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By George McCaa, H. C. Howarth

"During recovery operations following a recent coal-mine explosion, 12 small fires were encountered near the break line of pillar extraction in a large panel. All of the fires except one were quickly extinguished by the rescue and recovery parties. This fire had found its way into a large quantity of loose material at a corner of the cut-through between two rooms, about 100 to 150 feet from the break line of an extensive goaf; had it been necessary to seal the fire, the inclusion of this break line not only would have made the work difficult but would have made the section hazardous as it probably would have given off gas. The fire covered a floor space of about 100 square feet and when discovered was burning briskly, with the flame extending to the roof at a height of 3 or 4 feet; it was the cause of much apprehension on the part of those in charge of the recovery operations and resulted in delaying the work considerablyThe object of this article is to describe in detail the method by which the fire was brought under control and finally extinguished, so that other persons encountering similar conditions may have the benefit of the experience.When the fire was discovered a request for rock-dust, fire extinguishers, and other fire fighting equipment was telephoned to headquarters on the surface. The promptness with which fire fighting equipment and material was provided was a big factor in finally extinguishing the fire and illustrates one of the many advantages of a good organization for fire-fighting. Material was transported in mine cars to a point on the main hauling road about 1,200 feet from the fire. It was then carried to the scene of activity by workmen. The first material to be delivered at the fire was a number of fire extinguishers of various types. The contents of 30 to 35 of these were discharged on the fire and with the aid of a small quantity of rock-dust were sufficient to smother the flame temporarily. It was the opinion of several persons who were present when the fire extinguishers were used that the acid-soda type of extinguisher gave more effective results than the two or three other types used.When the contents of all of the fire extinguishers had been exhausted the fire was temporarily smothered, but as there appeared to be danger that the flame would burst forth again, means for completely extinguishing the fire were"

Feb 1, 1929

By A. W. Khair, M. Ahmad

"Bit wear has been proven to have a significant effect on respirable dust generation in coal cutting system. The mechanism of bit wear can be adhesion, abrasion. oxidation, or diffusion. depending on cutting conditions. This paper presents a portion of an extensive ongoing series of studies to better understand the principles of bit wear and dust generation. Used bits collected from underground coal mines were analyzed to identify the basic principle of bit wear in coal and rock cutting. Distribution of weight loss and conical height loss of worn bits were studied and bit wear was divided into four stages according to weight loss. Utilizing these worn bits, Laboratory experiments have been carried out to study the effects of bit wear on coal cutting system and respirable dust generation. An Automated Rotary Coal Cutting Simulator was use to perform the experiments. Acoustic emission monitoring is applied to study the effect of bit wear on fracture formation and dust generation. INTRODUCTIONContinuous miners were introduced in the 1950’s and became the major equipment in underground coal production. Now the larger production in the coal industry has increased the demand for continuous miners and their use. It is well known that serious dust problem is also introduced with the use of continuous miners, especially with recent increase in productivity. On the other hand, legal restrictions are made ·more strict by the Mine Health & Safety Administration for the respirable dust generated by the continuous miners to prevent coal workers from incidence of pneumoconiosis. The incidence of pneumoconiosis depends on dust concentration, exposure time, and physical properties of dust. Of them, dust concentration is the best parameter for the assessment of the risk of pneumoconiosis. Although a lot of research work has been done to reduce dust concentration substantially, some areas are still required further investigation to meet the strict regulations. One of the areas is about bit wear and dust generation. In this area, the principles of bit wear and effect of bit wear on dust generation are major concerns."

Mar 1, 1992

Improve safety at mineral operations that use cyanide leach solutions to recover precious metals from finely ground ores, Approach Provide an alternative, non-acidic means of cleaning processing systems such as the State-of-Maine filter system, thereby reducing the exposure of workers to toxic hydrogen cyanide gas (HCN), The Problem Many gold and silver mining operations use cyanide solutions to dissolve gold and silver from ores. The precious metals frequently are recovered from pregnant leach solutions by the Merrill-Crowe recovery process, whereby gold and silver is precipitated with zinc dust. When that method is used, suspended particles in the leach solution must be filtered out before zinc precipitation can occur. This filtering is accomplished with small packaged plants, such as the State-of-Maine (SOM) filtering system. Unfortunately, the filters become clogged with calcium carbonate scale after about 2 to 10 days of operation and must be cleaned before further precious metals recovery operations can continue, Cleaning the system is a hazardous task because the acid is not compatible with the alkaline cyanide leach solutions, and toxic hydrogen cyanide (HCN) gas may be produced when the acid and solution are mixed. That gas, if breathed or contacted with the skin, can cause cyanosis which may induce nausea and even asphyxia and death. To reduce this danger, the Bureau of Mines has devised a safer method of cleaning clogged filters,

