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By Joan Weinberg

The real gross national product (GNP) advanced at a annual rate of 3.1 % during the second quarter, following a revised 3.4% increase in the first quarter (see table 1). Export growth continues to play an important role in the rising output. Combined with the decline in imports, it resulted in a noticeably improved trade position. Imports of consumer goods, including automobiles and food, fell while exports rose. Imported cars have been losing ground to domestic cars. The foreign car share of the U.S. market fell from 36% in October 1987, to 29% in May 1988. Business spending for new plant and equipment contributed strongly to the GNP increase. Equipment purchases, particularly of computers, rose at a 14.8% annual rate, following a large first-quarter gain. Purchases of structures rose 11.8%. The other key component of business spending, change in business inventories, declined from the first quarter. Inventory buildup in late 1987 had been considered excessive.

Jan 1, 1988

By J. D. Dixon

The Bureau of Mines has developed structural design data for unreinforced concrete tunnel linings in the form of stress and deflection coefficients from which bending, axial, shear, and boundary stresses, moments, thrusts, and shear forces, and structural deflections can be determined at any point on the lining. Results were obtained by structural analyses of nine concrete-lined tunnel configurations subjected to 22 biaxial load conditions. The tunnel configurations include three basic shapes, circular, rectangular, and horse-shoe, with dimensions based on designs evolved by the mining industry. These analyses were made by the direct stiffness matrix method, a computer-oriented procedure. Numerical results agree closely with those obtained experimentally.

Jan 1, 1969

By A. W. Kbair, L. D. Gehl

"INTRODUCTION The rock-bit interaction during the cutting process in underground mines has been a matter of great concern to mining operators, researchers and manufacturers, particularly after the passage of strict environmental laws. Coal cutting bears directly on airborne coal dust generation and rock cutting generates frictional sparks which may cause face ignitions, jeopardizing the productivity, safety and economy of the industry. It is imperative to investigate into the factors which have influence on bit we.ar. Hurt and Evans (1981) concluded that the point attack bits have greater ignition potential than the conventional wedge shaped bits, and also worn bits were more responsible for ignition than the new bits. The results of a study (Khair et al., 1992) suggested that after 7% weight loss, the bit should be replaced. The polycrystalline compact diamond (PDC) tipped bits are reported to be cost effective in a study done by USBM (Twin Cities Research Center), and it was stated that the PDC tipped drill bits had 80 to 100 times longer life than the ordinary tungsten carbide (WC) tipped bits.This paper presents the results of the experiments which were conducted utilizing a coal cutting simulator at the laboratory of the Department of Mining Engineering, West Virginia University, USA. The description of the machine and the experimental set-up have been described elsewhere (Khair et al., 1989; Gehi & Khair, 1994), and therefore, will not be discussed here. The rock types which were used in experimen~ are Tennessee sandstone, Berea sandstone and Indiana limestone. The operating parameters include (1) drum speed, (2) water spray pressure and (3) bit type. Besides studying the wear characteristics influenced by the above mentioned variables, the effect of these parameters on the required cutting force, specific energy consumption, acoustic emissions rate and rise in temperature of the bit were also studied. A preliminary study was also done to compare we.ar characteristics of the WC bits with those of the poly-crystalline compact diamond tipped bits."

Dec 1, 1995

By C. H. Schwartz

A thermal radiation probe was constructed and tested in pulverized-coal-fired furnaces. A rotatable sensing head on the side of a water-cooled probe permitted measurement of radiant flux within a 7.20 cone from any desired direction to a point within a furnace. A response curve for a corner-fired furnace showed radiant flux of 130,000 Btu per sq ft per hr, when viewing flame, and 60,000 Btu per sq ft per hr, when sensing wall reflection. Detailed drawings and fabrication procedure are given.

Jan 1, 1970

By Oleg Terichow

Electrophoretic mobility measurements were made on samples of Florida phosphate slimes to determine the optimum conditions of coagulation and precipitation in aluminum sulfate solutions. The addition of silica sand and other selected materials as mutual coagulants has demonstrated the practicability of coagulating two dissimilar particle systems by elimination of the repulsive double layers. By proper selection of the solution and its concentration, the reduction of the double layer to a zero point of charge causes coagulation and rapid precipitation of both particle systems. Confirmation was found in filtration tests and sedimentation tests.

