Search Documents

By John Nagy

Large-scale tests in the U.S. Bureau of Mines Experimental Coal Mine show that the explosion hazard of coal dust on shuttle-car roadways can be con-trolled by proper application of water, dry rock dust, a saturated solution of ammonium phosphate, or mixtures of water or the water-phosphate solution with rock dust. The experiments were made with loadings of 1.0 and 5.0 pounds of mine size coal dust per linear foot of entry, and with a 3-or 4-inch-thick layer of coal rubble on the floor, The data from the tests with mine-size coal and rubble are comparable. The water contents of the dust loading were determined from samples collected just prior to initiation of a gas-air mixture in an ignition zone at the face Dust samples were collected 1 inch deep from the coal-rubble deposit. One experiment was made with the dust in the coal rubble bound with latex applied as a water solution by spray. The binding action was inadequate and explosion propagation was obtained.

Jan 1, 1970

By F. W. Lane

Some months ago the Bureau of Mines began research of a fundamental character on sulphur in petroleum. In the course of this work, the usual qualitative test for sulphur in organic compounds1 was applied to certain oils that were believed to contain approximately 0.5 percent sulphur. No sulphur was found, and, as a check on the qualitative test, the oils were subjected to quantitative determination of this element by the oxygen-bomb method.2 The sulphur content of the oils ranged from 0.10 per cent to 0.50 per cent. This experience led to further trial of the qualitative test for organic sulphur, both on the oils mentioned above, and on common sulphur-containing organic substances. No difficulty was experienced in detecting the element in the latter, but with the petroleum oils the test, as usually performed, could not be relied upon to detect less than 0.60 per cent of sulphur consistently. The use of mechanically polished pure sheet copper for the detection of free sulphur, hydrogen sulphide, and perhaps other sulphur compounds has been recommended.3

Jan 1, 1927

The role of government and the community has changed significantly over the last two decades in relation to environment protection, particularly in the mining sector. Increased community expectations have moved well ahead of regulatory requirements, and there is now a much greater appreciation generally of the concepts of ecologically sustainable development and intergenerational equity, and the gap between current practice and practices which would be in harmony with these concepts. Besides providing a `safety net' through regulations to ensure that basic environmental performance standards are met, government is now working proactively with the mining industry to encourage higher levels of environmental performance. This paper describes some initiatives between the Commonwealth government and the industry designed to achieve these higher levels of environmental performance, through programs aimed at the paradigms of best practice environmental management and continual improvement.

Jan 1, 1997

By K. C. Liddell

"Cu/Ni multilayers exhibiting giant magnetoresistance were deposited from a single electrolyte under stepped potentiostatic control. To enable transport measurements to be made without remounting the multilayer film, we developed a novel method that involved plating on a thin metallic basal layer atop a rigid non-conducting Si substrate. Rotating ring-disk electrode techniques were used to monitor the composition and thickness of individual plated layers. Transmission electron microscopy confirmed that the interfaces between adjacent layers were sharp and that the structure of the layers was uniform throughout the film. Atomic force microscopy images indicated that the film's surface was smooth and free of defects.ELECTRODEPOSITION OF THIN MULTILAYER MAGNETIC MATERIALSI. IntroductionElectrodeposition of compositionally modulated films will in all likelihood continue to be used to produce the read heads for stored magnetic data. However, the next generation of head materials will require both improved sensitivity and reduced film thickness. Certain multi layers consisting of thin alternating ferromagnetic and nonmagnetic layers exhibit giant magneto resistance and consequently are promising candidates for read head applications. We have successfully made multilayer films with giant magnetoresistance that have total thicknesses as low as 25 nm, approximately 120 times thinner than the thinnest similar films reported in the literature. This paper describes early results from our work on electrodeposition and characterization of Cu/Ni multilayers, a model system with enhanced magnetic and mechanical properties, including the GMR effect. The structure and composition of the multilayers were determined using TEM, AFM, and electrochemical methods, and their magnetoresistance was measured by the standard four-probe technique. A novel method developed in this work enabled the transport properties of the ultrathin films to be measured reliably without the need to dissolve the cathode or handle the films. To provide a context for these results, short accounts of other work on giant magnetoresistance and multilayer electrodeposition are also included."

