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By F. Cherpereel, R. Gabillard, J. P. Dubus

We present an electromagnetic method taken from the well known radiogoniometer that allows us to locate at the surface of the ground the vertical axis of a magnetic antenna transmitter buried at a depth h in the earth. The method and the equipment achieved are called R. E. P. E. (Relevé Electromagnétique de Points Enterrés). They are daily used to accurately survey old quarries by using triangulation instruments at the surface of the earth rather than in galeries where the setting difficulties considerably reduce their accuracy and increase the work length. The results of several surveys allow us to give the optimum working conditions of the instruments and show that, when the transmitter is at a 20 meters depth, its position is known at the surface with an error lower than 1 centimeter. The power transmitter is of about 8 watts and we can find its location with an error smaller than 1 meter when buried at a depth of about 100 meters. This equipment may be successfully used for location of subsurface miners. The space surrounding the transmitter must then be free from ferromagnetic bodies.

Jan 1, 1973

By Joanne L. Johnston

Researchers at the U.S. Bureau of Mines have developed a new technique for bonding strain gauges to rock bolts. These instrumented bolts are used to determine load at intervals along the length of the bolt so that reliable, consistent measurements for the design of support systems can be obtained. In this Information Circular, this technique is described in detail and should result in improved miner safety in underground mines.

Jan 1, 1993

Reduce the noise radiated by the auger miner cutting head (typically 105 dBA at the face) by 10 dBA without compromising the durability or productivity of the tool. Approach Research was conducted by the Bureau of Mines to identify the noise sources of auger miners with emphasis on the cutting head and coal cutting process. The overall noise level generated by the coal cutting process was found to depend greatly upon the structural characteristics of the auger cutting head. Based on this information, a quieter cutting head was

Jan 1, 1982

By G. E. McElroy

[During the period July, 1923, to April, 1924, we made a large number of careful determinations of the resistance to the passage of air in selected sections of airways in the metal mines of Butte, Mont. The experiments were conducted with the cooperation of the Anaconda Copper Mining Co., Frank D. Cannon, mining engineer of that company, and Fred P. Gaethke, mining engineer of the bureau, assisted in carrying out this work. This paper summarizes the, main group of data obtained in the form of a table, of friction factors, or coefficients of friction that is, values of K in the generally accented formula or air flow of [P = KSV or H = KSV2 ] where, in units customary to mining practice;]

Jan 1, 1925

By Edward D. Thimons, Jay F. Colinet

NIOSH conducted a strategic planning effort to identify those areas in mining with the greatest research needs. Data analysis and stakeholder input identified the need to reduce worker exposure to respirable crystalline silica dust as a high priority area. MSHA dust sampling data were analyzed to target the mining commodities and occupations with the greatest percentage of samples containing silica above compliance levels. In response, the Pittsburgh Research Laboratory (PRL) has implemented a multi-faceted research program to improve silica dust control for these problematic commodities and occupations. A review of silica compliance trends, PRL silica research programs, and recent control technology developments are provided here.

To quickly and more reliably measure the alignment and deflection of mine guides used to run skips and cages into a mine shaft. The Problem Conventional mine guide alignment measuring systems require the use of a plumb bob and tape measure. This method is not only laborious, but it is time consuming as well. Approach Aware of the drawbacks of the current measuring method, the Bureau of Mines designed a self-contained instrument system that can accurately perform vertical guide alignment and deflection measurements by remote control. How It Works The Bureau-developed instrumentation system, called the Guide Alignment Measuring System (GAMS), is based on conventional mechanical electronics using inclinometers and displacement transducers. The instrumentation system is attached to an operating skip or cage where it functions as a completely self-contained measurement system, operating in conjunction with nor-mal travel of the skip or cage. An on-board tape recorder or a mini-computer with memory can be used to record all telemetry.

