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By Fred N. Kissell

Methane flows and pressures were measured in mines in the Pittsburgh, Hartshorne, and Pocahontas No. 3 coalbeds. From the data, the permeability of each of these coal beds was computed. It was found to depend strongly on the type of coal and on the amount of water in the coalbed, and it was found to increase with time. All of the coalbeds had a high-permeability zone adjacent to the face or rib, and the Pittsburgh bed exhibited directional anisotropy. Surprisingly, little or no overburden effect was observed.

Jan 1, 1972

By J. G. Walters

In a survey of the coking properties of United States coals, the Bureau of Mines has accumulated data on more than 500 coals and blends tested by the Bureau of Mines-American Gas Association (BM-AGA) method.4/ The importance of these tests depends upon the fact that a greater number of different coals has been tested in this apparatus than in any other of similar scale, thus permitting comparison of the carbonizing properties of many coals. Evaluation of BM-AGA results with respect to industrial data supplied by member firms of the American Gas Association was one of the first objectives in developing this test apparatus and procedure. Early data showed that, de-pendent upon BM-AGA carbonizing temperature, BM-AGA and commercial results agree closely.5/ Because of limited data, statistical relationships were not established at that time.

Jan 1, 1959

By M. J. Kovalik

The effects of the process variables on the production of chemical coke on a chain grate stoker, a type of traveling grate, were studied. Six bituminous coals, ranging in volatile matter from 16.7 to 43.8 percent, were successfully carbonized, yielding chemical coke with acceptable physical properties. The coke yields were dependent on the volatile-matter content of the coal. The air fuel ratio had the most marked effect on the yield and characteristics of the resultant coke, and the general furnace performance. Results can only be predicted; the actual yield and quality of coke obtained from any given coal can only be determined by actual tests using the optimum processing variables to obtain a coke with minimum volatile-matter content and to retain as much of the fixed carbon in the original coal as possible.

Jan 1, 1967

By Jerry L. Huiatt

An accurate and reproducible procedure was developed using the gas-liquid chromatograph to quantitatively measure oleic acid on flotation products and in flotation water phases. The method comprised extraction of the oleic acid from the mineral surfaces with alcoholic NaOH, esterification of the extracted oleate, and chromatography of the methyl ester with an internal standard. Quantitative analysis of oleic acid on flotation products from test tube and bench-scale flotation tests with pure minerals and with natural ores proved the applicability of the method on a variety of minerals. The accountability of oleic acid added was 100 percent, ±5 percent.

Jan 1, 1968

By J. E. Chilton, Jr. Dubaniewicz

Many mines rely on toxic gas sensors to help maintain a safe and healthy work environment. This report describes a prototype monitoring system developed by the U.S. Bureau of Mines (USBM) that uses light to power and communicate with several remote toxic gas sensors. The design is based on state-of-the-art optical-to-electrical power converters, solid-state diode lasers, and fiber optics. This design overcomes several problems associated with conventional wire-based systems by providing complete electrical isolation between the remote sensors and the central monitor. The prototype performed well during a 2-week field trial in the USBM Pittsburgh Research Center Safety Research Coal Mine.

Jan 1, 1995

By James P. Rider

This U.S. Bureau of Mines report describes a viewing transformation algorithm that generates a perspective view of a three-dimensional scene. This tool may be used by researchers to improve mine safety by assessing the visual capabilities of a mobile equipment operator. Three-dimensional transformations used to build the viewing transformation and techniques used to project the image onto a two-dimensional display screen are defined. The algorithm is written in the C-programming language and designed to stress portability, allowing it to work without significant modifications on numerous computers. A listing of the computer routines along with sample output is included in the report.

Jan 1, 1992

By T. G. Carnahan

The Bureau of Mines conducted research to simulate in situ leaching of a porphyry copper sulfide ore. The purpose was to determine the effects on copper leaching of additions of NaCI to a conventional sulfate leach system and to analyze the oxidant requirements and the oxidation products that resulted from leaching of the sulfide minerals in the ore. Baseline sulfate and sulfate plus 2-pct-NaCl-leach-solution experiments employing 167-kg (367-lb) and 152-kg (333-lb) charges, respectively, were conducted. The minus 25.4-cm (10-inch) ore was leached at 90° C under flooded conditions with 2.8 MPa (400 psig) of oxygen bubbling through the system. Sixty-seven pct of the copper was extracted in 1,236 days of leaching in the NaCI experiment, whereas 47 pct of the copper was extracted in 913 days of leaching in the baseline experiment. Diffusion into and out of the ore fragments controlled the rate of leaching, which precluded enhancement of the leach rate by the chloride ions. The calculated oxygen consumption was 3.17 kg/kg of copper extracted in the baseline experiment and 3.46 kg/kg of copper extracted in the experiment to determine the effect of chloride ions.

