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By Bruce Cantrell, K. L. Rubow

"INTRODOCTIONMeasurement of the contribution of diesel exhaust to respirable aerosol in mine environments has become increasingly important because of current concerns over the occupational health effects resulting from exposure to diesel emissions. In response to this, the U.S. Bureau of Mines is developing and evaluating new sampling methods for measuring diesel aerosol in underground mines. Two such techniques are being studied by the Bureau, size selective sampling and Chemical Mass Balance (CMB) modeling. These techniques use measurable physical or chemical characteristics of a mine aerosol sample to infer the amount of diesel particulate material contained in the sample.Size selective sampling is being adapted for measurement of diesel aerosol by the Particle Technology Laboratory (PTL) of the University of Minnesota under sponsorship by the Bureau. 1 It is based on the premise that diesel and mineral dust aerosol can be physically separated by size and collected during sampling using inertial impaction. An independent effort by the National Institute for Occupational Safety and Health to develop a size selective sampling technique was also sponsored by the Bureau.The second technique, CMB modeling, is being developed by the Bureau as an alternative measurement technique to referee the results obtained using size selective sampling.3 It compares measured trace element ""finger prints"" of aerosol sources with similar profiles of mine aerosol samples. From these, the portions of the sample contributed by each source can be determined. Results of these investigations in underground coal mines have confirmed that diesel and coal dust aerosol are of different size and can be measured separately using size selective sampling techniques.A major difference in diesel usage among underground mines is the requirement for exhaust gas cooling systems in coal and gassy noncoal mines. Nongassy mines usually employ limited exhaust conditioning in the form of catalytic converters, which have limited effect on primary exhaust particulate. The cooling system in most general use in gassy mines is the water scrubber. This device has little effect on most of the gases but removes particulate material from the exhaust. 5 Because of this, exhaust aerosol characteristics in nongassy mines are expected to be different. To see if size selective sampling techniques can be used in such mines, the Bureau and the University of Minnesota conducted a second study in three metal and nonmetal mines, two nongassy and one rated as gassy."

Jan 1, 1990

By T. I. Weston

This is one of a series of papers being prepared for and published by the United States Bureau of Mines, describing mining and milling methods and costs at crushed-stone plants throughout the United States. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total production costs. It is recognized' tat publication of total production costs might in many instances cause embarrassment to individual producers, as well as to the industry as a whole. However, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no mis-understanding of the scope of the cost tabulations shall ensue. ACKNOWLEDGMENTS The author wishes to acknowledge the assistance-of F. W. Horton, mining engineer, United States Bureau of Mines, in the preparation of this paper.

Jan 1, 1933

By Peter Grandone, Ludwig Schmict

The injection of oil-field brimJs into subsurface formations containing mineralized water ·now is .recognizud as the most satisfactory and effective means of disposal in Kansas.· Other disposal ·methods, such as impounding brines in evapOTation nonds and controlled diversion into surface streams, have not prov-ed entirely successful, principally. because the volumes of brine to be disposed of were large, the soil f;?xtr~~mely porous, the net evaporation is low, and the rairiiall insufficient fc)r adequati.:~ dilution of the brine. The disposal of brine by subsurfaCE) inj'ection is often: more. expensive than by either of the above surface methods; nevertheless, surface dis:pos?,l ow.ing to the damaging effe-c.ts of· salt water to plant, animal and aquatic life and to potable water supplies has been:a long-continuing problem with many technical, economic, and 'legal·complexiti,2s

Aug 1, 1943

On July 1, 1969, the Explosives Research Center merged with the Health and Safety Research and Testing Center to form the Safety Research Center, with facilities at Pittsburgh and Bruceton, Pa. Subsequently, passage in December of the Federal Coal Mine Health and Safety Act of 1969 (Public Law 91-173) had a major influence on the activities of the new center. These activities were conducted under two main programs, Coal Mine Safety Research and Explosives Research. The Coal Mine Safety Research program was concerned primarily with two categories of hazards: health-related hazards associated with the mine environment, due to such factors as respirable dust, toxic gases and vapors, and excessive noise; and accidents due to mine fires, explosions, and roof falls.