Jan 1, 1986

By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

"An electro-optical method was used to quantify superoxide (SO) release from single rat pulmonary alveolar macrophages (PAM) exposed in vitro to respirable quartz and kaolin dusts and in vivo to quartz. Release was determined by measuring the reduction of nitroblue tdrazolium (NBT) to a diformazan precipitate at 550 nm from video-recorded images of individual cells. In vitro exposure to 0.025 or 0.05 mg/ml kaolin for 40 minutes resulted in no significant differences in either the total diformazan produced (max) or the maximum rate of diformazan production (R)./n vitro exposure to 0.025 mg/ml c1uartz decreased max 38 percent while no significant change was found using 0.05 mg/ml. However, R was decreased 31 percent and 24 percent for the low and high dose, respectively. In contrast, PAM obtained from animals exposed in vivo to quartz dust for two or four weeks in inhalation chambers exhibited increased production of diformazan. However, only PAM analyzed three days post-exposure showed significant increases, while PAM from animals sacrificed ten or 31 days post-exposure were not significantly different from control. The combined in vitro and in vivo quartz results might suggest that there is an initital acute response to exposure that decreases the ability of PAM to produce SO, followed by recruitment of production of PAM with increased SO producing capability. It appears that removal of animals from the source of exposure permits PAM to return to control levels of SO production by31 days. Whether this would be true for chronic exposure remains to be elucidated.IntroductionPulmonary alveolar macrophages (PAM) protect the lungs by phagocytizing foreign debris and bacteria.(1) This process involves ingestion as well as destruction of foreign matter. Phagocytosis usually is accompanied by a respiratory burst which increases cellular oxygen consumption leading to the release of highly reactive oxygen metabolites.(2) These agents have been implicated in the killing of bacteria by phagocytes, but they have also been shown to be toxic and,have been linked to cancer, emphysema, arthritis, diabetes, and other diseases.(3) Toxic effects may be a result of 1) an abnormally low production of metabolites, resulting in damage to lung tissue by the respired bacteria and/or dusts; or 2) an abnormally high production resulting in direct damage to lung tissue by metabolites themselves."

Mar 1, 1989

A significant amount of information regarding the crushed stone and sand and gravel industries in each State is available from State agencies and State trade associations. These organizations continuously monitor the State mineral industries and are therefore an important source of detailed information at the local level. This third edition of the directory was prepared to provide a listing of government agencies and trade associations that can assist the users interested in obtaining detailed listings of crushed stone and sand and gravel producers, in addition to the information published by the U.S. Bureau of Mines.

Jan 1, 1994

By J. M. Stuve

Heat of solution measurements of high-purity neodymium metal and neodymium trichloride (NdCls) in 4.360 molal hydrochloric acid (HCI) were used to determine the standard heat of formation (6EPr) of NdCls? From solution data obtained, the heat of formation of NdCls (c) was computed as -248,970 ±260 cal/mole at 298.150 K.

Jan 1, 1965

Coaxial cable structures form the subject of substantial theoretical and experimental investigations either directly related, or which can be extrapolated, to the communications needs and environments of U.S. coal mines. Communication systems based on "guided" waves, of which "leaky" coaxial cables are one implementation, are attractive candidates for providing a range of communication functions primarily along haulage ways, and possible also within sections up to the working face. (However, there are still strong reservations as to whether a practical coaxial cable sys tem could provide sufficient communications coverage within a section. ) In this Part, we present the results of some theoretical calculations of the performance of leaky coaxial cable communication systems. We also analyze the applicability of the theoretical and experimental results obtained by other researchers to the needs of U.S. coal mines. In particular, this investigation has been focused on the utility of relatively low cost, conventional, flexible, coaxial cable at frequencies covering the LF through HF bands and extending into the lower part of the VHF band, as opposed to relatively high cost, special semi-rigid, coaxial cable* at frequencies in the VHF and UHF bands. There are three major design alternatives for coaxial cable communication systems considered in this chapter: • Base station feeding a coaxial cable with high surface transfer impedance (holes in outer conductor, e.g., braid construction). • Base station feeding a coaxial cable with repeaters (U.K. experiments). • No base station, direct communication via a coaxial cable with periodic radiative structures.

