Search Documents

By H. E. Powell, T. E. Hill, W. A. Calhoun

The object of this investigation was to determine the effectiveness of certain cationic flotation collectors , Ethomeens , in recovering fine particles of lead minerals from mill tailings at a grade equal , at least , to that of the mill feed ( 1.7 percent lead ) . The Ethomeens , derived from tertiary amines having one fatty alkyl group and two polyoxyethylene groups attached to the nitrogen , were evaluated by bench- scale flotation tests . The 14 Ethomeens tested consisted of four groups : Coco amine , soybean amine , tallow amine , and stearyl amine . The best results were obtained with coco amine C / 12 , soybean amine S/ 15 , tallow amine T / 12 , and stearyl amine 18/20 . From a feed containing 0.23 percent lead , rougher concentrate grades of 2.12 to 3.89 percent lead were obtained , with recoveries of 17.3 to 27.5 percent of the total lead . Some of the lead mineral particles recovered had diameters of less than 1 micron . In comparative tests , the Ethomeens , or polyethoxylated amine types of cationic surface active agents , were more selective than conventional xanthate collectors for flotation of slimed lead minerals .

Jan 1, 1964

By R. L. Crosby

The Bureau of Mines investigated alloys of copper with 2, 3, and 4 vol pct alumina and with 2 vol pct yttria. Alloys were prepared by a coprecipitation process and were fabricated by pressing and sintering of powders, extrusion, and swaging. Tensile properties at room and elevated temperatures, stress-rupture strength, electrical conductivity, and density were measured. The superiority in elevated temperature strength of dispersion-strengthened copper to OFHC copper was confirmed. Increasing the oxide content from 2 to 4 vol pct produced only a small improvement in strength properties and decreased the electrical conductivity. The 3 vol pet alumina alloy had the best overall combination of properties.

Jan 1, 1969

By M. M. Fine

This report presents the results of laboratory mineral-dressing investigations by the Bureau of Mines of 14 individual or composite character samples from deposits in the Batesville manganese district. It will be noted that some concentrates have met or approached analytical specifications for metallurgical manganese ore although great variations in both physical and chemical composition from once deposit to another make each a new problem. In most cases it is evident that a substantial loss of manganese has occurred in the various slime and tailing products. An important aspect of this work is the research being conducted on manganese-bearing limestones. Recent reconnaissance indicates that this resource constitutes one of the major domestic reserves of manganese. Laboratory study has shown that ferrograde concentrates can be recovered from samples of manganese-bearing limestones from two properties. Research on samples from other areas is still underway.

Jan 1, 1957

By Doyle A. Ellerbruch

An FM-CW microwave system was investigated for measuring coal layer thickness. Measurements were made in three different mines near Pittsburgh, Pennsylvania, near Fairview, West Virginia, and near Coffeen, Illinois. Microwave frequencies in the range 1-2 GHz were used to measure samples up to 55 cm thick. All samples were backed with a naturally occurring shale. Measurements were also made on coal and shale samples compounded in the laboratory at the Bureau of Mines Pittsburgh Mining and Safety Research Center near Bruceton, Pennsylvania. The results indicate that layer thickness can be determined in most cases, although large anomalies may, in some cases, produce misleading results. Many anomalies that were detected with the FM-CW system were verified visually by drilling into the coal layer. The dielectric constant of coal apparently varies significantly within a coal seam. The form of the output signals from the FM-CW system seem to simplify the data interpretation and analysis process as compared to the manually swept microwave system used previously. It appears that this technique has the potential of measuring changes in the dielectric constant of a coal seam and providing an output that can be used for real-time corrections in layer thickness; measurement.

Jan 1, 1976

By Lewis M. McNay

Description of methods employed and cost data are given for surface-mined land reclamation in Moraine State Park, Butler County, Pa. This project was conducted under the authority of the Appalachian Regional Development Act; a total of 177 acres of land was rehabilitated for specific land use purposes. The use of large equipment expedited the project work, and similar results could be anticipated on similar reclamation programs.