Jan 1, 1972

By Gabriel S. Esterhuizen, Anthony T. Iannacchione

The roof rock in underground limestone mines in Northern Appalachia can be subject to high horizontal stresses in spite of the shallow depth of the workings. The high stresses can cause roof stability problems. The National Institute for Occupational Safety and Health staff have observed a distinctive asymmetrical mode of failure at the pillar-roof contact in two underground stone mines, which is different from the typical failure mode observed in response to excessive levels of horizontal stress. A dip of greater than 5° was identified as a possible cause of this mode of failure. Numerical model experiments showed that an increase in the dip of the workings can cause an increase in the stress at the up-dip corner of the roof beam. A case study is presented in which failure at the pillar-roof contact was observed where the dip of the workings was 7° in a high horizontal stress field. Numerical modeling showed that the relatively small dip of the workings could have induced stresses changes in the immediate roof that would explain the failures. The model results also showed that this mode of failure is less likely to occur if the limestone pillars contain weak bedding planes that provide stress relief. In addition, the results showed that for the conditions at the case study site, the stress in the roof beam was not sensitive to the thickness of the roof beam or to the excavation span. The high horizontal stresses at this site are an important contributing factor to the observed failures.

By George S. Rice, L. C. IlsLey

"A remarkable explosion of fire-damp caused by a discharge of lightning at the new shaft at the Sitalpur coal mine, has been reported by the Chief Inspector of Mines of India, who gave the following details:""The explosion occurred during a thunderstorm, and the evidence showed that a flash of lightning had, to all appearances, passed down the shaft caus¬ing disruptive discharges at certain points between the guides and the winding rope, rending the latter at two places situated respectively .228 .feet and 278 feet from the surface, The distance between the winding rope and the side of the shaft was 5 feet 4 inches, indicating a spark gap ;of this width, and an intensity of discharge which could not fail to ignite the explosive mixture of gas and air known to be present in the shaft.""The Compressed Air Magazine, January 1920 issue, which contained the above extract also goes on to state;""In 1915, M, Ferey described in a paper read before the Societe de l'Industrie Minerale phenomena of a similar character to the above. In a pit liable to sudden outbursts of gas, for the sake of safety, shot firing was carried out from the surface. During a storm, in the year 1905, shots went off in two places after the detonators had been connected to the conductors) we read in the Colliery Guardian, London. These shots were situated respectively 1,400 and 1,410 metres from the firing station, Realizing the possible danger from this cause, the precaution was taken to cut the conductors at the bottom of the shaft and to connect there just before firing, Even under these conditions a shot went off spontaneously, -.owing, it is believed, to lightning."""

Feb 1, 1920

By Stephen C. Tadolini, Thomas M. Barczak

A critical safety component for all underground mining is intrinsic and standing support systems. Specifically, tabular hardrock mining exploits a wide variety of deposits that require various methodologies to safely mine the ore material. Several new support systems have been developed in recent years for hard rock applications which have been modified or applied in a variety of ground control applications. These include prestressing devices, improved cribs, and free standing supports. Various standing support and prop-type systems have been designed for hardrock applications with seismic loading conditions to accept prestressing. The prestressing, using water-filled cells, creates an active load upon installation and is considered essential to maintain support during and after the blasting of the mine faces. Heavy seismic activity is also present in these mines and the prestressing units can provide some energy absorption capability to help preserve the integrity of the support. This paper presents an overview of these innovations in support technology.

By Dana Reinke, Launa Mallett

Interest in training evaluation in the mining industry was piqued with the promulgation of Title 30, Part 46, of the Code of Federal Regulations. Under Part 46.3, a training plan is considered to be approved if it contains certain information, including “The evaluation procedures used to determine the effectiveness of training.” The present paper is a broad overview of training evaluation and is intended to give trainers and decision-makers a framework for planning or assessing training evaluation strategies. It discusses questions to consider when starting an evaluation plan, Kirkpatrick’s model of evaluation categories, and various ways to collect data. It does not provide detailed instructions on how to develop evaluation methodologies, but reviews topics to consider when creating an evaluation plan. Training evaluation is a term that has many different meanings: assessing the quality of a course, effectiveness of materials used, teaching style of an instructor, or the comfort of a classroom. An evaluation can be done informally over lunch or with highly structured data-gathering tools. It can produce results that are useful to trainers, program administrators, corporate decision-makers, or no one. The key to a worthwhile evaluation is clearly defining why the evaluation is being conducted. Once the purpose is defined, planning the evaluation strategy can begin. For an evaluation to be effective, it should be incorporated into the development of the training activity itself. The training evaluation worksheet at the end of this paper can be used to guide evaluation planning.

