Search Documents

By J. Dean Warner

From 1984 through 1987, the Bureau of Mines investigated numerous prospects and new discoveries of columbium, rare-earth elements (REE), uranium, zirconium, and other metals associated with the multi-phased peralkaline granite at Bokan Mountain, southeastern Alaska. This report summarizes the mineral evaluations and estimates indicated and inferred resources for those prospects containing significant tonnage and grade. A total of approximately 96.2 MM lb Cb205 (43 pct of the tonnage at a grade exceeding 0.125 pct Cb205), and 11.8 MM lb U308, 27.9 MM lb Th02, 133.0 MM lb Y203, 637.6 MM lb ZrO2, and 241 MM lb REO are estimated to be contained within nine deposits totalling 37.8 million tons (at least 80 pct of resource tonnage also exceeds 0.5 pct Y203 + REO). Generally, half of the REO content is composed of the heavy yttrium subgroup. Several deposits also contain beryllium and tantalum; 2.1 MM lb of Ta205 and 8.9 MM lbs of BeO were estimated. These estimates would likely be substantially increased with additional exploration. Four deposit types were investigated; shear zones and fracture-related deposits, pegmatites, mineralized dikes, and placers. Mineralized dikes contain most of the beryllium, columbium, tantalum, yttrium, zirconium, and REE resources, whereas shear zones and fracture-related deposits (Ross-Adams mine) contain the principal of the uranium resource. Pegmatites are similarly mineralized as are dike deposits, and contain low levels of gold. Placer potential is suggested, but no deposits were found.

Jan 1, 2011

By Stanley P. Jacobsen

Samples of fine coal refuse were obtained from 11 coal preparation plants throughout the United States. These samples were characterized by ash analysis, particle size, and mineral composition. From the characterization, geographical locations, and the dewatering equipment being used by the plants, five sites were selected for obtaining bulk fine refuse samples. The selected coal preparation plants were using for final dewatering thickeners followed by: a vacuum disc filter, a filter press, a belt press filter, a centrifuge, and a settling pond. None were using thermal drying. The moisture content of the final cake varied from approximately 23% to 50% depending upon the feed material, flocculant addition, and the type of equipment. The filter press gave the lowest moisture content followed by a belt press and then either a centrifuge or vacuum filter. The centrifuge products were all dried to an approximate 5% moisture in a thermal dryer.

Jan 1, 1981

By Bolmerm R. L.

This information circular describes the application of modern methods and equipment in sinking a vertical, 916-foot-deep by 16-foot-diameter, concrete-lined access shaft for the Harold D. Roberts tunnel near Montezuma, Colo. Although the access shaft was merely a construction facility to expedite completion of a 23-mile water-diversion tunnel, a circular shaft of this type would be equally adaptable for mine development or other purposes. Comparable sinking methods and equipment could be used for similar shafts within a wide range of sizes and depths. SUMMARY In addition to excavation and support of the basic access shaft to tunnel grade, the overall sinking project involved initial preparation of a surface site and plant, subsequent construction of a tunnel-level station and loading pocket at the shaft bottom, and ultimate conversion of the basic shaft into a hoisting and access facility for tunnel operations. The sinking period for the basic shaft approximated one year. Actual tunnel operations through the converted shaft began on April 3, 1958, approximately 19 months after the project was initiated.

Jan 1, 1961

By George A. Morgan

Output of minerals was insignificant in 1981 and made a negligible contribution to the gross national product (GNP), estimated at $1.2 billion.2 Agriculture accounted for 40% of CNP and manufacturing accounted for 10%. The chief source of income was indirect taxes levied on traffic through the Port of Cotonou, an entrepôt. Trade statistics for Benin were incomplete and dated. Major trading partners were France and other members of the European Communities. Benin was a member of the West African Monetary Union and as such must coordinate its foreign currency, reserves, interest rate structure, and fund transfer with other member countries. Its currency, the Communauté Financière Africaine franc (CFAF), was fixed to the French franc.

Jan 1, 1983

The compliance sampling method for coal mine dust in the United States has not changed appreciably in the last 30 years. A call for more frequent sampling with immediately available results is leading to new instruments that may supplement or replace the existing sampler. This report discusses two such instruments that provide immediate results of dust levels. The first, called the Respirable Dust Dosimeter (RDD), is designed to supplement the existing U. S. cyclone compliance sampling method. It uses the pressure drop across a filter to provide an inexpensive screening type of measurement. The RDD has been tested in the laboratory and a limited number of coal mines. Side by side testing has compared the RDD performance with personal coal mine samplers in triplicate area sample measurements. Results show that the differential pressure of specific filtration media can be an effective surrogate for respirable mass. Data show that there is a dependence on coal type and an effect of relative humidity. There also appear to be two distinct responses related to coal type. For specific coals the coefficients of determination, R2, are better than 0.9. For general use the detector tube, using laboratory generated calibration curves, can be used to estimate respirable dust levels. However, a calibration to a specific coal type may substantially improve the accuracy. Another sampler in development is called the Personal Dust Monitor (PDM). Designed to give compliance quality accuracy, the PDM uses the frequency change of a vibrating element to measure dust and give immediate feedback of results. Results of laboratory comparison of the prototype PDM sampler to personal gravimetric samplers indicate R2 values of better than 0.99 for three different coal types. Work is in progress to package the components into a person-wearable unit combined with a cap lamp system with a total projected weight of less than 1.4 kg (3 lbs).

