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By James E. Cairelli

The NASA Lewis Research Center, under U.S. Bureau of Mines program direction, performed an assessment of alternative mobile power sources for mining applications. A wide variety of heat engines and energy systems was initially examined to ascertain which could be considered as potential alternatives to presently used power systems. The present mobile power systems are electrical trailing cable, electrical battery, and diesel - with diesel being largely limited in the United States to noncoal mines. Each candidate power source was evaluated in terms, of the following requirements: (1) Ability to achieve the duty cycle (2) Ability to meet Government regulations (MSHA certification) (3) Availability (production readiness) (4) Market availability (5) Packaging capability An initial screening reduced the list of candidates to the following: (1) Diesel (2) Stirling (3) Gas turbine (4) Rankine (steam) (5) Advanced electric (batteries) (6) Mechanical energy storage (flywheel) (7) Use of hydrogen evolved from metal hydrides This list of candidates was divided into two classes of alternative power sources for mining applications - heat engines and energy storage systems. A summary of each class follows.

Jan 1, 1981

By E. F. Divers

This Bureau of Mines report describes the results of a program to develop small, rugged mechanical dust collectors (scrubbers) with high dust collection efficiency and low energy comsumption for controlling dust in coal mining operations. All of the scrubbers described are similar in configuration and are powered by 6-hp, 2,000-ft3/min vane axial fans. Air pressure differential is less than 6 inches water column. Height of the scrubbers? including fan is less than 14 inches, width is less than 16 inches, and length is less than 45 inches. The flooded fibrous-bed scrubber achieved respirable (less than approximatey 7 µm) dust collection efficiencies of 95 percent. The small-diameter-cyclone scrubbers showed about 92 percent efficiency and can be best where excess water is a problem. The wetted brush scrubber showed 88 percent efficiency at low cost, and the wetted fan scrubber showed a slightly lower efficiency (87 percent) but offered the smallest size and cost. A suitable water droplet eliminator is described.

Jan 1, 1978

By Sterling J. Anderson

Through the use of nondestructive testing techniques, the Bureau of Mines is pursuing a goal of improving the efficiency of the rock excava-tion process. Toward this end, 44 laboratory tests were conducted to identify a practical method of monitoring fracture development in rock, as caused by an excavation tool. An acoustic emission CAE) transducer was used to monitor the test samples as they were loaded. The signal from this instrument was recorded in real time along with the radial and axial loads generated by the fracturing device. Through the review of these signals on a common-time base, it was possible to see the relationship between the developing fracture and the loading conditions. As a part of the posttesting investigations, samples that were pletely fractured were sawn and ground to expose the fractures. examination of these samples allowed approximations to be made incom-Visual of the total surface created. Surface area approximations were also made for the completely fractured samples. Quantitative analyses· of the AE signals were conducted for comparisons with the calculated surface areas.

Jan 1, 1987

By Thomas W. Camm

The U.S. Bureau of Mines has developed a system for estimating mining and processing costs as a function of process feed rate with the objective of applying this system to abandoned mine tailings and to evaluate the benefits, if any, of metal recovery. Cost analysis was applied to the mine wastes of Smelterville Flats: an extensive area of mine tailings in the Bunker Hill Superfund Site with high concentrations of lead, zinc, and other sulfide minerals. Results from previous site characterization and metallurgical processing studies were used as the input for the cost analysis. This analysis indicated that processing this site at an optimum production rate of 3,500 short tons per day (st/d) could generate a positive cash flow.

Jan 1, 1993

The works recorded in this Test Report have been performed by Rade Roncar - Electrotechnical Institute of Zagreb, SFR Yugoslavia in collaboration with Bureau of Mines. The main objective of these investigations was to investigate the possibility of fabrication of thin-walled square enclosures of satisfactory safety factor in accordance with requirements of effective technical regulations. The results and the investigations can be divided in three main fields: - investigations of thin-walled enclosures with the view of determination of pressures causing technological deformations before performing tests in accordance with effective applicable regulations, - finding the safety factor by means of tests of metal-foam pressure vents, - comparison of enclosures with and without pretreatment by technological deformation.

Jan 1, 1987

By Sidney Katell

This study estimates capital investment, operating costs, and selling prices for four underground bituminous mines producing coal with annual production ranging from 1.06 to 4.99 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of December 6, 1974, under the Bituminous Wage Agreement of 1974, and costs for material and equipment are based on 1975 indexes. Initial capital investment ranges from $20,799,800 for the 1 .06- million-ton-per-year (MM tpy) mine to $84,027,500 for the 4.99-MM-tpy mine. Total capital investment ranges from $32,506,800 to $1 22,983,500 for the same mines. Corresponding selling prices for the coal range from $12.87 to $11.64 per ton, assuming a 15-percent discounted cash flow rate of return after Federal income taxes.

