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By John J. Mulligan

Ear Mountain is an isolated mountain mass that rises abruptly from the coastal plain on the northwest shore of the Seward Peninsula. Geologically it resembles the more accessible Brooks Mountain and Cape Mountain areas to the southwest, being composed of a granitic core surrounded and partly capped by metamorphosed sediments. The occurrence of lode- and placer-tin deposits in this area has been known since the early 1900's, when the Seward Peninsula region was prospected extensively for both gold and tin. The Federal Bureau of Mines investigated the tin deposits in the Ear Mountain area during the 1953 and 1954 field seasons. The objectives were to delimit the areas in which tin minerals occur, as a guide to future prospecting, and to determine the amount of tin in the known prospects. Work by the Bureau of Mines included both placer and lode sampling.

Jan 1, 1959

By W. H. Ode, W. A. Selvig

Briefly, this swelling test consists in heating 1 gram of pulverized coal in a silica crucible over a gas flame under prescribed conditions to form a coke button which is compared in size and shape with a series of standard profiles numbered 1 to 9. These profiles are intended to cover the size and shape of buttons obtained from coals covering a wide range in plastic properties. The number of the standard profile with which the maximum cross-sectional area of the button most nearly corresponds is recorded as the swelling index. Although the swelling test showed poor relationships with the various tests that were used for measuring expansion or contraction of coal during carbonization, it gave indications of having value in measuring free-swelling and coking properties of coals when burned on fuel tests. An opportunity to investigate this occurred when an engineering company reported pronounced differences in burning characteristics on grates of various shipments of Pocahontas coal. Some of these coals gave trouble by swelling excessively and clogging the grate. Samples were obtained, and it was found that the troublesome coals gave radically higher free-swelling numbers than did the coals that performed satisfactorily. Also, it was found that the free-swelling index test gave better differentiation between coals than could be obtained from the coke buttons from the standard volatile-matter test or iron agglutination-value results. The results of the free-swelling test were confirmed by the Subcommittee on Plasticity and Swelling, Coal, a special group of the Subcommittee, under the chairmanship of R.A. Shuman, worked along with the test method. Estberg, Limacher, and Shuman of the Battelle Memorial Institute investigated the various factors affecting the test and found that the swelling index was a good indication of the suitability of coal for performance on residential-type stokers from the swelling characteristics of the coal. Data were presented that also showed that the index was helpful in the selection of coal for industrial underfeed stokers.

Feb 1, 1948

By Steven E. Mischler, Jon C. Volkwein

A diesel particulate matter analyzer capable of direct, real-time measurement of engine exhaust particulate is necessary to effectively institute source control technology currently being used on diesel equipment and to ensure that the control measures are working. To investigate the potential of a differential pressure monitor to measure diesel particulate matter in undiluted exhaust, samples were collected from three different diesel engines-Kubota, Isuzu, and Deutz-running under 12 different RPM and load scenarios. These measurements were compared to elemental carbon concentrations in the sampled exhaust as determined by using the NIOSH 5040 analytical method. Elemental carbon is used as a surrogate measurement for diesel particulate matter. The results of the two data sets were then compared using a linear regression analysis. The coefficient of determination (or R2) was calculated to be 0.98, 0.94, and 0.74 for the Kubota, Deutz, and Isuzu engines, respectively. R2 values of this magnitude indicate that this method can be successful in estimating elemental carbon emissions in the engines tested. In addition, for replicate samples, the coefficient of variation ranged from 7.1% to 10.2% with an average of 8.5%. These data indicate that this method could prove useful to mechanics as they work to maintain engines and DPM control technologies.

By R. J. Leary

Significant improvements in surface conditions or mechanical properties of steels have been attributed by several investigators to ladle additions of small quantities of rare-earth metals or their oxides. To investigate systematically these effects in wrought and in cast plain carbon and alloy mechanical steels containing approximately 0.35 percent carbon, heats of four representative compositions were melted by the Bureau of Mines in a 4-ton open-hearth furnace. Each heat was cast into three sets of ingots to exemplify respectively, treatments with (1) rare-earth metals, (2) rare-earth metal oxides, and (3) an untreated set as a control. The development of melting, casting and rolling practices is described and discussed. Lance injection of oxygen shortly after melt raised the temperature of the metal immediately as much as 500° F., principally because mechanical agitation exposed the high-carbon metal to the flame and furnace root. An exceptional degree of superheat in the metal at the termination of the refining period was attributed to oxygen injection during the refining period. Bath temperatures higher than industrial practice were permitted by the all-basic furnace lining. Rates of carbon elimination as high as 0.036 percent carbon per minute were achieved by oxygen injections.

