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By Rolland L. Blake

Petrographic methods of examination were used by the Bureau of Mines on a suite of samples of ultramafic rock from Soapstone Ridge, Ga., located about 8 miles south-southeast of Atlanta. The samples were analyzed to determine (1) their potential for releasing regulatory particles upon crushing and grinding and (2) their concentration of fibrous particles that approach the dimensions of amphibole and serpentine asbestos minerals. Such particles might be generated during grading and excavation for housing and industrial development and could become a health concern. Light optical microscopy, scanning electron microscopy, and X-ray diffraction were the techniques used to examine the samples. Six of the twelve samples contained amphibole as a major mineral; in five, it was a moderate to minor mineral. One sample contained no amphiboles, and serpentine was not observed or identified by X-ray diffraction in any of the samples. In nine of the samples, the amphiboles exhibited a habit that was either prismatic or acicular, but not asbestiform. Two of the samples did contain asbestos, occurring as small veins or fracture fillings, which represented only a minor percentage of the total sample. Similar petrographic screening is recommended for examining any rock deposit or mine location to delineate hazardous and nonhazardous mineral areas.

Jan 1, 1982

By S. E. Khalafalla

In support of its goal to maintain an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines has investigated a novel hydrometallurgical system with sulfur dioxide. Differential leaching with dissolved SO2 of manganese, nickel, and cobalt from their hydrous oxides was found to be very rapid and efficient--almost instantaneous and quantitative. In this method a given weight of mixed oxides previously ground to minus 200-mesh is slurried with a leach solution containing a specified quantity of dissolved SO2 for 10 minutes at room temperature and ambient pressure. An empirical leaching parameter, R, is defined as the ratio of the number of SO2 moles in the leaching solution to the weight of the metal oxide charge. Plots of the variation of metal extraction with the ratio R generate a series of sigmoidal-shaped curves, each of which is characteristic of a specific metal extraction. A threshold value of R is required to initiate the leaching of a given metal from the mixed oxides. Once this threshold is reached, the metal recovery can increase to more than 95 pct in very short times. For increasing values of R, the extractability of various metals by SO2 follows the order: Mn > Ni > Co >> Fe, Al, Cu. Differences in the threshold R values permit a variety of metal separations to be made simply by adjusting the quantity of SO2 in the contacting solution. Success in this leaching system depends upon comminuting the sea nodules to less than 0.149 mm (100-mesh). Above this critical size, leaching is slowed due to the inaccessibility of inner particle reacting groups to the SO2 leaching agent. This results in nonselective extraction and less extraction of preferred metal values. At or below 0.149 mm, leaching by SO, is possible with all its attributes of selectivity, sensitivity, and rapidity. Leaching with HC1 solutions of the same pH level as dissolved SO2 yielded mixed, slow, and incomplete metal extractions. This observation rules out any interpretation based on hydrogen ion as the leaching agent. The leaching curves resemble the complexometric titration curves of heavy metals with specific coordination species.

Jan 1, 1981

By S. M. Dar

The U.S. Bureau of Mines constructed a full-scale model of a 15-ft-wide coal mine entry to use in combination with finite-element analyses to investigate roof support systems and various types of roof bolts. The objective was to enhance understanding of the fundamental mechanics of the interaction between rock and supports and the relative integrity of bolted mine roof as a function of roof bolt type, length, spacing, and tension, and the basic characteristics of the roof strata. The laboratory test results, when correlated with computer simulations using fmite-element analysis and underground verification tests, should provide a basis for desigillng safer, more cost-effective roof control systems and help to establish guidelines for employing fully grouted resin and mechanically anchored bolting systems. The background for this research, the research approach, the methods and equipment employed, and the results are described in this report.

