Search Documents

By T. A. Johnson

Recovering from low demand in 1975, raw mineral production in the United States maintained a steady climb in value and quantity throughout 1976, keeping pace with the gross national product (GNP), which increased 11.5% compared with that of 1975. The minerals industry, in the past, has met ever-increasing demand while keeping production costs to a minimum. To maintain this capability, technological research and development of more efficient processing methods must continue. The role of Government and its increasing involvement in minerals industry actions received unfavorable comment from various segments of the industry in 1976. Government pricing controls were of concern to most industrial firms marketing like products. Public land withdrawals in large blocks were of concern to the mineral industry.

Jan 1, 1978

By John Millhiser, Stephen J. Kravits

The U.S. Bureau of Mines preproduction Wireless Survey System (WSS) and its performance during an in-mine test are discussed in this report. The WSS was developed to reduce downhole surveying time in order to increase the efficiency of drilling long horizontal methane drainage boreholes in coal. Borehole survey data are electromagnetically transmitted from the WSS7s downhole guidance probe, via the drill rod, to the uph'ole subsystem in less than 1 min per survey transmission, regardless of borehole depth. The WSS7s in-mine test consisted of providing borehole survey data during the directional drilling of a 2,538-ft horizontal methane drainage borehole in the Pittsburgh Coalbed. By considering available drilling time, which does not include hydraulic drill downtime and the time spent traveling portal to portal, 24 shifts were needed to complete the borehole. Of the available drilling time during the tcst, 50 pct of the time was spent drilling and 50 pct surveying and maintaining the WSS to keep it operational. Previous Bureau experience indicates drilling efficiency was increased 108 pct because of the WSS, in comparison with using a commercially available wire-run directional survey instrument at 10-ft intervals.

Jan 1, 1990

By Barbara J. Halpern

There?s no denying that mining is a male-dominated industry. Yet thanks to technologies developed over the last 20 years, societal changes in sex role stereotyping, individual determi­nation, and the willingness of companies to train women, there are no jobs in mining today where women are not represented. Women are drillers and electricians as well as drivers of heavy equipment and haulpack trucks. They perform jobs ranging from field exploration and metallurgy to clerical and janitorial and warehousing positions, from prospectors and underground blasters to geologists and land reclamation experts, from communicators to legal experts on mining law and more. The Women?s Mining Coalition, founded in 1994 to shepherd responsible legislative mining reform, estimates that 20 percent of the workers in the mining industry are women. Although women are concentrated in clerical and adminis­trative jobs, at least 10 percent are in non-traditional, hardhat jobs, claims the group. There are women in management, but the numbers in senior management remain small, especially in larger companies.

Feb 1, 1998

By H. W. Lang

The Bureau of Mines conducted an investigation to observe the effect of cetane improvers upon nitrogen oxides concentration in diesel exhaust gas. Amyl nitrite and amyl nitrate were used as additives to the fuel used in a four-cycle, single cylinder type test engine. It was concluded that nitrogen oxide concentrations were not enhanced at fuel-air ratios above 0.03 pound of fuel per pound of air.

Jan 1, 1969

By N. A. C. Smith

One of the most important considerations in any manufacturing industry is the production of stable material, that is, material which will not change in quality before it reaches the consumer. The manufacturer of gasoline, the refiner of crude petroleum, is handicapped in this respect by the varying nature of his raw material, but as far as it is commercially practicable, he has endeavored to improve his product, and in most cases he has been eminently successful. It sometimes happens, however, that a gasoline that is apparently normal when first made, will In time deposit small quantities of a gummy substance. The present Investigation was undertaken in the hope that it would throw some light on these gums and indicate how their formation might be prevented.

Jan 1, 1922

By D. T. Hahn

Adequate and cost effective erosion control is an important component in most plans for reclamation of surface mined land. Despite the fact that much is known about erosion of agricultural lands, insufficient conclusive knowledge is available about erosion of reclaimed surface mined land. Our study was conducted to characterize the erodibility of reclaimed surface mine land relative to unmined cropped land, and to evaluate the accuracy of the universal soil loss equation (USLE) in estimating erosion from reclaimed soils. A rainfall simulator was used to measure runoff and erosion rates from plots at three Indiana surface mines. The relation of erosion of the reclaimed soils was not completely constant with that from the cropped soils. Significant differences in erodibility were observed between reclaimed and nonreclaimed top soils, as well as reclaimed topsoils and reclaimed subsoils.