Jan 1, 1961

While coal occurs beneath about 18 percent of Utah, only 4 percent of the state has minable reserves. Utah's coal fields are mostly bituminous. Current coal production in Utah is largely by underground mining, making Utah unique among the coal-producing states. Most coal seams are more than 8 feet thick. Utah's coal resources are about 6.3 billion tons, 1.3 percent of the national reserve. Most of Utah's coal resources are held by the Federal Government and Indian tribes and are mined under lease. The climate of the Utah coal region is characterized by hot, dry summers and cold, relatively moist winters. Normal precipition varies from 6 inches in the lower valleys to more than 40 inches on some high plateaus. The growing season ranges from 5 months in some valleys to less than 3 months in mountainous regions. These extreme climatic conditions make reclamation difficult. Utah gained primacy when its regulatory program was conditionally approved January 21, 1981. Full program approval was obtained March 7, 1983. The Abandoned Mine Land Program was approved June 3,1983. A Federal Lands Cooperative Agreement was signed in March 1987; Utah performs all enforcement activities and some permitting activities on federal lands.

Jan 1, 1992

By Burke Cartwright, S. F. Ravitz, Lloyd R. Michaels

This method is similar to the reduction of dolomite by ferrosilicon, in that it does not require the direct use of electrical energy; like ferrosilicon, the calcium carbide must be produced in an electric furnace, so that the reducing agent in both processes may be considered in some respects as “stored” electrical energy. The reduction of magnesium chloride by calcium carbide is exothermic, takes place rapidly at ordinary pressure and at relatively low temperatures, and can be carried out in ordinary steel equipment, whereas the reduction of dolomite by ferrosilicon and the carbothermic reduction of magnesium oxide are endothermic, require high temperatures, and present serious problems with respect to materials of construction. Because of its apparent simplicity and other advantages, the Bureau of Mines has briefly investigated the reduction of magnesium chloride by calcium carbide. Published data on the reduction of magnesium chloride by calcium carbide are meager. Matignon states that reduction is fairly rapid at 1,200º C. Matsuura claims that magnesium chloride is not reduced by calcium carbide at atmospheric pressure and 800º C; however, by keeping the pressure under 10 mm. of mercury he was able to obtain small globules of magnesium at 800º C.

Mar 1, 1947

By Christopher Mark

Since it was first introduced, the Coal Mine Roof Rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. This paper discusses the application of the CMRR to another practical ground control problem. Extended cuts (cuts greater than 6 m (20 ft) in length) are commonly used with remote control continuous miners. Extended cuts can greatly increase productivity, but they have been associated with a number of fatal roof fall accidents. When extended cuts are attempted in weak roof, the roof may collapse before it can be bolted, causing hazardous conditions. Until now, it has not been possible to predict where conditions may not be suitable for extended cuts. In this study, data on the CMRR and extended cut experience were collected at 36 mines in 7 states. It was found that when the CMRR was greater than 55, deep cuts were routine in nearly every case. When the CMRR was less than 37, extended cuts were almost never taken. Between 38 and 55, extended cuts were feasible sometimes but not others. The data also shows that extended cuts are less likely to be stable if either the entry span or the depth of cover increases.

By J. P. Rider

Health surveillance efforts indicate that the development of lung disease and overexposure to respirable dust in underground coal mires continues to afflict mine worker. Results from the most recent round (1992 - 1996) of the Coal Worker's X-ray Surveillance Programs indicate that approximately 8% of the examined miners who had at least 25 years of mining experience were diagnosed with Coal Worker Pneumoconiosis (CWP) (category 1/0+). During the period between 1995-1999, mine operators and MSHA inspectors collected 9968 and 1365 dust samples respectively, from longwall designated occupation (DO) personnel. Analysis of these samples showed that 1970 (20%) of the mine operator samples and 25.8 (19%) of the MSHA samples5 exceeded the 2 mg/m3 dust standard. The continued development of CWP in coal mine workers and the magnitude of respirable dust over-exposures in longwall mining occupations illustrate the need for improved dust control technology on longwalls. Figure 1 illustrates the major longwall dust sources as determined in the early 1990's.4 This article describes the ongoing research to find ways to minimise shearer dust levels as a function of changes in dust control parameters, and research to determine the impact of high air velocities on shield dust entrainment.

