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By M. M. Kirk

Forced-air cooling of cold-mold arc furnaces for melting zirconium and similar metals has been investigated and found to be practical from the stand-point of heat transfer. It is believed that this technique offers a significant reduction in explosion hazard from that inherent in water cooling, the current industrial practice. A copper crucible, with longitudinal, integral-type fins and with an outer jacket to confine the airstream, appears to be the best general design for air-cooled operation. Cutting the fins into short segments and bending the segments to produce a herringbone effect increased the airstream's turbulence and was found, on test, to increase the heat transfer up to 35 percent.

Jan 1, 1959

By M. J. Kovalik

Lower Sunnyside seam coal from Utah was blended with various proportions of char and high-temperature coke to improve the quality of the coke obtained from carbonizing this coal. The Hanson 5-pound carbonizer was used as a "screening test" for the larger scale Bureau of Mines-American Gas Association (BM-AGA) tests, which were correlated with industrial production. Eighteen carbonization tests were made in the BM-AGA 13-inch retort, with a coal charge of about 90 pounds; the cokes were evaluated by the standard ASTM tumbler test. Carbonization of blends containing char and coke breeze yielded less fissured and blockier cokes of significantly higher ASTM I-inch tumbler indices as compared with the value for the straight Sunnyside coal. It was found that the simultaneous addition of char and coke breeze yielded stronger cokes than that obtained by the addition of either one of these additives. Addition of a small proportion of Pocahontas No. 3 or Sewell coal to an optimum blend improved the resulting coke strength further.

Jan 1, 1969

By Ben E. Lindsly

The study of "bottom-hole samples follows in natural sequence the study of samples obtained under high pressures at the well heads of flowing wells. The principal object of this phase of gas-solubility research, started actively in January, 1930, was to gain a more accurate knowledge of the physical and chemical characteristics of the oil-gas mixtures that exist in natural reservoirs.. In possession of actual data regarding the condition of the oil; the quantity of gas liberated from solution upon dimunition of pressure; and the relative volumetric proportions of gas to oil at various pressures throughout the flow string in a well, it should be possible to predict, with a fair degree of accuracy, That physical changes these mixtures would undergo throughout the life of a pool. Such information not only is important in designing flow strings in flowing Tells but is important also in solving problems relating to pumping efficiency and the power required for pumping. Although certain fundamental data were obtained in the study of samples taken at the well head, "bottom-hole" samples are more representative of subsurface mixtures of oil and gas because they are obtained at reservoir temperatures, and before the oil has had the opportunity of intermingling with extraneous gas; that is, gas which either was not in solution originally, or which was liberated from solution at higher pressure, and later became mixed with the original undissolved gas.

Jan 1, 1933

By T. M. Barczak

One of the primary goals of Bureau of Mines research is to reduce the cost of coal mining by improving the efficiency of longwall supports. One method of achieving this goal is the optimization of stress distribution within the support structure, resulting in a lower overall weight, more fully stressed shield. However, before stress optimization can be initiated, load conditions must be defined that cause maximum stress in the various support components. A finite-element model of a longwall shield was used to identify these critical load conditions. These load conditions were then evaluated in the Bureau's mine roof simulator (MRS) by instrumentation of a longwall shield and measurement of strains in each of the shield components. The critical (canopy-base contact) load conditions were identified that can cause structural failure at less than rated shield (hydraulic yield) capacity. Comparisons were made between full-contact and partial-contact load conditions. Other parameters investigated included the stiffness of the contact material, changes in shield geometry, rate of load application, and effects of horizontal constraint. Conclusions were drawn regarding the structural integrity of the major shield components and potential for stress optimization.

