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By Walter E. Lewis

Ventilation-air-heating plants are in use at several iron mines on the Menominee Iron Range, Iron River, Mich. Many of the mines are exceptionally wet; during winter months, when fresh air is forced down the wet air shafts into the mine, it is usually necessary to heat the fresh air to above freezing so that the openings will not be closed by ice. The problem of ice closing air shafts has been solved by the practice of reversing the air current before the openings have become completely closed. This procedure involves drawing warm air from the mine up the usual down-draft air shaft. The M. A. Hanna Co. has found, at some of their mines on the Menominee Range, that it is more convenient to heat the below-freezing air rather than reverse the air current. Intermittent freezing and thawing of ice that has formed in the air shaft tends to loosen the wall rock, requiring major shaft repairs. The openings are kept free of ice the year around by heating the fresh air during periods of below-freezing weather. Table 1 shows the monthly minimum moan, maximum mean, and mean temperatures for the Iron River area. Under normal conditions of temperature, the furnaces are fired in November and usually are not allowed to go out until April of the following year.

Jan 1, 1951

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. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operations at or near mines.

Jan 1, 1967

By R. L. Grant

The conventional gallery test used by the Bureau of Mines Explosives Testing Station and corresponding establishments in other countries to establish the permissibility of explosives serves principally to differentiate the relatively safe explosive from the positively unsafe one. It has been recognized for many years that a more definitive test is needed to measure the relative incendivity to firedamp of explosives and explosive devices. A new method - the oxygen-value test - for measuring this incendivlty quantitatively has been devised and is being tested at Bruceton, Pa. To date, this testing bas been limited mainly to straight nitroglycerin dynamites. It is planned to study application of the method to permissible explosives in the near future. These results will be reported later. In the present report, permissible explosives will not be considered specifically.

Jan 1, 1954

By Richard F. Hewlett

This report describes a comparison of methods for computing grade and tonnage of ore, leach, and waste material for a mined-out portion of the Silver Bell Oxide porphyry copper deposit, and these computed values are compared with the actual tonnage of these classes of material produced during mining operations. Comparisons with production records have been made by using both exploration drill-hole assays and development blast-hole assays. The polygonal method is the most accurate for this deposit, because it more closely represents the lateral mineral distribution in the deposit. This is demonstrated by plots of the total-copper assay distributions of the development blast-hole assays for a specific bench. The investigation also shows that the smaller vertical assay interval (based on a 5-foot vertical churn-drill-hole sample) yields a more accurate estimate of both grade and tonnage than the 40-foot composite assay interval (based on the average of eight 5-foot assay values). This can be attributed to the fact that selective mining within a bench can separate out much of the waste and leach material that is included as ore in the 40-foot composite assay computations.

Jan 1, 1970

By Nicholas Kyriazi

A performance comparison of 14 rescue breathing apparatus was undertaken as an assessment of past and present worldwide technology. Rescue breathing apparatus are self-contained, closed-circuit breathing apparatus used for entry into areas having atmospheres that are immediately dangerous to life and health. Apparatus tested were the Biomarine BioPak 45, 60, and 240; the Draeger BG 4 and BG-174A; the Litton LITPAC II; the MSA Custom 4500 II Air Mask, Chemox, and McCaa; the Sabre Selected Elevated Flow Apparatus (SEFA); the Scott Rescue-Pak; the Siebe Gorman Aerorlox and Proto Ten; and the SurvivairLP-120. The apparatus were tested on an automated breathing and metabolic simulator at the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH). Physiological parameters monitored during the testing were average inhaled CO2 and O2, minimum inhaled CO2, inhaled wet-and dry-bulb temperatures, and peak inhalation and exhalation breathing pressures. The metabolic demand on the apparatus was 1.35 L O2/min for most of the test with two 5-min intervals of 2.5 L O2/min, the first beginning 10 min into the test and the second beginning 10 min before the end of the rated duration of the apparatus. Results presented include apparatus service life and test-averages of monitored physiological parameters. Schematic drawings and photographs of the apparatus are also included. The Draeger BG-174A and BG 4 had the highest durations—295 and 291 min, respectively. The BG 4 hadthe lowest minimum inhaled CO2 levels, attesting to the effectiveness of its CO2-absorbent canister. The SabreSEFA had the lowest average inhaled CO2 levels, due mostly to the apparently low-dead-space mask andnose cup. The MSA Air Mask, the only open-circuit device tested, had the lowest wet- and dry-bulb temperatures, with the liquid-O2-source Siebe Gorman Aerorlox having the next lowest temperatures. The only apparatus with a CO2-absorbent not in a packed-bed design, the BG-174A, had the lowest exhalation pressures. The BG 4 had the highest level of positive pressure, with the Biomarine BioPak 60, Survivair LP-120, SEFA, and Litton LITPAC II nearly as high. The BG 4 had the lowest pressure swing, with the SEFA a close second.

