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By J. E. Chilton

Regular monitoring for methane gas is required near working faces in gassy underground mines where the potential for methane ignitions is greatest. However, high concentrations of methane can also accumulate outby the face where methane levels are monitored less frequently. Wearing a personal methane monitor equipped with an alarm could protect persons working in these outby areas from injury or death due to methane ignitions. The National Institute for Occupational Safety and Health (NIOSH) has conducted studies to evaluate methanometers that could be used as person-wearable monitors. For the present study, seven different person-wearable monitors that are not currently approved for underground use were evaluated. This paper describes test procedures used to evaluate performance of methane monitors that could be used underground for continuous personal monitoring of methane. The information in this report provides data that allows the reader to make side-by side comparisons of these instruments.

By N. T. Lowe, R. E. Miller

When two pieces of heavy equipment interact, jolting and jarring can occur. During haulage truck loading for example, there is a chance that the operator of one or both pieces of the equipment will experience jolting and jarring. Additionally, a jolt can occur when an off highway equipment operator drives over a road defect or inadvertently strikes a berm. Aside from the operators, there is seldom anyone else that witnesses the interaction and can accurately describe the extent of the jolting. This makes it difficult for health and safety managers to address jolting and jarring. The devices and software described in this paper constitute a method for installing “black boxes” called Shox Boxes onboard equipment that already have a GPS system onboard. The resulting configuration provides an objective assessment of jolting and a chance to determine the root causes of it. The Shox Box system reviews data in real time, onboard the vehicles, 24 hrs a day, and sends pertinent information via radio to a central database. The data generated shows whether jolts are above or below a supervisor defined target value for the equipment and the tasks being performed. This allows health and safety personnel to demonstrate safe operation of heavy equipment and recommend proactive actions to maintain jolting within a reasonable range.

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

APPENDIX C SCALING RELATIONSHIPS 1. Scaling Law for Fly Ash Crater Formation The scaling law derived for predicting crater diameters at different scales is developed below by considering the equation of motion of individual fly ash particles. It is assumed that the air drag on each particle is characterized by Stokes flow, and at the borehole - passage intersection the air velocity and the fly ash particle velocity are the same. The equations of motion for a fly ash particle are the following, (see Figure C-1).

Jan 1, 1973

By Charles L. Kimbell

This study is intended to serve three roles. First, it represents a global overview and summary to supplement and complement the five regional companion volumes of the 1991 edition of the Minerals Yearbook International Review. In this regard, it also extends previous time series under this title that appeared as the introductory chapter to the international volume of the Minerals Yearbook from the inception of that volume in 1963 until it was subdivided into separate regional volumes in 1989. The basic statistical presentations herein generally contain data through and including that for 1991, although in a few instances the most recent statistics are those for earlier years because more recent, comprehensive global statistics simply are not yet available owing to delays in data collection and processing in some countries and continued governmental suppression of data in others. The second role of this study is to provide an update to the coverage of events impacting the world's mineral industry that have occurred between the end of 1991 and the preparation of this study. Inclusion of this update is almost essential because of the potential effect of some of these events on global mineral industry activities.

Jan 1, 1993

Mine closing methods should be carefully considered. If not properly sealed, an abandoned mine may continue to produce acid water. Since 60 to 90 percent of the total acid discharged from all coal mines is from abandoned mines,(58) some states require that provisions for sealing be contained in the mining permit application. Closing an operation to prevent harmful mine drainage into nearby runs and streams is a subject of much concern to states as a result of continuing problems from long abandoned mines which were improperly closed.

Jan 1, 1970

Underground and strip mining (6,7) produce different hydrologic environments. Many underground mines are below the zone that is completely saturated with water and the mine openings may cause new and continuous contact between sulfurous material and water which flows from the saturated zone to the workings. Strip mines are usually above the zone of continuous saturation and contact between sulfurous material and water is generally restricted to periods of precipitation. A full appreciation of the problem of water pollution caused by drainage from deep mines requires a basic understanding of occurrences and movement of water in the ground and the modes of ground water entrance into mining areas.

Jan 1, 1970

Enhance coal mine worker safety and productivity by developing a means to control and predict coal mine mountain bumps. Approach The Bureau of Mines has been engaged in extensive research to understand coal mine mountain bumps and their effect on underground coal mining in the United States. Information was collected on the geologic conditions, mining techniques, and engineering parameters at five mountain-bump-prone mines. Although research has not yet evolved to the point where mountain bumps can be effectively predicted or controlled, such studies are invaluable for providing clues that can lead to the development of mountain bump mitigation technology. Case Study Results and Recommendations Mountain bumps in coal mines are explosions of the coalbed that violently release the strain energy stored within it into openings created by mining. Such an event is not only dangerous to mine workers, but can cause substantial amounts of damage to mine equipment, resulting in productivity loss and downtime. In a coal mine, the occurrence may cause coal to be expelled violently from the coal face or coal pillars or cause the mine floor to heave suddenly. Coal bumps are usually accompanied by a very loud noise and tremors or vibrations. Such ground failure:; usually occur in the vicinity of an active gob line in an active retreating room-and-pillar panel, or at or near the face in an advancing or retreating longwall mining panel.