Jan 1, 1987

By B. W. Madsen

A modified transpiration apparatus was devised by the Bureau of Mines to permit rapid and accurate measure of the vapor transport and vapor diffusion coefficients of antimony sulfide (Sb2S3) and other compounds at temperatures to 1,045 K. The apparatus was equipped with dual condensers and valves to switch the flow of vapor in a fraction of a second from one condenser to the other, thus allowing short-interval sampling under equilibrium conditions. Reliability of the technique was established by measuring the vapor pressure of ZnC12 as a function of temperature and comparing the results with published data. As part of an investigation of the vapor concentrations and species of accessory element sulfides associated with copper and zinc smelting, the apparatus was used to measure the rate of vapor transport and diffusion coefficients of vapor over liquid Sb2S3 as a function of temperature between 870 and 1,045 K. The calculated vapor density was combined with published direct measurements of vapor pressure to calculate the average molecular weight of the gaseous species. Average molecular weight of the vapor in equilibrium with Sb2S3 ranged from 286 to 112 g/mol over the temperature range studied.

Jan 1, 1983

By P. L. Sibrell

The U.S. Bureau of Mines has tested cyanide leaching for recovery of palladium (Pd) from spent petroleum processing catalysts. Three different catalyst samples were supplied by a spent-catalyst processor. These catalysts consisted of a zeolite base and contained 0.4 to 0.7 pct Pd. During alkaline cyanide leaching, the catalysts exhibited ion-exchange properties due to their zeolite matrices. Hydrogen ions were released from the zeolite in exchange for sodium ions in solution, resulting in a significant decrease in solution pH. This could present a safety hazard because of the potential for release of toxic hydrogen cyanide gas. A pretreatment step where the catalysts were contacted with a 1.0M sodium hydroxide solution was found to prevent the pH shift from occurring. Following the sodium hydroxide pretreatment, two stages of leaching at 160 °C with solution containing 1 pct sodium cyanide and 0.1[M] sodium hydroxide gave at least 75 and up to 95 pct Pd recovery. The Pd was quantitatively recovered from the leach solution by thermal decomposition in an autoclave at 250°C for 1 h. The Pd content of the precipitate was over 50 pct. Thermal decomposition also decreased the total cyanide content of the barren solution to less than 0.2 mg/L. The catalyst leach residues passed the Federal Toxicity Characteristic Leaching Procedure and the California Waste Extraction Test, indicating that landfill disposal of the leach residues would be acceptable.

Jan 1, 2010

By Graham W. Marks

The general positions of the absorption maxima of aqueous solutions of the violet and green isomers of chromic sulfate the visible spectral region have long been known, but, to the knowledge of the writer, no comprehensive studies have ever been made. To gain further knowledge concerning these inorganic complexes and to investigate the possibilities of developing an analytical method for determining the concentrations of the violet and green isomers in a mixture, a more complete investigation was made in the spectral range from 325 to 850 millimicrons.

Jan 1, 1951

By Curt D. Edgerton

This study was made to determine trends in fresh water usage by California petroleum refineries, to forecast fresh water requirements to 1975, and to evaluate water conservation practices. Statistical data used in the study were obtained largely from published sources and from records of selected companies. An adequate sampling of the State's refining capacity was obtained, and the data were extrapolated to the total California refining capacity. A breakdown of the data was then made on the basis of the following refining regions: (1) the Los Angeles Basin and Southern Coastal region, (2) the Southern San Joaquin Valley, and (3) the San Francisco Bay area. An unpublished forecast of crude oil input to refineries by a major oil company operating on the West Coast was used as a basis for predicting fresh-water usage. The 1963 fresh water intake by California petroleum refineries was 84 million gallons per day. This is expected to increase to 128 million gallons per day by 1975. The fresh-water to crude-oil ratio is increasing in all regions except the Southern San Joaquin Valley. At present, the supply of fresh water available to almost all of the State's petroleum refineries, mostly from surface sources and company-owned wells, is adequate, although shortages may develop within the foreseeable future. Present conservation methods are centered around the following four objectives: (1) minimum intake of fresh water of the lowest possible quality commensurate with sound technologic practice; (2) optimum recirculation; (3) proper treatment before discharge; and (4) substitution of air cooling for water cooling.