Jan 1, 2011

By B. W. Jong

As part of the Bureau of Mines program to develop substitute or improved performance refractory materials for metallurgical applications, the Tuscaloosa Research Center has evaluated the effect of additives on sintering and strength properties of aialon (silicon aluminum oxynitride) compositions fabricated by a conventional powder metallurgy technique. Additions of Y203, Gd203, CeO2, MgO, ZrO2, ZrSiO4, and MgA12O4 to a sialon composition containing 70 pct ß-Si3N4 + 30 pct a-A1203 increased sintered densities by as much as 50 pct over densities of undoped material. The studies also indicated that sintered densities reached a maximum between 20 and 30 mole-pct a-A1203 when a series of sialon compositions of a-Si3N4, having 6.7 to 57.9 pet a-Al203, were doped with Y203, Gd2O3, and MgO. In studies to establish the effect of the crystalline phase of the silicon nitride and alumina used, tests were made using a- and ß-Si3N4 and a- and ?-A12 03 as starting materials. The tests indicated that when using an addition of 5 wt-pct Y203, best results were obtained with a sialon composed of 74.4 mole-pct a-Si304 and 25.6 mole-pct ?-A1203. In other tests made with this sialon composition MOR values of 28,120 and 29,500 psi at 25° C, and 23,520 and 16,850 psi at 1,400° C, were obtained when doping with 5 wt-pct ZrSiO4 and ZrO2, respectively.

Jan 1, 1980

By W. E. Anable

A 180° magnetic deflection residual gas analyzer mass spectrometer with a mass range of 2 to 200 amu was used to study the nature of gases evolved during arc and electron-beam melting of certain reactive and refractory metals. The partial pressure of residual gases over molten Mo, Hf, Ti, and Fe, was found to be similar: Water and hydrogen were evolved from the samples and from the furnace components, carbon dioxide and carbon monoxide resulted from deoxidation of some of the melts. Argon and acetone were residuals in the system, and methane was a decomposed organic compound from the oil diffusion pump.

Jan 1, 1969

By D. C. Fleck

The Bureau of Mines, in a cooperative research program with four lead companies, has investigated ferric chloride leaching of galena to prepare lead chloride for molten-salt electrowinning to produce lead metal. The hydrometallurgical-electrolytic process is an alternative to the sintering-smelting-refining process currently used to produce lead metal and avoids the environmental problems associated with a conventional smelter. During investigations on the electrowinning aspects of the work, it was noted that certain cations, moisture, and sulfate in the electrolyte affect lead metal purity, cell voltage, current efficiency, and viscosity of the electrolyte. Results of bench-scale tests are re-ported on the effects of CaCI2, CuCI2, FeCI2, MgCI2, NaCI, ZnCI2, PbS04, and moisture on electrolysis. As impurities increased in the electrolyte, current efficiency decreased. CaCI2, CuCI2, and FeC12 decreased current efficiency by 12 to 47 pct. ZnCl2 gave a small voltage increase, while CaCI2 addition equivalent to 4.9 pct Ca caused a 50-pet increase in voltage. The lead metal was contaminated in direct proportion to the CuCI2 buildup in the electrolyte, Anode corrosion was observed with MgCI2 and MgC12?6H20. Viscosity increased appreciably with the buildup of NaCI, CaCI2, and sulfate. Electrolyte foaming occurred with ZnC12, MgC12?6H20, MgC12, FeC12?2H20, and FeCI2. Moisture inhibited the coalescence of the lead metal.

Jan 1, 1983

To develop an in-mine water treatment system in which bacterial sulfate reduction and limestone dissolution continuously remove metals and acidity from contaminated drainage. Approach A section of mine tunnel was converted into a water treatment bioreactor by constructing cinder block dams and fang the area between them with a porous substrate mixture of limestone gravel and compost. Readily fermentable materials such as dairy whey, spent brewing yeast, or sugar were periodically added to the reactor. Mine drainage was impounded behind one of the dams and continuously percolates through the reactor substrate at a controlled rate. How It Works The reactor substrate soon becomes anaerobic after it is saturated with mine water. Under anaerobic conditions, sulfate-reducing bacteria consume the organic materials that are added to the reactor and generate hydrogen sulfide (HIS) and alkalinity. The H2S reacts with dissolved iron and heavy metals to form metal sulfide precipitates. The alkalinity raises the pH of the water and induces aluminum to hydrolyze and precipitate as aluminum hydroxide [Al(OH)3]. Additional alkalinity is generated by the continuous dissolution of the substrate limestone. Metal sulfide precipitates and Al(OH)3 are retained within the reactor, and the treated water is discharged. The underground location of the system allows year round operation.

