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By M. V. Potter

"In nearly all fields of investigation, research laboratories and routine testing laboratories encounter problems in which the primary determinations involved in the study require the measurement of mechanical vibrations or motions. These vibrations,may be of an oscillatory nature covering frequencies from a few cycles per second up to hundreds of Kilocycles per second, or they may be more or less uniform study nations occurring at rather slow rates. In electrical, or mechanical methods. In the optical case the to cause the deflection of a light beam such that the motion of the mechanican system of the beam can be determined, then by direct the by direct observation on a suitable scale or by recording it’s the electrical methods the motions can be made to changes in resistance, capacity or inductance proportion to the mechanical displacement or electromagnetic means can used to generate directly a voltage that will be porpertuial to the instantaneous vicinity of the vibrations. Other devices are used in a special instance, also but in any cause the electrical methods produce a current that is an electrical counterpart of the mechanical motion, and the motion can then be studied by direct measurements of the current or by recording the current on suitable recording meters or oscillography. Mechanical methods are used in some instance but are generally not as convenient nor as flexible as the optical and electrical methods."

Feb 1, 1943

Develop a user-friendly, personal computer-based numerical modeling program that performs structural analyses of underground tabular deposits, making these readily available to the mining industry. Background When ore is extracted from an underground mine, the overburden weight is redistributed to unmined areas, recompacted gob zones, and artificial structures such as packwalls and/or cribs. This redistribution of stresses continually changes throughout the mining cycle and can be especially complicated when multiple-seam mining is involved. Numerical mine structural analysis methods provide a way of calculating the redistribution of overburden stresses and the resulting loading for any given area of an underground mine, thus enabling engineers to design safer and more productive mines. In 1973 Crouch and Fairhurst developed a mine structural analysis computer program called MINSIM. This computer program was based on the three-dimensional displacement-discontinuity approach, a subvariation of the boundary-element method. In 1979 Sinha expanded MINSIM's capability to provide an analysis of parallel multiple seams. Sinha called his program MULSIM. During 1984 and 1985, the Bureau of Mines upgraded and completely restructured MULSIM into what is now called MULSIM/BM.

Jan 1, 1990

Investigate the use and placement of lightweight concrete to improve ground control technology in deep mines where deformation occurs under heavy ground conditions and where there is danger of rock bursts. Approach Investigations of lightweight concrete properties and placement methods were conducted in the laboratory and in the field. Three test sections were completed: a monolithic, portal-type structure with integral walls and arch constructed aboveground; an underground test section constructed in a mine drift using plywood forms; and a test section constructed in a mine drift using an air-supported formwork. In the two underground test sections, the light-weight concrete was placed using a piston pump with concrete discharge line. A cooperating mine also used lightweight concrete, in the density range of 25 lb/ft3, to replace timber blocking in a raise preparation structure (the enlarged area across a vein where chutes and manway access arc placed). Other experiments included the use of precast lightweight concrete blocks in situations where ground support was needed, such as fur mine, ventilation doors, stoppings, and barricades.

Jan 1, 1990

By J. W. JOYCE

The Geophysical section of the United States Bureau of Mines has received many inquiries regarding the application of geophysical methods to the location of small, buried metallic objects. The object of this paper is fourfold: (1) To sketch as briefly and non- technically as possible the principles underlying the operation of several elec- trical geophysical methods of prospecting applicable to the finding of small, buried metallic objects; (2) to point out the possibilities and limitations of these methods; (3) to present, whenever possible, data showing actual results obtained from their use; and (4) to enumerate and describe methods that lack scientific background or foundation.

Oct 1, 1935

By John Ward Smith

The Bureau of Mines derived equations expressing the theoretical relationship between density of oil-shale rock and its organic content. Effects on theoretical shale density produced by variations in mineral composition and organic matter properties were evaluated. The theoretical relationship was extended to relate oil-shale density to oil yield in both oil weight and volume units by considering the fraction of organic matter converted to oil and the specific gravity of the oil produced. Corollary equations relating organic content by volume to organic content by weight and to oil yield were developed. The general relationships apply to an oil-shale deposit uniform in character. Application of the theoretical relationships to Green River Formation oil shales was demonstrated.