Jan 1, 1965

By Frank D. Lamb, Lloyg H. Baning

"The crushed-stone industry has long been troubled with the problem of producing a more or less cubical product for use as concrete aggregate. Its seriousness varies widely for each producer, depending upon the character of the rock employed for raw material and the ultimate use of the crushed stone. For many construction uses, such as the macadam or bituminous-concrete- type road, flat pieces are not objectionable and may even be preferable to more cubical rock. However, most specifications for concrete require that the stone must be reasonably free from flat and elongated pieces.The rigid specifications set by many contractors have resulted in the rejection of coarse aggregate that, except for the presence of an excessive amount of flat and elongated pieces, would be entirely acceptable. In many instances, if an efficient, economical method of removing flat and elongated pieces were available, local producers could meet the requirements of the contractor and thus eliminate the necessity for importing more cubical material.A brief investigation of the problem of removal of flat and elongated pieces from crushed aggregate, carried out at the Eastern Experiment Station of the Bureau of Mines, indicated that it is mechanically possible to remove flat pieces from crushed rock.TEST EQUIPMENTA number of mechanical devices are used by the coal industry for separating slate from coal; these depend upon the difference in shape of the crushed slate as compared with the coal. Such devices as shutter screens, spiral separators, and the Norman picker would be suitable for removing flat pieces from crushed rock in the same manner as they are used by the coal industry. None of these devices was immediately available for testing purposes, so an attempt was made to construct a simple device that could be used in commercial operations."

Sep 1, 1944

By W. F. Marshall

This Bureau of Mines report discusses tests conducted with four different catalytic reactor designs to determine the influences of exhaust treatment systems on emissions from diesel engines. Although there was significant differences in oxidation efficiencies at light to intermediate engine loads, all four catalysts were very effective in reducing emissions at heavy loads. Compositional determinations included carbon monoxide, carbon dioxide, unburned hydrocarbons, oxides of nitrogen, aldehydes, sulfur dioxide, sulfates, and particulate loading. Particulate size, exhaust odor intensity, and the character of the unburned hydrocarbon component were also determined.

Jan 1, 1978

By B. W. Jong

The Bureau of Mines studied reinforcement of sulfur concretes using glass, polyester, and aramid fibers. The objective of this research was to determine the feasibility of fiber-reinforcing the sulfur concrete to enhance the flexural properties. Optimum fiber sulfur concrete compositions were formulated with a cement-to-fiber ratio of 9.0:1 for glass-fiber and polyester-fiber sulfur concretes and 12.1:1 for aramid-fiber sulfur concretes. Test samples were prepared using techniques developed by the Bureau of Mines. Flexural strength values of up to 50 pct of compressive strength values were achieved with fiber additions. With non-fiber-reinforced sulfur concrete, the values ranged up to 20 pct. The impact strength and fracture toughness of sulfur concretes were increased sig-nificantly by reinforcement with glass or with aramid fiber and were adversely affected by use of polyester fiber. Strain tolerance was doubled and failure mode was shifted from catastrophic to noncatastrophic type by adding glass fiber. The glass-fiber and aramid-fiber sulfur concretes are resistant to acid corrosion and have proved durable in freeze-thaw cycles. This laboratory and field evaluation has shown that fiber reinforcement of sulfur concrete is feasible and that it enhances the flexural properties.