Jan 1, 1994

Synthetic dawsonite [NaAl(OH)2C03] has been prepared with crystallinity similar to that of dawsonite found in oil shale deposits of the Piceance Creek area of Colorado. Optimum experimental conditions were as follows: Na/Al atomic ratio, 43; temperature, 175° to 200° C; pCO2, 15 psig; and reaction time 5 hr. Chemical and spectrographic analysis revealed that the synthetic dawsonite was of high purity and Has essentially stoichwmetric. Similarity of the synthetic to natural dawsonite, demonstrated by X-ray diffraction, infrared spectrophotometry, and electron microscopy, suggests its suitability as a standard.

Jan 1, 1972

By Manuel Gomez

The purpose of this study was to evaluate the feasibility of using statistical response surface regression analysis to predict the sulfur and ash distributions and the washability characteristics of coal along a seam in advance of mining. Prediction equations were developed with experimental data from channel, bench, and core samples from the Pittsburgh coal seam in Greene County, Pa. It was not possible, with the available experimental data, to construct mathematical models to predict ash and sulfur concentrations between sample points. In the authors' opinion, however, the good agreement between experimentally determined and predicted values at given sample points demonstrates the usefulness of the method. More input data, such as geologic information, seam characteristics (rock-to-coal ratio), petrographic analysis, and chemical data, would perhaps make it possible to predict sulfur and ash concentrations and washability characteristics between sample points.

Jan 1, 1970

Reduce longwall intake contamination by controlling respirable dust generated by the stage loader. Approach Install a water-powered scrubber on the stage loader immediately outby the crusher. Dusty air from the crusher is drawn through the scrubber and a clean air discharge is delivered into the primary face airflow. How It Works The contamination of intake air is a significant dust control problem often overlooked on many longwall faces. This dust source contributes to the full shift dust exposure of all face personnel, and thus can significantly affect compliance with Federal regulations. Several sources contribute to contamination; however, dust generated by the stage loader crusher is the single largest source. The breaking action of the crusher generates a tremendous quantity of dust, which mixes with the primary ventilation airstream and is carried down the entire length of the longwall face. The installation of a water-powered scrubber (see diagram) has proven effective in controlling crusher-generated dust. The scrubber is mounted immediately outby the crusher. A duct is placed over the scrubber intake and attached to a flanged opening over the crusher discharge. In

Jan 1, 1982

By Louis A. Turnbull, JOSEPH J. SHIELDS

The Bell & Zoller Coal & Mining Co. recently completed construction of two slopes at Mine 3 near Zeigler , Ill . The slopes are in the Big Muddy River Valley , and construction was particularly difficult because the strata from the surface to a depth of 70 feet comprise water saturated sandy clay and sand . Many mining companies have similar shaft- and slope - sinking problems , and because these slopes were satisfactorily completed and now are in use the methods followed during construction are described in this information circular . It is believed that other companies with similar problems . will benefit by adopting the methods followed at Mine 3 .

Apr 1, 1949

By E. J. Ostrowski

The Bureau of Mines experimental blast furnace, Bruceton, Pa., was operated to determine the feasibility of replacing part of the burden coke requirements with solid fuels injected directly into the smelting zone. This report describes preliminary experiments and information resulting from such an interchange. These experiments were made on an all-sinter burden, using two parts sinter to one part fuel. Anthracite fines were injected intermittently into the smelting zone of the furnace by compressed air through auxiliary tuyeres. The interval between injection periods ranged from 5 to 15 minutes. A maximum of 28 percent of the stock column coke bur-den was replaced. This percentage replacement caused furnace malfunction, but the overall percentage of these experiments indicated that 20 to 24 percent of the coke requirements could be replaced in this way. The metallurgical coke consumption was decreased by as much as 377 pounds (25.3 percent) per ton of pig metal produced. Buckwheat anthracite No.4 was used in this experiment; however, such solids as bituminous coal or coke fines also could be used. The frequency as well as the quantity of solid fuel injected has a direct bearing on furnace performance.