Jan 1, 1989

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 Peter Kovalchikb, Gregory Colec, Syd Peng, R. J. Matetic, Jeffrey Petersond

Mine Safety and Health Administration (MSHA) data indicates that the roof bolting machine is third among all equipment and second among equipment in underground coal mining whose operators exceed the MSHA-PEL (Mine Safety and Health Administration-Permissible Exposure Limit). In response to this, the National Institute for Occupational Safety and Health (NIOSH) has conducted a study to reduce overexposures of noise to operators of roof bolting machines. An important segment of the research is to determine, characterize and measure sound power levels radiated by a roof bolting machine during different drilling configurations. The determined sound power levels generated during the drilling cycle are of major interest because the levels represent the overall sound power generated by the machine. These sound power levels, determined from laboratory tests, can be used to accurately assess the effectiveness of proposed controls for reducing noise exposure to roof bolting machine operators. By using the sound power level results obtained from the laboratory and a commercially available acoustical modeling package, a method for predicting sound pressure levels to roof bolting machine operators for differing drilling types and parameters could be determined. This paper provides a method for predicting sound pressure levels at the operator’s position of a roof bolting machine in an underground coal mine using sound power levels determined in the laboratory. To determine validity, underground coal mine data was also collected to compare predicted and measured sound pressure levels. The results of the predicted sound pressure level data were the same as the underground measured results. This research will provide the mining industry with a valid method for predicting a roof bolting machine operator’s noise dosage underground given any type of drilling configuration or drilling method utilized from laboratory testing.

By Jeanne A. Zimmer, Charles D. Taylor, Edward D. Thimons

On a continuous miner coal face methane concentrations are affected by the quantity of fresh intake air reaching the face. When mining the box cut on a 12.2-m (40-ft) two-pass extended cut face, the continuous miner is always at the point of deepest penetration, and operation of the machine-mounted dust scrubber and water spray system improve the flow of fresh air to the end of the box cut. However, when the continuous miner leaves the box cut to begin cutting the 40-ft slab, little is known about how much ventilation air reaches the end of the box cut. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health conducted a full-scale study to answer this question. Tests were run to determine how much ventilation air reaches the end of the box cut with the continuous miner at three locations in the 40-fttwo-pass extended cut mining sequence; at the end of the 40-ft box cut, at the start of the 40-ft slab cut, and 6.1 m (20 ft) into the slab cut. During these tests, methane gas was uniformly released at the end of the 40-ft box cut. Methane concentrations measured0.3 m (1 ft) from the roof and face of the box cut were used to estimate face airflow quantities. Fresh air flow rates of 1.89and 4.72 m/sec (4,000 and 10.000 cfm), scrubber flow rates of 0, 4,000 and 10,000 cfm, water spray pressures of 0 and3827 kPa (0 and 120 psi), and a blowing curtain setback position of 15.2m (50 ft) were used during these tests. To improve ventilation to the end of the 40-ft box cut when the continuous miner was starting the 40-ft slab cut and 20 ft into the slab cut, the blowing curtain was advanced from its 50-ft setback to locations 40-ft and then 8.5 m (28 ft) from the face. KEYWORDS: Face ventilation, Extended cut, Methane, Box cut, Continuous miner, Scrubber

By Kris Chatrathi, John E. Going, Kenneth L. Cashdollar

Two types of flammability limits have been measured for various dusts in the Fike 1-m3 (1000-L) chamber and in the Pittsburgh Research Laboratory (PRL) 20-L chamber. The first limit is the minimum explosible concentration (MEC), which was measured at several ignition energies. In addition to the three dusts studied previously (bituminous coal, anthracite coal, and gilsonite), this work continues the effort by adding three additional dusts: RoRo93, lycopodium, and iron powder. These materials were chosen to extend the testing to non-coal materials as well as to a metallic dust. The new MEC data corroborate the previous observations that very strong ignitors can overdrive the ignition in the smaller 20-L chamber. Recommendations are given in regard to appropriate ignition energies to be used in the two chambers. The study also considered the other limiting component, oxygen. Limiting oxygen concentration (LOC) testing was performed in the same 20-L and 1-m3 vessels for gilsonite, bituminous coal, RoRo93, and aluminum dusts. The objective was to establish the protocol for testing at different volumes. A limited investigation was made into overdriving in the 20-L vessel. The LOC results tended to show slightly lower results for the smaller test volume. The results indicated that overdriving could occur and that ignition energies of 2.5 kJ in the 20-L vessel would yield comparable results to those in the 1- m3 vessel using 10.0 kJ. The studies also illustrate the importance of dust concentration on LOC determinations.

