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Provide minx operators with means for evaluating dust generation and bit wear effects on Production without costly and extensive underground testing. Approach Develop personal-computer-based cutting system models that will simultaneously evaluate machine, Coal seam, and mine-operator-controlled parameters for their interactive effects on dust generation, bit wear, and Production by either a longwall shearer or a continuous miner. How It Works CSM Programs have been developed to analyze relative dust generated by a double-drum, ranging arm, longwall shearer and a continuous miner. These interactive programs Provide relative dust, culling forces, and production values for any given set of mining machine parameters, specific seam conditions, and operator-controllable parameters. Expanded versions of each program provide a dynamic evaluation of the effects of bit wear, over time, on production.

Jan 1, 1989

By David J. MacDonald

Stability constants, that is, equilibrium constants for complex-formation reactions, have been determined by a titrimetric method for complexes formed by the transition metal ions Ni2+, Cu2+, Zn2+, and Cd2+ with the structurally analogous bidentate ligands N-ethylethylenediamine and 2-(ethylthio)-ethylamine. The sulfur containing ligand was found to be the weaker of the two chelating agents for each of the four metals. Absorption spectra of the individual complexes have been determined in order to calculate their crystal field stabilization energies. The combined results suggest a linear relation between free energy of chelation and ionic radius of the metal ion.

Jan 1, 1972

By Parviz F. Rad

The Bureau of Mines conducted rock-cutting experiments under constant normal force and constant penetration in an effort to correlate laboratory data with those obtained in the field. Both independent and interacting groove spacing regions were studied, and optimum and critical cutter spacings were determined. For the laboratory work, the effects of specific energy, muck weight, groove depth, cutting coefficient, and size distribution of the muck for both independent and interacting grooves were studied. For field operations, forward thrust, torque, advance rate, and muck size distribution were the parameters studied. Satisfactory correlation is obtained between laboratory cutting results and field performance data.

Jan 1, 1974

Develop a method for control of groundwater inflow to chronically "wet" sections of underground coal mines, in order to reduce groundwater interference with mining activity and to minimize acid mine drainage. Approach In eastern coal regions, groundwater stored in fracture zones in the rock mass can create a significant water problem for underground mining operations. Fracture stored inflow to mine workings impedes mine productivity since storage water sources usually release at the active face, creating the poor mining conditions typical of a "wet" section. Fracture water can also contribute to AMD problems when the water subsequently contacts sulfide minerals in the coal, The Bureau of Mines has developed a mine-dewatering method that eliminates many of the problems associated with mine water inflow by draining these fracture zones before the water can reach the developing face and interfere with mining activity. How it Works The dewatering method removes large volumes of the stored groundwater through high-capacity pumping from a minimal number of wells placed strategically on fracture traces (the surface expressions of fractured rock zones). These fracture traces are located through low-level aerial photographic and geologic investigation. As shown on the map, dewatering wells are sited precisely on fracture trace intersections in order to take advantage of the increased pumping capacity gained from these zones of high permeability. Once well drawdown indicates that the stored water is depleted,

Jan 1, 1983

By G. W. Eiger

Bureau of Mines laboratory tests show that ilmenite concentrates with titanium dioxide contents as low as 33 wt--pct can be beneficiated to produce a crystalline substitute for natural rutile suitable for direct chlorination. The synthesized product prepared by a three-step procedure was comparable with natural rutile in titanium content. Reduction smelting of ilmenite removes iron as a pig iron byproduct, and the remaining slag phase is greatly enriched in titanium. Oxidation of the slag in the presence of phosphorus¬bearing slag additive converts the titanium-bearing phases to discrete rutile crystals and a glass phase containing most of the associated impurities. Rutile is separated from the glassy impurities by attrition scrubbing ground slag in dilute phosphoric or sulfuric acid solutions. Tests made in a laboratory fluid-bed reactor show that synthetic rutile responds to chlorination at the same rate as natural rutile and that more than 95 pct of the titanium contained in the feedstock was extracted as titanium tetrachloride.

