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By Jerry T. McLendon

The proper disposition of phosphatic clays has been the subject of research and debated for years by phosphate producers, State and Federal research agencies, regulatory authorities, and environmentalists. To date, no "universal" solution exists for the ultimate disposl of phosphatic clays. This Bureau of Mines report examines the state of conventional clay disposal technology and reviews the technical progress of innovative alternatives. Twenty impoundment sites were investigated by the Bureau of Mines using geotechnical methods and laboratory analysis of cored samples. In addition, quasi-static cone penetrometer soundings were conducted to define clay and/or sand-clay interfaces en masse. Samples of the top, middle, and bottom hole segments were obtained at each station for laboratory studies of clay densities, pore fluids, plasticity, and mineralogical properties. The results of this study support the continued use of initial clay settling impoundments but emphasize the need for "in-line" systems to reduce the initial volumes of plant-generated phosphatic clays. The effective use of sand tailings is also encouraged to promote further consolidation of clays via self-weight stressing, sand-clay admixtures, and/or surcharging sand caps.

Jan 1, 1984

By A. A. Cochran

The objective of the research was to determine the final distribution of cerium additions to steel, their effect on sulfide inclusions, and the usefulness of radiotracer methods in investigating steel problems. Fifty-gram heats of steel were prepared that contained either cerium 141 and nonradioactive sulfur, or sulfur 35 and nonradioactive cerium. These steels were studied by autoradiography, measurements of their surface radioactivities, optical microscopy, and chemical analysis. Samples of the crucibles were analyzed quantitatively for cerium or sulfur by radioactivity counting methods. The addition of cerium to steel melts reduced the size and number of iron sulfide inclusions in the resulting steel. A significant fraction of the sulfur and most of the cerium penetrated into the MgO crucible during the melting operation, The cerium inclusions in steel were identified as cerium sulfide. Radiotracer methods were found to be versatile and highly sensitive.

Jan 1, 1963

By Jack C. White

This U.S. Bureau of Mines report assesses the resource potential of trace metals present in commercial Ti mineral concentrates. Metals of greatest interest: are those defined as "strategic and critical" by the U.S. Congress in 1981. Metals of interest in Ti mineral concentrates are Cb, Cr, Ta, Th, U, V, and Zr. Commercially available Ti mineral concentrates were studied. Characterization and analysis of major and minor constituents were performed by X-ray diffraction, neutron activation, inductively coupled plasma emission, atomic absorption, and classical wet chemical techniques. Of the metals investigated, the Cb, Ta, and V content of some concentrates may be a significant potential resource, depending on their amenability to recovery.

Jan 1, 2010

By Joseph Gersic

In 1989-90, the Bureau of Mines appraised selected high resource potential areas containing gold, rare-earth-element, or pegmatite deposits in or near the Black Hills National Forest. Available mineral resource data were used to construct mine and mill models and to compute discounted cash-flow rate-of-return analyses. Using this information, the economic feasibility of possible operations and probability (in the nonmathematical sense) of exploration and development within the next decade were assessed. High exploration and development probabilities are forecast for gold deposits around existing and permitted mine areas near Lead-Deadwood and west of Galena. The area east of Galena has low to moderate exploration and development probability; the Rochford area has low to high exploration probability and low to moderate development probability; the Keystone area has low to moderate exploration probability and low development probability; the Medicine Mountain area has moderate to high exploration and low to moderate development probabilities. Exploration probability in the Bear Lodge Mountains area is high for rare-earth elements and gold; development probability is low. Exploration probability for gold in the Mineral Hill area is low to moderate; development probability is low. The current level of activity associated with pegmatite mining in the Black Hills would probably not change significantly in the next decade; both exploration and development probabilities are low to moderate.

Jan 1, 1990

As part of its regular program to provide timely information on domestic mineral commodities, the Bureau of Mines conducted an engineering appraisal of more than 1,300 lode and placer gold deposits in the United States to deter-mine their gold production potential. While these deposits were estimated to contain over 400 million ounces of gold, only 9 million ounces, or slightly more than 2 percent, was found to be producible at $35 per ounce under prevailing mining and metallurgical technologies. The study revealed that any significant increase in available gold in the United States is most likely to come from the discovery of new sources, intensive exploration and development of the more promising known mineralized areas, and development of new or improved mining and metallurgical techniques.