Jan 1, 1987

By S. D. Maksimovic

The Bureau of Mines evaluated the hydraulic stimulation of a gob-degasification borehole to determine if this procedure would aid in degasifying a longwall panel. The stimulated borehole did not degasify the longwall panel as expected either before or after mining of the panel started. It reduced the underground methane emission only 11 pct, considerably less than the reductions effected by two unstimulated boreholes in the same panel. Some probable reasons for the reduced methane flow from the hydraulically stimulated borehole are very low reservoir gas pressure, location of hydraulically stimulated zones within the grouted casing, a casing break caused by lateral shifting, possible vertical movement of rock strata during caving, grouting of a 4-inch pipe blocking three stimulated zones, plasticity of shales, and possible hole damage by swelling of water-sensitive minerals. The borehole was also located between two second-mined areas, which may have allowed partial degasification of the overburden and the coalbed in advance of mining. Finally, a period of 3 months is probably not long enough for the borehole to degasify the overburden before mining.

Jan 1, 1977

By Fun-Den Wang

A two-dimensional plane strain analysis by the stiffness matrix method was used to analyze two basic pit slope configurations. The magnitudes and the directions of stresses are given for a V-shape and for a flat-bottom pit with the slope angle varying from 30° to 90° at 10° intervals, Stress effects due to irregular pit configuration or to in-situ forces are discussed. Equations of similitude for gravity loading are given. Expressions are also given for the stresses at the toe as a function of slope angle. Procedures are given for finding the stresses in any geometrically similar pit slope of different dimensions and material properties from the stresses and equations presented in this report. Numerical results show that the V-shape pit slopes have lower stresses than the flat-bottom pit slopes; hence, they are inferred to be more stable.

Jan 1, 1970

By W. E. Lamont

The Bureau of Mines studied the potential for recovering marketable barite concentrates that meet oil well drilling-mud specifications from barite waste pond materials. The study was conducted as part of the Bureau's research program to conserve domestic mineral resources by advancing mineral recycling technology. The samples, which were obtained from Georgia, Nevada, Missouri, and Illinois, varied widely in character, particle size, and barite content. The samples were treated with sodium silicate and sodium cetyl-stearyl sulfate and then floated. The flotation flow sheet was modified to reject barren coarse and/or slime fractions from some of the samples, and one feed sample had to be scrubbed prior to flotation to remove residual flotation reagents. The cleaned concentrates had BaS04 contents ranging from 95.0 to 96.9 percent, while recovering 81.2 to 95.9 percent of the barite in the feed. The specific gravity of each concentrate exceeded the specification of 4.2. The removal of the flotation reagents from the flotation concentrate was not investigated.

Jan 1, 1982

By E. D. Gardener, Byron O. Pichard

"Methane, frequently called fire damp or marsh gas, is very well known to coal miners but to thy average gold miner it means nothing, as it is not associated generally with the rock formations in which gold is found.We have recently been conducting a study of mine air in typical gold mines on the Pacific Coast, and out of five California mines in which the air was sampled, three showed methane. Each of these three mines, referred to below as mines A, B, and C, have had accumulations great enough to be ignited. An authentic report from another California, gold mine, which has not yet been sampled, states that recently the superintendent was seriously burned by the ignition of a pocket of gas. This mine is later mentioned as mine D.Mine A is an old mine which had been abandoned for several years and permitted to fill with water. It has been unwaterad recently, and is now being developed at greater depths. During the unwatering, gas bubbles formed on the water and upon being ignited burned freely. It is reported that two men were seriously burned from accidentally igniting the gas. Samples of the bubbles on analysis showed high percentages of methane. Since the mine has been unwatered, no trouble has been experienced through gas being ignited. However, out of a total of six air samples which we took recently in scattered working places, all showed small amounts of methane, the methane content being 0.06, 0.04, 0.05, 0.04, 0.04 and 0.07 per cent, respectively. When these samples were taken methane was not suspected, but its general presence in the mine air indicates that it is being given off constantly."

Dec 1, 1921

By J. R. Wait, D. A. Hill

A survey of the literature on ELF and VLF atmospheric noise has been made. Most measurements have concentrated on the vertical electric field and the horizontal magnetic field rather than the vertical magnetic field which is of interest in transmission between horizontal loops. The limited vertical magnetic field data indicates that the vertical component is generally 10 to 20 dB below the horizontal component. Three laterally inhomogeneous earth models have been analyzed for conversion of horizontal to vertical magnetic field. The rough surface model examines surface effects, the inhomogeneous thin sheet model treats volume effects, and the buried cylinder model treats localized man-made effects. All three models predict the possibility of significant conversion from horizontal to vertical magnetic field. A thin sheet model has also been used to examine transmission from a buried magnetic dipole source. It is found that the pre- dicted fields more nearly model the measured data than does the homogeneous half-space model.