Jan 1, 1973

By Gordon L. Kinney

The only economically important mineral currently produced in Bangladesh was natural gas. Bangladesh was not a world? ranked producer of any mineral commodity, but the possibility of producing and exporting commercial amounts of liquefied natural gas (LNG) was being examined. Proved reserves of natural gas were sufficient to supply most of the country's industrial and domestic heating and electric needs and still support an export-oriented LNG plant. Other mineral production was of virtually no significance to the economy, although there were a few prospects for nonmetallic mineral development. Bangladesh continued to make economic progress during 1978 and into early 1979. Gross domestic product (GDP) at current prices rose from $6.6 billion in 1976-772 to $8.2 billion in 1977?78 and $9.3 billion in 1978.79.2 In fiscal 1979, the economic conditions were favorable until a severe drought hit most of the country. It W88 reported that conditions were the worst in 40 years, and 88 of July 1979, substantial crop losses were predicted. The agricultural sector accounts for over 53% of the GDP and about 75% of all employment. The poor weather will cause economic problems in the form of slower growth, larger trade deficits, and a higher rate of inflation. The 1978.79 statistics showed that real GDP increased just 4%.

Jan 1, 1981

By B. P. Martinez

This report presents the results of a research and development program in recovering waste-rolling oils conducted by the Bethlehem Steel Co., before 1954 at its Sparrows Point plant, Sparrow Point, Md., with the cooperation of the Bureau of Mines, U. S. Department of the Interior, College Park, Md. The objective of the program was twofold: First, to recover oil for reuse in the plant; and second, to stop pollution, by oil, of the stream and harbor areas in the immediate vicinity of the plant. The sequence of the investigations was laboratory and pilot plant studies on sedimentation, simple aeration, and flotation for the separation of oil and water; and construction of a production unit using standard flotation equipment. This work was only preliminary for the Bethlehem Steel Co. and it has continued research on this problem. Recent progress indicates that new, improved processes will soon replace the flotation units described in this report. The first efforts to separate oil and water by simple sedimentation were unsuccessful. To establish the cause of this failure, microscope examinations and measurements were made on cold-reduction rolling mill cooling-water effluents containing oil in suspension. It was discovered that an average oil globule, held in suspension, was only 0.001 inch in diameter and would not coagulate with other globules for normal sedimentation at room temperature. The next step in the sequence of studies was to coagulate the oil suspension by simple aeration with air under slight pressure. The aeration methods studied were effective in removing up to 68 percent of the total oil but were approaching flotation in principle. The final investigation of the series was flotation of the oil in conventional laboratory-size flotation cells. The small-bubble method, without reagents, floated up to 89 percent of the total oil held in suspension and was the process selected for pilot-plant development.

Jan 1, 1959

By G. Esterhuizen, C. Karacan

Methane can be a significant hazard in coal mine longwalling operations and extensive methane mitigation techniques are employed by coal mine operators. Reservoir modeling techniques are used to better understand the liberation and migration of methane from the surrounding rocks towards the mine ventilation system. The caved rock behind the advancing longwall face, known as the gob, can contain high void ratios, providing high permeability flow paths to the methane. The gob is progressively compacted by the weight of the overburden, resulting in a reduction in the void ratio and associated permeability. Estimating the permeability distribution within the gob poses challenges due to its complexity. The authors have developed a new methodology to determine both horizontal and vertical variations in the permeability of the gob. Variations of the permeability in the vertical direction are based on a model of caving and block rotation, which considers the effect of block dimensions and fall height on the void ratio. Gob compaction by the overburden and associated permeability changes are determined from a three-dimensional geo-mechanical model which simulates the gob as a strain hardening granular material. The resulting three-dimensional permeability distribution in the gob is then transferred to a reservoir model. The paper demonstrates the application of the method and shows that reasonable results are obtained when compared to empirical experience and measurements.

By Hal J. Kelly

A picture of the ceramic industrial potential of the Pacific Northwest States is presented by reviewing the present ceramic industries, raw-material resources, and current market demands. A resume is given of the industrial plants manufacturing ceramic ware as well as available information on raw-material resources. No attempt was made to prospect for new deposits but rather to evaluate, insofar as possible, those already known. Since much of the industry is concentrated on the Pacific coast, most of the information available on resources concerns deposits in that area. Large, undeveloped districts in Montana and Idaho, however, offer promise of larger reserves of ceramic raw materials. Average annual production, some operating costs, and annual power consumption are given for each of the plants. Production and some cost figures are listed to show the limited nature of the present industry and to suggest fields open for new development.

