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By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

3. Application of Proposed Revised Standards 57.11-50 to Mines Surveyed 3.1 Subparagraph (a) 1 "Each mine shall have at least two separate and properly maintained escapeways from each working place to the surface which are so positioned that physical or environmental damage to one will not lessen the effective¬ness of the other, and which meet the requirements of travelways and man hoisting standards These escape¬ways shall reach to within 1000 feet horizontally or 300 feet vertically of each working place " 3. 1. 1 Discussion This section will deal with the 1000 and 300 feet distance requirements, Section 3. 5 will deal with the "environmental damage" provisions. During the course of the mine surveys, it became obvious that one mine's 1000 foot distance was nowhere near equal to another' s --not in the actual distance but in the time required to traverse that distance. This -Ls true for the 300-foot requirement as well. The most obvious example is that one could traverse down a 300-foot raise much faster than climbing up the same distance. The temptation is strong to recommend that the distance requirement be changed to travel times instead. However, this approach would unfortunately lead to a lot of subjective evaluations. Having a time requirement for an entire mine evacuation (Subparagraph 6) is one thing, time requirements and the requisite inspection proce¬dures for each working place are quite another.

Jan 1, 1976

By H. P. Greenwald, G. E. McElrey

"Part IV.- The Resistance Caused by Right-Angle Bends. IntroductionThis paper deals with the fourth phase of an extensive research on coal-mine ventilation factors. A comprehensive report of the entire work is in course of preparation, but abstracts of the various chapters are being prepared in order to make the major results public as rapidly as possible. Parts I, II and III were issued as Serials Nos. 2621 (July 1924), 2647 (October 1904) and 2671 (March 1925) and dealt with the resistance of unobstructed entries, the resistance due to mine cars and, the resistance of timbered entries respectively.Description of the Tests With the last cutthrough between the two butt entries of the test section in the Experimental Mine open, the air flow was deflected, around two right-angle bends in the same direction, the butt entries being 50 feet center to center and approximately 6 by 9 feet in cross section. Each bend had a dead end opening off of it; that at the first bend was in the direction of flow and that at the second bond was at right angles to the flow. For a primary test condition the inner corner of each bend was trimmed square and the dead ends were closed off with board brattices set flush with the line of the cut-through.The two corners of the first band were, then modified both independently and in conjunction. Various modifications of both bends in conjunction were also tested with rather surprising results as to the effect of conditions at the first bend, upon the pressure losses at the second. To confirm the theory developed to fit these results a series of tests were made to give a direct comparison of the -pressure losses as between two bends with the air flow deflected in the some direction at each and with the air flow deflected in opposite directions. The former is designated ""double"" and the latter a ""reversed"" right-angle bend. This series of tests was conducted, however, on the bends at one of the intermediate cutthroughs at which the flow could be deflected us either direction at the second, bend. Here also the average cross-section was 6 by 9 feet and the bends were 50 feet apart."

Jan 1, 1928

Provide mine safety personnel, MSHA inspectors, and original-equipment manufacturers with guidelines and a check list for inspecting rollover protection structures (ROPS) being used in mining operations. The Problem ROPS are provided on mobile surface mining equipment to protect operators from such safety hazards as machine rollovers, falling objects, and collisions. However, the protective capability of a ROPS can be greatly reduced if it is damaged. Certain kinds of damage, such as hair- line cracks, corrosion, and loosened bolts, may occur as a result of normal machine use but may not be recognized as unsafe by untrained personnel. Therefore, the Bureau of Mmes designed a manual which can be used by mine personnel when inspecting ROPS equipment. The Manual The manual was prepared to help acquaint mine safety personnel and MSHA inspectors with typical ROPS deficiencies and their causes. It provides a systematic means for inspecting ROPS so that the identified deficiencies and their causes can be corrected. It is suggested that an inspection of the ROPS be conducted after every 1,000 h of equipment operation, or sooner if the structure has been subjected to any unusual loads which could cause damage, such as a rollover, highwall caving, or collision. The manual also details common deficiencies in the structure and attachment hardware which may affect the service life. The checklist, when used as instructed in the manual, provides a means for systematically inspecting the structure to ensure maximum protective capability and conformance with applicable Federal regulations.