Jan 1, 1960

By J. E. Gebhardt

External control of the electrochemical potential of a bed of mineral particles has been investigated by the Bureau of Mines as a method for controlling particle inter-action with organic collectors and thus, flotation response. A cylindrically shaped, 200-to 300-g bed of sulfide mineral particles was used as the working electrode to examine the potential distribution in the bed. The dissolved oxygen concentration of the electrolyte had a significant effect on the potential profile across the mineral bed. Low oxygen levels were necessary to achieve uniform electrochemical potential distributions. Flotation separation of a chalcocite-pyrite mineral mixture by controlled potential was achieved using ethylxanthate, but the flotation behavior of chalcocite and pyrite from the mixture does not follow the flotation behavior of the individual minerals. That is, the presence of another sulfide mineral alters the flotation behavior with ethylxan-thate. Galvanic interaction due to mineral-to-mineral contact between chalcocite and pyrite contributes to differences in the recovery. Chalcocite dissolution products had a deleterious effect on pyrite flotation by activating flotation below -0.1 V (saturated calomel electrode) and depressing flotation above -0.1 V. Pyrite dissolution products had no effect on chalcocite flotation.

Jan 1, 1985

By William K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating the electrochemistry of mineral flotation. A significant need in this area is greater reliability of sensors. The USBM is testing electrolytic methods to clean and condition redox-sensing electrodes to improve the reliability and extend the service life of these instruments in the harsh physical and chemical environment of mineral processing slurries. A novel method for removing scale from fouled electrodes has been developed that includes anodic polarization to 1.2 V versus the Ag/ AgC1 reference potential, followed by brief potentiodynamic conditioning. Laboratory results show that this technique removes calcarious deposits from gold sensing electrodes and returns the electrodes to useful service within approximately 10 min. Mechanical abrasion to remove the scale is thereby avoided.

Jan 1, 2010

By R. H. Thompson

Six different types of blasting caps, mainly of the type used in coal mines, were evaluated to determine both their 1lF and DC characteristics. Two of the caps were of foreign manufacture. All the American made caps had "no-fire" (0.1% firing probability with 95% confidence, as determined by the Bruceton test) levels above 0.04 watts. One of the caps of foreign manufacture had a "no-fire" level of 0.023 watts. A worst case analysis of blasting cap pick up of RF power in coal mines was performed and safe distance curves were generated.

Jan 8, 1973

By William G. Gruzenaky

The separation of yttrium and the individual rare-earth elements (lanthanons) from mixtures in which they occur has been a difficult problem through-out the years. Because of the increased interest in the various uses of these metals, the economy of their production may become of great importance. Studies relative to this problem, undertaken at the Federal Bureau of Mines Albany Metallurgy Research Center, resulted in the development of a solvent extraction method by which yttrium can be separated from the rare-earth metals. A separation factor of 10.93 was obtained between yttrium and cerium from a single-stage extraction, and a factor of 1.78 was obtained between yttrium and erbium from a multistage system. The valuable metals were extracted from euxenite by caustic soda fusion or by chlorination, and several separation methods were investigated. Partial separation of the yttrium and rare-earth element fraction was made by chemical methods and by solvent extraction. Thermal decomposition of aqueous rare-earth nitrates or selective ignition of yttrium and rare-earth oxalates yielded a fraction enriched in cerium. A fraction enriched in the light rare-earth elements resulted from a double sulfate precipitation, whereas a potassium ferrocyanide pr cipitation yielded a fraction enriched in yttrium. Precipitation with dimethyl phosphate yielded a fraction enriched in yttrium and heavy rare-earth elements. Enriched fractions were obtained with several solvent extraction systems. A system consisting of rare-earth nitrates, nitric acid, and tri-n-butylamine-3 methyl-2-butanone favored the separation of yttrium from the heavy as well as from the light rare-earth elements.

Jan 1, 1961

By S. J. Davenport

[The tremendous increase in mine mechanization since 1929 has increased markedly the application of electric power in and about the coal mines of the United States. Cutting, drilling, and leading machines have replaced hand-mining methods in nary mines. As a result, expansion of the gathering haulage has necessitated introduction of extensive feeder, trolley, grid other power wires. (1)3/ In spite of this vast mechanization the fatality rate from electric shock has been on the decline. However, there are still too many accidents, and efforts to eliminate electrical hazards cannot be relaxed. It is hoped that an acquaintance with the physiological aspects of electrical accidents will make workers end management aware of the lurking dangers of this very common and extremely dangerous form of energy.]

Jan 1, 1951