Jan 1, 1956

By J. Douglas Causey

In 1984, at the request of the Bureau of Land Management, the Bureau of Mines studied 29,020 acres of the 43,165-acre Terry Badlands Wilderness Study Area (MT-024-684) in order to evaluate its mineral resources. Within this report, these 29,020 acres are referred to as the study area. Located in Custer and Prairie Counties, MT, the study area is about 2 miles northwest of Terry. The study area is underlain by essentially flat-lying units of the Fort Union Formation of Paleocene age with some Quaternary alluvial deposits in stream valleys. No mines or prospects were found in the study area. Bentonitic clays and lignite coal units were examined and sampled; however, no clay resources or coal reserves were identified. Estimates of coal resources will be reported by the U.S. Geological Survey in a joint U.S. Geological Survey-U.S. Bureau of Mines publication. Gravel along the Yellowstone River, a source of agate for private collectors, could also be used as sand and gravel aggregate although material on the south bank of the river is closer to population centers and road systems. Clinker found in the study area could be a source of road metal, but is not well situated in relationship to areas of use. No geothermal resources have been identified although water suitable for direct heat applications may underlie the study area. All the area is leased for oil and gas exploration.

Jan 1, 1985

By S. M. Runke

[The coarse-grained granitic pegmatities of the United States have long been a source of many important industrial minerals, because of this, they have been studied intensively by geologists, mining engineers, end metallurgists. These studies have amassed a rather astounding array of published and unpublished information. Correlation of geological studies between individual pegmatites, as well as between major districts, has brought fort come semblance of order to the knowledge of the structure and mineralogical composition of those highly complex and irregular deposits, making it possible to classify certain pegmatites and pegmatitic zones into several grouts of associated minerals, based upon the presence or absence of the minor minerals of beryllium and lithium. This classification or trouping of minerals, with the methods that have been developed for recovering certain of these minerals, possible a systematic approach to the winning of many of the industrially important minerals from pegmatite rock by u single integrated process.]

Jan 1, 1952

By A. J. Barry

A method was developed for testing the anchorages obtained with 3/4-inch, expansion-type, headed bolt and shell assemblies. The apparatus is a modification of that used in testing -inch-diameter, slotted-type bolts. Four makes of expansion-type shells were used in 64 tests made in sandstone and shale roof. The results show that for 3 makes of shells the anchorage effectiveness is independent of the installed land, and for the fourth make of shell a better anchorage is obtained when instilled at a load of 8,000 pounds. The results also show that deformation of the expansion plug influences the majority of the anchorages obtained with two makes of shells. This deformation causes a larger increase in displacement for a given added increment of load. The data from 48 of the 64 tests were combined to establish a relationship between average displacement and increase in bolt load (above the installed load). This relationship can be used to evaluate the anchorage effectiveness of any 3/4-inch-diameter, expansion-type, headed bolt and shell assembly tested in the field.

Jan 1, 1956

By V. A. Nieberlein

Problems of design involving the high-temperature characteristics of materials of construction have focused attention on tungsten, the metal with the highest melting point. To study the properties of this metal a method was needed to produce tungsten of high purity easily and consistently. The Bureau of Mines has made tungsten metal in massive form on a laboratory scale by hydrogen reduction of tungsten hexafluoride (WF6). Metal made in this manner had a purity of 99.99 percent or better, with reference to all detectable impurities, including gases. The process tolerated a wide variation in operating conditions, and the results with respect to total impurities as low as 0.01 percent were reproducible.

Jan 1, 1959

By W. H. Young

PRODUCTION of bituminous coal and lignite increased substantially in 1963 compared with 1962 figures. The major items of production, consumption, exports, and productivity increased. However, certain key items declined. For the fourth year there was no upward trend in mechanization; the percentage of total tonnage mechanically loaded remained the same as in the 3 previous years and the percentage of total tonnage mechanically cleaned was smaller than in the previous year. Furthermore, the percentage of total production mined by stripping and by augers increased. Most significant was the continued decline in average value and employment. Production.-The output of bituminous coal and lignite in the United States in 1963--459 million tons-was 9 percent greater than the 422 million tons produced in 1962. Production was greater in 1963, largely because of expanded consumption by the electric utilities and an increase in exports.

Jan 1, 1964

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Jan 1, 2012

To test the feasibility of hydraulic borehole mining for the recovery of phosphate ore from the deep, water-saturated deposits of northeastern Florida. Approach Phosphate ore is remotely extracted through a Bureau of Mines-developed hydraulic borehole mining system. Hydraulic borehole mining can remove underground ore deposits that cannot be economically mined by the usual open pit or underground methods. It is environmentally compatible, causing none of the surface disruption or ground water pollution usually associated with other methods of mining. Selectivity of the borehole mining system also allows economical recovery of small or discontinuous ore deposits while minimizing the removal of host rock. The hydraulic borehole mining system has been used successfully in the past to mine uranium ore and oil sands. (For examples of these and other applications of borehole mining see T Technology News Nos. 97, 95, 63, 56, and 48) How it Works A 16-inch-diameter borehole is drilled from the surface down into the buried mineral deposit, and the mining tool is installed. The borehole mining tool consists of a 12-inch-diameter pipe string and accessories capped with a three-passage swivel, and ending with a mining section. The mining section has four slurry inlets and an eductor located near the bottom of the section and a single cutting nozzle located near the top. The tool generates a high velocity water jet that erodes and slurrifies the ore. The slurry is drawn through the inlet into the eductor which lifts it to the surface where it is deposited into a slurry discharge sump. All the support equipment is located and operated on the surface; only the mining tool portion of the system is underground during the recovery operation.