By Sinisa M. Djordjevic, Isaac A. Zlochower, Kevin J. Liekhus, Cindy A. Loehr, Kenneth L. Cashdollar

An experimental program was conducted to evaluate the accuracy of some current methods for predicting the flammability of gas mixtures containing hydrogen and flammable or nonflammable volatile organic compounds (VOCs) in air The specific VOCs tested were toluene, 1,2-dichloroethane, 2-butanone, and carbon tetrachloride. The lower flammability limits (LFLs) of gas mixtures containing equal molar quantities of the components were determined in a 19.4-1 laboratory flammability chamber using a strong spark ignition source and a pressure criterion for flammability. All but one of the LFL values for the individual components were in agreement with earlier literature values. However, the LFL of l,2-dichlorocthane was found to be significantly lower than the range of values reported for previous determinations in smaller chambers. Two methods for calculating the LFL of mixtures were considered. The Group Factor (atomic) Contribution Method was determined to he generally more accurate than the LeChatelier Method for estimating the LFL of the gas mixtures reported here, although the LeChatelier Method was usually more conservative. The Group Factor Method predicted higher values (nonconservative) for the LFLs of several mixtures than were experimentally measured. For the case of a mixture of hydrogen and carbon tetrachloride, the Group Method estimation of the LFL was seriously in error.

By J. C. Edwards, C. C. Hwang

A Computational Fluid Dynamics (CFD) program was used to model buoyancy induced Product-Of-Combustion (POC) spread from experimental fires in the National Institute For Occupational Safety And Health (NOSH), Pittsburgh Research Laboratory (PRL), safety research coal mine. In one application, the CFD program was used to predict spread from fires in an entry under zero airflow conditions. At a location, 0.41 m below the entry's roof at a distance of 30 m from the fire, the measured smoke spread rates were 0.093 and 0.23 m/s for a 30 and a 296 kw fire, respectively. The CFD program predicted spread rates of 0.15 and 0.26 m/s based upon the measured fire heat production rates. Based upon a computation with [c3h3] as the hydrocarbon fuel, a predicted 5 PPM co alert time of 70 s at a distance of 30 m from the fire is to be compared with the measured alert time of 148 s. In a second application, the CFD program was used to analyze smoke flow reversal conditions, and the results were compared with visual observations of smoke reversal for 12 diesel fuel fires. The CFD predictions were in qualitative agreement with visual observations of smoke reversal.

By Edward A. Barrett, Lynn L. Rethi

Recent studies have shown that miners performing construction, maintenance, and repair (CMR) work activities in the conduct of their jobs incur from 39 to 65 percent of all reported injuries in the mining industry, The number is particularly high at surface aggregate operations; however, the problem exists at all mining locations and commodities. To address this issue, an interactive, (3-D) slides training exercise, Hazard Recognition Training Program for Construction. Maintenance and Repair Activities, was developed. The purpose of the exercise is to teach work& to recognize CMR hazards in the workplace and to deal with them using accepted safe work procedures. It was field tested using a total of 340 persons from surface mining operations in six states. The subjects were tested before and after the training intervention to determine if objectives of the instruction were achieved. Results indicated that 7 1 percent of the participants showed improvement in ink test scores. Following the posttest, subjects responded to a seven question Likert scale. These questions related to the validity of the exercise and the utility of the training program. More than 93 percent of the miners reported that they "learned something new from the training" and over 94% said they "would use these practices to work more safely".

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

C. 7 Emergency Rescue Hoists There is a need, especially in mine development areas, for portable, on-call, man-rated equipment capable of lifting men through several hundred feet. Wire rope climbing equipment as shown in Figure 37 appears particularly suited to this need. It is portable, weighing approximately 100 lbs. , is currently man-rated for numerous above ground applications and can be electric or air powered. Commercial units currently have a lifting capacity of 1000 lbs. , and can be fitted with bosun' s chairs. Lifting speeds are in the 20-30 FPM range and the equipment is not depth limited. In a situation where miners are unable to climb to the top of a shaft this equipment could rapidly be anchored to the top of the shaft and lowered to them by hand. Since the self contained unit is controlled by the person travelling in the shaft he would be able to negotiate shaft obstruction himself. This would not be possible with other forms of easily deployed free-hanging equipment. Typical manufacturers of this type of equipment are Ohio Hoist Mfg, Co, 321 South Beaver St. Lisbon, Ohio 44432 216-424-7283 Sky Climber Inc. 17311 South Main St. Gardena, California 90248 213-321 -6414