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

The great expansion of production of aluminum for war purposes has aroused some concern regarding the available supply of carbon suitable for making carbon electrodes required in the electrolytic aluminum process. Approximately three-quarters of a pound of carbon electrode is consumed for each pound of aluminum produced. 5 Because of its small amount of impurities and its suitable physical characteristics, calcined petroleum coke is the standard material used by the aluminum industry for making electrodes As it may be necessary to use some substitute materials, the possibility of using coke made from coal has been considered. Besides this possible use, information concerning the source of low-ash coals is of general interest. Specifications of the aluminum industry for calcined petroleum coke suitable for the manufacture of electrodes are very stringent in regard to allowable impurities. In one such specification the maximum allowable ash is 1.0 percent; the maximum allowable content of iron (as Fe) is 0.06 percent and that of silicon (as Si) is 0.08 percent; the maximum for cal- cium (as Ca) and for sodium (as Na) is 0.12 percent for each, but the two combined may not exceed 0.12 percent; maximum allowable sulfur is 2.0 per- cent. The presence of barium, nickel, chromium, manganese, cobalt, or vanadium is objectionable, and only extremely small amounts are allowed. In regard to physical properties, the coke is required to be so thoroughly calcined that it has a real density of at least 2.02.

Nov 1, 1943

By Oliver Bowles

The following discussion of waste rock utilization constitutes the fifth paper of the current series of reports on lime- plant quarry problems . As here tofore lime manufacturers are invited to cooperate to the fullest extent by supplementing the Bureau's information with the results of their own experiences and observations . Waste utilization is the key to success in many enterprises , and with a broader knowledge of this branch of the lime industry more economical operation is made possible . Your assistance in compiling additional data on this subject is solicited , and such assistance may be rendered by writing answers to the questions on the final page of this report .

Apr 1, 1923

By W. E. Caspar, W. L. Eaton, W. M. Rohmiser, James Westfield, E. J. Podobrski, L. H. Johnson, S. H. Ash

A flood in mine workings is a crisis even if no lives are lost, and when the crisis is past and the excitement wanes there is usually a rapid return to unwarranted complacency in those regions where floods occur, even though the danger of imminent recurrence is known. Experience in flood control, regardless of its nature, has taught that in a flood the work does not cease when the emergency passes; rather, it increases as the water recedes. To do nothing, when it is known that a hazard exists, is inexcusable for those that should do something. To prevent floods in mines, data should be collected and something constructive done with those data, not alone for present conditions but for the future.

Aug 1, 1947

"The dust/lung research of the Center has several long-range objectives:* better methods for the early diagnosis of coal workers' pneumoconiosis (CWP);* methods to modify the disease process;* tests to identify toxic products; and* tests to identify individuals with heightened susceptibility to pneumoconiosis.A major immediate objective is to define the mechanism of dust-induced lung disease. This means determining:* dust characteristics that are important in causing lung diseases;* important interactions between dust and lungs; and* earliest detectable stages of the disease.Several of the Center's projects involve exposing lung cells in culture (in vitro) or animal lungs (in vivo) to samples of the suite of characterized mineral dusts described earlier. The responses of the lung cells or tissues to the dusts are being studied in order to better understand how inhaled dusts cause lung disease.One project is studying the effect of dust exposure on the production of mucus by rat tracheal explants in vitro. Mucus is a major factor in clearing inorganic dusts from the lung. Results thus far have shown that exposure of tracheal cultures to coal dust caused a decrease in micin production in comparison to parallel cultures without dust. To examine the effect of in vivo coal dust exposure, rats were maintained in an inhalation chamber for two weeks, and control rats were in an identical, but dust-free chamber. Tracheal explants results indicate that the effect of in vivo dust exposure is similar to that noted in the in vitro experiments.Pulmonary alveolar macrophages (PAMs) are a key component of the lung's response to inhaled particulates, and they play several important roles in pulmonary inflammatory and repair processes. PAMs are the cells that actually ingest dust particles. Other studies have shown that they play a critical role in the development of silicosis and asbestosis. The Center is studying the effect of dust exposure on the release of oxygen free radicals (superoxide) by PAMs. Intercellular production of superoxide occurs when PAMs phagocytize particles, such as inhaled bacteria, and is an essential mechanism by which PAMs kill ingested, bacteria. A number of complex physiological events occur during this process which are not clearly understood. It is thought that PAMs containing indigestible materials, such as mineral dusts, overproduce superoxide, or inappropriately release it into the surrounding tissues. If true, this would cause toxicity to surrounding lung cells by peroxidation of the lipids in the cell membranes. In vitro exposure of PAMs to low or high doses of kaolin is inert. Preliminary studies indicate that coating the quartz particles with a surfactant reduces toxicity."