Jan 1, 1989

By D. Harrington

The number of fatalities from mine explosions for the fiscal year 1945 dropped below that of the year before; continued improvement over the record of the years from 1940 to 1945 is hopeful, but the number of reported explosions has increased rather than diminished, and the number of victims claimed by explosions is often more definitely a factor of chance than forethought. Mine fires and explosions can be eliminated through the methods now well-known to those well-informed in matters pertaining to safety in mining but ignored by many coal-mine operators and employees who follow procedures of the past or their own short cuts, regardless of disasters that may result: Tried and proved safety measures for preventing mine fires and explosions have been recommended to the mining public repeatedly, yet only a relatively small but far-sighted minority have adopted these measures and made them a part of operating practice. That far more explosion disasters did not occur in 1945 is fortunate. In 1945 a coal-mine fire of electrical origin caused heavy loss of life, while several others from the same cause were controlled with but few fatalities; this hazard is now being curbed temporarily to some degree after the bad record of the two preceding years, but a real solution of the problem has not been reached, although cooperating committees trying to produce at least some answer have made progress.

Jan 1, 1946

By William E. Dennis

"At the request of Philip S. Hoyt, the Eagle Mountain fluorspar deposits in section 35, block 68, Texas & Pacific Railroad Survey No. 9, were examined by an engineer3/ of the Bureau of Mines during March 1943: As a result of this examination; a preliminary program of trenching, sampling and core drilling by the Bureau of Mines was begun in. June 1943.4/ Eight deposits were explored.The Federal Geological Survey mapped the properties and furnished geologic information throughout the program, while the Texas .Bureau of Economic Geology6/ made preliminary maps that facilitated planning the exploratory work on section 35.The eight deposits explored by the Bureau of Mines are in block 68, Texas & Pacific Railroad Survey No. 9, Hudspeth County, Tex., approximately 7-1/2 miles south of. Hot Wells and 12-1/2 miles south of Allamoore, which is 10 miles west of Van Horn and 20 miles east of Gierra Blanco on U. S. Highway 80(fig. 1). A graded gravel road, built by the Public Roads Administration, leads from Hot Wells to the deposits in section 35, and there are unimproved roads, passable,by automobile, to all the other deposits.Carload shipments can be made to and from Hot Wells on the Southern Pacific Railroad, and complete railroad facilities are available at Allamoore on the Texas & Pacific Railroad.Van Horn and Sierra Blanca are the only local source of labor and. supplies. The prevailing wage for common labor is 60 cents an hour. Living accommodations are obtainable in Horn and Sierra Blanca.No electric power lines pass near the deposits. Diesel and gasoline motors are employed to furnish power for mining and milling operations.Two recently 'drilled water wells on section 35 furnish water for the mill. Other wells will be drilled if the present supply is inadequate for prolonged Peak operation.The properties lie in the foothills on the northeast side of the Eagle Mountains at 5,500 feet altitude. The Eagle Mountain Range rises sharply from a broad, flat valley known as Eagle Flat. Eagle Peak, the highest in the range, has an altitude of 7,510 feet. In the vicinity of the fluorspar deposits the topography is moderately reliefs ranging from 50 to 300 feet."

Jun 1, 1946

By R. B. Anderson

As a part of a Bureau of Mines program on the conversion of coal to liquid and gaseous fuels, the kinetics of the Fischer-Tropsch synthesis on iron catalysts was investigated. Nitrided catalysts were studied at 21.4 atmospheres using feed gases ranging from 2H2+1CO to 0.25H2+1CO, and at 7.8 to 21.4 atmospheres using 1H2+1CO gas. The overall apparent activation energy increased with increasing carbon monoxide content of the feed gas from 19.5 kcal/mole for 2H2+1CO to 23.7 for 0.7H2+1CO. The rate of synthesis with 1H2+1CO feed increased linearly with operating pressure from 7.8 to 21.4 atmospheres. A semifundamental rate equation of the form [r=a'PH2 0.6pco 0.4- ?r0.5PH200.5] was shown to fit the data satisfactorily. The relative usage of hydrogen to carbon monoxide decreased with increasing conversion, passed a minimum, and then increased. Apparently water is the principal primary product and carbon dioxide is produced by subsequent water-gas shift reaction. In another group of experiments water, carbon dioxide, argon, and methane were added to 1H2+1CO feed to a nitrided iron catalyst. Argon and methane were only diluents. Carbon dioxide was a slight inhibitor and water vapor was a strong inhibitor to the rate of synthesis. Water accelerated the water-gas shift and usually increased methane production. Important factors of catalyst geometry in determining rate were found to be particle size and extent of reduction. Apparently the active portion of the catalyst is confined to a layer of 0.01 to 0.02 cm from the external surface of particles. A special solution was made of differential equations relating re¬action at the catalyst surface to diffusion in pores of the catalyst for spherical particles with an active layer surrounding an inert core. The equation derived expressed the experimental data reasonably well. Diffusivities determined by this equation varied from 3 to 24X10-6 cm2/sec; these values are of the same magnitude as observed for the diffusion of gases in liquid. The appendix presents a group of synthesis experiments at pressures of 21.4 to 103 atmospheres. In this range the rate of synthesis on nitrided iron catalysts increased with pressure to the 0.74 to 0.84 power.

