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By Wils L. Cooley

Several aspects of mine safety grounding systems and equipment are studied. Electrolytic corrosion of test ground beds has shown a high incidence of stray current damage, while efforts to build a reliable continuous ground bed monitor continue. Laboratory and field investigations of trailing cable splices have yielded strong evidence that splices can contribute to stray current problems in the mines, but a method is suggested for discovering deteriorating splices before they pose a serious hazard. A prototype device has been constructed to evaluate the electrical resistance of rail bonds underground as a source of stray current. Theoretical modeling of ground electrodes, has advanced considerably, now covering measurements of large cylindrical electrodes, multiple-rod ground beds, rod electrodes in stratified earth, and measurement of connected beds. A prototype instrument design is given for a potential gradient plotter to quickly evaluate voltage gradients near earth electrodes. Additional ground-check monitor testing is reported.

Jan 1, 1977

By Roy E. Williams

1. The major sources of heavy metal ions in wastewaters of the Coeur d'Alene Mining District are effluents from metallurgical processing plants. Effluents from mine operations provide a secondary source for heavy metal ions. Based on data analyzed by the Federal Water Quality Administration, mercury and arsenic are escaping from some mill waste ponds, but they are in the suspended phase. 2. Metallurgical process effluents are combined with mine waste effluents in tailings ponds, consequently, the quality of the tailings pond decant water is highly degraded. The major effect of combining metallurgical process effluents with mill wastes is a drastic change of pH in the tailings pond. This chance may be an increase or a decrease depending on the metallurgical process. The effluent from an electrolytic antimony plant drastically increases the pH in the tailings pond permitting the removal in solution of antimony via the pond decant system. The addition of low pH effluents to the tailings ponds results in a net decrease in pH which makes lead, zinc, cadmium, and copper more soluble, thereby permitting their removal from the pond via the decant system.

Jan 1, 2011

By R. W. Stahl

A survey of firefighting facilities and practices in coal mines conducted by the Bureau of Mines3/ showed such variations in equipment and apparent attitude toward fire protection that a comparison with other industry seemed advisable. Although other industry is confined generally to surface operations and the hazards probably are not as great, the same general methods of extinguishment are employed, so that the cost and protection at least should be comparable. An investigation of industry other than mines revealed a generally greater emphasis placed on fire-combating equipment, fire-brigade training, fire-fighting facility inspection, and fire-hazard elimination, as well as a greater average expenditure for fire protection.

Jan 1, 1959

By A. G. Galaitsis

The two volumes of this report summarize the noise control work performed by BBN on a rail personnel carrier operated in coal mines. Volume I of the report - submitted November 1977 - describes the aboveground work performed to identify the noise sources, design, fabricate, and install the treatments, and evaluate the treatments through noise and vibration tests. The current volume (II)-describes the underground work conducted by BBN to determine the deterioration, if any, of the treatments when the vehicle is operated normally in a mine. There were no significant changes in the acoustical performance or mechanical integrity of the treatments at the end of a three-month period.

Jan 1, 1980

By J. W. Holcomb

Many mines are opened into the coal beds by shafts; and, at some of these operations, the same cages or skips that are used for hoisting coal also are used for transporting men into and out of the mines. At some mines, separate man-and-material shafts are maintained, and the cages in these are utilized for transporting men and supplies only. In most instances, these cages are operated either singly or in pairs by a hoisting engine installed in a building near the shaft. Single ropes from the tops of the cages pass over bull wheels on the head frame to either electrically or steam-driven hoisting engines that require engineers to operate them. There are records of several instances where hoisting engineers have become incapacitated suddenly while hoisting men, and the passengers on the cages were killed or injured. Where the same cages are used for hoisting cars of coal and for lowering and hoisting men, especially where self-dumping cages or skips are used, safety pre¬cautions must be taken, such as providing steel bonnets for the cage deck, enclosed sides, adequate handholds, gates for closing the end openings, safety catches, and locking devices to prevent accidental dumping. Some of the newer hoisting installations are of the elevator type; where an operator rides in the cage in the same manner as an elevator operator in a building. These cages have single or multiple decks and are primarily for transporting men; but, in some instances, supplies also are transported. They are a great improvement over the installations where the same cages are used for hoisting cars of coal and transporting men.