Nov 1, 1988

By C. P. Bowie

"It is well known by all who are familiar with the oil industry in America that the oil pipe line is as fundamentally a part of this industry as the railroad is of most other American industries. The oil pipe line was first introduced about 56 years ago, and since that time has so demonstrated its superiority as a means of carrying crude oil froze the well to the refinery, that this method of transportation has largely superseded all others. This has made possible the building of refineries in or near the large consuming centers, rather than at the wells, which are usually remote from the centers of population.The pipes for conveying the oil are laid on the surface of the ground, or at a depth varying from 18 inches to 3 feet beneath the surface, and the main lines are generally eight inches in diameter. The oil is forced through the pipes by means of pumps operated either by steam or by internal combustion engines. The pump stations are located from 1 1/2 to 90 miles apart, varying with the condition of the country through which the pipe lines extend, and the viscosity of the oil to be handled.Some of the larger pipe-line systems and hundreds of miles in length. It is estimated by the U. S. Geological Survey that the total mileage of oil trunk lines in the United States today is approximately 34,000, and that the gathering systems, which are a fundamental part of the trunk systems, aggregate about 11,500 miles in length, making a total of 45,500 miles.Using those figures as a basis, some general conclusions as to the investment represented will be made. At the time most of the lines were constructed, the average cost per mile based on eight-inch pipe was about $6,500. The cost of the average pump station at that time varied from $130,000 to $250,000. The cost at the present time, on account of the increase in price of labor and materials, would be much in excess of these figures. The fixed investment in pipe lines is, therefore, very extensive. It corresponds closely with the actual cost of the property, and is estimated to be approximately $500,000,000."

Sep 1, 1920

By D. B. Dow

The transportation of any commodity which is actually or potentially a source of fire or explosion, has been made safe, insofar as humanly possible, by rigid requirements as to inspection mechanical safety devices, and by printed labels. For the most part these precautions have been sufficient. This is evident when it is considered that in the thousands of instances in which commodities with a great fire risk have been transported, few disasters have occurred. This paper deals with the recent gasoline explosion which occurred at Memphis, Tennessee. At 7:50 a.m. January 24, 1921, vapors from a tan: car of gasoline became ignited and resulted in a blast that killed eleven people and badly injured nineteen others. Probably forty or fifty men, women, and children received slight injuries from falling debris or from burns. The explosion wrecked an oil plant, leveled a block of frame buildings, and broke window panes within a radius of five blocks.

Feb 1, 1921

By H. H. Stoek

It would permit coal mines to operate continuously instead of intermittently . Intermittent operation increases the cost per ton for mining , and makes the yearly return to labor low . These conditions contribute to serious instability and unrest in one of the fundamental industries of the country and this can be changed only by coal buyers doing their part to insure steady work . The railroads are now required to transport the maximum amount of coal during the winter months when traffic is most interfered with by bad weather and when the maximum amount of coal is used by the railroads to handle other coal . The railroads now use nearly 30 per cent of the total output of coal . About one- third of their freight traffic is hauling coal , so that economy of fuel used by the railroads will produce a considerable gross saving .

Apr 1, 1920

By Oliver Bowles

This paper is the fourth of the current series issued by the Bureau of Mines on lime- plant problems . It is hoped that the information presented in these reports will develop sufficient interest among lime- plant operators to prompt them to discuss with the Bureau their own experiences , for it is believed by such an interchange of ideas conclusions will be reached that will be of practical benefit to the entire industry . Much valuable information has been obtained from replies to the papers already issued , but a more general response is greatly desired . It is hoped that many operators will contribute additions to the information on transportation systems now at hand by answering the questions on the final page .

Mar 1, 1923

By Russell J. Foster

This Bureau of Mines review focuses on the extent to which technologically and economically feasible programs in substitution, improved processing practices, including recycling, and design can achieve conservation of cobalt, chromium, manganese, and platinum-group metals, and thus reduce U.S. vulnerability to interruptions of supply. In addition, supply-side options--domestic and foreign resources, ocean minerals, and stockpiles--are identified. The report consolidates four major studies on these strategic and critical minerals sponsored entirely or partially by the Bureau in the last few years. These studies have been updated with further information from the recent literature.

Jan 1, 1985