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By Virgil J. Stachura

The Bureau of Mines conducted a series of delayed blasting experiments at a West Virginia contour coal mine that resulted in smoother highwalls. The 17; were smoother due to reduced overbreak and inherently safer A, to reduced likelihood of rockfall. Reduced overbreak was accomplished by an increase in the highwall hole delays, which changed the effective delay pattern geometry and the direction of burden movement. The blast delays in the highwall holes were 50 to 100 ms longer than the mine's nominal design pattern (flat V, 17- by 42-ms surface delays, 200-ms in-the-hole delay). The burden movement was effectively changed from a 45* angle to 90* with respect to the highwall. The results of the blast delay changes were evaluated using terrestrial photogrammetry to generate vertical profiles at regular intervals. This evaluation showed that delay changes produced generally smoother vertical profiles.

Jan 1, 1984

By Susan M. White

Increased coal production, wider use of indiscriminate mining techniques, improved cleaning methods, and greater emphasis on clean fuels is increasing the rate at which wastes accumulate Over the next several years, Colorado Plateau underground coal production is predicted to increase. Currently, mine refuse is deposited in canyons or lowland areas near mines. This study presents information on the nature of coal refuse and disposal practices on the Colorado Plateau. Samples were collected and analyzed to provide information to help formulate alternative methods for reclaiming refuse piles. The analyses were based on determining the capability of unmodified refuse to provide a suitable medium for plant growth. Local topsoils which would be used in reclamation were used as standards. Potential environmental hazards were assessed also. A general cost analysis was done for both surface and underground disposal and the advantages and disadvantages of each were assessed. Several problems were identified which, if solved, would increase the effectiveness of state regulatory programs.

Jan 1, 1982

Southeast Alaska's mining industry has come to life after nearly 50 years of relative dormancy. Commencement of operations of the Greens Creek Mine in 1989 marked a turning point in the industry as the first large scale mining operation in the region since closure of the Alaska-Juneau Mine in 1944. The Greens Creek Mine is now the nation's largest silver producer. Other large scale mining projects are now on the drawing board, including development of the Kensington Mine and reopening the Alaska-Juneau Mine, which could become North America's largest underground gold mine. The region's mining industry includes more than these large scale projects, however. For example, a significant level of mineral exploration occurs each summer in Southeast Alaska. In addition, mining operations in British Columbia and Yukon Territory are generating jobs and income in Southeast Alaska.

Jan 1, 1992

By John A. Breslin

Size distributions and concentrations of particulates emitted from diesel engine exhausts were measured with cascade impactors. Samples were taken from the exhaust of two types of engines using three types of fuel and operating under five different engine speed and load conditions. The measured mass median diameters of the diesel particulates were typically about 0.3 um. There was no significant difference in mass median diameter between engines or fuels and only a slight dependence on operating mode. Concentration measurements ranged from 14.2 to 250.9 mg/cu m, and calculated mass outputs, from 64 to 10,000 mg/min. Significant differences in mass output were found between engines, fuels, and especially between different operating modes. The quantity of clean dilution air that would be required to reduce the particulate mass concentration below the 2.0 mg/cu m respirable dust standard for coal mines was greater than the dilution air required to meet the standards for noxious gases for both engines tested.

Jan 1, 1976

By W. J. Boone, Will E. DeVaney, Lowell Stroud

This report is the fifth in a series presenting equilibrium vapor - liquid data for helium- bearing natural gases . It covers a 0.41 - mole - percent - helium natural gas that may be processed in the Department of the Interior's longrange helium conservation program . A Bureau of Mines phase equilibrium apparatus was used to obtain 139 samples of equilibrium vapor and liquid phases at 85 experimental conditions at temperatures from 0 ° to -299 ° F and at pressures from 100 to 500 psia . An appendix covers phase data at 100 , 200 , and 300 psia and at temperatures from -125 ° to -275 ° F for the dehydrated gas containing its original concentration ( 0.2 mole - percent ) of carbon dioxide , and the effect of a preliminary hydrocarbon trap upon subsequent vapor - liquid compositions .