Jan 1, 1986

By L. C. Headley

Surface areas of two synthetic and three natural consolidated porous samples were obtained by the Orr low-pressure permeametry technique. The results suggest that the Orr technique is a useful substitute for the low-temperature gas adsorption (BET) method for determining the surface area of rock samples. It was more rapid than the BET method, and the surface-area values obtained were larger but agreed better with BET values than values calculated from the Kozeny-Carman equation. Efforts were unsuccessful to demonstrate the influence of channel-size distribution on pressure-flow rate curves by means of experimental data and a parallel channel model.

Jan 1, 1971

By Harold L. Gibbs

The purpose of this paper is to encourage petrographers to prepare thin sections, as the demand for microscopic examination of rocks, ores, and metallurgical products is becoming more general in .the mining metallurgical-fields. This paper has been written with the knowledge that the successful thin-section methods and the several new techniques herein described will be helpful to all engaged in this field of work. Detailed instructions for making thin sections by methods developed at the Salt Lake-City laboratory of the Bureau of' Mines are given in this paper. Several new techniques are described for making thin sections of loose grains and fine sands and for making good thin sections of highly altered and friable rocks. The methods described insure superior bonding of the rock to the glass slide, thus virtually eliminating any failures due to parting of the section from the glass slide, and permit fast mounting, grinding, and finishing, thereby materially lessening the time required to prepare thin sections.

Jan 1, 1950

By G. W. Murrie, W. P. Diamond, C. M. McCulloch

It is estimated that more than 1 trillion cubic feet of methane is contained within the coals of the Mary Lee group in Jefferson, eastern Tuscaloosa, and southern Walker Counties, Ala. Most of this methane will be encountered by mining. Coals of the Mary Lee group are presently being mined at depths exceeding 1,000 feet and will in the near future be mined at even greater depths, where the problem of methane gas affecting the mining operations will be acute. It is calculated that approximately 90 pct of the methane is at depths greater than 1,000 feet, and over half of the gas is contained within only 12 pct of the study area which is under more than 1,500 feet of over- burden. Degasification in advance of mining will increase mine safety, reduce ventilation expenditures, increase productivity, provide an additional energy source, and make it possible to mine parts of deep coalbeds that probably could not otherwise be mined.

Jan 1, 1976

Improve transmission of data from an underground mine monitoring system to a remote, mass-data storage system. Background Instrumentation systems in underground mines must operate under environmental extremes of dust and humidity, local electromagnetic/radio frequency (EM/RF) interference fields, and potentially explosive atmospheres. During a recent roof-bolt study performed by the Bureau of Mines, it was necessary to transmit a large quantity of data to a data storage system. Conventional wire cable transmission presented several limitations which often required special electrical isolation or physical protection. Because conventional wire cable presented certain problems, the Bureau of Mines investigated alternative means of data transmission. The research investigation led to the selection of fiber optic cable for data transmission applications. The fiber optic method of data transmission offers several advantages: ? Since the transmission medium consists of light waves, it is safe to use in gassy mines. Where applicable, MSHA permissibility standards for peripheral devices must be met. ? It is lightweight and rugged. ? It can operate up to 131000 feet (4km) without repeaters and without EM/RF field interference.

Jan 1, 1986

To devise an economical, environmentally acceptable method for recycling scrap lead-acid batteries. Approach A combination electrorefining-electrowinning method for recycling lead metal and sludge from scrap batteries was devised which produces a 99.99 + percent pure lead product and eliminates the lead and sulfur oxide emissions that are the normal by-products of high-temperature smelting processes. How the Method Works Lead metal grids and lugs are separated from the battery sludge by washing and screening, and are melted and cast into anodes for electrorefining by the Betts process. The electrolyte used is fluosilicic acid, a large volume waste product generated during the production of phosphate fertilizer. During the electrorefining process, impurities in the anode are trapped and held in an adherent slime blanket on the surface as the anode dissolves while pure metallic lead is deposited on a lead cathode. The major problem in the past has been to recover the lead from the battery sludge which consists of approximately 60 percent lead sulfate, 21 percent lead, and 19 per-cent lead dioxide. In the flow sheet developed by the Bureau