By N. S. Dalal, X. Shi

"It has been recently suggested that the exceptionally high antitumor and antibacterial activity of natural fredericamycin A (FMA) is related to its ability to spontaneously generate the superoxide anion (02-) and hydroxyl (""OH) radicals in aerobic solutions [Hilton, B. D., Misra, R., & Zweier, J. L. (1986) Biochemistry 25, 5533]. With a view to understand the mechanistic details, attempts were made to reproduce earlier electron spin resonance (ESR) evidence for the oxygenated free radical formation in well-aerated solutions of natural FMA in dimethyl sulfoxide and dilute H 20 2• Little or no evidence was obtained for the formation of the 0 2- and methoxy (""OCH3) radicals, while the detected formation of the 'OH and methyl ('CH3) radicals was attributable largely to mechanisms not involving FMA. These results thus reopen the T question regarding the mechanism of its exceptionally high tumoricidal-bacteriocidal activity. This paper reports on an electron spin resonance (ESR) investigation of the formation of oxygenated free radicals in solutions of natural fredericamycin A (abbreviated as FMA) which has recently been reported to be a highly potent anti¬tumor antibiotic (Pandey et al., 1981; Warnick-Pickle et al., 1981). The impetus for this undertaking was provided by recent reports (Hilton et al., 1986; Stinson, 1986) suggesting that the strong tumoricidal activity with high therapeutic—toxic index of FMA was related to its ability for the spontaneous generation of superoxide anion (02-) and hydroxyl (OH) radicals. For example, the suggested mechanism for the formation of 02- by FMA was (Hilton et al., 1986)FMA-OH + O2 FMA-O + H+ + 02-Here FMA—OH is simply the FMA molecule emphasizing the —OH moiety which becomes FMA-O, the free radical rep¬resenting the oxidized form of the drug. While some other highly effective anticancer drugs in current clinical application, such as bleomycin, are also thought to exert their antitumor effects via the formation of reactive drug-based or oxygenated free radicals (Carmichael et al., 1985; Gianni et al., 1983), FMA was considered unique in that only in this case the free radical formation was thought to be spontaneous, rather than through a metal- or an enzyme-activated process (Hilton et al., 1986; Stinson, 1986). Thus it was suggested (Hilton et al., 1986; Stinson, 1986) that FMA could be the forerunner of a new class of anticancer drugs. However, we noted that while the hypothesis seemed plausible, the reported ESR spectral evidence appeared to be ambiguous. Because of the high significance of the earlier conclusions (Stinson, 1986), we undertook a systematic ESR study of the radical formation in FMA solutions, and as discussed below, our conclusions disagree with those reported earlier."

Jan 1, 1989

By J. P. Morris

This paper describes a gas-transport method for measuring vapor pressures of liquid metals. Vapor pressures of iron and nickel were determined at temperatures between 1,540° and 1,620° C. The results can be represented by the following equations: log Pmm (iron) -19,460/T + 9.147, log Pmm (nickel) -2l,030/T + 9.689. The study was undertaken as part of a program to determine thermodynamic activities in liquid iron alloys.

Jan 1, 1957

Reliably detect fires by sensing sub-micrometer-sized particles released into the air by smoldering or burning materials. Approach An extremely sensitive, ionization-type fire detector has been built that continuously draws air samples through its ionizing field and collects the ionized smoke particles downstream, thereby generating a proportional electrical output signal. (An offshoot instrument measures the size distribution and number of sub-micrometer particles in air.) How It Works Mine air to be monitored is drawn through the instrument assembly by a small pump. A pre-filter and cyclone remove dust particles and other particles larger than 0.6 micrometer diameter. The air and remaining aerosol-sized particles flow through a gastight tube which contains the detector. See diagram. Smoke and other sub-micrometer-size particles moving Into the detector, pass through an Ionizing field, and are struck by alpha particles released from radioactive source located on the axis of the tube, The alpha particles move radially outward until they strike smoke particles or molecules of air or water. When struck, a smoke particle or molecule loses an electron and becomes positively ionized.