Jan 1, 1964

By Donald E. Redmon

This Bureau of Mines report reviews injury experience in the metallic mineral industries for 1966-67. For each of the years, 27 tables summarize disabling work injuries by department, source of injury, extent of disability, part of body injured, and nature of injury. Correlative information on employment, worktime, and operating activity is also presented.

Jan 1, 1973

By A. Sainato, S. J. Schatzel, D. M. Hyman, J. C. LaScola

The Bureau of Mines determined the gas contents of 135 oil shale samples obtained from approximately 630 ft of core drilling. Drilling was done within a projected mining zone of the Cathedral Sluffs Mine, located in the Piceance Basin of western Colorado. Methane contents were determined by the modified direct method, which can measure the volumes of several gases released from or reacted with mine rock without destructive sample treatment. Over the duration of the test, nitrogen was largely unreactive, CO2 increased slightly, oxygen decreased markedly, and methane increased more than the total increase of all contained gases. The gas volumes were normalized per unit sample mass and are given in cubic centimeters per gram. Common time irzdices for test duration of 3, 40, and 125 days were used to compare methane desorption among samples. The means of the sample populations for these indices were 0.0316, 0.114, and 0.195 cm3/g, respectively. These quantities are lower than those reported in a Bureau emissions study at the Horse Draw Mine in the Piceance Basin. Oil shale samples that were gas enriched beyond the mean methane contents frequently contained bitumens and pyrite.

Jan 1, 1987

By James H. Gary

Data regarding the composition and physical properties of Florida land-pebble phosphate-waste slime are presented, and the feasibility of dewatering and beneficiating the slime by several different methods is discussed. Chemical analyses, electron micrographs, and X-ray diffraction data showed that principal constituents of the slime included quartz, attapulgite, and flaorapatite. Viscosity of the slime changed with pH; thixotropic, Newtonian, and rheopectic states were observed as the pH increased. Use of various flocculating agents was not effective in improving thickening properties of the slime. Dewatering tests using pressure filtration showed that temperature influenced the filtration rate more than pressure; the filtration rate at 165° C was tenfold that at room temperature. Selective flotation of the slime, using two different processes, gave promising results. About 25 pct of the phosphate was recovered in a concentrate assaying 31 pct P205, Other tests demonstrated that the slime could be successfully fractionated at 20-microns using a hydrocyclone. In hydrometallurgical tests about 80 pct of the phosphorus and alumina were chemically extracted from the slime using sulfuric acid. Limited bacteriological studies made of the slime showed that several types of microorganisms were present and grew in the material despite the presence of fluorine-bearing minerals.

Jan 1, 1963

By M. E. Tyrrell, J. Koster

This work was undertaken to determine the feasibility of making mixed diborides of two metals directly from the metal oxides , boron carbide and carbon . The diborides (Ti , V ) , B₂ , (Ti , Cb) B₂ , and ( Ti , Ta ) B₂ were prepared in a crucible resistance furnace at 2,100 ° C , and X- ray- diffraction analyses showed each was a homogeneous solid solution containing approximately equal molar contents of the given diborides . The diboride powders were cold - pressed ; sintered to 2,300 ° C , and evaluated for mechanical strength , rate of oxidation , and resistance to molten metals . The diboride ( Ti , Ta ) B₂ exhibited the best mechanical properties ; the diboride ( Ti , Cb ) B₂ , the lowest cumulative rate of oxidation . The mixtures were stable in the presence of molten aluminum and copper but were attacked by molten Ti , Zr , and Cr .

Jan 1, 1964

By Peter D. Lohn

The Bureau of Mines conducted both laboratory and field investigations to study the effectiveness of medium-pressure (up to 30,000 psi) water jets in controlling the generation of airborne respirable dust during the hydraulic fragmentation of coal. Laboratory studies were conducted at the Farmington High Energy Test Site of the Twin Cities Mining Research Center, and field studies were carried out at the Humphrey No. 7 mine, Mount Morris, Pa., in the Pittsburgh coalbed. The water jets were produced by commercially available triplex pumps. The dust samples were collected by midget impinger samplers, and analyzed by electronic and optical counting techniques. Respirable dust concentration for a full-scale production model was projected at below 2 mg/m3, the maximum exposure allowed by the Federal Coal Mine Health and Safety Act of 1969.