Jan 1, 2002

By L. J. E. Hofer, J. L. Snyder, J. N. Barn, J. E. Chilton, W. E. Thomas

Various silicone materials have been proposed for use in mining environments. The catalytic methane sensors now employed are poisoned by silicone vapors. Activated charcoal and carbon cloth adsorbents will increase the sensor lifetimes in an environment containing significant silicone vapor concentrations. The results of a study of catalytic methane sensor operation with adsorbent materials in hexamethyldisiloxane-air mixtures are reported. Sampling techniques developed for measuring silicone vapor content of mine atmospheres are described.

By D. K. Deardorff

The purpose of this work was to investigate the hafnium-carbon phase diagram. Alloys used to study this system were prepared from high-purity components by both consumable-and nonconsumable-electrode arc melting. Data for the diagram were obtained on the alloys by metallography, optical pyrometry, thermal analysis, heat treatment, and X-ray diffraction. The data indicate that a carbide compound occurs over considerable range of composition, and that one of each of the following types of reactions occurs in the hafnium-carbon system: Peritectoid, peritectic, and eutectic. The maximum melting temperature of hafnium carbide is 3,840° C at 49 to 50 atomic percent carbon, and the composition range of hafnium carbide at temperatures of 2,150° to 2,380° C is from 37.0 to 48.5 atomic percent carbon. The hafnium a-S transformation temperature is raised on alloying with carbon from 1,750° to 1,890° C, where a peritectoid reaction isotherm occurs. Alloying hafnium with carbon increases the hafnium melting temperature from 2,190° to 2,250° C, at which temperature a peritectic reaction occurs. Hafnium carbide and carbon react at 3,055° C to form a eutectic of 68.3 atomic percent carbon.

Jan 1, 1967

By C. W. Owings

Two problems perplex many coal-mine operators and employees. Is coal-mine dust harmful to breathe; and, if so, is it possible to keep the concentration below the danger point? The medical profession is not unanimous in its opinion of the danger of breathing bituminous-coal dust, but there appears to be ample and increasing evidence that coal-mine dust can be harmful if breathed in large enough doses for long periods. The question of controlling the dust at the point of formation is still unanswered in the minds of many in the mining industry. However, results of limited studies conducted by the Bureau of Mines in 9 bituminous-coal mines indicate that a full-shift average exposure of workers should not exceed about 20 million dust particles per cubic foot of air (m.p.p.c.f.) and that concentrations can be held within this limit without too much difficulty. Furthermore, these studies indicated that an exposure in the neighborhood of 40 m.p.p.c.f. should not be exceeded for an individual operation and that it is possible to hold within this ceiling.

Jan 1, 1957

By W. H. Rinkenbach, C. A. Taylor

"Among the recently patented detonating compounds that have been suggested as substitutes for the commonly used fulminate of mercury is the normal lead salt of trinitroresorcin, or styphnic acid. As no data concerning its use or practi¬cability were available, a study of its properties was made in the explosives laboratory at the Bureau of Mines experiment station at Pittsburgh, Pa. This paper embodies the results obtained.Normal lead trinitroresorcinate was first prepared and patented*** by Herz; it probably found some use during the World War, but no record of its performance is available,Preparation of Lead Trinitrpresorcinate.In his patent specifications, Herz states that the normal salt may be obtained in a quantitative way by precipitating a multiple of the equivalent weight of the lead salt of a strong inorganic acid - such as lead nitrate - in the presence of a weak organic acid - such as acetic acid - by heating with a Teak solution of the alkali-metal salts or alkaline-earth salts of trinitroresorcin. Herz gives the following example: 245 grams of dry trinitroresorcinand 290 grams of crystalline sodium carbonate are dissolved in in 18.8 liters of boiling water, to which 77 c.c. of glacial acetic acid is added. The toiling solution is mixed with a boiling solution of 650 grams of lead nitrate in 1.4 liters of water, stirring rapidly; and the mixture is boiled for two minutes, after which it is cooled quickly with constant stirring. The precipitated crystals are then filtered off, washed several times with cold water, and dried."

Oct 1, 1923

By Ronald T. Mayerle

A mineral survey of portions of two contiguous WSAs (Wilderness Study Areas) along the South Fork Owyhee River in southwestern Idaho and north-central Nevada was done by the U.S. Bureau of dines in 1984. The portions of the WSAs, known as study areas, have a combined area of 47,610 acres. The Idaho study area consists of 42,430 acres of the 42,510-acre South Fork Owyhee River WSA (ID-16-53). The Nevada study area consists of 5,180 acres of the 7,840-acre South Fork Owyhee River WSA (NV-010-103A). The Idaho study area is within the Boise District of the Bureau of Land Management, and the Nevada study area is within the Elko District. In the Nevada study area, no claims or hard rock mineral occurrences are known.