Jan 1, 1974

By C. H. Schwartz

A thermal radiation probe was constructed and tested in pulverized-coal-fired furnaces. A rotatable sensing head on the side of a water-cooled probe permitted measurement of radiant flux within a 7.20 cone from any desired direction to a point within a furnace. A response curve for a corner-fired furnace showed radiant flux of 130,000 Btu per sq ft per hr, when viewing flame, and 60,000 Btu per sq ft per hr, when sensing wall reflection. Detailed drawings and fabrication procedure are given.

Jan 1, 1970

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

MINE VENTILATION NETWORK ANALYSIS

Jan 1, 1977

By Harry W. Campbell

U.S. Bureau of Mines investigation; identified no mineral resources or evidence of mining activity in the Sheep Divide RARE II area. A deposit 10 mi (16 km) southwest of the area contains copper and silver minerals in the Triassic Wild Sheep Creek Formation which probably underlies basalt lava flows covering the study area. Abundant basalt in the area can be crushed and used as aggregate, but suitable deposits closer to markets are widely available No sand, gravel, coal, oil, gas, or geothermal resource, were Identified. INTRODUCTION Location and Access The Sheep Divide RARE II area [10 mi (16 km) west of the Snake River] encompasses 7,100 acres (2,800 ha) of the Hells Canyon National Recreation Area in the Wallowa-Whitman National Forest. Enterprise, Oregon, is located 23 air mi (37 (m) west of the area. Peripheral access is provided by the highway from Joseph to the community of Imnaha, Oregon, then south to the study area by the graveled Upper Imnaha Road (fig. 1).

Jan 1, 1983

By M. G. Zabetakis

The method of moving averages was found useful in assessing the nature of methane emission in coal mines. Emission rates were influenced markedly by the presence of abandoned oil and gas wells in the vicinity of the mine. Such wells appeared to increase the flow rate of methane into the mine by a factor of 2 to 30 in an active mine in the Pittsburgh coal seam.

Jan 1, 1972

Significantly reduce respirable dust exposures of longwall shearer operators when cutting out at the headgate. Approach As a result of Bureau research, a ventilation curtain is recommended to be mounted between the stage loader and the coal rib to more effectively prevent the ventilation air from blowing across the shearer drum as it cuts out at the headgate. Some mine operators already employ this method of reducing dust, but a vast majority do not. How It Works One source of extreme concentrations of respirable dust for longwall shearer operators is the shearer headgate drum as it cuts through into the headgate entry. As the drum cuts into the entry, it is exposed to the primary ventilation airstream. The high velocity air passes through and over the rotating drum, picking up large quantities of dust.

Jan 1, 1982

Provide better ventilation for mines by reducing air leakage around stoppings. Approach Most stoppings are constructed of concrete blocks and trowelled-on mortar and are not very airtight. Bureau of Mines research has shown that brushing on modified mortar containing fiberglass and/or other additives, that enhance strength and adhesion, minimizes air leakage around and through the stoppings. Airtightness is an important factor in building stoppings since an airtight stopping will provide for more efficient ventilation airflow and more cost-efficient use of the mine's ventilation system. How the New Technique Works After broken floor and rib material is removed, the stop-ping faces are covered with one or two coats of modified

Jan 1, 1982

By Wallace W. Roepke

The Bureau of Mines has a well-established health and safety research effort directed to fundamental studies of the mine cutting system. This report describes the ignition danger of using cutting bits with flat wear area on still-intact carbide inserts.

Jan 1, 1983

By Richard J. Mainiero, Michael J. Sapko, Marcia L. Harris

Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings and one fatality. To better understand the factors contributing to this hazard, the National Institute for Occupational Safety and Health (NIOSH) carried out studies in a 12-foot diameter sphere to identify key factors that may enhance the levels of CO associated with the detonation of several commercial trenching explosives. The gaseous detonation products from emulsions, a watergel, and ANFO blasting agents as well as gelatin dynamite, TNT, and Pentolite boosters were measured in an argon atmosphere and compared with those for the same explosives detonated in air. Test variables included explosive formulation, wrapper, aluminum addition, oxygen balance, and density. Major contributing factors to CO production, under these laboratory test conditions, are presented. The main finding is the high CO production associated with the lack of afterburning in an oxygen poor atmosphere. Fumes measurements are compared with the manufacturer’s reported IME fume class and with the Federal Relative Toxicity Standard 30 CFR Part 15 in order to gain an understanding of the relative toxicity of some explosives used in trench blasting.