Jan 1, 1964

By Barbee J. Scheibner

This Bureau of Mines report describes the geology and physical properties of core samples at the Sunnyside coal mine No. 1, Sunnyside, Utah, and was written in conjunction with the Single-Entry Program conducted at the mine. The objective of this program was to test the hypothesis that the single-entry system in the Sunnyside mine, supported in the center by open cribs and divided by a fire-resistant partition, is equivalent to or better than a two-entry sys-tem. Drill cores, taken underground at 15 sites in the single-entry study area, facilitated the construction of geologic cross sections of the entries. Physical property data obtained from the drill cores was used in a three-dimensional finite element analysis program to evaluate the stability of the openings, the support requirements, and the de formation characteristics of the roof and floor material. Data on 10 physical property parameters for 5 rock types plus coal are also tabulated and discussed.

Jan 1, 1979

By O. M. Bishop

"INTRODUCTION Early in World War II, the Bureau of Mines realized that reserves of fluorspar ore at many mines in the southern Illinois fluorspar district were not being developed as rapidly as the old ones were being depleted. At some mines the measured and indicated ore reserves were almost entirely depleted, although geologic factors favored new discoveries. The Leo mine, which had not been worked since 1938, was among this group of mining. The Bureau of Mines, together with the Illinois Geological Survey examined the property, studied the mine records and,geologic factors in 1944, and agreed that exploratory drilling was warranted Funds were,obtained for the work in the fiscal year 1945, and drilling was done; between October 27, 1944, and June 15, 1945.The property was owned in fee simple by the Hllside Fluor Spar Mines at the time exploration was begun in October 1944. Subsequently, in 1945, the Inland Steel Co. acquired of the Hillside property."

Jan 1, 1947

By M. Mentser

The exchange of oxygen between carbon dioxide and carbon monoxide that occurs reversibly on carbon surfaces was studied at temperatures of 750° to 850°C and a pressure of 1 atmosphere. Carbon-14 was used to detect and measure the exchange reaction. The extent of oxygen exchange was a linear function of com- position of the gas mixture, and this relationship was used to evaluate the forward and backward rate constants of the reaction. Equilibrium constants, directly determined for oxygen exchange in this study, agreed well with values in the literature that were derived only by indirect procedures. This result establishes the validity of oxygen exchange in the mechanism of carbon gasification by CO2. Rates of carbon gasification were less than an order of magnitude slower than rates of oxygen exchange. Activation energies for these two processes were 58 and 53 kcal/mole, respectively. The closeness in the activation energies argues against any change in the rate-controlling step over a wide temperature span at atmospheric pressure. The role of CO as a retardant on the CO2-C reaction, and the nature of the carbon-oxygen complex are also discussed in view of the data obtained.

Jan 1, 1973

This report describes the development, installation and performance of a lonpwall illumination system. The longwall illumination system was installed at the Greenwich Collieries 112, Cockport, Pa. It utilized flourescent luminaires, intrinsically safe power distribution and is the first longwall system installed in Pennsylvania.