Jan 1, 1970

By Jeffery L. Kohler, Harvinder Singh, Jon G. Bredeson

A survey of electromagnetic noise reports was performed and a summary of the results are given. Industrial concerns were surveyed for techniques to minimize the effects of electromagnetic noise and are presented. The common types of communication links used in mines today are presented. A mathematical development was presented which determines the probability of bit errors versus distance for various types of communication links designed for in mine use. The probability of undetected errors for the protocols of the communication links is given together with burst error detection.

Jan 2, 1981

By Neal M. Muir

The increasing demand for iron ores prompted the Bureau of Mines to investigate the sources of past production in Kentucky to determine whether reserves of usable ore still exist. Preliminary investigation showed that the holdings of the Rose Run Co. were the most promising, inasmuch as the deposit had not been exhausted by past mining and the property was near railroad facilities and but 80 miles from the blast furnaces at Ashland, Ky. The Bureau conducted a churn-drilling and sampling program to investigate the depth, thickness, and iron content of the ore beds so that they might be evaluated as a possible reserve of low-grade iron ores. The Rose Run area in Bath County, Ky., was explored by 74 churn-drill holes totaling 2,059.4 feet of drilling and 4 cuts and test pits. Fifty-seven drill holes and the four test pits penetrated the ore bed at an average depth of 22 feet. The bed had an average thickness of 2.54 feet. Analyses show that the calcium and magnesium carbonate content is more than sufficient to flux the silica and provides an excess that needs an admixture with other siliceous iron ores.

Jan 1, 1950

By Thomas M. Garland

A field study was made by the Bureau of Mines in cooperation with oil companies to determine the feasibility of changing the injection profile of water-input wells after water breakthrough at producing oil wells. A secondary objective was to study the particle size and quantity of plugging material required to change the input profile and the methods of applying these materials. Fifty-three injection wells were treated with various amounts and types of plugging materials and the injection profile was definitely changed in most of the wells treated. Increased efficiency of water injection after treatment was indicated by tracer surveys and injection-well performance. There were some indications that the rate of water production was reduced and the rate of oil production was increased as a result of selective-plugging treatments, but ,s found that an immediate change in the rate of oil and water production did not normally occur. In many cases, beneficial results from a treatment may never be observed in the rate of oil or water production due to the many factors that affect the performance of producing and injection wells.

Jan 1, 1966

By J. J. Hoeppner

Accurate determination of moisture in coals of various ranks has long been a subject of intensive investigation. Excellent reviews of methods developed over many years are given by Brown (9)4/ and, with experimental comparisons, by Goodman, Gomez, and Parry (11). As pointed out in these and other writings, one of the principal difficulties in assigning absolute merit to one or another procedure is the multiplicity of conditions under which water may exist in coal and the difficulties involved in obtaining sharp separation and distinction between these classes. Gauger (10) states: Water recoverable from coal is obtained from the following sources: (1) Decomposition of organic molecules (sometimes called combined water), (2) surface adsorbed water, (3) capillary condensed water, (4) dissolved water, and (5) water of hydration of inorganic constituents of the coal.

Jan 1, 1956

By R. E. Campbell

Uranium metal of improved purity was prepared by electrorefining commercial magnesium-reduced uranium in a molten sodium chloride-uranium trichloride electrolyte. The best operating conditions for the preparation of refined metal were established as follows: an electrolyte containing 8.7 to 13.3 weight-percent uranium; initial cathode current densities from 300 to 1,500 amp/sq ft; and a molten salt temperature of 860° C. Ingots produced from electrorefined uranium crystals prepared with these operating conditions were substantially free of metallic impurities. The only impurities in the refined and consolidated metal were present in low or undetectable amounts.

Jan 1, 1965

By R. V. Ramani

In this the available information friction factors and leakage report, on characteristics are reviewed and summarized. The use of Penn State Mine Ventilation Simulator (Volumes II and III of the Final Report) to analyze the sensitivity of the ventilation system to the changes in leakage and friction factors is discussed with examples. In simple ventilation systems, the results of changes in leakage and friction factors can be easily solved and explained by the laws of air-flow. In complex systems, with fixed quantity branches and multiple sections, the effect of changes in leakage and friction factors cannot be generalized. This study points out the importance of good input data for obtaining reliable information from computer analyses and demonstrates the application of simulators to analyze the effectiveness of ventilation systems. An extensive bibliography on friction factors, leakage characteristics and ventilation economics is included.

