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By John Jordan, Steven J. Knoll, Douglas Tesarik, Theodore J. Williams, David K. Denton, Douglas F. Scott

Highly stressed rock in stopes continues to be a primary safety risk for miners in underground mines because this condition can result in failures of ground that lead to both injuries and death. Personnel from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health studied two methods for identifying stress in rock. A seismic tomographic survey, finite-difference analysis, laboratory measurements of compression wave (ultrasonic) velocities in rock cores, and site geology were integrated to evaluate the use of seismic tomography for identifying induced pressures in an underground pillar at the Edgar Mine, Idaho Springs, CO. Electromagnetic (EM) emissions were also investigated in the Galena Mine, a deep underground mine in Idaho, in an effort to determine if these emissions could be used as indicators of impending catastrophic ground failure. Results of this research indicated that (1) seismic tomography appears to be a useful tool for determining relative stress in underground pillars, while (2) EM emissions do not appear to be significant precursors of impending catastrophic ground failure.

Jan 1, 2004

To improve the efficiency and speed of under-ground post-disaster rescue operations. The Approach: Develop a battery-powered mine-rescue vehicle designed to carry rescue crews, rescued miners, and their support equipment. How It Works: The experimental vehicle, shown below, was designed and constructed by the Mine Safety Appliances Company under contract to the Bureau of Mines. ATV Manufacturing Company and Delco Electronics were subcontractors. A rechargeable, silver-zinc battery provides power to a 3-horsepower permissible motor, the speed of which is regulated by a solid-state controller. Three wheels on each side are independently driven by a chain and mechanical trans-mission.

Jan 1, 1974

By G. R. Friggens

A nuclear method for continuously monitoring the coalbed and ash levels and void formation in commercial-scale, fixed-bed, pressurized gas producers is proposed. Measurement of gamma ray transmission through the coalbed is the basis of the method. The coalbed level is monitored by detecting the trans-mission of gamma rays from a 1 to 2 Ci Co-60 source positioned on the outside wall of the vessel. Coal bridging or, alternatively, ash level is monitored by a 10 Ci Co-60 source at the center of the coalbed. Source activities and geometries are calculated for a 12-foot-ID producer designed to operate at 350 psi. Source capsule and detector specifications and operational safety are also discussed.

Jan 1, 1973

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

B 5 Typical Input - Ouput The input data and the printed output for case 8 of the simulations (Section A.4) are shown in the following. The branch, level, node, miner and hoist numbers mentioned in the input and output refer to the corresponding numbers in Figures A-3, A-4 and A -5, The plotted ouput, already shown in Figures A,11 and A-12 is not repeated. The input data shown does not include the following simulation parameters: DTIME = 0, 05 FTIME = 130 JPLT(K) = 1 for K = 1, 2, 3 0 for other K TPLSTR = 0.0 TPLST P = 130

Jan 1, 1976

By Zachary J. Fink

A continuous-monitoring system has been developed for analyses of mine gas concentrations associated with spontaneous combustion, mine fires, and explosive and toxic levels. The analysis center, which is linked to sample locations by polyethylene tubes in bundles, has been successfully field tested by the Federal Bureau of Mines for analyzing carbon monoxide and oxygen; a computational scheme has been developed to process the data at the site. This report contains information on the design, purchase, installation, and maintenance of the tube-bundle system. A brief comparison of the tube-bundle system with the underground-analysis system and plans for future research are also included.

Jan 1, 1975

By Howard E. Parkinson

An environment monitoring and communication system has been installed in the Bruceton Mine, and research is under way to improve mine safety. Standard day-to-day mine communications are available, along with additional systems installed to permit experimentation with wireless radio, through-the-earth phones, along-the-roof paging, and mine face machinery communications. Research is continuing and the essential concepts for a dependable whole mine communication system, providing simple environment monitoring, improved day-to-day communications and post-disaster communications, will be demonstrated in a larger mine with about 900 feet of overburden.

Provide ear protection which allows normal, unaltered hearing at low noise levels, yet protects the wearer from excessive noise. The Approach: A commercial earmuff with integral speakers has been adapted with a special amplifier so that low sound levels are not affected, but higher noise levels automatically reduced. How It Works: The discriminating earmuff developed by the Bureau of Mines has two modes of operation. In the first mode, where input sound levels are less than or equal to 83 decibels, the wearer will perceive noise at its actual level. For inputs in excess of 83 decibels, the second mode of operation begins and the sound perceived by the wearer is progressively attenuated, or reduced, as the input level is increased. A recognizable difference still exists between two adjacent sound levels enabling the wearer to differentiate between them.

Jan 1, 1975

Provide a low-maintenance, reliable means of generating bubbles and controlling bubble size for column flotation. Approach Commercial sparger systems used in flotation columns to process minerals provide only limited means of controlling the size of bubbles generated and the rate of air injection. Generally, these limitations are a detriment to flotation performance, particularly in recovering coarse or fine mineral particles. In addition, conventional bubble generation systems require frequent maintenance, often requiring shut-down of the column itself for repairs. To permit greater control of the bubble size generated in the flotation column and to eliminate the counter-productive problems associated with the operation of current air sparger systems, the Bureau of Mines investigated alternative methods for generating bubbles. Based on the investigation, an external bubble generation system was designed, developed, and laboratory and commercially tested.