Jan 1, 1979

By J. Roger Loebenstein

Demand for arsenic exceeded supply in 1980, and the major domestic and foreign producers allocated available supplies to customers. Major demand was about evenly divided between industrial chemicals and agricultural chemicals. Legislation and Government Programs.-In June 1980, the Environmental Protection Agency (EPA) listed inorganic arsenic as a hazardous air pollutant.2 Proposed regulations on arsenic emissions were to be announced on an industry-by-industry basis at a future date, and public comment on the listing and on specific regulations was to be heard.

Jan 1, 1981

Eliminate the occurrence of false fire detection alarms caused by the operation of diesel-powered vehicles in underground coal mines. Approach Fire detection systems used in underground mines are based on measurements of airborne combustion products such as carbon monoxide or smoke particles. The effectiveness and credibility of these systems can be reduced by the occurrence of false alarms that result from the operation of diesel-powered equipment, which produces the same combustion products. False alarms end up being very costly to the mine operation in terms of downtime and labor needed for verification. To improve upon current fire detection systems used in the presence of internal combustion engine products, the U.S. Bureau of Mines developed a fire detector that can discriminate between the occurrence of real mine fires and the presence of engine smoke.

Jan 1, 1989

By T. O. Llewellyn

The Bureau of Mines conducted laboratory batch beneficiation tests on a waste granite sludge from New Hampshire to determine the feasibility of recovering a reusable silicon carbide product. The granite sludge responded to attrition scrubbing, desliming, and flotation in either alkaline or acid circuits using fatty acid as a collector. Recovery of over 80 percent of the contained silicon carbide at grades of up to 96 percent SiC was obtained.

Jan 1, 1975

By Richard E. Dawes

Physical variables, a principal factor in the economies of mineral production, affect both capital and direct operating costs. By using a revenue-cost system for the framework, the analyses of revenue and cost categories demonstrate the relative importance of groups of physical variables, whether explicitly defined or not, to a lead-zinc mining operation. Physical variables affecting the producer represent about 60 percent of the total system influence as expressed by cost ranking. Other physical variables affect the remaining costs as controlled by the smelter, the transporter, and the landowner. Such resource conservation aspects as mineral losses due to mining method and mineral processing constitute a portion of the total revenue effects of physical variables. The physical variable revenue-cost system presented in this report offers a framework for cost-benefit analysis of mineral related research.

Jan 1, 1969

By James J. Olson

The Bureau of Mines recorded peak particle-velocity levels and vibration frequencies to determine the nature and intensity of ground vibrations for tunnel blast rounds at the NORAD Complex, Colorado Springs, Colo. Previous Bureau of Mines studies in quarries and underground mines had shown that scaling (dividing) the distance from the blast by the square root of the charge weight removed the effect of the various charge weights on vibration amplitudes. The analysis of variance tests performed on the NORAD vibration data, however, indicated that the cube rather than square root scaling exponent grouped the data more effectively. The empirical propagation equation, V = 560 (D/w1/3)-2.04, where V is the maximum peak particle velocity in inches per second, D is the distance from the blast in feet, and W is the zero-delay charge weight in pounds described the attenuation, with distance, of the particle velocities from the tunnel blasts in the Pikes Peak Granite of the NORAD Complex.

Jan 1, 1972

By Charles L. Kimbell

For 1991, the aggregate value of world international export trade in mineral commodities was roughly estimated at $685 billion in current 1991 dollars. The estimated level was about 6 % higher than that for 1990, but still more than 3 % below the record high set in 1980, and the year was the fifth in a row in which the value of exported minerals advanced. Table 8 provides a data series for the estimated value of world export trade in all mineral commodities from 1979 through 1991, as well as a breakdown of this total into fuel and non fuel commodities. The data shown are based on the historically more traditional and realistic (from the viewpoint of data availability) practice of reporting trade values for the year before the year of review. Despite the considerable increase in the dollar value of mineral commodity exports, their share of total export merchandise trade declined to 19.1 % in 1990 from 19.7% in 1989. At 19.1 %, this share was very near the recent year record low of 19.0% reached in 1988. Comparable 1991 figures were not available in time for inclusion here, but it is expected that the mineral commodity share of the total will be little altered from that of 1990.

Jan 1, 1993