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By J. J. Bourquin, S. H. Katz

"Three types of respiratory apparatus namely, gas masks, hose masks, and self-contained oxygen-breathing apparatus - are now commonly used for protection from noxious gases, vapors, and smokes or ristes, but no particular type can be selected as best for all conditions. Many factors must be considered in connection with each situation, so that each must be considered as a problem in itself. Following are concise statements for comparing the types:Gas masks are the simplest and easiest to wear, also the least cumber-sore; but they protect only in comparatively low concentrations of noxious gases and should never be used where the air contains less than 16 per cent of oxygen. Special masks give protection from one gas or class of gases, but may give no protection against another gas or class of gases.Hose masks protect in any irrespirable atmosphere, but are somewhat cumbersome, the length of hose limiting the distance a wearer may go from fresh air. They are serviceable also where a supply of pure air moves with the wearer, as where a locomotive engineer in a smoky tunnel is using a hose mask supplied with air from the compressed air line of the locomotive. Hose masks consume no chemicals or materials and so are not limited in the time they may be used.Self-contained oxygen-breathing apparatus protect in any irrespirable atmosphere, but their weight is cumbersome, they can be used only by trained men, and frequent attention must be given them to maintain good working condition. On the other band they are the only safe means for exploring mines and other places filled with irrespirable gases in high concentrations."

Jun 1, 1923

By Susan M. Moore

The objective of this study was to evaluate the circumstances leading to fall from equipment injuries in the mining industry. Method: The 2006 and 2007 Mine Safety and Health Administration annual injury databases were utilized for this study whereby the injury narrative, nature of injury, body part injured, mine type, age at injury, and days lost were evaluated for each injury. Results: The majority of injuries occurred at surface mining facilities (~60%) with fractures and sprains/strains being the most common injuries occurring to the major joints of the body. Nearly 50% of injuries occurred during ingress/egress, predominately during egress, and approximately 25% of injuries occurred during maintenance tasks. The majority of injuries occurred in relation to large trucks, wheel loaders, dozers, and conveyors/belts. The severity of injury was independent of age and the median days lost was seven days; however, there was a large range in severity. Impact on industry: From the data obtained in this study, several different research areas have been identified for future work, which include balance and stability control when descending ladders and equipment design for maintenance tasks.

Jan 1, 2009

By Sivalingam Jeevan, R. L. McConnell

Ground check monitors may be made in several configurations. Each type has unique characteristics and provides different safety attributes when applied to different mine situations. In this paper, the monitor types are discussed in relation to the mine situations. It is shown that the selection of the monitor type can have a significant effect on the safety of the resistance grounded power system. The options are discussed, and the conclusion is drawn that only one monitor configuration can provide maximum safety. Unfortunately no monitors of this configuration are presently available. In addition, when the monitor capabilities and ground wire configurations are considered as a system, it can be shown that certain configurations will lead to maximum safety. This work was supported by U.S. Bureau of Mines grant G0144138.

Jan 1, 1979

By C. M. Mason

Mechanical mining produces large quantities of very fine coal dust called float dust. The associated increase in hazard requires a reexamination of the Bureau of Mines method of evaluating the incendivity of explosives in coal dust-gas-air mixtures. A technique recently developed by Bureau of Mines laboratories for evaluating the incendivity of explosives in coal dust-air mixtures was applied, with modifications, to coal dust-air-natural gas mixtures. A series of permissible explosives were evaluated by this modified technique. Results indicate that the modified technique could be the basis of a more discriminatory procedure than that presently in use.

Jan 1, 1968

Objective Develop field measurement and computer modeling methods to predict the potential for hang-ups and structural failures in underground mine ore paws. Background Analysis of Mine Safety and Health Administration (MSHA) accident statistics has identified ore pass hazards as a significant safety problem in underground metal mines in the United Stales. Recent ore pass failures have underlined the lack or ore pass design methods ant1 standards available to both MSHA and mine engineers. Injury and fatality data for the 20-ycar period between 1975 and 1095 show that nearly 75% of the injuries were directly or indirectly related to pulling or freeing ore pass chutes, the use of hand tools, falls or broken rock, and structural failures or chutes or gates and ore pass walls.

Feb 1, 1998

Create two air splits along the longwall face to isolate the shearer-generated dust to the immediate face area, maintaining a cleaner split of air in the workers' walkway.

Jan 1, 1994

By Ben A. Kornhauser

Petroleum production was the principal component of the mineral industry, followed by cement production and some salt output. The French Central Fund for Economics Cooperation loaned $9.15 million2 to the Communauté Electrique du Benin (CEB), which served Benin and Togo, toward financing the construction of a dam on the Mono River at Nangbeto, Togo. The dam was to supply hydroelectric power to reduce the energy dependence of the two countries and to irrigate crops. Nine other international financial organizations, including the International Bank for Reconstruction and Development (World Bank). the African Development Bank, the Arab Bank for African Economic Development, and the French Aid and Cooperation Fund, contributed to the estimated $140 million cost of the dam. The CEB also was to contribute to the financing. Contracts amounting to $60 million already had been awarded to West German and Canadian firms. The dam was expected to be completed in 1987.