Jan 1, 1985

By D. A. Rice

As part of its mission, the U.S. Bureau of Mines continues to develop technologies that will enable cost-effective compliance with environmental requirements. To this end, investigations to improve the kinetics of chalcopyrite dissolution by simultaneous grinding-leaching in ferric sulfate solution were conducted using the Bureau-designed turbo mill. The development of such a hydrometallurgical process would provide a nonpolluting alternative to conventional smelter technology. The effects of mill rotational speed and volume percent solids on the leaching time and energy required for copper extraction from chalcopyrite were evaluated. The results of this laboratory study have shown that the simultaneous grinding-leaching of chalcopyrite concentrate using the turbomill is technically feasible with essentially 100 pet extraction of copper being possible at 90° C. An optimal energy consumption of 1,153 kW?h/st of copper leached was found in batch testing with the mill operating at 400 rpm with a slurry containing 35 vol pet chalcopyrite. This energy consumption, while higher than other proposed leaching processes (about 600 kW?h/st), is of the same order of magnitude. Further refinement of the energy requirements would require additional testing using a continuous circuit. Leaching times of less than 1 h, for 80 pct copper extraction, are achievable using the turbomill grind-leach process.

Jan 1, 2010

By G. H. Keith

A vanadium-base alloy consisting of the following elements in weight-percent--molybdenum, 20; titanium, 10; carbon, 0.1; silicon, 0.5; and yttrium, 0.5--had exceptionally high strength at temperatures up to 1,200° C. This alloy was capable of fabrication to sheet of ~ 1 mm thickness by a combination of hot swaging and hot and warm rolling. In the warm-rolled condition at ambient temperature, its ultimate tensile strength was 1,205 MN/m2. The strength at 1,200° C was 150 MN/m2. Within the temperature range of 25° to 1,200° C, the ductility of the alloy as measured by elongation increased from 4 to >90 percent. Strengthening was achieved by both solid-solution and dispersed-phase mechanisms. Alloys of 20 percent molybdenum and 10 percent titanium were stronger than the other molybdenum-titanium alloy compositions tested. Strength was increased 15 percent in the temperature range of 25° to 800° C, with no accompanying loss in ductility, by the addition of 0.5 percent silicon. Workability was improved by additions of 0.25 and 0.5 percent yttrium.

Jan 1, 1970

By Ernest Ph. Hérivel

The mine and treatment plant of the Teziutlan, unit of the Mexican Corporation, S. A., are located at Aire Libre, in the District of Teziutlan, near the northwest edge of the State of Pueblo, Republic of Mexico. The property is leased from the Teziutlan Copper Co. The town of Teziutlan is the terminus of a branch railroad starting from Oriental Junction or the Mexico-Jalapa-Veracruz narrow-gage system of the National Railways of Mexico. A branch line 18 km in length from Teziutlan to Aire Libre belongs to the Teziutlan Copper Co. and is leased and operated in conjunction with the mine.

Jan 1, 1933

By W. C. McBee

Technology for the preparation of densifiable sulfur concrete (sulfapave) materials has been devised by the Bureau of Mines. The materials are intended as new construction materials for use in corrosive areas where conventional materials fail. A series of modified sulfur cements were developed, which can be used in combination with dense-graded aggregates to prepare sulfapave materials with excellent corrosion-resistant properties. The materials can be mixed, laid, and compacted into place with conventional hot-mix asphalt pavi.ng equipment. Mixture designs utilizing 5-to 30-pct-modified sulfur cements and dense-graded aggregates gave material properties ranging from rigid to flexible. Laboratory corrosion tests in sulfuric acid showed no material loss or deterioration of physical properties over a 1-year test period in concentrations ranging from 0 to 60 pct at ambient temperatures. Preliminary results on field testing the materials for durability to weathering, corrosion, and traffic have been excellent, with no evidence of failure in the materials.