Jan 1, 1952

By R. J. Leary, W. M. Mahan, F. X. Tartaron

A new type of apparatus for prerefining molten blast furnace iron and to reduce the cost of subsequent steelmaking consists of a funnel - shaped device lined with firebrick into which a horizontal stream of molten pig iron is directed tangentially at the top . The rotary motion thus induced causes the stream to flatten itself upon the wall and flow in a spiral path to the outlet ; thus , the device was termed " vortex cone .' Oxygen and other refining agents are impinged upon the flowing metal in the cone where reaction is facilitated by the large metal surface exposed and the turbulent flow pattern . Experiments with water in 1 - foot - diameter funnels provided an idealization of the flow patterns to be expected with molten iron . A brick - lined reactor 3 feet in diameter was built for desiliconizing molten pig iron in lots of 1 to 2 tons . At flow rates of 0.3 to 0.5 ton min - 1 (430 to 720 tons per day ) this apparatus was 64- to 90 - pct effective in desiliconization with oxygen efficiencies of 19 to 41 pct . Detailed experiments to develop basic engineering data are underway , and adaptation of this principle to other reactions and reactants is planned .

Jan 1, 1964

By Boyd Guthrie

The current use of Mid - Continent crude oil for the manufacture of war products , such as aviation gasoline and lubricating cil , has caused an acute shortage of available supply from established sources . Therefore , refiners who heretofore have had no reason to use West Texas crude oils now are considering them as charging stock and need more information concerning their characteristics . The Bureau of Mines has published several reports3/ giving analyses of the most important of these crude oils . However, to make the applicable data in these publications readily available to refiners , the present compilation of analyses of West Texas crude oils has been prepared . Data showing the effect of catalytic desulfurization of naphthas from West Texas crude oils have been presented in a restricted Bureau of Mines Report of Investigations . These analyses were made under the general supervision of R. A. Cattell , chief, Petroleum and Natural Gas Division, Bureau of Mines , Washington, D. C. , and N. A. C. Smith, supervising engineer , Fetroleum Experiment Station, Bureau of Mines , Bartlesville, Okla . , and under the direct supervision of Harold M. Smith, senior petroleum chemist, Bartlesville , Okla .

Jan 1, 1944

The principal activities of the Bureau of Mines Pittsburgh Mining and Safety Research Center during fiscal year 1971 (July 1, 1970, to June 30, 1971) are reviewed in part 1 of this paper. Part 2 summarizes publications during fiscal year 1971.

Jan 1, 1974

By Christopher Mark

Roof bolt system design means the selection of the type, length, capacity, and pattern of bolts for a particular application. Despite research efforts dating back 50 years, no design methodology has found wide acceptance. This paper begins by identifying four mechanisms that roof bolts use to reinforce the ground. It argues that the reinforcement mechanism is determined by the roof geology and stress level, not by the type of bolt. Next, the attributes of roof bolts are discussed in the light of recent research, including anchorage mechanism, installed tension, length, capacity, timing of installation, and installation quality. Several significant areas of controversy are identified. Design methods from around the world are discussed, including those based on empirical research, numerical modeling, and roof monitoring. Finally, some simple guidelines for preliminary design of roof bolt systems are proposed based on statistical analysis of roof support performance at 37 U.S. mines.

Jan 10, 2000

By W. H. Frederic, F. H. Gibson, R. F. Abernethy

This publication contains the quantitative values for phosphorus , chlorine , sodium , and potassium in United States coals . The samples tested were taken from commercial shipments and have been selected to represent the principal coal producing areas of the country . Due to combining the analytical results from two separate surveys , values for the four elements are not available for all samples .