Jan 1, 1975

By Foster Fraas

Under a very high vacuum of 10-8 torr the transfer of terrestrial mineral beneficiation methods to the vacuum ambient of extraterrestrial locations such as the lunar surface was investigated. In the size range for the electro-static and magnetic separation of ores (minus 35 plus 150 mesh) there is no adhesion of particles produced by crushing and grinding due to the limited contact area, and for repeated contacts area size has a frequency of occurrence in accordance to the normal law. The photoelectric effect which is successful in separating a few minerals in an air ambient has a wider application in a vacuum, while the lack of air viscosity and sound transmission provides for high feed velocities and the adaptation of particle vibration to dispersion and grinding. Contact electrification is reversible upon return to atmosphere.

Jan 1, 1970

By M. M. Fine

"Button" type ore from the Cason mine, Batesville, Ark., can be up-graded to plus-40-percent manganese by mineral-dressing procedures. A simple process including gravity concentration and. magnetic separation yielded more than 50-percent recovery of concentrates containing 38.1 to 40.6 percent manganese. These values in turn could be raised to 41.4 and 42.8 percent, respectively, upon sintering to conform to size specifications. The Bureau of Mines in the past has surveyed and tested many manganese ores and prospects in an endeavor to alleviate the shortage of manganese. The present period of emergency again emphasizes the strategic position of the metal, and manganese investigative work is being stressed to find new ore bodies and to apply newer beneficiation techniques to the known deposits.

Jan 1, 1953

By K. S. Gritton

The Bureau of Mines investigated the feasibility of numerlcally modeling the sorption of cobalt, a vulnerable strategic and critical metal, from spent copper leach solutions in a multiple-compartment ion-exchange (MCIX) column. Equilibrium resin loadings, cobalt-sorption kinetics, and resin-fluidization characteristics were determined in simple laboratory tests, and a numerical model was developed to predict cobalt extraction and the MCIX-column resin inventory based upon the test results. The model was implemented on a microcomputer to approximate the solution to the set of differential equations that govern model performance. Results compared very well with data from 12 pilot-scale MCIX-column experiments. The average difference between predicted and actual cobalt extractions was 3.2 pct; the maximum difference was 9.3 pet. The actual and predicted resin inventories differed by an average of 5.8 pet, and the maximum difference was 12.0 pct.

Jan 1, 1987

By Thomas J. Peters

The King Mountain study area is centered about 120 air km northwest of Blackfoot, and 30 air km north of Arco, Idaho. The study area makes up the southern one-third of the northwest-trending Lost River Range--the highest mountain range in Idaho. The area is predominantly underlain by Paleozoic-age marine limestone and lesser dolostone, with a relatively small inlier of silica-rich, Ordovician-age quartzite. There are vast, unquantified resources of these industrial minerals present; however, special markets need to be developed for these resources which are near enough for transportation costs to be competitive. Five prospects were found in the study area; however, only one, the Elbow quartz silica prospect, contains resources and current claims. There has been no mineral production in the study area.

Jan 1, 1993

By Albert F. Baker

Techniques were developed and circuitry was assembled for measuring the total and volume resistances to the flow of electric current through solid specimens of anthracite. The two-, three-, and four-terminal test methods demonstrated the extreme sensitivity of resistivity to differences in anthracite characteristics and showed response to changes resulting from variations in structure, temperature, and moisture content.