Jan 1, 1982

By Daryl E. Radcliffe

Ninety-seven roof bolts were instrumented with strain gages and resin-grouted in three areas of the Bear coal mine, Somerset, Colo., by the Bureau of Mines. Measurements taken with these instruments indicate roof support is achieved through a combination of point suspension and resistance to vertical and horizontal stresses caused by localized shearing in the roof. The localized shearing results in bending of the bolts, yielding due to high vertical stresses, and the transfer of high loads to the bolt head or plate.

Jan 1, 1980

"At the request of the Anthracite Institute, the United States Bureau of Mines during February, March, and April 1935, made a field survey of commercial anthracite shipped from collieries scattered throughout the Anthracite regions. In all, 268 samples were taken at 41 breakers from Carbondale at the northern end of the field to Pottsville at the south. These collieries ship approximately 50 percent of the industry’s total production. The geographical distribution of the breakers sampled was as nearly as practicable in proportion to the tonnage of the companies from each region cooperating in the plan.The following are the weighted average analyses, by sizes, of the samples taken in this survey;"

Jul 1, 1935

By Stephen W. Lambert, Michael A. Trevits

The Bureau of Mines examined the wellbore of a vertical gas drainage well in the Mary Lee coalbed to determine the results of specific completion procedures in coal. A jet-slotting tool was used to cut four vertical slots through the casing about 1 ft below the coalbed. Even though stimulation treatment pressure was excessive, hydraulically induced channels were contained entirely within the target coal zone. Sand-filled, induced channels were horizontal, inclined, and vertical, and were propagated in directions similar to bedding planes, rock joint, and coal cleat directions measured in the mine. Variable gas flow rates, recorded during the productive life of the well, were attributed to chronic downhole pump malfunction and the slotted casing below the production zone.

Jan 1, 1978

By Peter F. Steidl

As part of the Bureau of Mines methane control program, the Upper Free-port coalbed was studied in Fayette County, Pa., where this coalbed lies about 650 feet below the Pittsburgh coalbed and contains the largest remaining reserves of any coalbed in the county. Its estimated recoverable reserves in Fayette County are between 670 and 800 million tons. Coal and overburden isopachs, structure and joint pattern maps, and a fence diagram were prepared using data from gas and oil exploration logs and coal outcrops. These maps will aid in determining the need and/or feasibility of degasifying the Upper Freeport coalbed in the study area. Much of the coalbed in this area is under 600 to 1,400 feet of overburden. By correlation with data from the Pittsburgh coalbed, the gas content at depths of this order is estimated to be between 140 to 300 cf/ton of coal.

Jan 1, 1977

By K. O. Bennington

The thermodynamic properites of petalite (Li2A12Si8O20) were determined by the Bureau of Mines. The enthalpy of formation was determined by hydro-fluoric acid solution calorimetry. The values from the elements and from the oxides are ?Hf°298.15 = 2,335.8 ± 3.0 kcal/mole and ?H°295 (from oxides) = -50.60 ± 1.20 kcal/mole. Low-temperature heat capacities were determined by adiabatic calorimetry from 10.69 to 302.11 K. The derived standard entropy is S°298.15 = 111.0 ± 1 cal/deg-mole. Enthalpy increments above 298 K were measured by copper block calorimetry from 298 K to 1,193.6 K. The various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of the measurements. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature from the elements and constituent oxides. The Gibbs energy of formation is ?G°f298.15 = 2,203.8 kcal/mole.

Jan 1, 1980

By Joseph Cervik, J. H. Perkins

The Bureau of Mines has conducted desorption work on fine coal particles at near atmospheric pressure. An apparatus has been developed that uses a capacitance manometer to measure desorption of methane from coal particles up to 2 inches in diameter and pressures up to 1,000 psi. This will make it possible to duplicate the desorption process as it occurs in its natural under- ground environment.

Aug 1, 1970

By Alton B. Cook

Data are presented to show oil vaporization resulting from the passage of natural gas through a sand-packed tube saturated with synthetic reservoir oils. The Bureau of Mines performed 13 experiments, using reservoir oils synthesized with base crude oils of approximately 22°, 35°, and 45° API, at 100°, 175°, or 250° F and 1,100, 2,600, or 4,100 psia. It has been determined that the amount of vaporization is significant if proper conditions exist. These experiments show that oil vaporization depends on pressure, temperature, volatility of the oil, and amount of gas cycled. Increases in each of these conditions increase the volume of oil vaporized.