Reduce the number of accidents in which large mining trucks crush objects that were not visible to the driver. Approach Improved rear view mirrors, light-bending plastic lenses, and a closed circuit TV, are combined in a rugged system that allows the driver to see almost all areas around a large raining truck. How It Works Improved mirrors, used in place of ordinary left and right rear view mirrors, give wider angle viewing. Fresnel lenses, two mounted on the front edge of the hood and another one mounted above the right front fender, show objects close to the front and right side of the truck. A rugged closed circuit TV camera mounted above the rear axle reveals objects behind the truck. See diagrams showing reduction of blind area around a 150-ton mining truck. The improved mirrors for rear viewing are approximately rectangular. The left rear view mirror has a flat reflecting surface 10 inches wide by 20 inches high. The right rear view mirror is curved to give wider viewing angles, both from left to right and up and down. This mirror is 12 inches wide by 16 inches high. Its convex reflecting surface has the same curve as the surface

Jan 1, 1979

By Steven A. Hawkins

This report details the conduct and results of a 5-month study to collect data on the use of steel support for ground control in European underground coal mines. The report summarizes European steel support design practices and describes the applicability of steel supports to U.S. mining conditions.

Jan 1, 1980

By Gene F. ] [Faufaul

This contract was concerned with the design, development, fabrication and testing of an improved tamper-proof filter cassette assembly for use in the, collection and evaluation of dust particulates, primarily in mining areas. This report presents the design effort, fabrication and tenting of five- prototypre unit$ as well as the design and production of 1000 filter cassettes with sampling heads. This new improved filter cassette has been tested and approved by NIOSH as meeting the requirements specified in the contract.

Jan 1, 1978

By O. Q. Leone

A processing unit was developed for the complete cleaning of titanium alloy chips. The process uses solvent degreasing, magnetic separation, and anodic solution of nonmagnetic impurities in 10 weight-percent sulfuric acid. Vacuum arc-melted ingots weighing approximately 10 pounds each were prepared from cleaning chips according to ingot specifications.

Jan 1, 1973

By J. H. Wiggins

The evaporation of crude oil without doubt causes one of the largest single losses to which the oil is subjected after it is taken from the ground. The few days during which crude oil is stored on the lease before being taken by the pipe line, causes an aggregate loss per year from evaporation estimated at 122,100,000 gallons of gasoline in the Mid-Continent field alone. This has a value, at 22 cents per gallon, of $26,880,000 and represents about 3 per cent of the total gasoline produced in the United States from all fields and all sources. The following table shows this in more detail:

May 1, 1920

By E. Morrice

As part of its efforts to maximize process efficiency and decrease energy requirements in mineral processes, the Federal Bureau of Mines has investigated methods for beneficiating bastnäsite ores from Mountain Pass, Calif. The results of a bench-scale study on the flotation of bastnäsite ore are presented. Flotation at a pulp temperature of 40° to 45°C yielded a cleaner concentrate containing 58.7 pct RE203 at a rare-earth recovery of 67 pct. These results are comparable to those reported for the commercial beneficiation method in which the pulp is heated to boiling before flotation. An attempt was also made to recover a barite flotation concentrate from the bastnäsite rougher tailing. Concentrates containing only 70 pct barite were obtained.

Jan 1, 1982

By Russell J. Foster

Public awareness of, and involvement in, recycling has increased significantly in recent years. Nevertheless, recycling is generally perceived as a new development, and is familiar only in the context of municipal solid waste management. The actual magnitude and scope of metals recycling in the United States have gone virtually unnoticed. Over time, both the quantitative and qualitative aspects of secondary metals recovery and reuse have changed substantially, while the attendant regulations have become increasingly stringent. This U.S. Bureau of Mines report examines trends and developments in major metal demand and recycling, and analyzes the possible impacts of regulations with regard to recycling activities.

Jan 1, 1994

By R. B. Schluter

Magnetite pellets were simultaneously reduced and indurated on a laboratory scale in order to determine the effects of temperature, induration time, degree of metallization, and sulfur content upon the physical and chemical properties of prereduced pellets. The reductants were commercially-pure tank gases. Among the findings were these: 1,100° C is the minimum temperature that will produce acceptably hard pellets using carbon monoxide as the reduc-ing gas. Prolonged treatment time improves the pellets' crushing strength, but the rate of improvement falls off sharply after 2 hours' induration. At 1,120° C, 75-percent metallization produces the maximum crushing strength; there was no corresponding peak at 900° or 1,050° C. Sulfur in the furnace atmosphere lowers the required induration temperature. A few tenths of 1 percent sulfur in the pellet increases the sintering rate of metallic iron in pellets by forming a liquid FeS phase that facilitates iron transfer.