Jan 1, 1967

By E. G. Noble

The effects of HBr concentration and temperature on the solubility and hydration state of AlBr3,' CoBr2, PbBr2, MnBr2, KBr, and NaBr were investigated by the Bureau of Mines. Saturated aqueous solutions of the AI, Pb, K, and Na bromides were sparged with HBr gas at 20°, 40°, and 60° C, and saturated solutions of Co and Mn bromides were sparged at 20° C. Increased HBr concentration caused decreased salt solubility because of the common ion effect for all the investigated bromides except PbBr2. Aqueous solubilities at 20° C were, in percent, 51.7 for AlBr3, 53.2 for CoBr2, 1.1 for PbBr2, 59.6 for MnBr2' 39.5 for KBr, and 47.4 for NaBr. At 60° C, the solubilities were, in percent, 53.3 for AlBr3, 2.2 for PbBr2' 46.0 for KBr, and 53.8 for NaBr. Solubilities in solutions sparged to HBr saturation at 20° C were, in percent, 0.5 for AlBr3, 42.0 for CoBr2, 32.2 for PbBr2, 21.0 for MnBr2, 0.6 for KBr, and 0.3 for NaBr. At 60° C, the solubilities at HBr saturation were, in percent, 1.8 for AlBr3, 41.4 for PbBr2, 1.3 for KBr, and 0.4 for NaBr. CoBr2 precipitated out to a minimum solubility of 27.2 pct at 28.7-pct-HBr concentration. Further increases in HBr concentration increased CoBr2 solubility because of the formation of bromide complexes. PbBr2 in-creased in solubility as HBr concentration increased.

Jan 1, 1988

By M. R. Geer, H. F. Yancey

Fuel requirements of the Pacific Northwest have been increased greatly by the war . To the normal peacetime demands for fuel have been added the requirements of new industrial and metallurgical plants engaged in war production , the increased demand arising from expansion of existing industrial establishments , increased amounts of railroad fuel required to handle wartime traffic , and increased quantities of domestic fuel required by the influx of war workers . In the face of these augmented demands for fuel shipments of fuel oil have been curtailed , wood fuel which normally is an important factor in both industrial and domestic markets of the area is less abundant , and the production of coal in Washington has decreased sharply . The fuel requirements of the region have been met so far by shipping large tonnages of coal into the Pacific Northwest from Utah , Wyoming , Montana , and Colorado ; the quantity received from these States and Canada in 1943 amounted to 2,688,9124/ tons , 175 percent of the Washington production . or The proximity of the Washington coal mines to large centers of war production has resulted in widespread migration of miners to employment in shipyards and aircraft plants ; the ensuing shortage of miners largely accounts for the decreased production of coal in the State . Hence , strip mining , which requires relatively few workers and a shorter time for development , offers an attractive means of alleviating the local coal shortage and obviating the necessity of shipping coal from the producing areas of the Rocky Mountain States to the Pacific.coast . So urgent has been the necessity for augmenting local coal production that any coal property that promises to be amenable to strip mining , even though the coal may be inferior in quality , has warranted examination . Even low- grade coals that cannot compete in the normal market can be used locally , thus releasing better coals for shipment to critical centers. of consumption ... One such deposit of low- rank fuel examined by the Bureau of Mines is in western Lewis County , about 9 miles east of Toledo , Wash . The coal is lignitic and on the as - received basis has a heating value of 6,000 to 6,500 B.t.u. per pound . The property is of interest primarily because the physical conditions favor operation by stripping and offer opportunities for low- cost production with very low manpower requirement .

Jan 1, 1945

By R. M. Becker

As part of the Bureau of Mines program for examining the Nation's iron and titanium resources, magnetic, gravity, and geologic surveys were made to permit an estimate of the extent and magnitude of the Iron Mountain, Colorado, titaniferous magnetite deposit. Gabbro is the dominant rock type of the area. Within the gabbro are lenses of titaniferous magnetite, 5 to 25 feet wide and as much as several hundred feet long. These lenses comprise a zone which has scattered occurrences of magnetite for 2,200 feet. To the west, the gabbro grades into a strip of pyroxenite that in turn borders a large monzonite mass. A wedgelike broadening of the pyroxenite with depth accompanied by little or no increase in the titaniferous magnetite is considered a reasonable interpretation of the field data. The iron deposits appear to be limited and discontinuous.