Jan 1, 1965

By Michael Sokaski, M. R. Geer, H. F. Yancey

This report is one of a series describing investigations by the Federal Bureau of Mines of the performance of various types of coal - cleaning equipment ; other reports in the series are listed in the bibliography . The information in these reports is useful to the coal industry and the manufacturers of coal - cleaning equipment in several ways : First , it assists the coalpreparation engineer who is planning a new plant to select the type of process best suited to the requirements by enabling him to forecast the yield and quality of clean coal obtainable with each type of equipment . Second , the information serves as a yardstick by which the performance of a plant can be judged and thus helps determine whether it is operating at satisfactory efficiency . Both these functions promote better coal - preparation practice ; that is , they help provide coal of more suitable quality for the market and likewise minimize the waste of good coal . This serves the interest of conservation with which the Bureau is vitally concerned . The present report deals with three plants using the Tromp dense - medium process , named after its inventor , K. F. Tromp , who developed the process in the Netherlands in 1936.5/ Selection of this particular dense -medium process for investigation was entirely a matter of convenience , and reports dealing with other dense -medium systems are planned for the future . Two baths are employed in one of the plants investigated . The first of these , handling 6- to 3 - inch coal , exhibited an exceptionally sharp separation between coal and impurity . This was characterized by an error area of 12 and a probable error of 0.023 . In the second bath , treating refuse from the

Jul 1, 1960

By J. C. Franklin

The Spokane Mining Research Center of the Federal Bureau of Mines is placing major emphasis on chemical stabilization as part of the ground support program. Development of polymeric material suitable for bonding rock fractures around the mine opening is one phase of the program. Some of the problems that must be considered are viscosity, applicability, adhesion, cure times, strength, toxicity, and flammability. Epoxies and polyesters were investigated, but shrinkage in polyesters caused redirected effort toward epoxies. Test results with the latter showed that bonded fractures in mine-roof strata were stronger than the virgin rock. Further tests showed that polymeric materials have good potential for bonding, and in conjunction with polymer roof bolts, are expected to result in an economic and useful new support concept.

Jan 1, 1974

By W. L. Crentz

The Black Mesa coal field is part of the Hopi and Navajo Indian Reservation in Apache, Navajo, and Coconino Counties, Ariz. The field is in an isolated area with the nearest railroad 70 to 90 miles to the south. Travel is restricted by roads that become impassable during inclement weather. The area is a mesa and rises from 500 to 2,000 feet above the surrounding territory. Water is very scarce, and the nearest stream of any consequence is the Colorado River about 90 miles northwest from the center of the field. Coal beds are found in the Mesaverde formation of the Cretaceous age, but they are uncorrelated and range from subbituminous to bituminous in rank. Huddle2/ estimates the reserves of subbituminous coal in Arizona at about 15 billion tons, most of which is in the Black Mesa field. The geology of the field has been reported by Campbell and Gregory.3/ Coal production is small, and the output is used almost exclusively for domestic fuel in the Indian schools, missions, and trading posts.

Jan 1, 1955

By Albert W. Deurbrouck

This report describes the preparation characteristics of the significant coalbeds in Russell County , Va . Almost 2 million tons of coal was mined in 1961 ; 75 percent of the coal was cleaned mechanically in preparation plants in the county . The coal of Russell County is ranked as medium- to high- volatile bituminous , contains small amounts of sulfur , and generally requires some cleaning to reduce the ash content to limits acceptable for metallurgical purposes .

Jan 1, 1963

By H. E. Camargo

In an effort to decrease noise-induced hearing loss (NIHL) in coal preparation plant employees, the National Institute for Occupational Safety and Health (NIOSH) is conduct­ing research to identify and control dominant noise sources in vibrating screen (VS) machines. To this end, acoustic measurements of the noise radiated by a dewatering VS were conducted at the Pittsburgh Research Laboratory (PRL) using microphone phased-array technology. These measurements allowed for the identification of the screen as the dominant source in the 250 Hz 1/3-octave band. The sidewalls are the major contributors in the 315 and 400 Hz bands, whereas the eccentric mechanisms and the electric motor are the dominant sources in the 800 and 1,000 Hz bands, respectively.