Jan 1, 1969

By Peter G. Kovalchik, Lawrence W. Scott, Thomas H. Dubaniewicz, Frank T. Duda

Overheating of electric cables on shuttle cars has long been recognized as a cause of premature insulation failure leading to shock and electrocution. Use of cable reels on shuttle cars can cause excessive heat build up which, in turn, causes the cable insulation to soften and become easily damaged This heat-softened insulation reduces the life of the cable. Repeated cycling of a cable in this manner can cause premature aging of the insulation; it becomes bridle, cracks and allows electrical leakage paths to farm. These leakage paths provide the opportunity for shock and electrocution to occur if miners come in contact with the damaged section of cable. It is imperative that cable operating temperatures be maintained at safe thermal limits. This paper discusses a research project conducted by the National Institute for Occupational Safety and Health, Pittsburgh Research Center to determine dynamically the conductor temperature of reeled shuttle car cables using fiber optics technology. The research portrays typical shuttle car loading cycles (both current and time cycles). Root-mean-square current loading is calculated based on the results. The thrust of this effort is to provide the scientific basis for ampacity derating factors specifically for mine machinery using reeled cables This information will reduce the probability of electrical hazards from reeled cables

By S. Gallagher, A. Mayton, R. Merkel

The prolonged exposure of equipment operators to shock and whole-body vibration (WBV) is linked to cumulative back, neck and abdominal disorders. In low coal mines, space restrictions make it difficult for seat suspensions to isolate operators from shock and WBV Researchers at NIOSH's Pittsburgh Research Laboratory are responding to these issues by investigating viscoelastie foams. For the full-load case, an ergonomic seat made with viscoelastie foams can isolate the shuttle-car operator from shock at 15 Hz. Researchers used results from additional foam testing using an analytical model to identify viscoelastic foams that provide shock isolation at a frequency below 5 Hz.

By David A. Benjamin

In 1989 and 1990, the Bureau of Mines conducted a mineral resource investigation of the 122,000-acre Trinities study area, located in the Trinity Mountains of south-central Idaho. No identified mineral resources were delineated during this study. There are 58 lode mining claims within the area. Five localities contained elevated metal concentrations which may indicate precious metal mineralization at four localities and molybdenum-precious metal mineralization at another. Four of the five localities appear to form a northwest trend through the center of the study area. Twenty-eight individual sites contain anomalous concentrations of gold, silver, bismuth, molybdenum, and beryllium.

Jan 1, 1991

By Henry E. Blake

The purpose of this Bureau of Mines investigation was twofold. The first phase of the work was to determine the technical and mechanical feasibility of defluorinating low-grade siliceous fluorspars on an intermediate scale by high-temperature pyrohydrolysis in a rotary kiln. The second phase was to react the liberated hydrogen fluoride (HF) offgas with alumina monohydrate to produce commercial-grade aluminum fluoride (85 percent AIF3). The two phases of the work were to be integrated into a single continuous process. Evaluation of the data shows that low-grade siliceous fluorspars can be successfully defluorinated, either in a solid or a molten state, in a gas-fired rotary kiln in the presence of water vapor at 1,250° to 1,350° C. The water produced by combustion of propane was sufficient to yield defluorinatians of 75 to 85 percent.

Jan 1, 1962

By Robert A. Jankowski, Ellsworth R. Spencer, Jay F. Colinet

Longwall mining is the most productive method of under- ground coal mining in the United States (U.S.), and record levels of production have been reached in recent years. These ever-improving production levels have the potential to generate significantly higher quantities of respirable dust. Consequently, the longwall industry continues to struggle with controlling dust liberation and maintaining compliance with the federally-mandated respirable dust standard. In response, longwall operators have increased the application of primary dust controls, airflow and water flow, in an effort to improve respirable dust control and reduce worker exposure. Pittsburgh Research Center (PRC) personnel conducted dust surveys at 13 longwalls operating throughout the U.S. and collected information to: identify current operating practices on these longwalls, identify the types of dust controls in use, document the levels at which these controls are being applied, and measure the respirable dust levels present. This data was analyzed to quantify the dust levels generated by the major sources on the longwall section and to evaluate the relative effectiveness of the control technologies in use.