Jan 1, 1977

In spite of advances in measurement techniques and an explosive increase in the volume of research, our understanding of human strength remains in its introductory stages. It is clear that muscle strength is a highly complex and variable function that depends on a large number of factors. It is not surprising, therefore, that large differences in strength exist not only between individuals, but even within the same individual tested repeatedly on a given piece of equipment. The issue is compounded by the fact that correlations of strength among different muscle groups in the same individual are generally low, and tests of isometric strength do not necessarily reflect the strength an individual might exhibit in a dynamic test. As a result of these and other influences, great care needs to be exercised in designing, evaluating, reporting, and interpreting muscular strength assessments. Traditionally, tests of muscular strength were in the domain of the orthopaedist, physical therapist, and exercise physiologist. Such tests are also an important tool for the ergonomist, however, because of the high strength demands on workers in manual materials-handling tasks. In some cases, task demands may approach or even exceed the strength that an individual is voluntarily willing to exert in a test of strength. In such cases, evidence suggests that the likelihood of injury is significantly greater than when the task demands lie well within an individual's strength capacity. Because the relationship among strength capabilities, job demands, and musculoskeletal injury has been established, it is apparent that tests of muscular strength may benefit the ergonomist both in designing jobs and in ensuring that individuals have sufficient strength to safely perform physically demanding jobs. Several strength assessment techniques have been employed for these purposes, each possessing unique characteristics and applicability to job design and worker selection procedures. Our main purpose has been to elucidate these strengths and weaknesses, so that tests of strength may be properly applied in designing jobs and selecting workers. One of the crucial points we have emphasized is that any test of strength used in job design or worker selection must be directly related to the demands of the job.(1) For example, if an occupational lifting task has a high dynamic component, a test of isometric strength is not likely to provide the data necessary for proper design of the job. Of course, dynamic strength tests would also be misapplied in assessing a job requiring isometric exertions. Another potential pitfall is using tests of strength on isolated muscle groups and assuming that they are indicative of whole-body strength. For example, one might mistakenly assume that dynamic trunk extension strength represents a person's capability to perform a lifting task. However, an individual's lifting capacity may be entirely unrelated to trunk extension strength. It may, instead, be limited by an individual's arm or leg strength, depending on the task being performed. A final point on strength assessment should be made. An individual's strength capability cannot be considered a fixed human attribute. Strength training regimens can increase an individual's strength capability by 30%-40%. Whether