Jan 1, 1997

By Hetland Donald L.

Regional Tertiary formations and basins of local sedimentation which contain uranium deposits west of the Rocky Mountains are mainly of Oligocene, Miocene, and Pliocene age (fig. 1). The host rocks have been derived mainly from intrusive and extrusive igneous rock. The major host formations which cover broad geographic areas include the Esmeralda, Truckee, Humboldt, Thousand Creeks, Payette, Panaca, Cedarville, Coso, and San Joaquin Formations. Local areas of Tertiary sedimentation containing uranium deposits occur near Yuma, Safford and Artillery Peak, Arizona; Dillon and Canyon Ferry, Montana; Spokane Indian Reservation and Pend Orielle River, Washington; Topaz Mountain, Utah; Stanley Basin, Idaho; and Sonora Pass, California. Uranium deposits in these sediments have been classified into five categories based on environment (fig. 2). They are: (1) Deposits in lake sediments consisting mainly of water-laid tuffs; (2) Deposits in lake sediments intruded by volcanic plugs; (3) Deposits in lake sediments interbedded with arkoses near batholiths; (4) Deposits in coarse volcanic sediments in local sedimentary basins; (5) Deposits in arkosic conglomerates in local sedimentary basins.

Jan 1, 1969

By A. C. Fieldner

"Purpose and Nature of Tests:The rapidly increasing use of motor vehicles and trucks in the United States is creating an entirely new problem in the proper ventilation of tunnels, subways and other confined spaces through which such machines must pass. This problem has become of immediate importance because a tunnel 3,000 ft. long is being designed to pass under the Hudson River between New York City and New Jersey. Another tunnel at Pittsburgh 5,700 ft. long through the South Hills, is already under construction, and a third tunnel, 6,000 ft. between Boston and Past Boston is proposed. It is probably that other tunnels will be started in various parts of the United States in the near future.The ventilation of such tunnels is a serious matter, on account of the poisonous nature of automobile exhaust gases. It not uncommon to read about finding a man dead in his garage. Generally this happens on a cold, winter morning, after he has been running the engine with the doors and windows closed."

Mar 1, 1920

By C. L. Brown

Coal has been transported by belt conveyors in mines for many years; however, only since the beginning of the general mechanization period have complete transportation system of this type been employed. Aside from my complete belt-conveyor transportation systems, belt conveyors are frequently used in conjunction with other transportation. Many early installations, for the most part, were made without standards as a guide. As a result, some States have outlined certain requirements based more or less on experience following mine fires. Correlation of these regulations should result in more uniformity in connection with standardization of regulations. The National Electrical manufacturers Association has published standards for mining-belt-conveyor installations2/ that should be helpful to the coal-mining industry generally. Bureau of Mines Schedule 2F3/ requires certain controls for permissible-belt- conveyor drives, and similar requirements are listed in Bureau of Mines bulletin 514.4/ Committees of the American Mining Congress have prepared much valuable information concerning operation of belt conveyors, and a subcommittee on fire-resistant belting has been active. 5/

Jan 1, 1956

By Jeongbok Seo

The Dulles Corridor Metrorail Project (DCMP) involves the design and construction of a 23.1-mile extension of the Washington Metropolitan Area Transit Authority (WMATA) rail system. The initial 11.7-mile extension, with five transit stations and a new service and inspection yard, is to be constructed. The construction plan for the initial 11.7-mile extension includes installation of a total of an estimated 4,250 or 160,000 linear feet of driven 12x53 steel H-Piles at more than 80 different locations. At the time of this paper, approximately 40 percent of the piles have been installed and the remainder of piles will be installed by the end of 2010. This paper describes: 1) subsurface investigation program, 2) application of existing Codes and impact on the design of H-Pile, 3) design methods to determine geotechnical bearing capacity and pile tip elevation, 4) verification of capacity including PDA and Static Load Tests, 5) project specific pile load tests, and 6) QA/QC during pile driving.