Jan 10, 1999

By S. H. Ash

Unusual mining conditions prevail in the State of Washington because the majority of the coal seams lie on extra steep dips, and the roof and floor of the seams are of such a character as to require an excessive amount of timber- ing. The seams as a rule give off a considerable amount of methane, which makes good ventilation imperative. Due to physical conditions, supervision is costly and travel about the workings is difficult. Because of the facts stated, the accident rate has been above the average, and for some time considerable thought has been given the idea of making promotion of safety in and about the mines a responsibility to be shared equally by the employees and the management. With this idea in mind the legislature of the State of Washington, turing March, 1927, passed laws providing that safety committees be selected to function at the coal mines of the State and at the same time recognizing the fact that first-aid education is an integral part of any safety movement; legislation was passed making it mandatory to have all persons in and about the ines trained in first-aid administration. The provisions of the State mining law3 are as follows: "In every mine a general safety committee shall be selected, composed of the mine superintendent or manager of mines, one man selected by the employees or any association of employees in or around said mine, and a third member selected by these two. "The general safety committee shall elect one of the members to act as chairman and one to act as secretary. The duties of the chairman shall be to preside at all meetings of the general safety committee, enforce its rules and regulations and see that its business is conducted in a prompt and business-like manner. The secretary shall keep an accurate written record of the proceedings of all meetings, conduct its correspondence and post notices of regular and special meetings and other matters pertaining to safety. The duties of the general safety committee shall be to investigate all serious and fatal accidents; make bi-monthly.

Jun 1, 1930

By M. J. Reasor, J. M. Antonini, L. Wu, K. Van Dyke, Z. Ye

The inhalation of silica has been shown to produce a dramatic inflammatory and toxic response within the lungs of humans and· laboratory animals. Currently, no effective treatment exists for workers who may have been exposed to the inhalation of silica. The objective of this study was to develop an animal model in which we could evaluate the effect that anti-inflammatory steroids have on the acute silica-induced pulmonary inflammatory response. Male Fischer 344 rats were pretreated with either dexamethasone (2 mg/kg) or saline vehicle (i.p.) on days 1, 3, and 5. On day 6, the animals from the two groups were then intratracheally instilled with either silica (20 mg/0.5 ml saline vehicle) or saline vehicle (0.5 ml). Twenty-four hours after the instillations in the non-steroid group, significant increases occurred in total protein, total number of cells, neutrophils, and lymphocytes recovered from the lungs of animals treated with silica compared to saline controls. Silica also caused dramatic increases in the luminol-dependent chemiluminescence (LDCL) of lung tissue and bronchoalveolar lavage (BAL) cells. The LDCL reaction was markedly decreased by either superoxide dismutase (SOD) or N-nitro-L-arginine methyl ester hydrochloride (L-NAME). SOD is involved in the enzymatic breakdown of superoxide anion, while L-NAME, a nitric oxide (NO) synthase inhibitor, prevents the formation of NO. When the superoxide anion and NO react, they form the highly oxidizing substance peroxynitrite. This study then implicates peroxynitrite as an agent which may be involved in the silica-induced oxidant lung injury. When the animals were pretreated with the steroid dexamethasone, there was a complete protection against the biochemical, cellular, and chemiluminescent indices of damage caused by silica. The mechanism in which the steroid protects the lung from damage may be due to the ability of dexamethasone to block the induction of NO synthase. With further study in animals, the anti-inflammatory steroids may be useful in the treatment of silicainduced lung injury.