Jan 1, 1998

By R. V. Ramani, J. Qin, R. A. Jankowski

"Longwall mining is generally recognized as safer, more productive and economic when compared to room and pillar underground coal mining. There has been, however, increasing concern for the control of airborne coal dust concentrations in long wall faces. The airborne dust cloud at a longwall face is a complex aerosol system containing particles of varied size, density, shape and state of aggregation. For the development of more effective dust control practices in longwall faces, it is necessary to understand more clearly the characteristics of the longwall dust cloud.In this paper, results of a research study on dust concentration distributions along longwall faces are presented. The objective of this study is to characterize the longwall dust cloud behaviour and provide necessary fundamental data for a better understanding of the longwall dust problem. MSA personal samplers and gravimetric total dust samplers were employed to collect respirable and total airborne dust samples. The size distribution of these samples was determined by MicroTrac SPA. The instantaneous respirable airborne dust concentrations were recorded using RAM-I. The dust concentrations are related to face operations, particularly the shearer location and activities. The size distribution of airborne dust, instantaneous respirable airborne dust concentration, and air quantity distributions along longw all faces reveal a complex dust flow phenomenon. Additional fundamental studies are needed for characterizing the temporal and spatial behaviour of the dust cloud at longwall faces.IntroductionModern mechanized longwall mining was introduced in the United States in the 1960's and has become more common in the last twenty years. United States longwalls are multiple-entry retreating faces. According to a recent survey, 91 of the 102 longwall faces employ double-drum shearers (1). Several recently installed longwall faces have consistently produced over 4 000 to 5 000 tons per shift over extended periods of operation. The trend in under-ground coal mining in the U.S. certainly is toward the introduction of longwalls. This trend is true not only for new mines but also for renovation of existing mines. While longwall mining has many advantages over other mining methods, including improved safety, such as higher pro-duction. greater productivity and enhanced reserve recov-ery, it is associated with severe problems of dust control. The increase in longwall production has been accompanied by an increase in respirable dust problems which limit realizing the full potential of the longwall mining system. Despite the efforts to develop improved equipment and operational procedures to control the dust levels at longwall faces, it is still difficult to bring several double-drum shearer operations into compliance with the Federal stand¬ards of 2,0 mg/m 3 respirable dust without loss of produc¬tion. In fiscal year 1987, fifty-eight of the longwall sections were found to be in non-compliance once, and an additional 31 were cited two or more times'''. If the full potential of the longwall mining method is to be realized, new measures must be implemented to control the dust concentration to mandated levels. There is a need for detailed and extensive sampling of longwall faces to understand the dust source-sink relationships and the transient ambient concentrations. These must be related to the mining activities on the face. This paper is to characterize the longwall dust cloud behavior through a series of experiments in operating faces and provide necessary fundamental data for further studies to develop improved dust control practices."

Mar 1, 1992

By B. W. Jong

As part of the Bureau of Mines program to develop substitutes for critical and strategic materials for metallurgical applications, the Tuscaloosa Research Center has evaluated the effect of additives and starting materials on the sintering and strength properties of sialon (silicon-aluminum-oxynitride) compositions fabricated by conventional pressing and sintering techniques. Sintering and MOR (modulus of rupture) data were developed for sialon compositions produced from three components, Si3N4, A1203, and AIN. When doped with Y203 to aid in sintering, the highest MOR values were obtained with compositions containing between 20 and 30 mole-pet (A1203 + AIN). The effect of the crystalline phase of the Si3N4 and Al203 used in the three-component system on MOR also was investigated. Alpha-Si3N4 and ?-A1203 were found to be the best starting materials. A sialon composed of 67.4 mole-pct a-Si3N4 plus 32.6 mole-pct (?-AI203 + AIN), doped with 5 wt pct Y203, had MOR values at 25°, 1,200°, and 1,400° C of 40,300, 40,300, and 31,100 psi, respectively. Samples of this composition doped with Gd203, MgO, Zr02, and ZrSi04 also were evaluated. The ZrSi04-doped sialon had higher MOR values than Gd203-, MgO-, and Zr02-doped materials but lower MOR values than the Y203-doped sialon. The MOR values of ZrSi04-doped sialons were 25,000 and 25,900 psi, respectively, at 25° and 1,400° C.

Jan 1, 1981

By James S. Browning

Research by the Bureau of Mines demonstrated that organic heavy liquid adhering to or adsorbed on fine mineral particles can be effectively removed by a novel method embracing pulping or displacement washing with hot water alone or in combination with a detergent. Displacement washing with steam alone or in combination with a detergent also was effective for removing the heavy liquid. In tests of sized minus 48-plus 200-mesh mineral charges, both the hot water washing with detergents and detergent steaming effectively reduced the heavy liquid losses on the particles to about 0.2 pound per ton of mineral or less. Centrifuging of the wash solutions permitted an almost complete recovery of heavy liquid from the solution as a pure heavy liquid product.

Jan 1, 1966

By Albert W. Deurbrouck

This report describes the preparation characteristics of the significant, presently producing coalbeds in Mercer County, W. Va. Approximately 650,000 tons of coal was produced in Mercer County, W. Va., in 1960, of which over 630,000 tons was cleaned in four preparation plants. In 1960 the Pocahontas Nos. 3, 6, and 11 coalbeds supplied 99.5 percent of the total coal mined in the county. Because the number of working mines In this county was small, only six samples were collected; four of which were of metallurgical quality as mined. The remaining two samples could be upgraded by washing at suitable specific gravities. Many of the samples taken were of metallurgical quality as mined; however, the float-and-sink analysis on these coals has been included to point out their amenability to the production of premium quality, special purpose coals. In general the coals were low-volatile bituminous in rank with low ash and sulfur contents.