Jan 1, 2010

By D J Williams

Coal washery wastes comprise tailings, finer than 0.5 to 0.1 inn depending on the sophistication of the washery, and coarse reject, typically finer than 50 mm. Subaerial disposal of coal tailings slurry at about 30 per cent solids by mass results in the formation of a delta with an average slope of about 1 in 100, representing one extreme. The ravelling of coarse reject on loose-dumping, results in an angle of repose slope with an angle of about 37" (1 in 1.3), representing the other extreme. The pumped co-disposal of coal tailings and coarse reject results in the formation of an upper delta with an average slope of about to one in ten, between the two extremes. The depositional behaviour of these three waste streams is discussed and compared in this paper. The important depositional and material parameters, and a theoretical description of the processes involved, are also presented. Comparisons are made between the depositional behaviour of the various coal washery waste streams, and natural depositional systems, such as rivers, alluvial fans, and scree slopes.

Jan 1, 1998

By K. J. Liles

To encourage the development and conservation of the Nation's ceramic raw materials, the Bureau of Mines, U.S. Department of the Interior, under an agreement with the Georgia Department of Natural Resources, evaluated samples from a clay resource located in Clay County, Ga., for use as a raw material for lightweight aggregate. The physical properties of clay samples, taken from 5-foot increments of drill cores from 11 holes, were determined. Raw materials were plasticized and extruded to produce 1/2-inch by 1-inch pieces and fired in a rotary kiln to produce lightweight aggregate samples. The resulting expanded material had excellent loose pour weights ranging from 30 to 37 lb/cu ft. The expanded test materials were crushed, sized, and used as aggregate to form concrete cylinders. The unit weight and compressive strength of the cylinders averaged 106 lb/cu ft and 3,350 lb/sq in, respectively; these values meet American Society for Testing and Materials specifications for structural concrete. The clay from the drill cores was also used to make test bars that were evaluated for building brick.

Jan 1, 1980

By J. A. Finch

Solvent-coated air bubbles in the Air-Assisted Solvent Extraction (AASX) process achieve the dual role of high solvent specific surface area and ease of phase separation. The thickness of the solvent film is of fundamental interest but difficult to measure directly in the process itself. As an approach interferometry (in the UV-vis region) was used to measure the time dependent thickness of a film formed by blowing an air bubble in kerosene-based solvents. The film was stabilized by the presence of 1.5 ppm silicone oil, as employed in AASX. The film appears to comprise two layers; an outer "free" layer of almost constant thickness and an inner "bound" layer which decreased in thickness with time. The bound layer is considered relevant to AASX. For a 20 mm diameter bubble blown in LIX/kerosene solvent the initial thickness was ~ 3 um which decreased over 10 minutes to a final rupture thickness of 500 nm. The bound layer thickness and time to rupture decreased with decreasing bubble size. Correspondence to prior indirect estimates of solvent layer thickness is examined.

Jan 1, 2006

By N. Afrin

The microstructure and tensile properties of AZ31B-H24 magnesium (Mg) alloy after friction stir welding (FSW) were evaluated. The grain size was observed to increase from approximately 5 µm to about 9 µm after FSW. The obtained Hall-Petch type relationship showed a strong grain size dependence of the hardness values. While the FSW led to about half of the yield strength of the base magnesium alloy, the ultimate tensile strength after FSW could reach about two thirds of that of the base alloy. The hardening capacity of the FSWed samples was about twice of that of the base alloy. The strain hardening exponent of the base alloy was found to be about 0.1 whereas it became larger than 0.3 for the FSWed samples. After yielding the base alloy showed a high initial and almost constant work hardening rate, corresponding to linear hardening stage II, followed by stage III with a decreasing hardening rate. Stage II linear hardening was observed to be absent in the FSWed samples.