Jan 1, 1983

To concentrate coarse mica particles using a dry beneficiation technique. Approach Concentrate coarse, II berated mica particles using a Bureau-designed system of crushers, screens, and a two-stage zigzag air classifier. How It Works Because mica has a flat plate-like crystalline structure, mica particles are significantly lighter than blocky gangue particles of the same size fraction. Thus an air classification technique can separate the flat, light mica particles from the heavier gangue particles. The ore, which Is first run through a standard jaw crusher, a roll crusher, and a hammer mill to liberate the mica, enters the rougher Zig-zag section through a rotating air lock. See photograph and diagram of a 2-stage air classifier. Airflow through the classifier can be varied according to the size of the particles being separated. The gangue material falls through the airstream of the rougher zigzag section and is discarded as tailings. The mica flakes are carried by the air-stream to the cyclone shown on the right side of the diagram, where they are collected. This rougher mica concentrate is fed to the cleaner zigzag section through another rotating air lock. The mica particles are again carried by the airstream but they are now collected In the cyclone on the left side. The cleaner concentrate leaves the left-side cyclone through a third rotating air lock and is rescreened to remove under-size material missed by the first screening. The final product of this pneumatic process is generally a high-grade mica concentrate. A generalized flow diagram for the pneumatic concentration method Is shown In the second diagram.

Jan 1, 1981

By D. J. Bauer

Liquid-liquid extraction techniques were investigated by the Federal Bureau of Mines for the fractionation of rare-earth solutions. Separatory funnel work using tri-n-butyl phosphate (TBP) for extracting ceric nitrate from solutions containing sulfate ion resulted in almost complete extraction. Similar tests using primary amines for splitting trivalent rare-earth pairs and fractions gave promising results. The ceric nitrate extraction procedure was scaled-up by use of pressure-bubbler equipment, a series of spray towers for extraction, washing, and stripping. In this case only 84 percent ceric nitrate extraction efficiency was achieved. This work was done using dilute sulfuric acid for stripping.

Jan 1, 1960

By Karl R. Becker

Detonators representing a sampling of various domestic commercial delay detonators were fired at various direct-current (dc) firing levels. Results of firings using well-below-recommended firing levels showed marked increases in delay times above the nominal values. There was also a marked increase in variation, to the extent that out-of-sequence firings would be essentially assured in any typical blasting round at these low firing levels. Within the range of recommended levels the effects of current increases were not considered to be of great importance relative to other overriding effects, such as the significant difference noted in average values of detonators from different lots having the same nominal delay. This effect, when combined with the normal variation noted among members from the same lot, would cause out-of-sequence firings with detonators from a neighboring delay period. Where comparisons with results from another study were possible, it was found that both studies observed quite similar variations in delay times about the average values, and a lower probability of out-of-sequence firings for the shorter delay period groups. The criterion of the previous study for assessing the likelihood of observing out-of-sequence firings, when applied to the Bureau of Mines data, properly identified two neighboring delay period groups where out-of-sequence firings would occur.

Jan 1, 1981

By J. B. Janus

This Bureau of Mines publication updates a series of reports on the quality of coal purchased under specifications for Government use. Listed are analytical data on the composition and quality of tipple and delivered samples of coal collected during the period July 1975 through September 1976.

Jan 1, 1977

By William A. Hoffman

In This Chapter [MSHA regulations for coal mines MSHA regulations for metal/nonmetal mines OSHA regulations for tunnel construction Types of respirators used in mines and tunnels Filter materials and filter efficiencies Donning, seal checking, and maintenance Filter service life and Respirator information resources] In many cases, engineering controls are not adequate to achieve satisfactory dust levels, so respirators must be used. This chapter explains the Federal regulations governing the use of dust respirators in mines and tunnels and describes the most common dust respirators used. Filter materials and filter efficiencies for respirators are discussed. This chapter also gives some guide-lines for respirator use and recommends sources for more dust respirator information. Respirator effectiveness in reducing dust exposure usually exceeds the effectiveness of most engineering control methods. RESPIRATOR REGULATIONS [Different regulations govern respirator use in coal mines, metal/nonmetal mines, and tunnels under construction.] Coal mines under Mine Safety and Health Administration (MSHA) jurisdiction. Coal mine operators are required to meet dust standards using only engineering control methods. Typical engineering control methods include ventilation and water sprays. Respirators are not regarded as an engineering control method, so respirators cannot be used in lieu of engineering controls.