Jan 1, 1963

By Leonard F. Heising

At the Groveland mine iron ore is mined by open-pit methods and concentrated by means of spirals and flotation. A brief history of the mine and its early development is given. The ore deposit is described, with emphasis on those physical characteristics that affect the choice of mining and milling methods. Development and mining, which include breaking ground, loading, transportation, engineering, and operating control, are explained, and the milling method is described Mining and milling costs are given in percent of total cost.

Jan 1, 1963

By S. M. Shelton, F. D. DeVaney, M. M. Fine

Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced ; although it is well -known that there are large deposits of low - grade ore in the United States , the production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stockpiled ore is depleted through inability to obtain adequate supplies from foreign sources . Consequently, a program of laboratory and pilot - plant investigations designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines . This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program . The scope of the program and the organization that was set up to direct and supervise the work were discussed in the foreword of the first paper of this series , Report of Investigations 3606 , Manganese Investigations 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent , and C. H. Schack . Other reports will be published as the work progresses .

Feb 1, 1942

By J. Roger Loebenstein

This report presents a U.S. Bureau of Mines study of the flow of arsenic-containing materials in the United States, based on the best data available in 1991, includes a consideration of arsenic as a byproduct of the processing of nonferrous metals, the fate of arsenic in manufacturing wastes, the quantity of arsenic used in products, tile fate of arsenic in dissipative uses, and the useful life of discarded products. Where possible, estimates are given of the amounts of arsenic lost from the materials flow. Arsenic byproduct of mining nonferrous metals. Historically, most U.S. production has been from the states of Montana, Washington, and Utah. The smelters in these states are believed to be the areas of the country where arsenic is most concentrated in the soil, tailings ponds, and waste dumps. Since the closure of the last domestic producer of arsenic in 1985, all arsenic has been derived from imported sources. Historically, arsenic was important in agricultural applications as an insecticide, herbicide, and cotton desiccant. As the environmental movement gained momentum and the toxicity of arsenic became better understood, most of the agricultural uses for arsenic were banned. Beginning about 1975, the use of arsenic as a wood preservative began to grow. After 1980, wood preservative uses became more important than agricultural applications. By 1990, 70% of the arsenic consumed in the United States was used by the wood preservative industry and 20% by the agricultural industry. The major source of domestic arsenic emissions in 1989 was from the U.S. copper processing indus¬try. About 7,800 mt/yr of arsenic was discarded in leach dumps, tailings, and slag. Another 800 mt/yr was liberated to the atmosphere and 1/100 mt/yr was exported in copper concentrates. On the consumption side, 9,200 mt/yr was lost, mostly from dissipative agricultural uses and the disposal of obsolete arsenical products.

Jan 1, 1994

By William P. Diamond

In this U.S. Bureau of Mines study, production trends have been analyzed for 82 gob gas ventholes on 7 longwall panels in the Lower Kittanning Coalbed, Pennsylvania. Cumulative production from individual holes was found to vary considerably, ranging from 0.03 x 106 to 10.1 x 106 m3. Peak production rates were generally about 0.03 x 106 to 0.06 x 106 m3/d, but rates over 0.10 x 106 m3/d were observed. The variability of gas production from individual holes can be attributed to' several factors, including completion practices and problems, the extent of fracture development in the strata above the extracted panel, water production, and location on the panel. Of particular significance is hole location. Holes on the ends of the panels, where overburden strata are in tension because of the support of the surrounding pillars, were generally the highest and longest producers. This observation led to the experimental placement of gob gas ventholes in the zone of tension along the margin of a panel, instead of in the traditional centerline location, which is in compression. Analysis of 7 months of gas production data indicates that the experimental near-margin holes produced 77 pct more gas than did centerline holes on the same panel.

Jan 1, 2010