Jan 1, 2007

By James S. Browning

The purpose of this investigation was to develop a dependable and economic method for recovering spodumene and mica from pegmatites of the type found in Gaston County, N. C. Laboratory batch tests and continuous flotation tests were made by the Federal Bureau of Mines to determine the feasibility of treating the ore by flotation to recover high-grade spodumene and mica concentrates. The spodumene flotation circuit yielded concentrates containing 6.50 percent lithia (Li20), with an overall recovery of 81.8 percent of the lithia in the ore, The mica circuit yielded concentrates containing 97.5 percent mica, with a recovery of 82.5 percent of the mica in the spodumene tailing.

Jan 1, 1961

By J. S. Browning

The Bureau of Mines investigated the concentration characteristics of high-clay sylvinite ores from potash companies operating in the Permian basin near Carlsbad, N. Mex. These ores, containing 14 to 19 percent K20 and 3 to 5 percent clay slimes, cannot be effectively processed by current commercial flotation methods because of their high clay content. A solution to this problem was shown to be the use of two-stage moderate scrubbing conditions for clay disaggregation and removal as opposed to strenuous attritioning. Bench-scale beneficiation techniques for recovering potash minerals by flotation from the scrubbed material resulted in acceptable product grades and recoveries. By using a coarse grind, emphasis was placed on production of premium granular and coarse products. Flotation results showed that concentrates of 59.6 to 60.4 percent K.0 values can be obtained. Continuous pilot plant beneficiation techniques for recovering potash minerals by flotation resulted in concentrates containing 58.8 to 59.8 percent K20 with recoveries of 69.7 to 81.4 percent of the K20.

Jan 1, 1975

By G. R. M. Del Giudice

A survey of the flotation literature of the past 10 years indicates an increasing use of the microscope as a tool for investigation. Thus, the metallurgical microscope has been used by Tucker and Head;' Taggart, Taylor and Ince;2 Ince,3 and del Giudice4 to examine mineral surfaces that had been subjected to the action of various flotation reagents and to the action of slime pulps. It has also been used by Gaudin, Groh and Henderson;5 Martin;6 Morrow and Griswold;7 and others to examine bakelite briquets of mill products. The microscope with transmitted light, both with bright-field and dark-field illuminations, has been used by Taggart, Taylor and Knoll8 and by Ince9 to observe Brownian motrement and flocculation in flotation pulps. The use of the microscope at low-power magnifications with incident illumination for the examination of mill products has been known for years.10 Finally, del Giudice11 has used a relatively new type of illumination, the Ultropak, for the examinntion of slime-coatings.

Jan 1, 1935

By Claude A. Goode

Large quantities of high grade coal exist in thick seams in the United States. Many of these thick seams are too deep to be surface mined and do not lend themselves readily to underground extraction. To develop the new mining technology required to effectively mine thick seams, the Department of Energy has entered into a Cooperative Agreement with Mid- Continent Resources, Inc. to demonstrate the multilift longwall mining technique in a 28 foot-thick seam at their L.S. Wood No. 3 mine near Redatone, Colorado. The seam will be extracted in two lifts, with a 5-foot natural partition of coal left between the upper and lower lifts. Proper selection of face supports is critical to the success of this project. Specifications were defined for the roof supports, and it was concluded that the supports selected must provide full coverage, yield at the legs, and have a 60-inch push- out cantilever that can be set at any position under full load. A Hemscheidt two-leg shield was judged as the best qualified candidate and was selected for the multi-lift trial.