Jan 1, 1986

By J. J. Hoeppner

Accurate determination of moisture in coals of various ranks has long been a subject of intensive investigation. Excellent reviews of methods developed over many years are given by Brown (9)4/ and, with experimental comparisons, by Goodman, Gomez, and Parry (11). As pointed out in these and other writings, one of the principal difficulties in assigning absolute merit to one or another procedure is the multiplicity of conditions under which water may exist in coal and the difficulties involved in obtaining sharp separation and distinction between these classes. Gauger (10) states: Water recoverable from coal is obtained from the following sources: (1) Decomposition of organic molecules (sometimes called combined water), (2) surface adsorbed water, (3) capillary condensed water, (4) dissolved water, and (5) water of hydration of inorganic constituents of the coal.

Jan 1, 1956

By Margaret R. Egan

The Bureau of Mines experimentally burned Pittsburgh Seam coal and other combustible materials found in mines in order to obtain a better knowledge of their emission products. These experiments were conducted in the Bureau's intermediate-scale fire tunnel, which simulates environ-mental conditions in underground mines. Smoke characteristics, gas concentrations, mass loss, and ventilation were measured. From these values, heat-release rates, particle sizes, obscuration rates, combustion yields, and production constants were calculated. This information was sought as part of a comprehensive study of combustible materials that will ultimately advance the design of more efficient fire detection and suppression systems. The coal combustion measurements presented in this report, together with previous analyses of wood and transformer fluid fires form a data base by which future studies of other mine combustibles can be compared.

Jan 1, 1987

By Peter. PH. D. Cain

Smoky River Coal Ltd. mines low-volatile metallurgical coal by surface and underground methods in the foothills of the Rocky Mountains of Alberta, Canada. Current underground operations are confined to the 5B-4 Mine. Development of 5B-4 began in January 1998; production from depillaring sections commenced in July 1998. This paper describes the history of underground mining on the Smoky River property in terms of extraction methods and pillar design. The development of the present pillar design guidelines is discussed in this context. Recent work to prepare a number of case histories for back-analysis using the Analysis of Retreat Mining Pillar Stability (ARMPS) method is described, along with the modifications developed for calculating the ARMPS stability factor for retreat extraction of thick seams. The design criteria are described, as well as the geotechnical program implemented in order to verify its applicability.

Jan 5, 1999

By D. L. Paulson

The Bureau of Mines studied the feasibility of producing copper matte in an electric furnace from blends of copper concentrate similar to those currently smelted in a gas-fired reverberatory system at an installation in Tacoma, Wash. A 800-kva electric-arc furnace was used to determine the distribution of constituents when arseniferous concentrates are being smelted in an electric-arc furnace. Test results from smelting 40 tons of materials indicated that electric smelting is more like a conventional gas-fired system than originally expected. Although gas composition over the molten bath is much different in an electric furnace, the secondary constituents such as arsenic, lead, zinc, and antimony behaved the same as in a reverberatory furnace. The results established that an electric furnace would be compatible with sulfur and particulate recovery facilities that are being used.

Jan 1, 1976

By George A. Morgan

The 53 countries that constituted Africa in 1990 accounted for a significant portion of total world output of a number of mineral commodities. Among the most significant to be produced in Africa were andalusite, antimony, asbestos, bauxite, chromite, coal, cobalt, copper, diamond, fluorspar, gold, lithium minerals, manganese, phosphate, platinum-group metals, the titanium minerals-ilmenite and rutile, vanadium, vermiculite, uranium, and zircon. Several of these, chromite, cobalt, diamond, and manganese, were not produced in the United States. Despite the underdevelopment of much of Africa, mineral raw materials playa very important part in the national economies of many of its countries. In many cases, the production of minerals is the dominant economic activity in the country, often having the largest and most sophisticated work force. In several countries, one or two mineral commodities are dominant in a weakly diversified economy. Among these are petroleum and diamonds in Angola, petroleum in the Congo, gold in Ghana, bauxite in Guinea, uranium in Niger, phosphate in Senegal and Togo, and copper and cobalt in Zaire and Zambia.