Dec 1, 1995

By C. K. Lee

This Bureau of Mines report presents results from experimental studies on wood fires in a laboratory-scale tunnel network. Experimental measurements include ignition delay time, flame spread rate, ventilation air and gas flow rates, wood temperature, gas temperature, pressure and composition, thermal flux, and smoke particulates. These measurements form a data base for fire-scaling studies and provide information on various fire processes, such as flow interaction between ventilation air and fire, fire throttling and reverse flow, and duct fire energetics. Results show how hazards of duct fires relate to the development of (1) asphyxiating and toxic fumes, (2) explosive gas mixtures, (3) throttling of ventilation air, and (4) high-temperature combustion products. Such fire hazards should be carefully considered when testing flammabilities of materials used in a confined underground mine environment.

Jan 1, 1980

By Paul R. Coyle, Anthony T. Iannacchione

A close look at the Loyalhanna Limestone of southwestern Pennsylvania reveals a complex structural environment. Most exposures of the Loyalhanna occur along Chestnut Ridge and LaurelHill within the Allegheny Mountain Section of the Appalachian Plateaus Province. Because the Loyalhanna is rated as a super-pavement aggregate by the Pennsylvania Department of Transportation and because of its proximity to the population centers of southwestern Pennsylvania, the Loyalhanna has been extensively mined along these prominent anticlinal structures. Geologic and engineering analyses were performed using gas well and core logs, outcrop examinations, underground observations, and mine maps. Strata exposures from both outcrops and quarries were used to construct geologic maps, stereo net, and rose diagram projections so that the Loyalhanna’s structural environment could be understood better. Many of these structural conditions cause ground control problems at local quarries. These problems ranged from small-to-moderate sized rock falls associated with roof jointing to pillar failures associated with dipping discontinuities. Stresses ranged from tensional on structural domes where weathering dominates, to high levels of compression within structural saddles. A greater understanding of these characteristics is a prerequisite to develop engineering controls, such as improved mine layouts, pillar sizes, etc., that lessen miner exposure to these hazards.

By F. P. Miknis

Previous studies at the Bureau of Mines have shown that broad-line nuclear magnetic resonance (NMR) techniques have potential applications for rapid evaluation of oil-shale deposits. In a continuation of this study the techniques of pulsed NMR have been applied in a similar manner. The basis for the pulsed NMR oil-shale assay method lies in the assumption that the free induction decay (FID) amplitude following a 90° pulse is proportional to the potential oil yield. This assumption was tested on two groups of oil-shale samples, numbering 141 and 263 samples, from two different oil-shale cores. For both groups of samples a small number were selected as calibration samples. Free induction decay amplitude measurements were made on the 141 and 263 samples. The best least-squares regression line was obtained for the calibration samples, and the oil yields of the remaining samples were calculated using the slopes and intercepts obtained in the regression analyses. The agreement between measured and calculated oil yields was good, the indexes of determination being 0.93 and 0.89 for the groups of 141 and 263 samples, respectively.

Jan 1, 1974

By Paul W. Johnson

An evaluation is made of a lime-soda sinter process for extracting alumina from anorthosite. In this process, alumina is extracted by sintering anorthosite with soda ash and limestone, and then leaching the sinter with a dilute sodium carbonate solution. The sodium aluminate solution formed during leaching is separated from the residue and treated with lime in autoclaves to remove dissolved silica before alumina trihydrate is precipitated with carbon dioxide. The trihydrate is then calcined to a-alumina. Two options, dry grinding and wet grinding, are used in the sintering step. For plants producing 1,000 tons of alumina per day for the dry grinding and wet grinding options respectively, the estimated operating costs are $75.40 and $74.36 per ton of alumina when charging $2.50 per ton for anorthosite and $1.00 per ton for limestone. The fixed capital costs based on a Marshall and Stevens chemical equipment index of 240.0 are $76 million and $70 million respectively. This process, when treating anorthosite, using either option, is not competitive under current economic conditions with the Bayer process treating bauxite to produce alumina.