Jan 1, 1976

Coal-bearing beds underlie 23,000 square miles, about one third of Missouri's total area. Twelve out of more than twenty named coal seams have been or are being commercially mined. The remainder are too thin for commercial production. The coal is high volatile bituminous, with reserves estimated to be six billion tons, 1.24percent of U.S. coal reserves. Coal-bearing strata are generally thin seams which can be up to five feet thick. Typically, mined seams are about 28 inches thick. Coal deposits were first mined in Missouri in the 1840s, with the coal used primarily for domestic heating and blacksmithing. Production increased with the introduction of steamboats on the Mississippi. Coal production in 19 17 was six million tons. Production has steadily declined from a high of nearly seven million tons in 1984 to 2.3 million tons in 1991. Declining production is the result of several factors, including competition from other energy sources and the high sulfur content of Missouri coal. Today, coal-fired electric generating plants are the biggest consumers of Missouri coal. The Missouri regulatory program was conditionally approved November 21,1980, and fully approved January 17,1983. Its Abandoned Mine Land program was approved January 29, 1982.

Jan 1, 1992

By J. C. Edwards, C. C. Hwang

In the design for a fire or smoke emergency, a main concern is maintaining an evacuation path that is free of smoke and hot gases. In ventilated tunnel fires, smoke and hot gases may form a layer near the ceiling and flow in the direction opposite to the ventilation stream. The existence of the reverse stratified flow has an important bearing on fire fighting and evacuation of underground mine roadways, tunnels, and building corridors. In the present study, a computational fluid dynamics (CFD) program is used as a design tool to model floor-level fires in a ventilated tunnel. The fire is simulated by a diffusion flame of propane issuing from a circular hole on the tunnel floor. The computed profiles of velocity and temperature along channel cross sections are similar to those obtained experimentally. The computed reverse-flow layer length has been correlated with a densimatric Froude number with some success. A non-dimensional parameter involving the source fire intensity is also used for the correlation. These analyses show that an appropriate ventilation air current must be maintained to provide an evacuation path from the source fire clear of smoke and hot gases. It is believed that CFD modeling, employed correctly and interpreted carefully, can be a useful design tool for fire protection.

By John L. Reuss

A laboratory study was conducted by the Bureau of Mines to investigate the technical feasibility of decomposing hydrous magnesium chlorides by using a steam pyrohydrolysis technique. This procedure consisted of injecting steam into the atmosphere of a decomposition furnace containing samples of hydrous magnesium chloride and determining the rate of hydrolysis by measuring the rate of chloride evolution. The variables investigated were temperature, amount of water vapor in the decomposition atmosphere, and hydration stage of magnesium chloride. The application of steam was shown to accelerate both the rate and completeness of magnesium chloride decomposition reactions. For example, when magnesium chloride hexahydrate is exposed to a furnace temperature of 600' C in an air atmosphere for 20 minutes, the decomposition is 37 percent. Under identical conditions in a steam atmosphere, the decomposition is in excess of 70 percent. The magnesium oxide produced by the steam pyrohydrolysis of magnesium chloride dihydrate at 800° C contained 98 percent magnesium oxide. Based on magnesium oxide composition, this is equivalent to that of burned magnesite produced at temperatures in excess of 1,300° C. To demonstrate the quality of the product on a practical basis, metal reduction tests have shown it to be equivalent to reagent-grade magnesium oxide as a carbothermic reduction feed material.

Jan 1, 1974

By Sean Gallagher, Thomas G. Bobick, Diane M. Doyle-Coombs, Richard L. Unger

The U.S. Bureau of Mines has developed an in-house facility to evaluate selected effects of whole-body vibration (WBV) levels experienced by underground mobile equipment operators, Vertical vibration data were collected from a coal haulage vehicle via a uniaxial accelerometer attached to the machine frame under the operator&apos;s seat. Data were analyzed and processed so a computer-controlled platform could approximate the vibration signals. Eight men (35.5 yr 2 6.5 SD) participated in a pilot study to evaluate the effects of shock and kBV on heart rate (HR), blood pressure (BP), and subjective discomfort. Subjects were exposed to vibration for 30-min periods while seated in a typical seat (backrest angle at 90° or 130°) &apos;that was plain steel or modified with 2 in foam padding. Subjects repeated the same protocol on a separate day, without the vibration. Results indicated the vibration significantly increased the HR (Q< 0.01), systolic BP, mean BP, the number of times subjects reported discomfort, and overall subjective discomfort rating (pc 0.85). When seated in the steel seat, the overall discomfort rating (E< 0,081) ad the number of times discomfort was reported (p< 0.05) increased significantly. Seatback angle had no significant effect on any of the dependent measures.