Jan 1, 1986

By A. D. Mah

Thermodynamic data on compounds of arsenic and sulfur were critically evaluated by the Bureau of Mines. Changes of standard enthalpy and Gibbs energy, and logarithms of the equilibrium constants were tabulated as a function of temperature for reactions involving these compounds.

Jan 1, 1982

By Robert P. Vinson

A sequential sampler, based on the Archimedes screw, has been developed by the Bureau of Mines. Its initial purpose was to collect air samples during tracer gas studies in underground mines. However, the basic concept can be applied to other sampling needs, including sampling of liquids. A prototype was built and successfully tested in the Bureau's Experimental Mine at Bruceton, Pa. The simple design makes the sampler inherently durable and low in cost.

Jan 1, 1976

Improve underground mine roof bolt support systems by alleviating problems associated with certain ground support systems currently being used. Approach Convert a passive resin-grouted roof bolt system into a uniform, tensionable roof bolting system. Background Resin-grouted roof bolts are one of the most common forms of ground support in U.S. underground coal mines. These support systems can be installed with a full-column of grout and be loaded with subsequent roof movements after installation. This is called a "passive" support system. An alternative to the passive support system is the mechanically-anchored, tensioned roof bolt system. This system is installed with resin grout. This system is designed to load or tension the support during installation by using a mechanical anchor, coupling, or threaded nut after the resin has properly cured. It is called an "active" support system and is used extensively for improved strata control in a laminated geologic deposition or in difficult ground conditions. To ensure that active bolts have been properly installed, the bolt loads must be checked by using a torque wrench or other suitable equipment. Unfortunately, this practice presents potential safety hazards and has limited accuracy. Laboratory and field experiments also reveal that the torque-to-tension ratio developed on active support systems can vary by 50% from bolt-to-bolt. Variations in bolt load installations can induce stress concentrations and lead to roof degradation or failure.

Jan 1, 1991

Develop personal computer (PC) based software for analyzing and/or filtering time- and frequency-domain attributes of seismic and electromagnetic signals from geophysical surveys for the enhanced interpretation of rock masses and subsurface geologic structure. The Problem Both mining and petroleum geophysicists utilize seismic signals to characterize rock masses for delineating subsurface stratigraphy and structural conditions. However, a vast amount of information available in seismic project evaluation data often is unavailable for interpretation unless these data are enhanced. New processing technology increases the quality of these signals for analysis and interpretation. Comprehensive signal processing software is mostly written for petroleum exploration companies. Commercially available signal processing programs are often limited to a single application or are restricted for use with specific hardware, e.g., a digital oscilloscope or a mainframe computer. The programs may use computer codes that are proprietary, restrict user modification to expand capabilities, or may be hard to interface. They may have insufficient documentation for easy use and be support dependent.

Jan 1, 1990

By James C. Cawley

A summary is presented of existing leaky feeder communications systems currently in operation in North America. Background information pertaining to previous use of leaky feeder technology is discussed along with the survey methodology. A review of some pertinent facts concerning propagation in tunnels and specific reference to mine tunnel propagation is presented. A summary of the characteristics of each mine visited is presented in tabular form, and methods of procurement and maintenance are discussed. The role of user training in efficient system use is presented. Seven sites representing eight mines are included in the survey. Economic and technical topics are considered.

To improve the efficiency and speed of under-ground post-disaster rescue operations. The Approach: Develop a battery-powered mine-rescue vehicle designed to carry rescue crews, rescued miners, and their support equipment. How It Works: The experimental vehicle, shown below, was designed and constructed by the Mine Safety Appliances Company under contract to the Bureau of Mines. ATV Manufacturing Company and Delco Electronics were subcontractors. A rechargeable, silver-zinc battery provides power to a 3-horsepower permissible motor, the speed of which is regulated by a solid-state controller. Three wheels on each side are independently driven by a chain and mechanical trans-mission.