Jan 1, 1966

By John R. Bitler

The Bureau of Mines conducted this study to provide information concerning the availability of and the demand for construction-mineral aggregates in the Baltimore, Md., Standard Metropolitan Statistical Area (SMSA). The demand is discussed with reference to the area's current consumption and estimates of the area's demand for aggregates through 1990. Estimates of aggregate supply are presented in conjunction with an examination of the geology of the area, the availability of substitutes, and the effect of transportation costs. A discussion of the constraints affecting aggregate availability precedes the conclusions and recommendations. The availability of aggregates is subject to geologic, economic, and political constraints. As of January 1974, an estimated 20,100 million tons of stone was available to meet the demand projected through 1990 (188.7 million tons). An estimated 139 million tons of sand and gravel was available to meet the demand projected through 1990 (84.3 million tons). Several alternative actions are available within the area to insure the adequacy of the stone supply and to increase the supply of sand and gravel: (1) The establishment of special mineral resource zones; (2) the application of sequential land use techniques; and (3) the exploration of previously undeveloped regions.

Jan 1, 1975

By Helen W. Lang

This report describes a monitoring system applied by the Bureau of Mines to provide rapid, continuous determination of the main constituents of exhaust gas during the Bureau's approval schedule testing of diesel engines for under-ground use. Commercially available continuous analyzers with strip chart readout are employed for nitric oxide (mass spectrometric), carbon dioxide (nondispersive infrared), methane (NDIR), carbon monoxide (NDIR), and oxygen (polarographic). Good correlation is obtained between the continuous instrumental results and those obtained by batch chemical and gas chromatographic methods.

Jan 1, 1969

By D. W. Bridges, L. Crocker, R. O. Dannenberg

About 95 pct of the beryllium was dissolved from most ore samples by agitation leaching with 600 lb of H2SO4 per ton of ore for 24 hours at 65 ° C and 35 pct solids . Leach slurries generally were viscous , and the limiting pulp density for thorough mixing was about 35 pct solids . Settling of the leached pulp required 0.6 to 0.8 lb of a polyacrylic flocculant per ton of ore leached with 600 lb of H2SO4 per ton , whereas ore leached with 800 lb of H2SO4 per ton required only 0.2 to 0.3 lb of flocculant per ton . Terminal densities of the settled pulps were about 28 and 35 pct solids , respectively , from leaches using 600 and 800 lb of H2SO4 per ton . Vacuum filtration of settled pulps at 15 in . Hg resulted in a filter cake containing 50 to 59 pct solids . Roasting the ore at 500 ° C before leaching increased the limiting pulp density for effective mixing to 50 pct solids . Acid requirements , however , were not diminished , although leaching roasted ore with 600 lb of H2SO4 per ton resulted in densification of settled pulps to about 40 pct solids . Filter cake from leaching preroasted ore contained about 20 pct less water than that from unroasted ore .

Jan 1, 1963

By Daryl R. Tweeton

The Bureau of Mines compared the effects of surface-active chemicals with those of pure water on core-drilling rock and quartz and on fracturing quartz. The objectives were to determine if these chemicals assist drilling and fracturing rock and if zeta potential control was worth pursuing as an aid to full-scale drilling. All tests were performed in the laboratory. No significant increases in drilling rates were observed for 1 to 10,000 ppm Al (as AlC13) in flushing water when drilling microcline or serpentine, nor for 1 to 10,000 ppm Mg (as MgC12) when drilling microcline or marble. Concentrations near those giving a zero zeta potential were used with microcline and marble. A 50-pct rate increase was observed for drilling quartz in 0.7 ppm oleylammonium acetate, which gave a zero zeta potential. No other concentrations were used. No effect on the tensile strength of quartz thread in 0.05 ppm Al (as AlC13), which gave a zero zeta potential, was observed. Heptanol, reported to give a zero zeta potential on quartz, did not reduce the bending strength of small quartz bars below that in water. These generally negative findings raise doubt about the usefulness of zeta potential control in full-scale drilling. The results, combined with previous studies, suggest that controlling physical properties of drilling fluids, such as viscosity, is more useful than altering chemical properties.

Jan 1, 1976

The principal activities of the Bureau of Mines Explosives Research Center from July 1, 1963 to June 30, 1964 are described briefly in part 1. Part 2 gives short abstracts of publications that appeared during fiscal year 1964; in general, the research reported in these publications antedates the report period. Part 3 describes a short-term investigation into safety problems associated with shipping of molten sulfur; this investigation is not at present destined for publication elsewhere.

Jan 1, 1965