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By T. J. Ballard

The Rickard mine in York County, S. C., named for the original owner, Alexander Rickard, was operated about 50 years as. No records are available of the quantity of corundum shipped. Pratt states, "Many tons were picked up from the surface and shipped." The mine was visited on August 6, 1943, by the author, accompanied by Gilbert W. Withers of Atlanta, Ga. Investigation of the property was begun by the Bureau of Mines after some initial work by the Mi-Cor Corp., a company organized by Gilbert P. Withers of Atlanta to explore the property. In conducting the Bureau program, 754 linear feet of trenches were dug, 110 feet of old drifts cleaned out and examined, and 38 feet of shaft retimbered.

Jan 1, 1948

By Bernard Porter

Differential thermal analysis measurements were used to characterize a phase diagram for the KF-YF3 system at compositions between 0 and 60 mole-percent YF3, A congruent melting point compound was observed at 3KF?YFs, which melts at 965°±5° C and undergoes solid-state decomposition at 725°±2° C. One peritectic and two eutectic compositions are also defined.

Jan 1, 1969

Lower noise exposure levels for operators and cleanup personnel working in portable nonmetallic mineral crushing and screening plants.

Jan 1, 1983

By L. C. Headley

Surface areas of two synthetic and three natural consolidated porous samples were obtained by the Orr low-pressure permeametry technique. The results suggest that the Orr technique is a useful substitute for the low-temperature gas adsorption (BET) method for determining the surface area of rock samples. It was more rapid than the BET method, and the surface-area values obtained were larger but agreed better with BET values than values calculated from the Kozeny-Carman equation. Efforts were unsuccessful to demonstrate the influence of channel-size distribution on pressure-flow rate curves by means of experimental data and a parallel channel model.

Jan 1, 1971

By K. D. Luxbacher

Understanding methane emissions in underground coal mines is critical for a safe and productive mine. In addition to reasonable estimation of initial coalbed reservoir parameters, it is also crucial that changes in effective stress due to mining and pore pressure reduction are taken into account due to their effects on porosity and permeability. Primary parameters for estimation of emissions or modeling of the mining environment for this purpose are porosity and permeability which can change dramatically as a result of stress redistribution associated with mining and gas desorption from a large coal volume. These parameters affect the emission rates and ventilation requirements, as well as water inflow into the working environment. Stopping leakage, on the other hand, is a secondary stress dependent factor in estimation of emissions, as convergence of the roof and floor strata, compromising the integrity of the stopping, may result in leakage, making prediction of ventilation requirements difficult. This paper aims to examine the effects of porosity and permeability changes of the coal seam on methane emissions in an underground continuous miner section. The models were developed and executed in a dynamic fashion to simulate an advancing section. Through this process, the changes of effective stress in coal, particularly their change paths, on porosity and permeability were incorporated into the models and methane emissions, concentrations, air requirements, water inflow and possible leakage from the stoppings were investigated using a conventional coalbed methane reservoir model.

Jan 1, 2009

By Forrest T. Moyer

General injury experience in the mineral fuel industries was less favorable in 1965. Of the major industry groups, the coal mining and the coke industries had higher injury-frequency and severity rates than in 1964. The oil and gas industries had an increased Tate of occurrence of injuries although the severity rate improved. However, in the relatively small peat and native asphalt industries, the injury experience was more favorable than in 1964. Overall operating activity for the mineral fuel industries, as measured by the average number of men working daily and the total worktime, was higher than in 1964. Moderate declines in employment and worktime in the coal and peat industries were more than offset by gain in the other groups. In addition to the industry classifications included in this chapter, similar injury, employment, and worktime data on the metal, nonmetal, stone and aggregate industries are presented in volume I. Corresponding data for broad classifications of mineral industry groups arc given by States in volume III of the Minerals Yearbook.

Jan 1, 1967

This report was limited to a search of available literature on under- ground methods to combat acid water pollution. From this review it is evident that very little work has been done in this specific area. It is also evident that there are specific areas of mining engineering and mining related hydrology and geology that need further research efforts to solve the many water problems. They are: (A) Composition, variation and availability for oxidation of sulfur in strata. (B) Rate of oxidation of sulfuritic materials. (C) In situ limestone and its influence on underground acid drainage. (D) Structural, stratigraphic and hydrologic character of old mining areas as a basis to make decisions about adjacent new mining areas. (E) Operational changes in mining methods to prevent pollution. (F) Sealants for underground coating to exclude water from contact with pyrite to inhibit formation of the contaminants. Such a program has been initiated on refuse piles. The prime purpose of this report is to investigate those practices which have been used to regulate or control water accumulation and prevent harmful mine drainage. A supplemental purpose is to indicate those areas which need further research to prevent underground mine water pollution.