Jan 1, 1976

By Thomas P. Dolley

Building stone, cassiterite, kaolin, gold, lime, and peat were the only commodities mined, The country's main economy was in agriculture, primarily in coffee exports. Tribal violence occurred again, between the Hutu and Tutsi tribes, causing an estimated 50,000 deaths, mainly in rural and mining areas. The inflation and a large deficit continued. The country continued to import cement, fertilizers, oil, and petroleum products. Burundi possessed numerous small gold deposits. The northwest and north-east were the country's two most important gold-bearing regions. A large kaolin deposit was found at Ngozi, and its mining was specified in the fifth 5-year development plan for 1988-1992. In the area of Rugombo, limestone was being explored with the intention of opening a cement plant.

Jan 1, 1990

By V. F. Parry

[Approximatel~r 7-1/2 illion tOlls of subb1tnminous coals are mined an-nuall in Colorado, Wyo~ing, and Montana, of which 50 percent probably reaches dome ,-tic conswno:os. r:L'he moi s t'_re of the se subbi t1.Uninous coal sis high, averae;:t.:ug about 25 :!,)ercent \-Then they are :nined. T'ne coals are non-caking d ~~ack to a vari ble degree when exposed to nornal atmospheric conditions. ~hey a~e gpod domestic fuels, are considered to be smokeless in most furn~ces, and have been used. f, r f!1an: y ars in hand-fired domestic furnaces in hich tnc practice i~ to e~ploy large lureps for efficient com-]

Jan 1, 1941

By C. P. Mishra

The Bureau of Mines performed a study of the availability of cobalt from market economy countries. The study entailed the detailed analysis of 97 deposits which contain 3.9 billion lb of cobalt at the demonstrated level; in 94 of the deposits cobalt is recovered as a byproduct, and in 3 it is considered the primary product. Since 97 pet of all recoverable cobalt is derived as a byproduct from copper and nickel deposits, the report focused on these two sources. At an assumed market price of $0.89flb for copper, $3.45/lb for nickel, $475/tr 021 for platinum, and $7/lb for cobalt, 1,330 million lb of cobalt at the demonstrated level are potentially available. This total includes 1,105 million lb of cobalt from copper properties, 190 million lb from nickel, 29 million lb from platinum, and 6 million lb from primary cobalt. This analysis indicates that the production cost for 589 million lb of cobalt can be totally covered by the revenues obtained from the other metals produced. The impacts of increases in capital investment and energy costs are also discussed.

Jan 1, 1985

By Martin Berman

Tables of 28 positions for all the transitions for nine common analyzing crystals for first, second, and third order reflections were compiled by the Bureau of Mines to facilitate elemental X-ray fluorescence analysis on multi-element systems. The tables are based on a compatible set of wavelengths for 2,346 observed X-ray transitions of the elements lithium to americium. The results are tabulated in order of increasing wavelength as well as by increasing wavelength for each element.

Jan 1, 1969

Geological discontinues in the coalbed, such as faults, sandstone channels, permeability facies, lithotype changes, and large scale partings in the coal seam, can cause intermittent production problems or produce unexpected amounts of water or gas from degasification boreholes. These discontinuities not only can impact methane emissions into the mine workings, especially if they hinder proper and effective degasification of the coalbed but may act as conduits for methane flow from gassy strata into advancing mine workings. The effects of these discontinuities are still under debate by mining and gas production experts. This study presents a numerical investigation using reservoir simulations of the effects of partings and permeability facies and lithotype changes on the production performances of vertical and horizontal degasification boreholes, as well as the emissions during longwall operations. In this work, the grid block was designed in a multi-layer 3-D structure which enabled spatial descriptions of the geometries and properties of the discontinuities within the coal seam. The studied coal seam discontinuities and their properties were distributed arbitrarily within the model. Production was simulated by vertical and horizontal boreholes. Degasification boreholes operated two years prior to start of the mining. The results of this numerical study show that in coal seams with major heterogeneities and discontinuties, the geometry and location of the boreholes are important for improved gas production. These considerations are also important for controlling methane and water inflow into the working environment during longwall mining.