Jan 1, 2009

By Hugo E. Camargo

Noise Induced Hearing Loss (NIHL) is the most common occupational disease in the U.S. with devastating consequences particularly in the mining industry. A study conducted by the National Institute for Occupational Safety and Health (NIOSH) revealed that 90% of coal miners have hearing impairment by age 50, compared to only 10% of those not exposed to occupational noise. According to the Mine Safety and Health Administration (MSHA), Continuous Mining Machine (CM) operators account for 30% of workers exposed to noise doses exceeding the Permissible Exposure Level (PEL). This number becomes more dramatic considering that 49% of the total national underground coal production is extracted using these machines. In this context, NIOSH is conducting research to identify and control dominant noise sources in CMs. Previous noise source identification was performed using a Brüel &Kjær (B&K) 1.92-m diameter, 42-microphone phased array. These measurements revealed that the impacts from the conveyor chain onto the tail roller, and the impacts from the conveyor chain onto the upper deck are the dominant noise sources at the tail-section of the CM. The objectives of the work presented in this paper were: 1) To rank the noise radiated by the different sections of the conveyor, and 2) to determine the effect of a urethane-coated tail roller on the noise radiated by the tail-section. This test was conducted using an Acoustical and Vibrations Engineering Consultants (AVEC) 3.5-m diameter, 121-microphone phased array. The results from this new test show that a urethane-coated tail roller yields reductions in the tail-section of 2 to 8 dB in Sound Pressure Level in the frequency range of 1 kHz to 5 kHz. However, integration of the acoustic maps shows that the front-section and mid-section of the conveyor also contain dominant noise sources. Therefore, a urethane-coated tail roller in combination with a chain with urethane-coated flights that reduces the noise sources in the front and mid sections of the conveyor is required toyield a significant noise reduction on the CM operator?s overall exposure. These results show the applicability of phased array technology for low frequency noise source identification.

Jan 1, 2008

By D. S. Kingery, F. F. Kopsch

The practice of using two or more main ventilating fans is common at large coal mines throughout the coal-mining industry. To assure adequate and efficient ventilation at may mines, such multiple-fan systems are necessary. The hazards associated with interrelated ventilating currents if a fan fails are controversial, and to date little effort has been made to study this specific problem and to determine corrective measures. The obvious questions are: 1. Is there a hazard? 2. Under what circumtances does it exist? 3. How serious is it? 4. What are corrective measures? Most members of the mining fraternity agree that reduced quantities of air and changed airflow patterns introduce potential hazards, especially where gaseous conditions exist when mechanized methods are used in concentrated mining 0 The seriousness of the hazard depends on the ease with which methane accumlates in face areas or haulage roads, the quantity of methane in workedout areas, and the extent to which reversed air currents interfere with escape and recovery operations after mine fires or explosions. These studies cover three mines and give the distribution of air for the specific conditions show. Each mine probably has somewhat different airflowpressure relationships between fans. This depends on the number of fans, the

Jun 1, 1959

By A. W. Deurbrouck

This report describes the preparation characteristics of the significant coalbeds from which samples could be obtained in Webster County, W. Va. In 1964, approximately 825,000 tons of coal was produced in the county, of which 732,000 tons was mechanically cleaned in three preparation plants. The Sewell coal bed accounted for 94 percent of the coal produced. Twelve samples were collected from five coalbeds. Four of the samples would require upgrading to meet metallurgical requirements; two others of just over 8.0 percent ash would require some upgrading. In general the coalbed samples collected in the county were of medium-sulfur and medium-to low-ash content as received or after removal of the sink 1.58-specific-gravity material.

Jan 1, 1966

Lower workers' dust exposures during bag stacking while ergonomically improving the bag stacking process. Approach Install a new pallet loading dust control system which uses a push-pull ventilation technique along with a hydraulic lift table to control the pallet loading height throughout the entire loading cycle. How It Works A low-volume, high-velocity blower system operating at approximately at 120 cfm blows a stream of air over the top layer of bags on the pallet. The blower system is composed of two 3-inch air jets (approximately 1,200-ft/min velocity) directed toward an exhaust system on the opposite side of the pallet. As these air jets travel across the pallet, they en-train dust generated during bag stacking. The dust laden air is then captured by the exhaust ventilation system which draws approximately 2,500 cfm through an exhaust hood on the opposite side of the pallet.

Jan 1, 1989

By Albert W. Deurbrouck

This report describes the preparation characteristics of the Pittsburgh and Upper Freeport coalbeds in Hancock , Brooke , Ohio , and Marshall Counties , W. Va . Over 4.5 million tons of coal was produced in these four counties in 1962. Most of this production came from the Pittsburgh coalbed . Twelve coal samples were collected for this study , 11 from the Pittsburgh bed and 1 from the Lower Freeport bed . Two of these samples could be upgraded to produce metallurgical - grade coal . The sulfur content of the Pittsburgh- bed coals was generally excessive --as high as 4.9 percent in the raw coal and 3.19 percent in the float 1.30 specific gravity fraction . The rank of the coals in this area ranges from high-volatile A to high-volatile B bituminous .

Jan 1, 1964