Jan 1, 1974

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

Provide respiratory protection for escape in a toxic or oxygen-deficient atmosphere with a device small and light enough to be belt-worn. Approach Combine a 10-minute, belt-worn respirator with a stored, larger, long-duration (60-minute) attachment that can be plugged into the 10-minute unit without removing the mouthpiece. How It Works The 10-minute device will be carried by the miner at all times, and the 60-minute canister or attachment will be stored near the miner. In the event of a disaster, the 10-minute device would be donned immediately. The miner would then proceed to the stored 60-minute unit and plug it into the 10-minute unit. For the 10-minute unit, a breathing circuit was developed in which air is passed through the KO2 bed twice per respiration. The 60-minute canister differs from the 10-minute unit in that air is drawn only once through the chemical bed per respira-

Jan 1, 1981

By Laurance L. Oden

The Bureau of Mines studied three processes for preparing NaAl(OH)2C03) the intermediate compound which is calcined to produce alkalized alumina: (1) Mixing of Na2 C03 and of A12 (S04)3 solutions, (2) digestion of aluminum hydroxide in solutions of Na2C03 and NaHC03 at 90° C, and (3) addition of CO2 at 25° C to caustic solutions of aluminum to precipitate aluminum hydroxide followed by digestion at 90° C. The first process had the highest raw material consumption and washing requirements, and successful application of process 2 depended upon the availability of active aluminum hydroxide. Process 3 was the most effective, considering both process technology and raw material requirements. Procedures were also investigated for washing, filtering, drying, and calcining precipitates. Analytical methods included X-ray diffraction, atomic absorption spectroscopy, differential thermal analysis, and thermogravimetric analysis.

Jan 1, 1969

By W. S. Anderson

The use of flexible liners for support of underground openings has been investigated by the Bureau of Mines. This report presents installation procedures and instrumentation results of a full-scale flexible liner field installation in the Burgin mine. The flexible liner is a part of the mine support system and has provided maintenance-free support for 22 months

Jan 1, 1975

Improve the safety, reliability and overall effectiveness of mine stench warning systems and to provide a means of remote control stench injector operation. Approach Industrial gas odorants were analyzed for their suitability for use in mine stench warning systems. A prototype stench injector capable of precise flowrate control was designed, fabricated, and tested using the odorant chosen as having the most favorable properties. Based on the results of the field tests, a second generation injector was developed. The second generation unit features optional remote control operation, and in addition, is simpler to refill and is less expensive than the original injector. A complete second generation system, consisting of two manually operated injectors and one remote controlled injector was in-mine tested through actual mine fire drills. How It Works Ethyl mercaptan mixed with Freon is the predominant stench agent used in the U.S. underground metal and nonmetal mines. However ethyl mercaptan's toxicity,

Jan 1, 1982

By J. Hudy

The performance of six dense-medium washers was evaluated in five preparation plants. Three of the plants were making a two-product separation that produced a clean coal and a refuse; one plant employed dense-medium vessels in series to effect a primary and a secondary separation; and one plant was equipped with a two-compartment washer effecting two separations in one vessel. The separate secondary drum-type washer produced a low-ash metallurgical coal and an intermediate-ash product suitable for plant fuel or steam generation. The two-compartment washer produced a premium anthracite product and a middlings product. The sharpness-of-separation values ranged from good to excellent for the five primary separations and for the secondary separation.

Jan 1, 1968

By C. Q. Cupps

Rate of gas diffusion in reservoir oil has been investigated in an effort to explain the variation in oil characteristics observed in the Weber Sandstone reservoir, Rangely field, Colorado. Coefficients of gas diffusion were determined experimentally for the Rangely oil system and used in a mathematical simulation of gas diffusion during the probable life of the Rangely reservoir, estimated at 65 million years. The simulator involved solution of Fick's law for diffusion in two dimensions by the method of finite difference and successive over-relaxation. The results show that continuing gas diffusion is a logical explanation for the variation in oil characteristics at Rangely and that the pattern of gas distribution by diffusion in an asymmetrical reservoir will not conform to structural contours as originally proposed.