Jan 1, 1976

By Frank E. Chase, Deno M. Pappas, Christopher Mark

Multiple seam interactions are a major ground control hazard in many U.S. underground coal mines. The two most common types are: • Undermining, where stress concentrations caused by previous full extraction in an overlying seam is the primary concern, and; • Overmining, where previous full extraction in an underlying seam can result in stress concentrations and rock damage from subsidence. The National Institute for Occupational Safety and Health (NIOSH) has completed a major study aimed at helping to identify the location and likely severity of these interactions. In the course of field visits to mines throughout the U.S., more than 300 multiple seam case histories were assembled into the largest data base of multiple seam case histories ever collected. These data were analyzed with the multivariate statistical technique of logistic regression. The study also employed LaM2D to estimate the multiple seam stresses, ALPS and ARMPS to determine pillar stability factors, and the CMRR to measure roof quality. The study resulted in the development of a computer program, called Analysis of Multiple Seam Stability (AMSS), which can help mine planners to evaluate each potential interaction and take steps to reduce the risk of ground control failure. AMSS first evaluates pillar design by calculating the single seam Stability Factor (SFSS) using ALPS or ARMPS. It also automatically generates a LaM2D analysis that provides the additional multiple seam stress so that the final, multiple seam SFMS can be determined. The second part of the AMSS procedure builds upon the statistical findings that overmining is much more difficult than undermining, isolated remnant pillars cause more problems than gob-solid boundaries, and weaker roof significantly increases the risk of multiple seam interactions. AMSS quantifies these effects and predicts the outcome in terms of three levels of risk: GREEN (where a major multiple seam interaction is considered unlikely), YELLOW (where adding a pattern of cable bolts or other equivalent supplemental support could greatly reduce the probability of a major interaction.), or RED (a major interaction should be considered likely, and it may be desirable to avoid the area entirely).

By R. S. Olsen

Although aluminum is easily leached from calcined clay with boiling mineral acids, the presence of fines and slimes in the leached residue has hindered the application of acid leaching processes. A feed preparation method was, therefore, devised that provided a dense, smooth-surfaced, fine-grained clay. The important factors affecting feed quality were determined to be (1) crushing the raw clay to the size desired for the leaching process, (2) moistening the crushed clay with a fine mist of water while tumbling on a rotating disk, (3) drying the misted clay, and (4) calcining the dried clay at 750° C in a fluidized bed. Clay treated by this method was leached with HCI, and its residue was washed by water displacement in 4-ft-deep beds. Bed permeabilities on the order of 47 darcys or 4.6 x 10-7 cm2 were obtained with the leached residues.

Jan 1, 1983

By E. J. Lintner

This paper is one of a series being prepared by the Bureau of Mines describing; gypsum mining and crushing methods and costs at various operations throughout the, United States. These papers are designed to dissemminate technical information regarding methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that publication of total production costs may in many instances cause embarrassment to the individual operator as well as to the industry as a whole; on the other hand, operating costs are essential to the technical discussion and. study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulation shall ensue. The following report deals specifically with the mining and primary crushing methods employed at the plant of the Ebsary Gypsum Co., Inc., Wheatland, Monroe County, N. Y. This company is capable of maintaining a maximum yearly production of 220,000 tons of crushed gypsum, thereby ranking as one of the largest gypsum operators of the State. The methods and practices employed typify the standard methods followed by gypsum producers in western Now York State, The bed of gypsum mined lies only 35 feet beneath the surface and is above average thickness for this vicinity.

Jan 1, 1937

By B. W. Dunning

This paper describes studies conducted by the Bureau of Mines to achieve its goal of developing methods for increased recovery and utilization of valuable constituents in a wide variety of domestic and industrial wastes, In this particular study, 36 units of obsolete electronic equipment from military aircraft were disassembled into their modular components by hand to determine materials distribution. Further modular disassembly into individual parts was used to identify metal composition. After identifying the metals in some of the more difficult to dismantle modules, similar modules were grouped together, shredded, mechanically separated, and using metal composition data from hand separation, classified along with the hand-separated materials. Although this equipment is normally classified as law-value iron-bearing aluminum, data were obtained that indicated the potential for moderately higher value classification. The electronic units were classified as to precious metals, copper, iron, and aluminum contents, and scrap values were estimated.