Jan 1, 1970

By Jeffrey M. Listak

The Respiratory Hazards Control Branch of NIOSH routinely conducts laboratory and mine-site evaluations of dust control technologies. Gravimetric and instantaneous dust sampling instruments are used in these evaluations to measure and document dust levels to determine worker exposure. The Thermo personal DataRam (pDR) is an instantaneous sampler that uses light-scattering technology to provide relative measures of airborne respirable dust. The pDR can be used in active and passive modes to measure respirable dust levels. Tests were conducted to evaluate the sampling performance of active and passive pDR operation relative to each other and. against a gravimetric sampler (the accepted standard for respirable dust measurement). The purpose of the test was to determine if the pDR can be used effectively in the passive mode in higher velocity airflows (up to 5.1 m/s (1000 fpm)). Studies of the pDRs in both modes of operation were conducted in a controlled laboratory environment and in field situations. Dust measurements using pDR units in both modes of operation were recorded in ve¬locities ranging from 1.0 to 5.1 m/s (200 to 1000 fpm). Tests were conducted in ambi¬ent air and in air with the addition of moisture. Results show that, although the units measure different concentrations in their respective modes of operation as compared to a gravimetric sample, the relative readings can be corrected to yield accurate dust measurements.

Jan 1, 2007

By John Owens, Wayne Howie, Hamid Maleki

After an analysis of the hazards of room-and-pillar retreat mining systems, it became apparent that safety could be significantly improved by considerations of (1) human factors, (2) remotely controlled mobile roof supports (MRS=s), (3) mine layout designs, and (4) ground monitoring systems. Initial studies of the effectiveness of MRS=s focused on their interaction with mine strata and evaluations of suitable measurements for detecting roof stability problems during pillar extraction. These studies indicated that overall stress distributions and strata movement were most influenced by the stiffness of coal-measure rocks and the design of mining layouts. Thus, to improve worker safety, mine layouts should be carefully designed and a pillar extraction method chosen for specific geologic and stress conditions. Pillar failure was often associated with an increase in pressure on the hydraulic gauges of the MRS, and roof failure was often preceded by rapid changes in the rate of roof-floor convergence. These studies led to development of a monitoring system that displays loading rate on an MRS in real time. A major MRS manufacturer cooperated in installing and testing the system on an MRS. New field studies focus on evaluating the performance of the system, measuring roof-floor convergence, and optimizing the safety of MRS operations through proper mine layout design.

By Fred Baldassare, Marcia Harris, Kenneth K. Eltschlager

Surface mine blasting was recently investigated as a potential source of high concentrations of stray gases found in nearby residences of western Pennsylvania. In one incident carbon monoxide was detected in a home and in the other, high concentrations of carbon dioxide were found in a home. Both carbon monoxide and carbon dioxide are by-products of blasting. However, other potential sources of these gases may also exist in a residential setting. In each case, gas chromatography (GC) and carbon isotopic analyses were used to define atmospheric concentrations inside the homes, and to determine the source of a stray gas. Molecular and isotopic analyses provide geochemical evidence as to the origin and source of the stray gas. This paper discusses elements of a stray gas investigation and the analyses necessary to identify the source of a stray gas.

By G. W. Murrie, W. P. Diamond, C. M. McCulloch

It is estimated that more than 1 trillion cubic feet of methane is contained within the coals of the Mary Lee group in Jefferson, eastern Tuscaloosa, and southern Walker Counties, Ala. Most of this methane will be encountered by mining. Coals of the Mary Lee group are presently being mined at depths exceeding 1,000 feet and will in the near future be mined at even greater depths, where the problem of methane gas affecting the mining operations will be acute. It is calculated that approximately 90 pct of the methane is at depths greater than 1,000 feet, and over half of the gas is contained within only 12 pct of the study area which is under more than 1,500 feet of over- burden. Degasification in advance of mining will increase mine safety, reduce ventilation expenditures, increase productivity, provide an additional energy source, and make it possible to mine parts of deep coalbeds that probably could not otherwise be mined.