Jan 1, 1961

By J. M. Stuve

Thermodynamic properties were determined by the Bureau of Mines for the intermetallic compound, TiA13. Heat capacities were obtained from 5 to 303 K by adiabatic calorimetry. The derived value of S2 1s is 22.08±0.07 cal/deg¬mole. Enthalpies relative to 298 K were obtained from 298 to 1,413 K by copper-block drop calorimetry. No anomalous thermal behavior was noted in the temperature ranges investigated. Low- and high-temperature data were combined with a known enthalpy of formation at 298 K to give values of enthalpy of formation and Gibbs energy formation, 0 to 1,400 K.

Jan 1, 1974

Develop a means of determining both the fill level of material in an ore pass or bin and the location of bridging material causing a blockage.

Jan 1, 2000

By James H. Russell

The Bureau of Mines used a statistical approach to evaluate the effects of temperature, current density, and composition of the electrolyte on the purity of boron prepared by electrolysis of a fused mixture of boric oxide in potassium fluoborate. The quadratic equation which best fits the data was calculated for a temperature of 650° to 850° C, a cathode current density of 40 to 1,150 amp/ft2,and a boric oxide content of 0.3 to 7.1 molal. The best products, better than 95 percent boron, were obtained when the current density was less than 2 amp/ft2 and the boric oxide content was less than 2 molal.

Jan 1, 1967

By Hillary W. Clair

An equation is derived for the rate of reaction of a sphere of metal oxide in a restricted enclosure through which a reducing gas is flowing . The equation takes into consideration the reaction rate coefficient , transport through the gas and through the porous shell of reduced oxide , the rate of gas flow , and the volume of the enclosure . The equation serves as a model for predicting the course of reduction of a particle of metal oxide in a shaft furnace .

Jan 1, 1964

By R. W. Stahl

Gas accumulation and dust suspension are the major safety hazards in coal stockpiling and reclaiming operations. This report presents a schedule of safety precautions and plant design features devised by the Bureau of Mines to reduce danger from these and other sources.

Jan 1, 1965

By Victor Kalcevic

A gas-flow retort for thermal processing of oil shale to recover shale oil was developed by the Bureau of Mines at its Oil-Shale Demonstration Plant, Rifle, Colo., from 1948 to 1952. The retort is a crossflow gas-to-broken-solids heat exchanger. The heating medium is the gas produced in the shale retorting process. The gas is heated in specially designed stoves outside the retort and recycled to the retort. Oil shale from the Mahogany ledge section of the Green River formation in northwestern Colorado was the material processed. Indicated maximum oil recoveries for 20-to 25-gallon-per-ton shale in a l2-inch-thick shale bed and a 20-inch bed are 96 and 91 weight-percent of Fischer assay, respectively. Heat requirements for maximum recovery are 600 to 750 B.t.u. per pound of shale. Properties of the recovered shale oil are affected slightly by shale-bed thickness and extent of retorting. Oil recovery from oil shales assaying over 30 gallons per ton is lower than that from leaner shales.

Jan 1, 1959

By Jon C. Volkwein

The U.S. Bureau of Mines investigated a method of using inert gas to prevent the formation of explosive gas mixtures in auger highwall mining of coal. A combination of gasoline and diesel engine exhaust gases was introduced into the auger drill hole using a short section of pipe located at the collar. Gas samples were taken and analyzed on-site with infrared detectors for oxygen, carbon dioxide, methane, and carbon monoxide. Evacuated bottle samples were also taken and analyzed by gas chromatography in the laboratory. These gas results were analyzed for explosibility. Coal samples from various depths were used to obtain the gas content of the coal using the modified direct method. Personal expo- sure to carbon monoxide was also monitored. The highest methane level observed was 9.55%. The levels of inert gas (carbon dioxide and nitrogen) were sufficiently high to prevent any ignition of the methane. Results showed that for all conditions during mining, gas concentrations were nonexplosive. The gas content of the coal was about 0.30 cm3/g. The maximum personal time-weighted average Sample for carbon monoxide was 20 ppm. This system provides a safe, inexpensive, simple method for preventing explosions during auger mining.