By Michael J. Gallagher

Diamond-bit performance data accumulated by the Bureau of Mines in core-drilling limestone and dolomite show that the physical characteristics of the diamonds and the sizes and types of bits used are economically significant. An analysis of the data establishes one trend of particular significance to those engaged in core drilling: Bits set with small, low-quality drill bort are the most economical. Detailed analysis of the factors that affect diamond-bit performance, such as size and quality of diamonds, sizes and types of bits, percentage of core recovered, and physical characteristics of bit matrices are assessed in the tables, bar charts, and discussion.

Jan 1, 1958

By Robert J. Timko

Water-jet-assisted cutting involves the use of a mechanical cutting bit in combination with a high-pressure water jet directed just in front of the bit tip. Such a jet can offer benefits in terms of improved cutting, reduced dust and fines, and improved bit wear. The Bureau of Mines, through a contract with the British National Coal Board, has re- searched the use of water-jet-assisted cutting on roadheaders. After several engineering design problems were overcome, this program led to the successful underground testing of these roadheaders. Today, more than 60 water-jet-assisted roadheaders are in operation around the world, and numerous others are on order. This paper details the evolution of these machines and the benefits to be gained by their use.

Jan 1, 1986

By Jan M. Mutmansky, Christopher J. Rise

"One of the most serious long term health problems associated with underground,mining is Coal Workers Pneumoconiosis (CWI'), more commonly known as Black Lung Disease. It occurs in some coal workers, normally after 15 or more years of exposure to coal mine dust, and leads to a variety of respiratory problems. Two types of pneumoconiosis are recognized simple CWP, which has been estimated to affect 6.9 percent of miners and is a condition that does not impair the miner's ability to work nor reduce life expectancy; and a more severe form of black lung (called progressive massive fibrosis) that occurs in about one percent of the cases and results in severe lung damage.Although the relationship between coal dust and CWP has long been recognized, detailed knowledge of the relationship is insufficient for setting up authoritative guidelines to reduce the health risks for those employed in dusty,underground environments. CWP is not only a health problem for workers that causes considerable distress, it is also a very expensive problem the total annual costs associated with CWP approach two billion dollars.As part of its efforts to combat CWP, the U.S. Bureau of Mines in 1983 established a Generic Mineral Technology Center to carry out basic research into all aspects of respirable coal dust:— control of dust generation — the behavior of dust in the mine — characterization of dust particles interaction of dust and lung— the relationships among dust generation and mobility and the mine environment, geology, and seam characteristics,Penn State, West Virginia University, the University of Minnesota, and the Massachusetts Institute of Technology are involved in this research, which is administered from the Department of Mineral Engineering at Penn State.Our work is one of the seven projects to be conducted at Penn Slate. We are concerned particularly with the characterization of dust and its relationships with the mine environment, and our main goal is to establish standard procedures for describing and measuring these variables.Coal DustCoal dust is a very complex material that varies greatly in chemical and mineralogical properties. Moreover, it is not the only constituent of respirable dust in the mine. When a coal seam is mined, it is inevitable that rock particles other than coal are included in the material. This rock comes from the mine roof, the floor, and the partings and inclusions within the coal scams. Since the roof and floor strata, the partings and inclusions are often stronger than the coal, mining them frequently causes more dust than mining the coal itself. One of the objectives of our research is to find the relationships between a specific coal's characteristics before it is mined and the respirable dust characteristics after it is mined. We are particularly interested in the size distribution of particles, the chemical properties, and the mineralogical properties."

Jun 1, 1988

By Doris M. Hyde

New mineral activity focused on increased petroleum exploration activities, while the established construction-oriented minerals sector operated without substantial change from previous years. After showing a 1 % real growth in the $154 million II gross domestic product (GDP) for 1983, preliminary estimates for 1984 indicated that the same growth pattern prevailed. The negative trade balance at midyear had worsened over the negative balance for the same period in 1983. An upward trend in import costs partly reflected the impact of Mexican inflation, which made that country's goods more ex-pensive and led to increased imports from North America and Europe. On the other hand, by midyear, the reexport trade with Mexico indicated an upward climb from the 1988 low of $12.7 million.