Jan 1, 1974

By Edward A. Mihok

Laboratory batch-flow tests conducted on a highly ferruginous acid mine water with an activated carbon showed that ferrous iron is rapidly oxidized. This indicates that air oxidation of ferruginous acid in mine waters is catalyzed by activated carbon. The ferrous iron content of an acid mine water flowing through an aspirated activated carbon column was reduced from about 700 to about 10 parts per million in less than 1 minute. Highly efficient ferrous iron oxidation was achieved by conditioning the activated carbon by repeated treatment with acid mine water and air. The reaction proceeds rapidly in the acid environment (pH about 2.5) engendered by ferrous iron oxidation. The activated carbon was used repeatedly with little loss in efficiency, no discoloration, or solids deposition. In these batch tests, about one-third of the iron was adsorbed by the carbon, but with continuous flow, little iron adsorption is expected. Incorporating a catalytic oxidation step in the treatment of acid mine waters containing ferrous iron would greatly facilitate neutralization--precise control of pH, lower reagent costs, elimination of aeration equipment, and smaller holding ponds.

Jan 1, 1969

By Zachary J. Fink

A continuous-monitoring system has been developed for analyses of mine gas concentrations associated with spontaneous combustion, mine fires, and explosive and toxic levels. The analysis center, which is linked to sample locations by polyethylene tubes in bundles, has been successfully field tested by the Federal Bureau of Mines for analyzing carbon monoxide and oxygen; a computational scheme has been developed to process the data at the site. This report contains information on the design, purchase, installation, and maintenance of the tube-bundle system. A brief comparison of the tube-bundle system with the underground-analysis system and plans for future research are also included.

Jan 1, 1975

Early American history is filled with records of the search for and extraction of minerals-a Northwest passage to the treasures of the Indies-an overland route to the goldfields of California. Mining and its associated minerals industry have heralded advancing civilization throughout the ages. The two basic resources on which we all depend for our food, clothing, shelter, and other comforts are agriculture and minerals. Our endowment and how we use it; the spirit and industriousness of our people; our form of social organization all converge to make up our standard of living-our way of life.

Jan 1, 2012

By H. J. Heinen

Malononitrile [CH2(CN)2J, which forms a carbanion in basic solutions, was investigated as a potential leachant for gold and was shown to be an effective extractant in alkaline pulps. Malononitrile was comparable to equal molar quantities of sodium cyanide (NaCN) in leaching gold from an oxide ore and yielded 10 to 20 percent higher recovery in leaching a refractory carbonaceous ore, although dissolution was slower with malononitrile than with cyanide. Complete recovery of the gold from the pregnant solutions was achieved by coprecipitation with a lead salt on zinc dust; the leachant was shown to be capable of regeneration and recycling a limited number of times. Addition of an anion-exchange resin to the carbonaceous pulp containing malononitri1e increased gold recovery from 67 to 95 percent. Some malononitrile derivatives were also shown to be gold solvents.

Jan 1, 1970

Provide a central source of subsidence reference in formation for industry, academia, and government agencies interested in improving subsidence prediction and analysis under U.S. mining conditions. Approach Develop a comprehensive bibliography about mining related surface subsidence and store this information in a computer file. Make specific references accessible through a key word retrieval program. Supplement these key word identifiers by entry of author's name, title of publication, subject of text, or sponsor of publication. How It Works Requests for subsidence in-formation are made by phone or mail to the Bureau of

Jan 1, 1982

By Fun-Den Wang

A new approach for evaluating pit slope stability by the limiting equilibrium method has been developed by the Bureau of Mines. The finite element method of plane strain analysis is used to find the stress field of the pit slope structure. This stress field is then used to find the normal and shear stresses along a potential failure surface. The normal stresses are used with the Coulomb equation to calculate the shear resistance. The shear stresses are integrated to determine the total driving force. The factor of safety is evaluated from the ratio of the resisting force to the driving force along a failure surface, and is found to be affected by the elastic material properties, modulus of elasticity, and Poisson's ratio.

Jan 1, 1970

By L. C. IlsLey, Charles M. Means

The descriptive rather than the strictly technical meaning of many of the terms and expressions used in the electrical rules is given in order to assist in their interpге- tation . ALIVE . At a potential measurable with a voltmeter and different from that of the earth or another conductor . (Static charges should be determined with an electrostatic voltmeter . This condition may apply to current - carrying parts , to noncurrent - carrying parts and adjacent material where a failure of insulation has taken place , and to objects having stored or static electricity . ) ALTERNATING CURRENT . A current that changes in direction -- positive or negative-- a certain number of times per second , depending upon the number of poles and speed of the generator . AMMETER. An instrument for measuring current , indicating in amperes . AMPERE . A term applied to denote the rate of current flow . ( Analogous to " gallons per minute " in a hydraulic system . ) APPROVED . Accepted as suitable by a competent committee , board , or organization designated by those adopting the rules . ductors . ARMOR . A steel or equivalent metallic covering for one or more electric con- AUTHORIZED PERSON . Anyone commissioned by the official in charge of the mine or his deputies to carry out certain duties incident to the generation , transformation , and distribution or use of electric energy in the mine , such person being one who is competent within the purpose of the rule in which the term is used .

May 1, 1930