Jan 1, 1971

By Robert L. Lagace, Alfred G. Emslie

This report presents a mathematical model for the propagation of UHF radio waves in the large cross-section tunnels of a room and pillar limestone mine, and describes the analysis of a small amount of propagation data obtained in a limestone mine. The model and analysis is based on the waveguide mode theory developed earlier for the transmission of UHF waves in coal mine tunnels, with allowance for propagation losses due to refraction into the tunnel walls, to scattering by wall roughness, and to long range random tilt of the walls. Propagation around corners and through pillars is also examined based on a ray theory approach, together with the beneficial effects of placing reflectors at intersections to significantly reduce corner losses. The theory is found to be in fair agreement with the data; however, additional in-mine measurements are needed to provide a more conclusive test of the model.

Jan 1, 1979

By E. G. Valdez

Iron foundries that melt automobile scrap produce flue dusts averaging about 32 percent zinc and 6 percent lead. Some is sold to smelters, but because of the meager return and difficulty in handling, most of the dust is discarded. As part of the Bureau of Mines program to find uses for mineral wastes, research was initiated to develop an economical process to recover zinc and lead from the flue dust. Research encompassed the extraction of zinc and lead by fuming, leaching, and agglomeration. Controlled vacuum fuming of zinc to produce Prime Western zinc and a lead-rich residue was the most effective method for treating the dust. This process involved two distillations, or fumings, with carbon and methane as reductants, and resulted in recovery of 91.4 percent of the zinc in a Prime Western grade product, and 98 percent of the lead. Hydrometallurgical techniques involved several leaching methods, but the simultaneous extraction of iron, manganese, and copper resulted in contamination of the solution and made the zinc recovery processes too complicated. Agglomeration was done by pelletizing or briquetting the dust for possible use as feed to a zinc smelter.

Jan 1, 1975

By C. M. McCulloch

Examination of several coalbeds in Walker County, Ala., Cambria, Greene, and Fayette Counties, Pa., and Raleigh and Wyoming Counties, W. Va., indicates that cleat orientations are similar throughout a vertical sequence of strata. Studies of cleat orientation were carried out in underground mines that are operating in separate coalbeds vertically above one another. The data show that over a vertical separation of 100 to 400 feet, the average difference in coal cleat orientation between mines is 04° for the face and 08° for the butt cleat. Variations of coal cleat direction between coalbeds examined in strip-mined areas show similar values. Cleat orientations measured at outcrops agree well with the directions measured underground, suggesting that the amount of vertical separation between coalbeds has little effect on the resulting differences in cleat directions. The largest variation of cleat directions between adjacent coalbeds occurs where a large horizontal distance separates two sample locations. Cleat orientations for deeper coalbeds are most reliable where the data are taken from directly above.

Jan 1, 1976

By Wesley A. Grosh

The Sutherland copper prospect is situated in Floyd County, Va. The immediate area was prospected around 1850, and one of the adits possibly dates from that time. Little or no ore has been mined from the deposit. The deposit is a mineralized sulfide zone occurring in mica schist and consisting mostly of pyrrhotite with minor amount of copper. A magnetometer survey of the deposit by the American Metal Co. in 1939 showed an anomaly that was thought to indicate a zone: of secondary enrichment. The Bureau of Mines diamond-drilled 14 holes, totaling 913 feet, and opened an adit during February and March 1943. No appreciable copper values or indications of secondary enrichment were found.

Jan 1, 1948

By John Nagy

Data from experiments and literature on gas and dust explosions in closed vessels are presented to show the effects of the vessel size and shape; the initial pressure, temperature, and turbulence; and the fuel-air ratio and the strength of ignition source on pressure and rate of pressure rise. An attempt is made to correlate some of these parameters with an elementary mathematical model. Analyses of data on 17 vessels--spherical, cubical, cylindrical, and rectilinear in shape--ranging from 0,018 to 905 cubic feet in volume were made. Although the study was initiated to provide information primarily on dust-explosion phenomena, some data were obtained for gas explosions so that the factor of initial turbulence caused by the pneumatic blast used to disperse dust could be evaluated. The mathematical interpretation of the explosion phenomena was in general accord with the experimental data, and correlation was obtained for several factors affecting explosion development. Neither vessel size nor shape affected maximum pressure (when heat loss was neglected). The rate of pres-sure rise decreased as vessel size increased, and the rate was proportional to the ratio of the surface area of the vessel to its volume. Induced initial turbulence markedly increased the rate of pressure rise and slightly increased the maximum pressure. Changes in initial pressure produced proportional changes in maximum pressure and rate of pressure rise. Initial temperature and maximum pressure were inversely related, but initial temperature had little effect on the maximum rate of pressure rise. Comparative experiments showed no appreciable difference in explosion development of gas and dust fuels. The vessels and experimental work are described, and all data are given in tables. The mathematical model will facilitate extrapolation from laboratory to industrial conditions and will allow comparison of results obtained in different laboratories.