Jan 1, 1987

By P. Yant, A. C. Fieldner

"IntroductionIn its investigations relative to reducing the hazards of carbon monoxide poisoning, the Bureau of Mines recently had its attention drawn to a compound2a sold under a trade name for which claims are reported to have been made regarding its efficacy in reducing that type of poisoning in automobile garages. Accordingly, some of the product was obtained and analyzed for its power to absorb, oxidize, or destroy carbon monoxide; and the results are herein reported.Description of ""Compound"" (quoted from manufacturer's circular)While the circular does not actually state that the ""compound"" protects against carbon monoxide, the inference is therein, because each of the two following quotations is below these respective headings; ""Carbon-Monoxide Poisoning,"" and ""Chronic Gassing Among Garage Workers.""The ""compound"" holds chlorine and oxygen gases in solution with formaldehyde, which unites with the hydrogen to form hydrochloric acid., giving an over-supply of oxygen which burns up carbon just as a piece of wood is burned in the fire. The formaldehyde in the composition of the ""compound"" is a great affinity for ammonia and hydrogen sulphide."

Apr 1, 1924

Control dust generated during mining in salt mines. Approach A machine-mounted exhaust ventilation system which moves with the cutting machine from place to place was developed. The system captures the dust at the face of the heading and exhausts it downstream of the heading in the crosscut. This helps cause fresh air from the crosscut to flow over the machine operator's position, and aids in keeping the dust cloud close to the face. How It Works The system consists of (1) a circular intake hood with a 10-inch slot extending 250 degrees around the base, bolted to the gearhead; (2) 20-inch-diameter wire-wound flexible ducting to connect the intake hood to the fan (25 ft. is allowed sufficient slack for bar movement); (3) an industrial exhaust fan capable of generating 10,000 cfm with 13 inches water gage pressure at 1435 rpm; and (4) 150 ft. of collapsible 24-inch tubing for the exhaust duct which is de-played and returned In each heading by the cutter operator and/or his helper.

Jan 1, 1983

Develop a down-hole replaceable diamond core bit that will reduce overall drilling costs and increase total available drilling time per hole. Approach A one-piece diamond core drill bit of unique geometric shape has been designed, fabricated and field tested. The bit can be withdrawn (or replaced) from the bottom of the well-bore without removing the drill rods from the hole, saving a significant amount of non-productive drilling time. How It Works The replaceable bit system consists of two basic subsystems: the removable core bit, and the equipment necessary to replace the wornout bit without pulling the drill rods out of the hole. The geometric configuration of the bit is that of a one-piece diamond studded cutting element created by "slicing off" two parallel sides of a conventional diamond cone bit. This geometric configuration, along with some minor modifications to the outer core barrel, allows the bit to be rotated in two planes and, with the retraction-insertion tools, raised or lowered through the interior of the drill rods using a conventional wire-line system. For example, to retrieve the bit, a retraction tool is lowered through the drill rods using a conventional wire-line system and at the hole bottom, the tool automatically orients itself within the outer core barrel.

Jan 1, 1981

Measure dangerously high concentrations (20 to 500 g/m3) of flammable, airborne dust. Approach Development of high concentration dust monitor (HCDM) which will measure mass concentrations of air borne dust by the principle of beta-ray attenuation. How It Works The HCDM is a battery powered, portable instrument that weighs 10.5 kg. It is capable of making continual (10 sec. time resolution) measurements of high concentrations of airborne dust and can record up to 8 hours of data in an internal memory. The data can be read out later on an analog or digital recorder. An internal pump pulls airborne dust into the sampling section, which contains a low-energy beta-ray source and a Geiger counter detector. No beta radiation escapes from the instrument, and no license is required for the operator. The mass concentration measurement is made while the dust is still airborne. Beta-ray attentuation is independent of particle size and composition of the dust, so the HCDM can he used with many types of dusts which may be airborne in flammable concentrations. A knowledge of the composition and minimum explosive concentration of the dust is necessary to understand the significance of the data from the HCDM. The HCDM was designed to measure air-

Jan 1, 1982

Use instantaneous sampling to pinpoint dust sources and to Improve dust control on longwalls. Approach Use a dust monitor developed under a Bureau contract. How It Works Sampling can be done by either a moving or a stationary method. In the "moving' method, the dust monitor is carried by a survey engineer walking at the midpoint of the shearer Dust levels and face position (support number) are taken during all phases of the mining cycle while the shearer is cutting. These measurements can show how changes in airflow along the face, face specific; (rock partings) and cutting sequence (cutting the wedge) variables affect dust levels. In the "stationary sampling" method, the survey engineer stands with the RAM at a fixed location on the face. As the shearer approaches, the dust level and the distance to the shearer are recorded at 10-second intervals. Typically measurements start when the shearer is 20 feet from the sampling position and continue as the shearer passes the position until it is 20 feet away on the other side. Dust profiles around the machine are obtained at several fixed locations along the face only while the shearer is cutting.