Jan 1, 1981

By John R. Reeves

The development of an new industry, which must prepare its marketable products at or near the source of the raw material, and ship them to a market which may cover half a nation, is more or less influenced by a number of natural and cultural conditions such as (1) location of plants with respect to a large market, (2) climatic conditions, (3) transportation facilities, (4) labor supply, and (5) water supply. An effort is made in this pager to give in detail a number of the more important of these conditions as they affect, either favorably or unfavorably, the development of the oil-shale resources of southeastern Indiana. The utilization of the New Albany formation for the production of oil will be similar to a large scale low-grade ore proposition in which the raw material can be obtained in very large quantities at a relatively low cost. It appears, therefore, in considering the value of this shale or its economic position in relation to other oil shales, tie cost of mining and preparation for the retort are of prime importance.

Jan 1, 1923

By Martin C. H, Met B

INDEX OF CONTENTS:1. Introduction, Explanatory; and Reasons for Coal Cleaning.2. Principles on which Coal Cleaning is based.3. Location of Broken Hill Proprietary Co. Ltd. Plant.4. Description of Processes Selected Barvoys Bath Process; Barvoys Medium Preparation and Treatment; Static Dry Cleaning Plant.5. Detailed Description of Plant.6. Typical Results of Cleaning Operations.INTRODUCTION, EXPLANATORY, AND REASONS FOR COALCLEANING:The Institute proceedings have not previously published any matter on coal cleaning and the reasons thereof; in consequence it has been deemed advisable to allot a part of this paper to explanatory matter, prior to entering into a detailed explanation and description of the Newcastle plant.At the outset it would be as well to consider briefly the kinds of materials from which coal has originated. All coals represent some stage in the decomposition and transformation of vegetable matter laid down in prehistoric times, the vegetable matter undergoing numerous geological changes, such as submergence, overlaying by sediment, with subsequent pressure and re-elevation; these processes may...

Jan 1, 1946

By R. E. Johnson

The No. 3 reverberatory furnace at Phelps Dodge. Corporation's Morenci, Arizona copper smelter first received oxygen from a new oxygen plant during October 1982 and began operation with oxygen-fuel and oxygen sprinkle smelting burners which burn concentrate with oxygen. The furnace was completely converted to roof-mounted oxygen-fuel firing in October 1982. All conventional air-fuel bridge wall burners were extinguished at that time. The novel arch-mounted oxygen sprinkle smelting system began continuous operation April 1983. Since startup, unit fuel requirements decreased and furnace throughput significantly increased. Furnace off gas SO2 strength increased from an average of 1.5% SO2 to an average of 20% using only oxy-fuel burners. Oxygen sprinkle burner operation also has given excellent results, with the furnace off gas strength increasing to 35%-60% S02. There has been a reduction in overall arch temperatures, an increase in matte and slag temperatures, and a lowering of furnace bottom buildup with oxygen smelting. Furnace off gas is blended with converter off gas and treated in a sulfuric acid plant.

Jan 1, 1983

By David M. Davidson

Seven intrusive phases have been mapped to date in the 1 b.y. Red Bluff Granite Complex (RBGC) near El Paso, Texas. This batholith is 20 km2 in area and intrudes older supracrustal units as well as a trachyte ignimbrite cap. Two early microgranite sills are spatially separated 6 km from a porphyritic, three-phase "ring complex" by a tin-bearing, biotite granite which cores the RBGC. These units are intruded, in turn, by a riebeckite granite which locally exhibits lineated and pegmatitic textures as well as exceptionally high light REE and Zr values (800 ppm La; 3,000 ppm Zr). The riebeckite granite is exposed in three separate occurrences within the Franklin Mountains. REE values in the RBGC are depleted in HREE and show distinct negative Eu anomalies. Typical La/Yb ratios are 5:1-2:1 with Eu values ranging from 10-80 ppm. The mineral source of the high REE values in the riebeckite granite has not yet been specifically identified, but is believed to be zircon.

Jan 1, 1988