Jan 1, 1985

By E. G. Davis

Large-scale ultrafine grinding tests of a coarse kaolin were made using the Bureau of Mines developed attrition grinding process in continuous open-and closed-circuit systems. A 20-inch diameter attrition grinder, designed and constructed at the Tuscaloosa Laboratory, was used. Studies included single- and multiple-stage open-circuit grinding, and also continuous grinding tests in closed-circuit with a 6-inch-diameter solid bowl centrifuge. Clay feed, containing 9.0 percent minus-2-micrometer esd, was used at fates up to 840 pounds per hour. Multistage grinding tests gave better results than single-stage treatment when equivalent clay feed rates were used. Closed-circuit grinding tests yielded ground products containing slightly more minus-2-micrometer-esd clay than the open-circuit grinding when using the same clay feed. Energy consumption was lower in closed-circuit grinding than in batch or open-circuit grinding. A modified two-stage closed-circuit grinding system gave the best grade of product and amount of minus -2-micrometer-esd clay produced per pound of clay feed. The ground product from this test contained 88.5 percent minus-2-micrometer-esd material and electrical energy consumption was 327 kilowatt-hours per ton of minus-2-micrometer-esd material produced.

Jan 1, 1973

By G. R. Peterson

The Bureau of Mines evaluated the potential supply of cobalt from known domestic resources, both as a primary product from some deposits and as a byproduct from others, and found that U.S. production could play an important role in meeting U.S. cobalt needs by the mid-1980's. This production would be of a relatively short duration, however, with production declining significantly before the year 2000. As part of the study, a tonnage-price relationship was developed indicating the quantity of cobalt that could be produced from known cobalt-bearing deposits at various primary commodity prices and at a 15-percent rate of return on the required capital investment. All capital and operating costs are calculated in August 1980 dollars, and commodity prices are based on August 1980 prices. Known U.S. cobalt-bearing deposits which represent the current U.S. cobalt reserve base contain some 310,800 metric tons of cobalt in slightly over 1 billion metric tons of demonstrated mineralized material. Approximately 37 percent of the cobalt contained in the reserve base is considered recoverable using existing technology. Of this quantity, some 87,000 metric tons of cobalt is economically recoverable assuming a cobalt price of $25 per pound, a copper price of $1 per pound, and a lead price of $0.40 per pound. Assuming that the cobalt price decreases to $15 per pound, keeping copper and lead prices constant, the quantity that is considered economically recoverable declines to some 45,700 metric tons. Domestic cobalt consumption in 1979 was 7,900 metric tons (17.4 million pounds). Currently, no primary cobalt is produced from domestic resources, and none has been produced since 1971.

Jan 1, 1981

By L. B. Pankratz

The Bureau of Mines measured heat capacities of alpha and beta spodumene (LiAlSi2O5) and of beta eucryptite (LiAlSiO4) over the temperature range 51° to 298° K. The entropies at 298° K were found to be 30.9 ± 0.2 cal/deg mole for alpha spodumene, 36.9 ± 0.3 cal/deg mole for beta spodumene, and 24.8±0.2 cal/deg mole for beta eucryptite. High-temperature heat content measurements above 298° K were conducted for the same compounds. Measurements were made to 1,150° K for alpha spodumene, 1,600° K for beta spodumene, and 1,470° K for beta eucryptite. Tables of heats and free energies of formation are given from the elements and from the constituent oxides.

Jan 1, 1967

By C. C. Shale

Current-voltage relationships for air at high temperature in negative corona are compared with relationships predicted by theory. Deviations are discussed. Eased on the latest theoretical concept of electron detachment from negative ions and recent findings in basic research on free electron gases, results of applied research show the existence of free electrons in air at high temperature and high field strength-to-pressure ratios.

Jan 1, 1967

By Agnes Y. Lee

The Bureau of Mines has developed an effective hydrometallurgical method to recover high-purity Pb metal and elemental S from concentrates. This low-temperature process eliminates S gases and Pb emissions, in contrast to the current high-temperature smelting technology. The method consists of (1) oxidative leaching with H202, Pb02, and waste fluosilicic acid at 95° C to produce a solution of PbSiF6 and a residue containing elemental S, (2) electrowinning the PbSiF6 solution at 35° C to produce 99.99 pct Pb metal and H2SiF6, and (3) solvent extraction to recover S, leaving a residue containing Cu, Ag, and other metal values. Spent electrolyte was recycled repeatedly, with impurity buildup controlled by controlling the leach parameters.

Jan 1, 1986