Jan 1, 1969

By Philip B. Lorenz

A Bureau of Mines feasibility study on the use of tracer pulses to assess the degree of fracturing in an underground formation consisted of three phases: 1. A laboratory study on sand packs and open tubes, which developed a correlation between dispersion of the pulse and size of the flow channels. 2. A test on a retort, 11 feet in diameter and 45 feet high, packed with shale rubble. Void volume was measured, but evaluation of channel size was not possible because of interference from the space unoccupied by the matrix. 3. A field test on an explosively fractured shale formation. Pressure, flow, and transit time led to qualitative estimates of fracture pattern, but quantitative detection of dispersion in the formation was overwhelmed by dispersion effects in the well.

Jan 1, 1973

By Francis R. Redfern

Newton's method of solving a nonlinear equation is employed to develop a least-squares acoustic emission source location method in which the spatial residuals of the location equations are minimized. These residuals, related to the distances from the least-squares source location perpendicular to the surfaces described by the location equations, permit location error to be estimated to first order along the spatial axes. The solutions obtained by this method are the best spatial solutions to the location equations in the least-squares sense. Also presented is a procedure by which the geometrical control of a transducer array can be evaluated using the rate of change of source location with fractional velocity change.

Jan 1, 1982

By Yael Miron

Ammonium nitrate-fuel oil (AN-FO) mixtures are used as blasting agents in mining pyrite-bearing ores. The temperature of these ores can increase by the continuous, though at times slow, oxidation weathering of the pyrites. At elevated temperatures, AN-FO reacts exothermally with pyrite, and the reaction becomes self-sustained at 120° C ± 10° C. The Bureau of Mines has conducted an investigation to determine the reactivity of mixtures of AN-FO with pyrite containing ferrous sulfate. The results of tests in a heated vessel simulating a hot borehole demonstrate that small amounts of ferrous sulfate, a major product of pyrite weathering, initiate a self-sustained exothermic reaction with AN-FO at 80° C. Five pct by weight of urea was found sufficient to prevent a reaction among the three ingredients, at least within the limits of the test, which reached 180° C. Smaller amounts of urea and of potassium oxalate slowed down the reaction and delayed its onset to higher temperatures, but did not prevent it.

Jan 1, 1979

By Timothy J. Rohrbacher

This report presents a U.S. Bureau of Mines study that incorporates coal mining factors, coal recovery factors, and economic factors into the definition of an economically recoverable coal resource. The relationship between these factors to the Energy Information Administration's estimate of U.S. coal resources-the "Demonstrated Reserve Base"-is discussed. The Matewan 7-1/2 minute quadrangle in eastern Kentucky was selected as the initial study area. Results indicate that of the original 1,193 million tons of resource in the quadrangle, only 89 million tons (7.5%) are economically recoverable at a cost of $25 per ton or less. At the current production rate of 5.3 million tons per year, this represents only 16.8 years of remaining reserves.

Jan 1, 1993

By A. F. Jolly

As a part of ongoing research into the sulfidation partitioning of selected complex minerals, the U.S. Bureau of Mines conducted research designed to selectively recover Cu from sulfidized chalcopyrite (CuFeS2). Ferric chloride (FeCI3) solutions leached >90 pct of the Cu and <20 pct (sometimes < 10 pct) of the Fe in the sulfidized concentrates. Cupric chloride (CuCI2) leaches were even more selective, solubilizing essentially 100 pct of the Cu and < 5 pct of the Fe. In contrast, leaching non-sulfidized CuFeS2 with either FeCl3 or CuCl2 showed that somewhat more Fe than Cu dissolved. These studies demonstrate that Cu is substantially more leachable from sulfidized CuFeS2 than from nonsulfidized CuFeS2? The Cu-and Fe-bearing constituents generated as sulfidation products, CuS (covellite) and FeS2 (pyrite), respectively, are differentially dissolved. The solubility of Fe from pyrite in sulfidized CuFeS2 is much lower than the solubility of Fe from complex nonsulfidized sulfide where Fe and Cu are bound in the same crystal lattice. Thus, the Cu dissolves selectively, producing a high-Cu filtrate from which Cu can be recovered by cementation or by electrolysis. Flotation of CuS-FeS2 mixtures indicates partitioned phases can be physically separated if effective liberation can be achieved. Magnetic separation tests yielded less promising results.

Jan 1, 1991

By Robert J. Timko, Edward D. Thimons

Sulfur hexafluoride (SF6) is an odorless, colorless, nontoxic gas that has found acceptance as a tracer gas in research on ventilation pat- terns, measurement of air leak rates, respirable dust reductions due to bagging hood modifications, and the study of airflows relating to gob boreholes. Following a short review of the SF6 sampling technique, this report describes recent Bureau of Mines projects in which SF6 was used successfully as a tracer gas, enabling researchers to acquire representative data quickly and inexpensively.

Jan 1, 1982