Provide reasonably priced, reliable fire protection for large walking draglines. Approach Fire hazards on large draglines were analyzed, then appropriate automatic fire sensing and suppression systems developed and in-mine tested. How It Works Five fire hazard areas identified for special attention are: electrical control room, high voltage transformer enclosures, circuit breaker rooms, collector ring/roller path area, and the automatic lubrication rooms. Automatic fire sensing and suppression systems were separately designed for each area. The design of each system was tailored to the hazards and equipment protected. Spot thermal sensing and Halon 1301 suppression were specified for the electrical

Jan 1, 1981

Enable mine personnel to determine the effectiveness of and to optimize the mine fire stench warning system without resorting to costly trial and error fire drills. Approach The mine fire stench warning system is used by underground metal/nonmetal mines to warn mine workers of a fire or other emergency. Stench is released directly into the mine ventilation and/or compressed air lines, and its repulsive odor warns miners to evacuate the mine or to follow other established emergency procedures. Unfortunately, since most deep metal mines have complex ventilation systems, some areas of the mine may receive nauseatingly high concentrations of stench while other areas, in more remote locations, may receive no warning or greatly delayed warring at best. The Bureau of Mines, through research, endeavored to solve this problem with a computer modeling system designed to calculate the distribution of odorant by the stench warning system.

Jan 1, 1986

Measure the leakage through individual crosscut stoppings quickly and economically so that the worst ones can be identified and repaired. (Typically 60 to 80% of the air supplied to a mine short circuits before reaching a working face.) Approach Most of the leakage through a permanent stop-ping is channeled through two windows in a temporary stopping, and air velocities through the windows are measured; leakage is determined from a formula. How It Works A temporary stopping made of plastic brattice is erected in the same cross cut as the permanent stopping, either upstream or downstream. The brattice is fastened to the roof, bottom, and ribs of the entry with spads. Normal leakage of brattice was allowed for in deriving formula, and does not effect results. For best accuracy the brattice and the stopping should be separated by a distance of one hydraulic diameter.

Jan 1, 1979

By Collin Stewart, Greg Hunt, Christopher Mark

Bowie Resources maintains one of the most pro-active ground control programs in the U.S. mining industry today. Its guiding philosophy is that everyone in the organization, from the miners at the face all the way through the top management, are involved in ground control. Some of the unique elements of the Bowie ground control program include: • Roof bolt operators log the stratigraphy of test holes in nearly every cut. These “lith-graphs” are used by section foremen to determine the need for additional roof support, and they are entered into the geologic data base for use in geologic modeling and mapping. • Underground core drilling is conducted to obtain data for CMRR and stability maps. • Weekly “Quality” meetings, involving mine management and technical staff, are held to ensure that ground control information is integrated into production operations. The paper will describe the program in detail, discussing the involvement of roof bolters, section foremen, surveyors, technical staff, and production managers. It will also show how the program has contributed to the mine planning process. Case histories of successful ground control interventions will be discussed.

By R. J. SHAW

Oil shale has been defined as, "a compact, laminated rock of sedimentary origin yielding over 35 percent of ash and containing organic matter that yields oil when distilled but not appreciably when extracted with the ordinary solvents for petroleum." The oil-yielding organic matter in oil shale, commonly called kerogen, decomposes upon application of heat to form bituminous materials that are soluble in organic solvents and may be extracted from the inorganic residue. However, separation usually is accomplished by continuing the heating and thereby cracking the primary bitumens to gas and oil, which distill, leaving a carbonaceous material on the mineral residue. It has been suggested that this conversion takes place only at relatively high temperatures - 750°F or higher. On the other hand, other workers have found that transformation may take place to some extent at temperatures as low as 400°F. In either a solvent extraction or a destructive distillation process for separating organic material from the inorganic portion of oil shale, the quantity of heat required to raise the temperature of the oil shale sufficiently to induce a satisfactory rate of conversion of kerogen to oil is important in determining the design of an economical process. Likewise, the quantity of heat recoverable from a spent shale is important in determining the overall heat balance of the process. Published data on the specific heat of American oil shales are meager. Gavin and Sharp present data for two samples of Colorado oil shale, one from near DeBeque and one from Parachute Creek, and for a sample of spent shale over a temperature range of 68°F to 1940°F. McKee and Lydor present data on the specific heat of two samples of oil shale from near DeBeque, Colorado. Additional thermal data on various grades of oil shale over a wider range of temperature are needed in order to apply sound engineering practices to the design of equipment for processing oil shale.

Nov 1, 1947