Jan 1, 1992

By Richard J. Mainiero

The Bureau of Mines has developed a prototype nonincendive explosive rock-breaker charge that can be fired unconfined in underground bituminous coal mines without the danger of igniting a flammable atmosphere that might be present. At present, unconfined shooting in underground coal mines is prohibited, but there are situations where the use of such shots would yield an overall improvement in safety. The charge consists of 1-1/2 lb of permissible water gel explosive in the form of a short cylinder 7 inches in diameter and 7/8 inches high, surrounded by a 1 1/2-inch-thick layer of damp salt, and encased in latex rubber reinforced with cheese cloth. The latex rubber housing provides a charge package that is strong enough to resist rough handling yet is pliable enough to conform to an irregular stone surface. A charge of this shape was found to be more effective at breaking rock than charges with lined or unlined cavities. Incendivity tests in a gallery have shown that the prototype charge will not ignite a flammable methane-air atmosphere when fired. Rock- breaking tests made with limestone boulders indicate that the charge will satisfactorily break stone slabs weighing 1 to 2 tons, and that two or more charges might be effective for slabs weighing up to 10 tons. In cooperation with the Mine Safety and Health Administration (MSHA), a test protocol for the certification of these charges as "permissible" for use in flammable atmospheres is being developed.

Jan 1, 1982

Multiple-seam interactions are a major ground control hazard in many U.S. underground coal mines. In some U.S. coalfields, particularly in central Appalachia and the West, the majority of today’s mines are operating above and/or beneath previously mined seams. The effects of multiple-seam interactions can include roof falls, rib spalling, and floor heave. These can seriously disrupt mining operations and threaten the safety of miners. In early 2006, a West Virginia coal miner was killed by rib roll that occurred in a high-stress zone beneath a remnant structure in an overlying mine. Fortunately, not every multiple-seam situation results in hazardous conditions. Indeed, the vast majority do not. For the past several years, the National Institute for Occupational Safety and Health has been conducting research to develop better techniques for predicting the location and severity of multiple-seam interactions. During this investigation, more than 50 mines were visited across the U.S. coalfields. Nearly 300 case histories were collected and analyzed using multivariate statistical techniques. The study also employed the numerical model LaM2D to estimate the multiple-seam stress, the Analysis of Longwall Pillar Stability (ALPS) and the Analysis of Retreat Mining Pillar Stability (ARMPS) programs to determine pillar stability factors (SFs), and the Coal Mine Roof Rating to measure roof quality. The study focused on the two most common types of multiple-seam interactions: • Undermining, where stress concentrations caused by previous full extraction in an overlying seam is the main concern; and • Overmining, where previous full extraction in an underlying seam can result in stress concentrations and rock damage from subsidence. The study confirmed that overmining is much more difficult than undermining, and isolated remnant pillars cause more problems than gob-solid boundaries. For the first time, however, it was possible to quantify these effects in terms of the equivalent thickness of interburden needed to compensate for them. The study also found that pillar design is a critical component of multiple-seam mine planning. Many of the failed cases involved pillars whose SF seemed inadequate once the multiple-seam stresses were accounted for. Weaker roof was also found to significantly increase the risk of multiple-seam interactions. The most important result of the study is an equation that predicts the critical thickness of the interburden required to minimize the likelihood of a multiple-seam interaction. This equation was incorporated into a step-by-step methodology that allows mine planners to evaluate each potential interaction and take steps to reduce the risk of ground control failure. Such measures could include installing cable bolts or other supplemental support, increasing the pillar size, or changing the mine layout to avoid the remnant structure entirely. These Proceedings also contain several previously published papers that cover other facets of multiple-seam mining research. Two papers describe the LaModel family of software developed by Professor Keith A. Heasley of West Virginia University. The LaModel programs were designed for calculating the stresses and displacements in coal mines or other thin, tabular seams in layered media. The original three-dimensional version of LaModel is essential for detailed analyses of complex multiple-seam scenarios. LaM2D, by contrast, implements a simplified two-dimensional model that is suitable for quick approximations of the multiple-seam stresses and strains. Three additional papers in these Proceedings describe the extensive multiple-seam experience of the Harris Mine, examples of extreme multiple-seam mining from the central Appalachian coalfields, and longwall mine experiences in Pennsylvania, West Virginia, and Utah. The final paper reports on a numerical modeling study that provided some insight into the mechanics of multiple-seam mining.

Jan 5, 2007