Jan 1, 1968

By H. E. Blake

An evaluation was made to determine the economics of utilizing waste fluosilicic acid for production of (1) calcium fluoride, and (2) anhydrous hydro-gen fluoride. Two versions of each process were considered and compared. The evaluation showed that both products could be produced and marketed competitively. Lowest estimated product sales prices required to yield a 25-percent return on investment before taxes (discounted cash flow basis) was $339.34 per ton of hydrogen fluoride and $48.64 per ton of calcium fluoride.

Jan 1, 1971

By Kevin Connor

The Government's ban on all commercial mining operations, except for small-scale artisan exploitation of alluvial gold deposits, continued throughout 1985. Minerals produced were kaolin and lime for agricultural uses, and experimental peat harvesting for energy applications. The total value of the minerals produced during the year was estimated at $1.1 million .2 In early 1985, an agreement between the Government and Amoco International Oil Co. was ratified for a petroleum exploration concession covering 248,000 hectares of Lake Tanganyika. Onshore exploration in the Ruzizi Plain was already under way the last half of 1985. By yearend, enough seismic information was available that Amoco hoped to complete data analyses, determine onshore drilling sites, and begin drilling operations before the end of 1986. Also to begin in the latter part of 1986 were seismic studies of Lake Tanganyika. Throughout 1985, Amoco officials were negotiating with the Government of Zaire for expanding the exploration acreage into that country's portion of northern Lake Tanganyika and the Ruzizi Plain. An agreement between Amoco and Zaire could have important beneficial economic implications for both Zaire and Burundi, and onshore seismic work in Zaire logistically supported from Bujumburi could begin almost immediately.

Jan 1, 1987

By R. E. Mussler

Electrowinning of copper from chloride solutions in a diaphragm cell was studied by the Bureau of Mines. The copper powder product was shaken periodically from the cathode and removed from the bottom of the cell. The effects of copper concentration, brine concentration, copper chloride species, and cell voltage were investigated. Power consumption of 1.1 and 2.1 kW-hr/kg were obtained with cuprous and cupric chloride solutions, respectively.

Jan 1, 1975

By Eliot J. White

The physical properties and clay mineral content of the major oil-producing formations in the Powder River Basin of Wyoming were determined by analyses of cores from 100 wells. Interrelationships were established among permeability, restored water saturation, clay content, and bulk swelling capacity of the crushed sample and used to estimate the susceptibility of the formations to water damage. The ratio of water permeability to gas permeability (kw/ki) offers a convenient scale for semiquantitatively estimating the water sensitivity of sands. The irreducible water saturation was also found to have a similar relationship to the clay mineral content and the water sensitivity of the sands. The average relation of water permeability to gas permeability is different for each sand, as shown by the curves, and the relative positions of the curves indicate the degree of water sensitivity of each sand from which the susceptibility to water damage may be estimated. How accurately these estimates show formation behavior under field operations will not be known until studies of field performance can be made. The water permeabilities of the Muddy, Minnelusa, and Tensleep sands average about the same as the gas permeabilities, and these sands are classified as insensitive. The water permeabilities of the Sussex and Shannon sands, at the other extreme, are much less than the gas permabilities [when average ki is 30 millidarcys (md), kw is 6.1 md], and these sands are classified as highly water sensitive. The sensitivities of the five other sands are between these extremes.

Jan 1, 1962

By John C. Edwards, Gerald S. Morrow

The U.S. Bureau of Mines has constructed a smoke chamber and developed sensitivity tests for smoke detectors. Response of ionization- and optical-type commercially available smoke detectors have been investigated. Six smoke detectors were measured with respect to visually obscuring smoke characterized by a corresponding optical density for smoldering and flaming coal combustion in the smoke chamber. It was determined that for one type of ionization smoke detector the alarm time was nearly equivalent to that of an odor monitor's alarm for smoldering coal combustion experiments and earlier for flaming coal combustion experiments. The experiments showed that an average CO concentration of 5 ppm corresponded to an optical density of 0.022 m for smoldering and flaming-1coal combustion. Two of the commercially available ionization-type smoke detectors were more responsive to flaming than smoldering coal combustion at an optical density of 0.022 m, whereas the optical smoke detectors-1showed the opposite trend. The responsive characteristics of the detectors evaluated with respect to known smoke conditions in the smoke chamber shows their potential for use as mine fire sensors or part of a mine atmospheric monitoring system to improve mine safety.

