compared production of prostaglandin E2 (PCE2), thromboxane A2 (TXA2), leukotriene B4 (LTB4), interleukin-1 beta (IL-1B ), and tumor necrosis factor alpha (TNfa.) by cultured AM from normal human subjects and coal miners. The recovery of AM from miners' lungs by bronchoalveolar lavage was significantly greater than that from control subjects. Mean eicosanoid and cytokine production by AM from active miners was also increased compared to AM from control subjects, but this increase was not statistically significant. AM from control subjects produced significantly more TXA2 and TNFa. when exposed to lipopolysaccharide than did AM from miners. The cyclooxygenase inhibitor suprofen reduced PGE1 and TXA1 production and TNF0t. release but had no effect on LTB4 production or IL-1B release by miners' AM. The lipoxygenase inhibitor nordihydroguaiaretic acid attenuated TNFa release, as well as that of LTB4, but had no effect on IL-1B release. Inhibition of thromboxane synthase by UK 38,485 also reduced TNFa release by active miners ' AM but had no effect on PGE1, LTB, production, or IL-1 f3 release. The results of these studies suggest that occupational inhalation of coal dust may increase total lung eicosanoid and cytokine levels and reduce the reactivity of AM to bacterial endotoxin. Furthermore, coal dust-induced changes in both eicosanoid and cytokine release may be subject to pharmacological modulation.The alveolar macrophage (AM) is a primary defensive cell in the lung and is one of the first cell types to encounter inhaled mineral dust. The response of the AM to invading foreign material is designed to enhance the defensive capacity of the lung. However, in the case of occupational inhalation of mineral dust particles, this response may be inappropriate, resulting not in the defense of the lung but in chronic inflammation and fibrosis (Rom et al., 1987; Takemura et al., 1989). The reaction of the AM to chronic mineral dust exposure may involve the exaggerated release of paracrine mediators of lung function, including eicosanoids (oxygenated derivatives of arachidonic acid) and peptides, including cytokines and growth factors (Sibille & Reynolds, 1990). Eicosanoids are involved in bronchial and vascular smooth muscle reactivity, vascular permeability, fibroblast growth, and the recruitment of additional immune cells to the alveolar space (Barnard et al., 1992; Elias et al., 1985; Scott et al., 1982). AM-derived cytokines such as interleukin-1 beta (IL-1 B) and tumor necrosis factor alpha (TN Fa) have a variety of biological activities including the regulation of fibroblast growth and proliferation (Becker et al., 1989; Libby et al., 1989; Schmidt et al., 1984). Interestingly, in vitro studies with macrophages suggest that the production of cytokines may be linked to eicosanoid production, in particular that prostaglandin E2 (PGE2) may down-regulate IL-1 f3 and TN Foe production by the AM (Bonta et al., 1989; Kunkel et al., 1986; Monick et al., 1987)."

Dec 1, 1996

By Robert C. Bates

This Bureau of Mines report converts published data on the cost of ventilating uranium mines to a common price base and analyzes these data to determine the cost per ton of uranium ore at various levels of radiation exposure control. There appears to be an exponential increase of cost as the radiation level is lowered. The 1967 base costs are extrapolated to present dollars, and some cost comparisons are given for other radiation control measures.

Jan 1, 1981

By Fred D. DeVaney

Copper sulphate is a common flotation reagent for blonde ores. Metallic iron also is present in the mill circuit, and a reaction between the iron and the salt would be in accord with well-known chemistry. The abundance of metallic iron in a flotation food may be noted by even perfunctory examination. First of all the mine contributes metallic iron, then the coarse-crushing machines add their share, and finally the fine-grinding medium its portion. If the grinding is with cast-iron balls the amount of metallics is greater than when steel is used. Thus it, is that much more metallic iron is present than would be indicated by noting the ball consumption. An estimate that the total amount of metallics is twice that supplied by the balls and liners might not be far amiss. That copper sulphate plates out on iron in an acid solution is well known, but since flotation is practiced commonly in solutions where acid has not been added this reaction has not been given sufficient thought.

Jan 1, 1929

By M. K. Quinn, N. P. Reddy, A. W. Khair

"An analysis of coal fragmentation due to the action of a continuous miner is presented. Underground coal cutting by a drum-type continuous miner was simulated in the laboratory using a specially designed unique automated rotary coal cutting simulator (ARCCS). The rotary coal cutter provided the versatility of varying the operating and in-situ parameters to provide information on the effects of generating 37 pm (0.0015 in) particles. In these tests, coal blocks with an approximate dimension of 50.8 x 35.6x 20.32 cm (20x 15x 8 in) were first subjected to confining pressures equivalent to in-situ conditions. The blocks were then cut by the rotary cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters 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. During the test, all the cut products were collected for size distribution analysis. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using a camera attached to an optical microscope.The results led to a better understanding of the mechanisms of the fragmentation process during coal cutting and the effect of operating parameters, in-situ conditions and coal type on the size distribution of the cut product:"

Jan 1, 1989

By Thomas J. Peters

In 1987, at the request of the U.S. Bureau of Land Management, the Bureau of Mines studied the 350-acre Henry?s Lake Wilderness Study Area (ID-035-077) in order to evaluate its identified mineral resources. The Wilderness Study Area is located in northern Fremont County, ID, approximately 140 air miles north-northeast of Pocatello and 3 miles south of the Montana border. The Wilderness Study Area is near the north shore of Henry's Lake at the foot of the southwest-facing slope of Black Mountain. Archean hornblende gneiss, the main rock type present, crops out northeast of the Madison Range Fault, which trends northwest across the southwest corner of the Wilderness Study Area.

Jan 1, 1988