Jan 1, 1986

By Terry S. Cory

This report covers magnetic field strength measurements vs range and frequency in low-medium coal mines. Both quasi-conductor-free and conductor-proximity areas were investigated. The program covered 5 mines, 4 seams, 6 measurement sets, and 3 geographic areas. The results have been summarized in terms of maximum communication range expected per seam and noise condition. Scatter gain is further explored as a simple measure of energy coupled to conductors.

Jan 6, 1978

By d&apos, Kathleen J. Amico

THIS summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S mineral production also is included.

Jan 1, 1964

By Karl C. Dean

The Bureau of Mines studied the precipitation of copper from dilute acidic sulfate solutions using shredded automobile scrap in a rotary drum. The tests established that the scrap in the rotary drum precipitated copper faster and more completely than shredded, detinned, tinplate scrap in a launder, with comparable iron consumption. Although power is required to rotate the drum, the faster precipitation and continuous recovery of cement copper are advantages of the tumbler method. Cost evaluation indicates that the rotary drum method, which uses relatively low-cost and readily available shredded automobile scrap, is competitive with the launder method, which uses relatively high-cost shredded tinplate scrap or detinned shredded cans.

Jan 1, 1968

By Joseph N. Harstead

This Bureau of Mines report provides information on the first 49 water-flood projects (or units) in Nebraska. All injection was in the ?D? or "J" Cretaceous sands of western Nebraska. Specific data presented include location, map, discovery and development, water supply and injection, oil and water production, estimates of oil in place, primary and secondary recoveries. The 49 projects studied) including four dual-zone projects, should recover about 126.5 million barrels of oil. Eighty-six percent of the estimated oil had been recovered by the end of 1966. Abundant water was found near most projects.

Jan 1, 1967

By A. F. Jolly

As a part of ongoing research into the sulfidation partitioning of selected complex minerals, the U.S. Bureau of Mines conducted research designed to selectively recover Cu from sulfidized chalcopyrite (CuFeS2). Ferric chloride (FeCI3) solutions leached >90 pct of the Cu and <20 pct (sometimes < 10 pct) of the Fe in the sulfidized concentrates. Cupric chloride (CuCI2) leaches were even more selective, solubilizing essentially 100 pct of the Cu and < 5 pct of the Fe. In contrast, leaching non-sulfidized CuFeS2 with either FeCl3 or CuCl2 showed that somewhat more Fe than Cu dissolved. These studies demonstrate that Cu is substantially more leachable from sulfidized CuFeS2 than from nonsulfidized CuFeS2? The Cu-and Fe-bearing constituents generated as sulfidation products, CuS (covellite) and FeS2 (pyrite), respectively, are differentially dissolved. The solubility of Fe from pyrite in sulfidized CuFeS2 is much lower than the solubility of Fe from complex nonsulfidized sulfide where Fe and Cu are bound in the same crystal lattice. Thus, the Cu dissolves selectively, producing a high-Cu filtrate from which Cu can be recovered by cementation or by electrolysis. Flotation of CuS-FeS2 mixtures indicates partitioned phases can be physically separated if effective liberation can be achieved. Magnetic separation tests yielded less promising results.

Jan 1, 1991

By Howard E. Parkinson

The mine pager phone to public telephone interconnect system permits mine paging telephones to be interconnected with the public phone system, thereby providing emergency and off-hours communications. The system, a push-to-talk, push-to-listen system, is compatible with any mine paging system utilizing dc voltage on the line to enable paging. A tone generator of the proper frequency enables an outside caller to page over mine pager system loudspeakers. A caller inside the mine can make an outgoing call to a preselected, preprogramed number with the use of a proper frequency tone generator. The system includes an automatic hangup timer that restricts the time off-line due to a wrong number or incorrect hangup to 20 seconds and 6 minutes, respectively.

Jan 1, 1974