The instrumentation specification in the National Academy of Engineering (NAE) report of March, 1970, set forth some rather general guidelines that the seismic surface system should follow. The fact that there was no comparable equipment in existence at that time, and the need to produce a system from presently available equipment, was spelled out in that document. The features that the system should include were listed, and included: • Quick and simple deployment • Portability • Battery-powered operation • All-weather operation • Computational simplicity and speed • High reliability and long shelf-life • Dual service for location and communication • Adaptability to widely varying seismic velocities. topography, and geologic structures • Minimum maintenance • Capability of continuous operation for extended periods, and • Reasonable cost Since that report, there has been a substantial amount of field work addressing the trapped miner detection and location problem carried out by Westinghouse Corporation under contract with the Bureau of Mines. Two complete surface systems have been designed, built, and field tested and substantial documentation has been produced on the mine environment and background noise using these systems. These systems, built from off-the-shelf equipment, have been designed with maximum flexibility in mind in order to explore what con¬figuration a field unit should have.

Jan 1, 1974

By B. W. Madsen

Bureau of Mines research to recover arsenic from mining industry waste material and process streams is reported. Batch and column approaches were investigated for adsorbing arsenic from acid leach solutions and ion-exchange eluate solutions with hydrated titanium dioxide granules. A method for producing hydrated titanium dioxide granules was devised to provide material suitable for use in a packed adsorption tower. Selective adsorption of arsenic from acidic leach solutions was achieved. The loading capacity of arsenic on the granules was 14 wt-pct when synthetic solutions were used, but lower when actual leach solutions were used. Other elements in the leach solution were Zn, Cd, and In. The granules were used in an attempt to lower the arsenic content in a solution containing 0.95 g/l W and 0.027 g/l As from a process devised by the Bureau of Mines to treat Searles Lake brine. The arsenic content was lowered to less than 0.001 g/l, but unacceptable amounts of tungsten also were adsorbed by the granules. Adsorbed tungsten was partially stripped with pH 11.5 NaOH, and both tungsten and arsenic were completely stripped with 5M NaOH solution. Repeated loading and stripping of the granules had no effect on the loading capacity for arsenic.

Jan 1, 1983

Aid mine operators as well as mine inspectors in making quick but sufficiently accurate measurements of the rock dust content of coal/rock dust mixtures. The Problem Past research has shown that accumulations of volatile coal dust in underground coal mines can be rendered non-explosive by dilution with chemically inert rock dust (usually limestone). Consequently, rock dusting is required by law in U.S. underground coal mines. However, mine officials and inspectors have no quick and reliable means to determine whether enough rock dust has been applied to achieve a mixture that is in compliance with the law. Even the compliance tests used by the Mine Safety and Health Administration (MSHA) are slow and involved. MSHA assures that a mine has been rock dusted adequately by collecting samples from rock dusted areas of the mine and sending the samples to a laboratory for analyses of the inert-dust content. The analyses may not be completed for more than two weeks, during which time the mine in question might be inadequately protected against coal dust explosions. To solve this problem, the Bureau of Mines devised a quick, simple and reliable device that can immediately determine the rock-dust content of a mixture of coal and rock dust.

Jan 1, 1985

By Willard L. Hunter

The Bureau of Mines smelted samples of chromite ore and concentrate from the General Services Administration (GSA) purchasing depot at Grants Pass, Oreg., in a submerged-arc furnace to establish smelting conditions and the energy requirement to produce high-carbon ferrochromium. Raw material, in the form of ore, flux, and reductant, and electrical energy are available on the Pacific coast to smelt the chromite. The concentrate can be smelted without prior agglomeration by employing hogged wood (wood chips) as a major portion of the reductant. The energy requirement is relatively low, about 3,960 kw.-hr. per ton of alloy. The ferrochromium produced will contain about 60 percent chromium. In addition to the smelting data, a statistical summary of the grade and amount of chromite purchased during the stockpile program and estimated chromite reserves and production volume are given. It is estimated that 632,000 tons of Cr203 contained in chromite of all grades is available in the western coastal States. Of this total there appears to be sufficient metallurgical-grade and beneficiable ore to sustain a smelting operation for 25 years at a consuming rate of 25,000 tons a year, utilizing material comparable to that delivered to the Government stockpile.

Jan 1, 1961