Jan 1, 1983

By Todd M. Ruff

The lack of visibility near earthmoving equipment resulted in six fatalities in U.S. surface mining operations during 2003. These accidents were the result of either a piece of equipment striking another vehicle or worker, or the equipment traveling over the edge of an embankment. Figure 1 is an example of a recent accident that resulted in serious injuries to one worker and fatal injuries to two others when a van parked in front of a haul truck. Two fatalities occurred in separate incidents when front-end loaders struck workers. Another two workers were killed when their equipment backed over the edge of a highwall or dump point [1]. There is clearly a need to provide better information to equipment operators regarding their surroundings. [ ] Researchers at the National Institute for Occupational Safety and Health (NIOSH), Spokane Research Laboratory, are working to reduce these accidents by developing systems that sense obstacles and changes in terrain near the equipment and provide this information to the operator. Many off-the-shelf proximity warning systems that were developed for automobiles, light trucks, and recreational vehicles were evaluated on off-highway dump trucks [2]. Many limitations were found with existing systems, including frequent false alarms, limited detection range, a lack of specific information on an obstacle (e.g., location, identity), difficulties in finding suitable mounting locations, and an inability to withstand the environment. These limitations have necessitated the development of new systems designed specifically for large, off-highway, earthmoving equipment. New off-the-shelf systems available for mining equipment include radar and tag-based detection systems. Prototype systems now being developed include a proximity warning system based on the Global Positioning System (GPS) and a computer-assisted stereovision system. Development of these new systems was accomplished by working with manufacturers to modify existing systems to meet the needs of surface mining and through cooperative research with organizations to develop completely new solutions. A typical proximity warning system consists of a sensor or antenna mounted on the equipment that detects the presence of obstacles and an alarm interface in the cab of the equipment. Some systems, as described in more detail below, also require that other vehicles and personnel on the ground be outfitted with electronic tags that transmit an “I’m here” signal back to the system (e.g., radio signal detection systems or GPS). Many types of proximity warning systems are on the market, but they are not all discussed in this paper. APPROACH In past work, engineers at NIOSH evaluated several off-the-shelf proximity warning technologies in order to verify their effectiveness on off-highway dump trucks [2]. Dump trucks were chosen because of the number and severity of accidents involving this type of equipment and because extensive blind areas around these trucks are typical. This experience allowed engineers to limit the number of systems chosen for long-term tests at mine sites to those systems showing

By Joseph V. Mather, E. H. McCleary

"INTRODUCTION Workmen are transported in shafts in various types of cages or skips, most of which were designed primarily for hoisting cars and materials. Therefore, in general the cages or skips are not completely enclosed, adequate and gates are not always provided, and at many mines signaling devices and telephones are re¬stricted to those at the various landings in the shafts.Shaft accidents are usually severe - frequently fatal - and as a rule such an accident is caused by failure to comply with company rules or by ignoring them.Sixty men were killed and 555 men were injured in shafts of the anthracite and bituminous coal mines of the United States during the 5-year period 1938-42. 4/ Many of these accidents could have been prevented by having properly enclosed cages and adequate locking devices on doors to prevent workmen from falling into the shafts.The officials of the Heidelberg Coal Co. contemplated utilizing an old coal-hoisting shaft as a man-hoisting shaft; however, it was their desire to avoid the use of the conventional cage and to try to provide a safer means of transporting men in the shaft. Investigations and studies made by the officials revealed that an elevator similar to those used in large buildings would be more economical in first cost, maintenance, and operating costs would be less, and it would be safer and more convenient for the workmen. Effective safety devices for such elevators have been developed to such a high degree that those properly installed seldom fail. The elevator or man cage finally chosen cannot be pulled above the top landing through mechanical or man failure; it stops automatically at each landing and cannot be moved while a door is open; when the cage leaves the landing the doors opening to the shaft are automatically locked by mechanical and electrically operated locks; electric lights, telephone communication, and push-bottom controls are available on the cage, and adequate safety switches and overspeed controls are provided."

Jun 1, 1947

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Jan 1, 2011

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Jan 1, 2012