Jan 1, 1976

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

The Federal Coal Mine Health and Safety Act of 1969 has dictated major changes in mine ventilation with regard to both air quantity and quality. Requirements have also been placed on the ventilation of beltlines, gob and face areas, and air velocities on trolley haulage roads are limited. Escapeways, separate from trolley haulage roads and on an intake split of air, must be maintained continuous to the surface. These and other similar requirements have not only precipitated several modifications to existing ventilation systems but also have greatly increased the complexities of new mine ventilation planning. It is apparent that the use of computers in ventilation system analysis and design is a necessity. SUMMARY Although computer oriented analysis of mine ventilation systems was introduced over two decades ago, it has yet to receive widespread acceptance in the United States. Central to this problem is the fact that, while many computer programs for network analysis have been developed, no attention has been paid to the development of computer input data. Consequently, without this foundation, program applications have been infrequent. This thesis has directly attacked this problem and has presented all pertinent information basic to the development of good computer input data. The areas that were covered include quantity measurement, pressure measurement, fan testing, survey data balancing, and the development of a network schematic from the ventilation survey results. These discussions on data collection and the corresponding reduction to computer coding have been illustrated by an application of a ventilation simulation program to an existing mine in Southwestern Pennsylvania. The use of a ventilation

Jan 1, 1977

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

By R. V. Ramani, A. S. C. Owili-eger

The origin of gaseous hydrocarbons in coal, predominantly methane, can be traced to the natural processes of coalification. The higher rank coals or the more deeply buried seams retain more gas than low rank coals or shallow seams. It is estimated that up to 460,000 cubic feet of all types of gases are produced during the formation of one ton of coal (Cervik, 1969). The chief components of these gaseous products are methane, carbon dioxide, nitrogen and water vapor. Most of these gases escape during the various stages of decomposition but with eventual presence of overlying impermeable beds, there may be as much as 2,000 cubic feet of gas retained per ton of coal. Over geologic time, diffusion and other processes such as geologic disturbances in the earth's crust remove all but 500 to 2000 cubic feet of gas per ton of coal (Cervik, 1969). It is this residual methane which is of primary concern when mine openings are made in coal measures. Extensive data compiled by the United States Bureau of Mines reveal that some coal mines in this country emit up to 20 million cubic feet of methane per day (Spencer, 1970; Irani et al, 1972). Toxic, poisonous and respirable gaseous pollutants and explosive gases, predominantly methane, are injected into the ventilation stream from active sections and gobs. The liberation of methane in gob areas may, under certain circumstances, become extremely large. In some instances it may constitute up to 70 percent of the total yield of gas in a mine. The basic physical factor which determines the yield of gas into the mine environment is the gas content of the seam. The influence of the gas content of a seam on the overall yield of gas

Jan 1, 1974

Control dust generated during mining in salt mines. Approach A machine-mounted exhaust ventilation system which moves with the cutting machine from place to place was developed. The system captures the dust at the face of the heading and exhausts it downstream of the heading in the crosscut. This helps cause fresh air from the crosscut to flow over the machine operator's position, and aids in keeping the dust cloud close to the face. How It Works The system consists of (1) a circular intake hood with a 10-inch slot extending 250 degrees around the base, bolted to the gearhead; (2) 20-inch-diameter wire-wound flexible ducting to connect the intake hood to the fan (25 ft. is allowed sufficient slack for bar movement); (3) an industrial exhaust fan capable of generating 10,000 cfm with 13 inches water gage pressure at 1435 rpm; and (4) 150 ft. of collapsible 24-inch tubing for the exhaust duct which is de-played and returned In each heading by the cutter operator and/or his helper.

Jan 1, 1983

Lower costs associated with hands-on training in donning and using a CSE ,self-contained self-rescuer (SCSR). Background In June 1987, the Mine Safety and Heath Administration (MSHA) issued an Emergency Temporary Standard (ETS) requiring that all persons entering underground coal mines must be given bands-on SCSR training. The ETS will shortly be replaced by a new standard requiring this hands-on training. Bureau of Mines research has shown that the most effective means of delivering this training is to have the trainee go through a six-step training procedure while in a kneeling position. Once the miner has looped the neckstrap over his or her head, he or she completes the donning sequence in this order: 1) activate oxygen; 2) insert mouthpiece; 3) put on nose clips; 4) put on goggles; 5) adjust neck and waist straps; and 6) replace miner's cap and prepare to move out. This procedure is repeated until the miner demonstrates that he or she is proficient at the task.

Jan 1, 1988

Improve the field-of-view into the front-right blind spot for drivers of large haulage trucks, thereby reducing the growing collision hazard in surface mines. Approach Reduce the glare problem found in the first generation fresnel lens blind area viewer design by eliminating the upward-looking section of the fresnel lens and adding a rear hood to reduce backlighting. How It Works The first generation blind area viewer was developed and in-mine tested as an aid to improved visibility for large haulage trucks. Other aids were improved left-and right-hand mirrors. Evaluations showed that a blind area viewer mounted on the right-front of the radiator deck was effective and was readily accepted by drivers. Nevertheless, because glare was a problem under certain conditions, a low-profile viewer was developed. Glare control louvers from the earlier design were kept and a backlighting glare control hood was added. The height of the hardware was reduced by eliminating the top three inches of the fresnel lens. This portion of the lens contained an upward-looking segment which originally was thought to be needed so the driver could see the horizon when he looked through the viewer and be better