Jan 1, 1995

Assure fail-safe stopping of a mining vehicle immediately following a loss of electric power. Approach A separate emergency brake system which actuates when electrical power is interrupted, was installed on several mining vehicles and tested in a long-term underground mining demonstration. How It Works Separate, spring-actuated brakes, which press against brake discs, are used to stop the vehicle following power failure. To allow norm al movement of the vehicle, hydraulic oil under pres? sure from the vehicle's hydraulic system is directed to a spring? loaded piston in each emergency brake housing. That pressure causes the piston to compress the spring and relieves the spring pressure against the puck, thereby allowing the brake disc to turn freely. See Figure 1 A. If the electrical power fails or if the machine is turned off, a valve in the hydraulic line to the emergency brakes opens. That valve, shown as ?Solenoid Valve (automatic)" in Figure 1, which is normally held closed by its electrical solenoid while the vehicle is electrically powered, is opened by the spring in the valve assembly. The pressure in the hydraulic line which is connected to the emergency brakes then drops to

Jan 1, 1978

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

1, Introduction This report is submitted in fulfillment of the requirements of USBM Contract No. J0255017, "Development of Emergency Escape Systems Guidelines for Underground Metal and Nonmetal Mines" Under this contract the history of past mine fires was studied. Representative metal and nonmetal mines were surveyed and escapeways, refuge chambers, life support, and emergency hoist requirements were studied to determine the problems in complying with the proposed regulatory standards and their enforcement by MESA Mine Inspectors. In addition, a computer program was written to evaluate mine evacuation performance. The completed program is included in the appendix. 1. 1 Historical Review of Metal and Nonmetal Mine Fires Early records of mine fires are poorly documented because there was no statutory provision for reporting fires to the Bureau of Mines. The survey of representative mines during the course of this contract indicated that many small fires still go unreported even though they are now required to report all fires A recent report survey approximately 80 disasters in metal and nonmetal mines, (6 ) Table I is a summary of some of these fires. Historically most metal and nonmetal mine fires have been caused by electrical problems. Spontaneous combustion and the use of welding equipment are the other major causes of mine fires(14) Although not documented, many mine personnel agree that 30 percent to 40 percent of underground metal and nonmetal mine fires have their origin from cigarettes and other smoking related materials. The number of fires related to spontaneous combustion is decreasing and equipment fires are on the increase. The reduction of spontaneous combustion fires can be attributed to the use of sandfill in more mines and the increase in equipment fires to the increased use of LHD equipment.

Jan 1, 1976

By John C. Machisak

THE INJURY data and related employment experience of the coking industry in the United States for 1955 arc presented in this publication under the following general sections: (A) General Injury experience: Tables 1 to 9: Contain current and comparable data on operating statistics, number and classification of injuries, injury-frequency rates, and accident agencies involved in causing injuries. Data are tabulated for the industry as a whole, for each typo of oven: and for the States in which coke is produced.

Jan 1, 1958

By Jack R. Woodyard

Bonding angles, promotion energies, and relative atomic sizes can be estimated through the solution of a set of algebraic equations generated from simple atomic models, and quantum mechanical parameters such as bond strength can be estimated from simple, hydrogenic form-wave functions. The precepts of The Engel-Brewer Theory are melded with the "Crystal Approximation Model" to produce atomic-structure models making these predictions, The two-valence-electron case is presented in this report. For the candidate atoms Be, Mg, Ca, Sr, and Ba the calculated promotion energies agreed within a few percent of their experimental values. These atomic parameters determine the possible crystal structure of the candidate atoms when alloyed. This is part of the effort at the U.S. Bureau of Mines to develop methods for alloy design in response to requirements for new high-performance alloys that conserve critical or rare materials.

Jan 1, 2010