Jan 1, 1982

By W. E. Robinson

Oil-shale samples selected from a core of the Green River Basin (Wyoming) were studied to ascertain differences in the composition and/or chemical structure of the organic material in the samples relative to stratigraphic position within the Green River Formation. This involved a systematic study of the soluble organic material and the insoluble kerogen present in the samples. Emphasis was placed upon the distribution of the alkanes (normal and isoprenoid compounds) in the soluble extract and upon the aromaticity of the kerogen. In general, it was concluded that significant differences exist in the chemical structure of the oil-shale organic material from various strata within the Green River Formation of Wyoming. Most of the compositional and structural changes were not related to burial depth but were related to source material variations, environmental differences, or other factors.

By J. D. Sargent

Selenium might be described as a paradoxical element, being a metal or a nonmetal, a conductor or nonconductor, amorphous or crystalline, colorant or decolorant, and a hydrogenator or dehydrogenator. Selenium was discovered in 1817 by the Swedish chemist, Berzelius, while studying flue dust from the lead chambers of the sulfuric acid works at Gripsholm, Sweden.

Jan 1, 1954

By William P. Diamond

A 3-inch pilot hole was directionally drilled to intercept the Freeport coalbed horizon horizontally at Mather, Pa., as part of a Bureau of Mines degasification project. The original concept was to continue the horizontal drilling into the coalbed, after the initial intercept, with a total of three horizontal holes eventually being completed. However, the erratic thickness (0.0 to 4.3 feet) of the Freeport coalbed at Mather was not sufficient to support the horizontal drilling degasification technique, and the site was abandoned after six attempts to locate adequate continuous coal thicknesses. The drilling of coreholes in the immediate vicinity of proposed well paths to evaluate coal thickness is essential prior to future slant hole operations. Although mechanical failures of the new directional drilling equipment, mud pump and rig breakdowns, directional control problems, and exploratory horizontal drilling in the Freeport horizon more than doubled the anticipated cost of the pilot hole, continuing improvements in directional drilling equipment and techniques should significantly reduce the time and costs of future drilling operations.

Jan 1, 1977

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Jan 1, 2011

By Fred Leighton

The least squares method of rock noise source location presented is shown to be more accurate and reliable than standard direct solution methods. This method is particularly effective in improving solutions from rock noise locations outside of geophone array boundaries. A least squares solution for a medium .in which the seismic velocity is the same in all directions is also presented. In this special case, one can solve for both the source coordinates and the velocity.

Jan 1, 1972

By John R. Benham

The Long Swamp RARE II area contains no prospects, claims, or mines. It has a low potential for ore deposits. There are no geothermal, oil, or gas leases in the area. APPRAISAL There are no mining districts in the study area. The nearest is Chewack Mining District, which is 6 mi (9.6 km) north of the area. This district had numerous claims located for tungsten; the principal tungsten ore mineral was wolframite. Wolframite was found here in 1898 by surveyors of the International Boundary Commission. The area was staked in 1908 and developed during 1915 and 1916. Only in 1936 was ore shipped; the 30 ton (27.2 t) shipment proved to be unprofitable for the claimants (Culver, 1945, p. 41).

Jan 1, 1982

By Edward P. Barrett

[Iron oxides, when reduced at temperatures below 900° form a dark gray substance, very porous bait otherwise in almost the same form as the original particles. In the temperature ire range of 1,000 to 1,100° the product is pertly sintered but still shows the outlines of the original particles. Those products are known as "sponge iron." At temperatures of 1,100 to 1,2000 the metallic iron begins to flow together and to a semifused, pasty, porous mass called a "bloom," which can he worked under a hammer to form a product similar to wrought iron; it contains slag inclusions and is too low in carbon to make steel. If the temperature is 1,300 to 1,300°, part of the iron will fuse enough to absorb more carbon. The dissolved carbon lowers the melting point and still more carbon is absorbed. The melted portion acts a flux for the unmelted metallic particles until the entire mass becomes a high-carbon fluid known as "cast iron." Sponge iron was probably the form in which the first iron was recovered from the ores. As early as the eighth century the Catlan forge3 developed into a low-shaft furnace known as the "high bloomary," in which iron eras produced in the form of a pasty mass. In 1340 the first blast furnace was built in Belgium. The greater part of the iron was made into wrought-iron blooms by crude puddling processes. Charcoal was used as the fuel until tie latter part of the 17th century when coke was used in England. In 1865 Bessemer built his first converter in. England, and within a few years the Siemen's regenerative open-hearth furnace was developed, also in England. Enormous expansion in the metallurgy of iron followed. The idea of "direct processes" for the production of iron arid steel has persisted throughout all this time. The production of steel from sponge iron has theoretical advantages over the present-day standard methods, and handreds of so--called "direct processes" have been proposed or tried during the past century.4]

Jan 1, 1929