Jan 1, 2008

By J. F. Barkley

[There 1 s [\ general conce:!?t in the coal trade tha t the ;noi sture-and ash-free B. t.'I. of coal from t.he oome seam, and surely from the same mine, is substantially a cor.stant: that calculatio!: of the ::1oisture-and ash-free B. t. u. value f~~oJl t he proxima te ru:al~rsi sand. 3. t. u. determined in tl19 laboratory 111ill reveal v:?letller a coal came f~'om a. given : area or seam; and that, having this constant, the 3.t.u. value of a coal sample can be c lculatcd fairl...' closely 11:0on a? dry or as~received basis from the r.lois]

Jan 1, 1941

By J. F. Barkley

[There is a general concept in the, coal trade that the moisture- and ash-free B.t.u. of coal from the same seam, and. surely from the same mine, is substantially a constant; that calculation of the -moisture- and ash-free B.t.u. value from the proximate analysis and B.t.u. determined in the laboratory will reveal whether a coal came from a given area or sears; and that, having this constant, the B.t.u. value of a coal sample can be calculated fairly closely upon a dry or as-received basis from the moisture and ash values of its proximate analysis.]

Jan 1, 1941

By B. E. Blair

The physical properties and related geological and petrographic data for 81 rock types obtained from operating mines or selected test sites are presented in this report. Most of these rock data were obtained to supplement structural studies in underground mines; however, the data may be equally applicable to other problems where the physical properties of rock are an important factor. Stress-strain curves are presented, where available, and free medium velocities from laboratory and field measurements are compared for several rock types. Rock-type, geographical, and geo-logical indexes are included for reference relative to physical property data in this and previously published Bureau of Mines physical property reports. INTRODUCTION This report presents the physical properties of 81 rock types from 16 different projects (sections 53-68). Three previous physical property reports2 3 4/ (herein after referred to as parts I, II, and III) presented data on 244 rock types from 52 project areas. (Part I included sections 1-25, part II sections 26-36, and part III sections 37-52).

Jan 1, 1956

By John S. Berber

Acids, neutral oils, and pitch were produced by distillation of low-temperature lignite tar and processed to upgrade them into more valuable products: The acids were separated from the distillate and catalytically dealkylated to produce phenol, cresol, and xylenol. Aromatic and naphthene fractions of the neutral oil were converted into phthalic and maleic anhydrides by catalytic hydrodealkylation and vapor- phase oxidation. Paraffins and n-olefins from the neutral oil were processed into alkybenzene sulfonate, a biodegradable substance. Aromatic materials from the neutral oil were also extracted with organic compounds and the extract hydrogenated under pressure to produce jet fuel. The pitch was processed by various means to change its characteristics and make it suitable for similar applications as high- temperature tar pitch, including preparation of carbon black and metallurgical electrodes. In most cases, products obtained from the low-temperature tar were examined for physical and chemical characteristics and for potential commercial utility. Information obtained from this research would be helpful if a new coal- chemical industry based on tar utilization were established.

Jan 1, 1973

By D. L. Bickel

This report presents a Bureau of Mines study intended to determine if horizontal stress trends exist and if the stresses can be projected for improved mine design in a selected coalfield. The horizontal stresses were determined in three mines in the Yampa Coalfield and one mine in the adjacent Danforth Hills Coalfield of northwestern Colorado. Stresses were determined from stress-relief measurements using a three-component borehole deformation gauge and overcoring techniques developed by the Bureau. A least-squares method of calculating the average rock stress components in the horizontal plane was performed. Physical properties of the rock from the test sites are also included. For the Yampa Coalfield, the maximum horizontal compressive stress in the floor ranged from 363 to 1,956 psi, and the maximum horizontal compressive stress in the roof ranged from 235 to 875 psi. For the Dan-forth Hills Coalfield, the maximum horizontal compressive stress in the floor ranged from 360 to 1,494 psi, and the maximum horizontal compres-sive stress in the roof was 1,033 psi. Results indicated a trend of low horizontal stresses in the Yampa Coalfield that have not impacted ground control conditions in mines less than 1,000 ft deep.

Jan 1, 1988