Jan 6, 2003

Reduce longwall equipment transfer time between panels by utilizing a predriven recovery room, and thus eliminate the premove preparation associated with most equipment recovery methods. Background and Approach The recovery point for a retreating longwall is a predetermined position near the end of the panel where mining is terminated and equipment is disassembled and removed. However, to prepare for equipment removal at the recovery point, bolting and wire meshing arc required before the recovery point is reached. Usually, preparations for equipment recovery begin about 35 ft from the recovery point, significantly impeding the normal rate of advance of the longwall and, consequently, production. Recently, BethEnergy Mines, Inc., and the Bureau of Mines cooperated to evaluate the applicability of utilizing predriven recovery rooms to improve longwall equipment recovery. A predriven recovery room is an entry driven parallel to the longwall face at the end of the panel, having standard dimensions (for that particular mine) and supported with bolts, wire mesh, and supplemental support. The preparation of this entry is completed before it experiences mining-induced effects from the approaching longwall face. This enables the face to continue to mine at its normal rate of advance until the panel is completed. The supplemental support is required to control the loads imposed by the front abutment and is the most vital component of the recovery room.

Jan 1, 1989

By A. G. Kim

Coal formation begins in peat swamps or bogs, in which microorganisms alter plant material and initiate the formation of carbonaceous sediments. Methane, which constitutes about 98 percent of the hydrocarbon gas in coalbeds, is known to be a product of anaerobic microbial metabolism. To determine if other hydrocarbon gases could be produced in an environment similar to that of a swamp, samples of wood cellulose and lignin were inoculated with soil micro-organisms and incubated anaerobically. The resultant gases included methane, ethylene, propane, propylene, butanes, pentanes, and carbon dioxide. Hydrogen was also produced from the wood samples during the first month of incubation. Over 90 percent of the produced gas was methane; C02 was the other predominant component. Concentrations of all other hydrocarbon gases ranged from l to 20 parts per million, approximately 0.1 percent of the total hydrocarbons, which was less than the concentration in coalbeds. Therefore, although higher hydrocarbons could be produced in a swamp environment, subsequent mechanisms, either concentration by adsorption or formation during geochemical reactions, must affect the final concentration of higher hydrocarbons in coalbeds.

Jan 1, 1972

By M. MacLaughlin, J. Whyatt

A case study is presented that relates statistical descriptions of joint sets to the distribution of local wedge failures along the crest of a catch bench at the Yellowstone Talc Mine. The fracture sets and bench width were mapped by teams of geological engineering students from Montana Tech under the direction of Dr. Mary MacLaughlin. The students analyzed the fracture data, conducted physical property tests, and used a beta version of a NIOSH program “Bwedge” to predict the distribution of surviving bench widths. In the course of this analysis the students developed evidence of software performance issues that, unfortunately, frustrated their analysis. These have now been addressed and a full analysis completed. The analysis confirms the validity of the student mapping program and provides insight into the effects of blasting and excavation practices on the bench. It also provides a tool for exploring the pattern of bench crest failure that would result from variations in both bench geometry and blasting practices.

By Travis Q. Lyday

Gold continued to dominate mineral production in the group of volcanic islands and atolls of Melanesia in the southern Pacific Ocean, which comprise the British Commonwealth nation of Fiji. The Fijian mineral sector, however, remained of minor importance in terms of export earnings, Government revenues, and employment to the economy of the country, which was primarily agrarian with sugar as its mainstay. The Vatukoula gold-silver mine on the north side of the main island of Viti Levu remained the largest and most important mining operation, as well as Fiji's only operating metalliferous mine. In October, Western Mining Corp. (Fiji) Ltd. (WMCF), a wholly owned subsidiary of Australian-registered Western Mining Corp. Holdings Ltd., increased its interest in the Vatukoula joint venture from 10% to 20% by exercising its option with Emperor Gold Mining Co. Ltd., also of Australia. The assumption of mine management operations at Vatukoula in 1983, with its attendant influx of additional capital and technological expertise, enabled WMCF to increase both efficiency and output at the mine during 1984. Higher output was obtained owing to an increase in underground ore production, which was partly offset by a reduction in opencut tonnage, as well as to modifications in the recovery circuit. Rate of recovery increased from about 15% to over 82% of the gold contained in the ore and from about 40% to 45% of the contained silver.