Jan 1, 1980

By D. Harrington

Seldom, if ever, has any mining hazard presented itself that some method has not been devised to control it to some extent; the degree of success of such control depends largely upon the intensity of desire to prevent suffering, injury, and death. The economic saving to be realized and the more definitely this is realized by all concerned, the more quickly and effectively will the hazards be handled is an important incentive to prevention of accidents. Preventing coal-mine explosions is by no means a complex problem; all that is necessary is sensible, conscientious, sustained effort. The fact that explosions can be prevented has been well-demonstrated by the record of the post few years; the average annual death toll from explosions for the 5 years 1906-1910 was 438, and for the 20 years prior to 1929 it was 265: during the past 4 years an average of only 32 deaths per year resulted from this cause, although the annual production during that time varied but slightly from that of 1906-10. This is a truly remarkable reduction, and if other types of mine accidents had been reduced in the same ratio only about 300 would be killed annually in our mines instead of the nearly '1,300 killed in 1936 and the approximately 2,000 killed annually for many years. Although frequency of occurrence of explosions has not lessened greatly during the last decade, their severity decreased markedly, which would indicate that effective means are being taken to prevent the spread of explosions, even though ignitions and their causes are not being handled nearly as effectively as they might or should be handled. Several large coal-producing States, which in the past have experienced numerous disastrous explosions, have been free from such disasters for continuous periods as long as 8 years in the relatively recent past. The application of rock dust to underground surfaces has been an important factor in preventing widespread explosions; some of the mast dangerous mines have been rock-dusted fairly adequately, and this has been amply repaid in the reduced severity of explosions, as heretofore indicated; however, many have applied rock dust apparently without giving much consideration to the amount required to prevent

Jan 1, 1938

By J. Douglas Causey

In 1988, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied part of the 12,740-acre Blue Canyon Wilderness Study Area (OR-003-073) in order to evaluate its identified mineral resources. The study area is in Malheur County, OR, about 27 miles northwest of Jordan Valley. The study area is underlain by Tertiary welded tuff, tuff, perlite and tuffaceous sedimentary rocks capped by basalt. Jasper has been mined from several localities. Some mining has been done by hobbyists. However, the area has been covered by mining claims since 1964, with mining done by commercial operators. This region has been a source of "Owyhee picture" and other similar jaspers. More recent exploration has focused on the gold potential of nearby areas such as Quartz Mountain and Red Butte.

Jan 1, 1989

By Albert L. Toenges

The purpose of this paper is to describe some of the methods and practices of mining coal mechanically where more than one shift is worked, with the view of determining the advantages and disadvantages of various types of equipment and mining systems now in use. This paper is in the nature of a progress report, and, as the number of mines discussed in it is limited, the conclusions drawn in the comparison of various systems are not final but may be revised after subsequent investigations. Physical conditions vary in different and in the same mining districts and determine, more

Jan 1, 1938

By L. Kaufman

Fifteen boride composites were synthesized by hot pressing and evaluated by physical and incendivity testing as non-sparking tool materials. The incendivity tests, conducted at the U. S. Bureau of Mines, Albany Research Center, compared the boride compo-sites with standard cobalt-bonded tungsten carbide material used for coal cutter bits. Two titanium diboride composites and two zirconium diboride composites out-performed cobalt-bonded tungsten carbide in wear resistance and reduced tendency to cause ignitions. However, three of these candidates exhibited undesirable chipping. The remaining candidate, a TiB2-(Ni, Cu) composite, did not chip, nor did it cause ignitions at levels where cobalt-bonded tungsten carbide tools caused ignitions in the incendivity tests. Thus, this material appears to be a logical candidate for further development.

Jan 1, 1973

By E. L. Garton

Michigan is becomining one off the important oil-producing States of the country, The amount of crude oil produced within its boundaries has increased from only 4,000 barrels in 19253/ to nearly 16 million barrels in 1935.4/ The Bureau of Mines method of crude-oil analysis and classification indicates that the oils from the several producing fields are predominantly paraffin-intermediate-base, wax-bearing crudes. In general, they will yield 25 to 35 percent of highly paraffinic gasoline and about the tame amount of kerosene and gas-oil combined, 12 to 15 percent of lubricating oil stock, and 20 percent of residuum with a carbon residue of about 6 to 7 percent. In addition, there appears to be some correlation between certain properties of the crude oils and both the geographical location and geological structure of the oil-producing areas within the State. These general conclusions are based on the analytical data presented in this report, which is one of a series of papers that record the general characteristics of crude oil from the many producing fields of the United States. This report discusses briefly the oil fields of Michigan and the characteristics of the crude oils produced from them. The analyses of 15 samples are given. These samples were obtained from 13 fields in S counties in the lower peninsula and represent crude oils produced from the Berea sandstone, Upper Traverse and Traverse limestones, and the