Jan 1, 2010

By A. W. Fahrenwald

Coarse sand flotation, both alone and in conjunction with gravity concentration, is a subject of research at the U. S. Bureau of Mines Field Office, Moscow, Idaho. One of the most important results of this work which is being carried out in cooperation with the University of Idaho, has been the development of a concentration process embodying flotation, classification, and tabling, in the order named. The flow sheet of the process is given in Figure 1. The type of feed desired for this process is coarser than is common in present "all flotation" practice, and is about the size of table feed.

Jan 1, 1929

By W. J. Fene

The lowest number of fatalities from coal-mine explosions in the United States in any year since records have been kept was the total of 8 in 1949 and again in 1950. Even incomplete records as far back as 1870 reveal a larger annual loss of life from explosions. From 1890 to 1948 the lowest annual loss was 32 in 1946. A smaller total of 15 fatalities was reported in 1952. Figure 1 shows the total yearly loss of life from explosions in all coal mines since 1880. Those in anthracite mines alone are shown by the shaded area. The erratic variation of the chart line shows the difficulties that have confronted the industry in the struggle to control and eliminate mine explosions. Potential hazards have existed in marry mines without realization that only a small change in conditions could initiate a disaster. Many disasters causing great loss of life occurred in mines that had been regularly operated without incident for long periods. Although the number of coal-mine explosions causing great lose of life has been kept down in recent years, the exceptions still make the record anything but satis¬factory. There have been almost no widespread explosions for several years, but in a few instances many lives were lost from afterdamp. Although the violence and spread of mine explosions may be controlled, the loss of life may be heavy if many of the men happen to be in the path of the smoke and gases. For these reasons, the strictest controls must be maintained to eliminate all factors that might combine to cause even a small ignition of gas or dust.

Jan 1, 1953

By J. M. Singer

Quenching distances for flames of methane-coal dust mixtures were determined with air and oxygen-enriched air. Coals used were Pittsburgh, Sewell, and Pocahontas No.3. Quenching distances were greater for flames of hybrid mixtures of coal dust and methane than for methane flames of corresponding stoichiometry. From the data of quenching distances and methane-coal dust concentrations was calculated the quenching equivalence, which is the increase in coal dust concentration required to maintain a given quenching distance value as the methane concentration decreases. These equivalences could be useful in identifying hazardous methane-coal dust mixtures in mines.

Jan 1, 1966

By A. C. Johnson, McHenry Mosier

The Bureau of Mines has adapted its activities to needs of national defense and to conditions brought about by the war program . Its work is now oriented solely to war problems . After studying about 1,600 deposits of war minerals , exploration projects have been undertaken on 96 of the most promising , of which 56 have proved successful . These have indicated that 56 million tons of ore of commercial or near -commercial grade can be utilized to meet war requirements . Included in this amount are 1 million tons of tungsten ore ; 4 million tons of chromite ore, 10 million tons of manganese ore , 2 million tons of antimony ore , 1 million tons of mercury cre , and 28 million tons of iron ore . Work done in connection with exploration projects included 172,000 feet of surface trenching , 210,000 feet of drilling , and 21,000 feet of shaft sinking . Nearly 100,000 samples were taken, on which 500,000 analyses were made . Extensive metallurgical tests were made on ore from many of these deposits , both in the laboratory and in pilot plants , in connection with research to develop metallurgical processes for their treatment .

Jan 1, 1943

By Paul Zinner

An exhaustive program of geologic studies and mapping has been conducted by the Geological Survey in the Iron River district of Michigan since May 1943. Means of contributing to the success of these studies were sought by the Bureau of Mines, and eventually a program involving geophysical studies and core-drilling was undertaken in the area. All of the work was done either to develop data that would contribute directly to geologic studies or to investigate geophysical methods that might be used as a primary means for the discovery of minable iron ore.

Jan 1, 1949