Jan 1, 1986

By Raja V. Rarnani, Robert L. Frantz

"Scientific, engineering, and biomedical research teams synergystically developed major topical research areas in the Respirable Dust Center. Descriptions of their interactions and resulting accomplishments demonstrate how cooperative research within and among these study groups benefits the overall respirable dust research and practical application needs of the mineral industries.The development of a state-of-the-art small animal inhalation exposure facility suitable for studies of fresh and aged coal mine dust, a major goal of this research group, will contribute toward the GTCRD goal of advancing the understanding of causative mechanisms for the occupation-related lung impairments and the airway diseases of mine and mill workers. Such understanding includes improved definition of the role of various aspects of the lung environment (e.g., surfactant and the mucociliary system) in the disposition and toxicity of respirable dust, comprehensive characterization of the role of the pulmonary alveolar macrophage (PAM) and its secretory products on the development of dust-related lung disorders, and an expanded search for methods to reduce the toxicity of respirable dust both before and after it enters the lung. The National Academy of Sciences has recommended, in Measurement and Control of Respirable Dust in Mines, that respirable dust research should include study of the behavioral and constitutional factors affecting individual susceptibility to workers' pneumoconiosis occupational disease and the development of methods for detecting the potential onset of pneumoconiosis earlier and more conclusively than can be done using X-ray methods. These recommendations have guided the research group in its goals of establishing and disseminating a scientific protocol for standardizing the inhalation testing for all research objectives within the Generic Center which involve small animal exposures and implementing the infrastructure necessary to make lung tissues obtained during inhalation studies available to all researchers within the Generic Center."

Jan 1, 1995

By G. S. Rice, H. P. Greenwald

"Experience and experiment have goth shown that a cloud of coal-dust in air can be inflamed and an explosion developed only when a certain minimum concentration of the dust in air has been equaled or exceeded. Those who have had experience in the handling of coal know that dust is frequently present in the air and may be of sufficient density to obscure an ordinary electric light at a distance of 40 or 50 feet; yet flames may be, and times without number have been, introduced into such clouds, when no additional coal-dust has been stirred up, with no effect other than the burning of the dust particles which actually enter flame. Evidently the density of the dust cloud is insufficient to give self-supporting combustion.The minimum amount of dust in air required to give a spreading flame will vary with a number of factors such as the composition of the dust and its size. This amount in a unit space may be considered analogous to the lower limit of inflammability of fire damp (methane) in air, although the variation in limit of explosibility of gas is small even when conditions of the experiment are altered. In large-scale determinations of the lower limit of inflammability of coal-dust there is no certain method by which a sample of the dust cloud can be snatched and its density determined. It is necessary to produce the best possible dust cloud from a known weight of dust, in a known volume and assume - probably with considerable error - that the dust cloud is reasonably uniform. The dust cloud must be formed and the source of ignition applied to it simultaneously; this is generally accomplished by the use of blow-out shots of black blasting powder, dynamite, or similar explosive so prepared as to blow out like a cannon shot, or by a gas explosion. The more violence attending the source of ignition, the greater is the probability that all the dust is raised in a uniform cloud; and the greater the length or intensity of the flame, the greater are the chances of ignition. As a result one may obtain a variation in apparent minimum density with different sources of ignition. This difference is more apparent than real and must remain until devices for instantaneous sampling of dust clouds during explosions are perfected."

Aug 1, 1931

By T. Whitrnoyer, J. Sneckenberger

"The acOustic impedances of seven rat lungs were measured at frequencies between 100 and 6400 Hz. Rats were divided into two groups: a silica exposed group (N=3) and a control group (N=4). The silica exposed group was injected intratracheally with silica solution. Three of the control group were intratracheallyinjected with saline. Between four and six weeks after theinjections, all lungs were excised and degassed. Lungs were,suspended in a pressure Chamber, with the trachea canula attached to the end Of a tapered impedance tube. The lungs were subjected to transpulmonary pressures between -30 cm H2O and 6 cm H2O to simulate deflation and inflation. With transpulmonary pressure being held constant, the impedance tube was excited with random noise. A dual channel analyzer calculated H12(f), the transfer function between the two microphones. This function was used to calculate the lung's impedance at that pressure. The impedance magnitude spectra of both groups typically had peaks at 2000,3500, and 5500 Hz. Statistically significant differences. (90%confidence level or greater) between the two groups occur at the 3500 Hz peak at transpulmonary pressures of 20, 8, 6, 4, and 2 cm of H2O. This fact seems to confirm that this method can detect. lung disease. Further research will indicate whether this method will be able to detect the onset Of coal worker's pneumoconiosis.INTRODUCTIONOne of the first studies of impedance Of the human lung were conducted by DuBois et al.[2] using the forced OscillatiOn technique. This technique, however, was limited to frequencies below 30 Hz. Further studies by Van Den Berg [6] revealed thatthe lung reflected higher frequency sounds (100-10,000 Hz), instead Of behaving as an anechoic termination. This discovery has lead to several studies of the acoustical properties of both human and animal lungs at high frequencies [3,4,5]."

Jan 1, 1988