Jan 1, 1937

By Frank G. Horino

This report presents a method of utilizing the Coulomb strength criteria for estimating the strength and stability of pillars and pit slopes containing planes of weakness. It is assumed that the Coulomb theory, as a special case of the Mohr envelope, is a satisfactory first approximation of failure in uniaxial compression or triaxial loading with low lateral loads. Accepting this assumption for brittle materials, an expression for the strength decrease of rock pillars containing a plane of weakness or fracture at any angle of orientation is derived. As few as six samples (three solid cores and three fractured cores at a failure-oriented angle) are required for testing uniaxially and triaxially to statistically determine the coefficients of friction and the shear strengths of both the solid rock and the fracture plane and the range of failure angles of the fracture plane. Interpretation of the data shows that the mean normal stress and maximum shear stress technique of analyzing the data is superior for solid core and that shear and normal stress values using angles of failure should be used for fractured specimens with failure-oriented angles. Plots of either the strength or strength ratios against fracture angles obtained from oriented drill core samples give a useful first approximation of strength decrease due to fracture. Using the same test conditions for both fractured and unfractured material increases the validity of the tests.

Jan 1, 1970

By Curtis H. Elder

In studies conducted by the Bureau of Mines, two test areas were hydraulically stimulated and exposed by mining: One in the Pittsburgh coalbed at the Vesta No. 5 mine, Washington County, Pa.; and one in the Illinois No. 6 coalbed at the Inland mine, Jefferson County, Ill. Induced fractures were contained totally within the coalbed with no adverse effect on the stability of associated rock strata. Induced fractures were vertical and were propagated normal to the direction of least residual tectonic stress. Gas production was increased fivefold to twentyfold by hydraulic stimulation.

Jan 1, 1977

By John P. Shubilla1, Nicholas Kyriazi

A joint effort by the Pittsburgh Research Center (PRC) and the Mine Safety and Health Administration (MSHA)3was undertaken to determine how well self-contained self-rescuers (SCSR's), deployed in accordance with Federal regulations (30 CFR 75.1714), held up in the underground environment with regard to both physical damage and aging. This report presents findings regarding laboratory-tested SCSR's in the fifth phase of testing from mid-1993to early 1996. The SCSR's were tested on human subjects and on a breathing and metabolic simulator (BMS) at PRC. These results indicate that most of the apparatus, if they pass their inspection criteria, perform satisfactorily.

Jan 4, 1996

By David A. Monaghan

This report describes the results of a 2-year investigation of extensible face ventilation techniques and systems for use at the working face in underground coal mines. The goal was to provide a safe and convenient method of maintaining the extensible system within 10 feet of the face, thereby ensuring good ventilation. A summary of approximately 20 extensible ventilation systems proposed or tried in the past is included for reference, together with a detailed description of the design, construction, and underground testing of a new extensible brattice panel and a new fiberglass duct system. The extensible brattice system utilized a special panel which could be pushed forward as the miner advanced. Brief testing in three mines revealed some conflict with the mining cycle and led to recommendations for two improved designs. The extensible duct system was designed for a Goodman borer and utilized a telescoping tube on the left side of the roof, so that it could be extended without interfering with the miner operator. For mine sections with right-hand return ventilation, a special flat tube section is used to cross over the entry. Underground testing showed substantial improvement in face ventilation without interfering with production.

Jan 1, 1976

By Pedro Lilienfeld

The objective of this program was the development, design, fabrication, and laboratory testing of a mine-worthy continuous respirable dust monitoring system (CRDMS). The operation of the sensor unit of this system is based on the light scattering intensity of the respirable fraction of airborne dust. The CRDMS is compatible with the typical environmental rigors that characterize coal mines and, in particular, the shock, vibration, impact, moisture and dust conditions prevailing at active training machines. The sampled area must be within the breathing zone of the mining machine's operator, whose dust exposure is to be monitored by the CRDMS sensor unit. Instantaneous, as well as shift-averaged dust concentrations, are displayed and recorded for later retrieval, Alarm indications and other diagnostic information are provided. The project was completed with the delivery of three sensor/display units (SDU), one data retrieval unit (DRU), two mining-machine-compatible power supplies, and two [auxilliary] battery packs.

Jan 1, 1983