Jan 1, 1982

Continuously separate mixture of non-magnetic materials (such as scrap, precious metals, or certain ores) at a reasonable cost. Approach Nonmagnetic materials of different densities are rapidly float/sink separated by an augmented lifting force produced In a magnetic fluid (liquid) by the effect of an external magnetic field. The magnetic fluid is a colloidal suspension of magnetite In kerosene, prepared by a low-cost process. How It Works Separation is accomplished in an open trough filled with magnetic fluid. A magnetic field is established in the fluid, by energizing an electromagnet having poles on each side of the trough. Due to the design of the magnet poles and air gaps, the magnetic field is strongest at the bottom, about 10,000 oersteds, and uniformly decreases in strength to about 2,000 oersteds at the top of the fluid. Therefore, the magnetic field gradient increases with depth. The magnetic force attracts the entire separation medium (magnetic fluid) creating a reaction force of equal magnitude and acting in the opposite direction. This reaction created within a magnetic fluid/magnetic field combination is called a magnetic levitation force. It increases with the field strength. In this case because the magnetic field is strongest at the bottom of the trough, the magnetic levitation force will quickly float lighter material while heavier material sinks.

Jan 1, 1980

By Oscar Lee

"Flotation is generally regarded as a process that is only applicable to metallic minerals. However, its scope is now known to be greater than this, because some of the nonmetallic minerals are floatable, such as graphite, sulphur, and fluorite. Recent observations show that limestone may be added to the list of floatable nonmetallic minerals. Such work is being done on a laboratory scale at the Southern Experiment Station (Tuscaloosa, Ala.) of the Bureau of Mines, Department of Commerce, where experimental magnetic concentration of the low-grade iron ores of the Birmingham district is in progress. Certain experiments have demonstrated that the limestone may be floated from the magnetic log-washer tailing, and then incorporated in the iron concentrate.If the loss of lime could be prevented, some ores though low in iron and high in insoluble contain enough lime to make their concentrates self-fluxing. Since this loss in the magnetic log-washer can not be avoided, the Time must be recovered from the tailing by some method and added to the magnetic iron concentrate before sintering. Then the resulting concentrate will be self-fluxing.While seeking a suitable means of treating the tailing for recovery of lime, flotation was tried. It was at once evident that this method had possibilities, during the early part of the investigation, soap solution made from a common soap was used as a flotation reagent. The froth obtained was a fairly good lime concentrate. This result was an important clue, and led to tests with the use of such reagents as oleic acid and sodium oleate. Later, cresol, creosote, coal tar and other similar flotation reagents were tested in combination with the oleic acid and soap solutions. As a result, oleic acid and cresol used together were found to be satisfactory.The tailing from the magnetic log-washer is in excellent physical condition fur flotation. The iron ore had been ground in a ball mill to 100 mesh for magnetic concentration. Hence the bond between the lime carbonate and the other constituents of the tailing was well broken."

Apr 1, 1926

By Michael J. Pazuchanics, Thomas J. Fisher, John J. Sammarco, Jeffrey H. Welsh

This report (An Introduction to Safety) is the first in a nine-part series of recommendations addressing the functional safety of processor-controlled mining equipment. It is part of a risk-based system safety process encompassing hardware, software, humans, and the operating environment for the equipment's life cycle. Figure 1 shows a safety framework containing these recommendations. The reports in this series address the various life cycle stages of inception, design, approval and certification, commissioning, operation, maintenance, and decommissioning. These recommendations were developed as a joint project between the National Institute for Occupational Safety and Health and the Mine Safety and Health Administration. They are intended for use by mining companies, original equipment manufacturers, and aftermarket suppliers to these mining companies. Users of these reports are expected to consider the set in total during the design cycle. • 1.0 Safety Introduction.—This is an introductory report for the general mining industry. It provides basic system/software safety concepts, discusses the need for mining to address the functional safety of programmable electronics, and includes the benefits of implementing a system/software safety program. • 2.1 System Safety and 2.2 Software Safety.—These reports draw heavily from International Electrotechnical Commission (IEC) standard 61508 and other recognized standards. The scope is "surface and underground safety mining systems employing embedded, networked, and non-networked programmable electronics." System safety seeks to design safety into all phases of the entire system. Software is a subsystem; thus, software safety is a part of the system's safety. • 3.0 Safety File.—This report contains the documentation that demonstrates the level of safety built into the system and identifies limitations for the system’s use and operation. In essence, it is a "proof of safety" that the system and its operation meets the appropriate level of safety for the intended application. It starts from the beginning of the design, is maintained during the full life cycle of the system, and provides administrative support for the safety program of the full system. [ ]

Jan 4, 2001