Jan 1, 1968

By J. Koster

[Boron is an element whose metallurgical possibilities never have been investigated thoroughly, probably because of the difficulties experienced in the preparation of elemental boron and its intermetallic compounds. The southwestern United States contain the world's s largest deposits of boron minerals. In general, the mineral is readily available, and mining costs are not excessive. The most important boron mineral of commerce is borax (sodium tetraborate) however, there are large deposits of colemanite (a mineral having the composition represented by 2CaO 3B2O3 5H2O) in Clark County, Nov. This material was worked in times past by converting it to sodium tetraborate. In recent years the deposits have laid idle because of a mire readily available source of borax in the old lake beds of California.]

Jan 1, 1940

Severe whipping of shuttle car trailing cables occurs when the car stops suddenly or reverses direction. This causes cable damage, and can seriously injure personnel near the cable. FMC has contracted with the U.S. Bureau of Mines to design, build and demonstrate a reel control system that will significantly reduce or eliminate whipping. II. CONCLUSIONS Results of engineering effort show that the following conditions are primarily responsible for the whipping problem. Causes may exist individually, or in combination.

Jan 1, 1972

By Robert F. Stewart

The oxidation of structural materials at high temperatures in gas-cooled systems can be greatly retarded by the addition of small amounts of hydrogen to the inert coolant. In experimental equipment for gasifying coal with heat transferred by helium, the oxidation of graphite and metals (molybdenum, tungsten, and certain stainless steels) by trace impurities in the coolant helium was virtually eliminated by adding 0.1 to 1.0 percent hydrogen. The reaction of hydrogen with praphite does not preclude its use to retard oxidation; at 2,400° F. only 0.2 pound of graphite per square foot per year is lost for each percent of hydrogen in the helium. The addition of hydrogen appeared to prevent the mass transfer of carbon often associated with oxidation of graphite, without causing noticeable embrittlement of stainless steels and molybdenum or other damaging effects. This method has been tested in precision gas-recycle systems and applied successfully for more than a year in a pilot-scale unit operating at 250 pounds per square inch gage and 2,400° F. It is now used routinely and can be applied to many gas-cooled systems operating at high temperatures.

Jan 1, 1962

By William F. Hahn

This project focused effort on three separate areas: demonstration of a low seam longwall illumination system, design of illumination systems for low coal auger miners, and an assessment of machine lighting systems for machinery used to mine low seam coal. Results indicated illumination systems can be purchased by the mine operators of low coal seams. These systems can be supplied with the equipment as a factory integrated system or can be retrofitted to the machine or longwall equipment.

Jan 1, 1982

By Leslie S. Rubin

A ventilated helical boost pump was developed that can handle varying flow rates and/or solids concentrations while operating at a single rotational speed and without computer assisted feedback controls. The boost pump developed and briefly tested during this program was designed to accomodate flows suitable for a 3-in. diameter pipeline. The boost pump's ventilated design provides the automatic pressure regulation needed to meet the system's requirements for supporting transient pipeline flow.

Jan 1, 1984

By R. W. Stahl

The use of continuous mining machines has greatly minimized the necessity for blasting in coal mines, even during pillar recovery; however, explosives are still used to blast stumps. The use of improper blasting materials, improper procedures, or both has caused mine explosions and fires, with loss of life and property damage. Researchers and manufacturers are continuously improving explosives and blasting accessories; use of the more recently developed materials will make the blasting operation safer. Extreme caution is mandatory when blasting stumps, as the ignition of methane or coal dust may trigger an explosion or cause a fire. Since the blasting of stumps will no doubt continue, although often unnecessarily, this paper summarizes recent findings published by the Bureau of Mines and recommends safer methods.

Jan 1, 1962

By Tyler Blake

This report describes a study designed to evaluate a pro-posed modification in the cap lamp battery cord intented to reduce the incidence of snagging and catching of the cord. A three phase evaluation was performed comparing a prototype with the standard, currently available cord. First, a ?pull test? equipment was run. The second evaluation was a body conformity study. The third evaluation involved subjects performing common tasks in a low seam coal mine simulator. The results of these evaluations clearly demonstrated significant safety advantages of incorporating coiled cord into the design of the cap cord. The coil cord presented less of a snagging hazard, allowed the wearer more time to respond to a snag, and transmitted lower levels of force to the helmet when snagged. The research team recommended that cap lamp cords be commercially developed which incorporate coiled cord at the battery and helmet.

Jan 1, 1980