Jan 1, 1971

By Deno M. Pappas, Christopher Mark, Eric R. Bauer

During 1998-99, groundfall incidents resulted in 27 fatalities and were responsible for over 70% of all deaths in U.S. underground coal mines. To obtain a better understanding of where and why these incidents occurred, a comprehensive analysis of ground fall injuries and fatalities was conducted. The first portion of the study examined various factors associated with roof and rib fall injuries and reportable roof fall noninjuries that occurred during 1995-98. The study found that the room-and-pillar mining method has twice the groundfall incident rate than the longwall method. Mine locations with high groundfall rates seem to correlate to regions where there is a higher concentration of problematic coalbeds. For example, the Illinois Basin has very high groundfall rates, which can be traced back to several key coalbeds-Kentucky No. 13, Herrin/No. 6/Kentucky No. 11, and Springfield No. 5/Kentucky No. 9. High rib fall rates were found in mines located in thick seams. Groundfall rates were found to be 30% to 40% higher during the months of July through September, possibly due to high humidity that may cause the shale mine roof to deteriorate. The second part of the study examined the root causes of failure by reviewing all groundfall fatality reports for 1996-99. Primary and secondary hazard factors were assigned to each groundfall incident. The primaryf actors resulting in these groundfall fatalities were pillar extraction, traveling under unsupported roof, skin failure, construction, longwall faces, intersections, and geologic discontinuities. Defining prominent ground control incident trends and hazards will identify areas where additional study is needed and where innovative solutions need to be developed to reduce these severe occupational hazards.

Jan 10, 2000

Avoid accidents that can occur when applying belt dressing from an aerosol can, particularly when can pressure has dropped or when spraying against wind. Approach Use a garde-type sprayer. How It Works Commercially available garden-type sprayers can be used for applying conveyor belt dressing from 12 feet away, or more. Pressure is easily raised and maintained at about 50 psi. Most sprayers have a hand pump, but a battery-powered cordless model is also available. Garden-type sprayers are available in various sizes from 11/2 to 18 gallons, with the larger models wheel mounted. The 3-gallon model evaluated by the Bureau has a shoulder carrying strap, which gives additional safety advantages. Use of the strap frees both hands for climbing ladders or holding onto catwalk rails. When spraying, one hand can remain on a handhold to lessen the chances of touching a moving belt.

Jan 1, 1980

By Andrew J. Fergus

A study of the flotation characteristics of columbium-tantalum minerals was made by contact-angle and microflotation methods, and the findings were confirmed by flotation of two natural ores. In the contact-angle study conditions for collection of columbite, pyrochlore, and tantalite were determined for (1) sodium oleate with a sulfonate; (2) sodium isooctyl phosphate; (3) a short-chain primary amine; (4) a long-chain primary amine; and (5) a quaternary amine. These conditions were confirmed in microflotation tests. Information about collector action on common gangue minerals was also obtained by these two methods. In batch flotation tests on a pyrochlore ore and a columbite ore, it was demonstrated that collectors selected on the basis of contact-angle and micro-flotation studies would float columbium minerals from a complex natural ore. However, multiple cleaner and scavenger flotation steps will be necessary to produce commercial concentrates. From a pyrochlore ore containing 0.54 percent Cb2O5, a 44.4 percent Cb2O5 concentrate was made containing 36.4 percent of the total Cb2O5. For a columbite are the corresponding values were: 4.35, 54.6, and 67.1 percent. During the batch flotation study, wetting agents were found to aid in the gangue-ore mineral separations.

Jan 1, 1968