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By P. Delogne, L. Deryck, R. Liegeois

So far as the propagation of electromagnetic waves is concerned, an underground tunnel behaves like a pipe or hollowed waveguide. Waves propagate in this tunnel with a low attenuation only if their frequency is higher than a so-called critical frequency which depends on the shape and mostly on the cross -dimensions of the tunnel and which value is in the neighbourhood of several tenths of MHz. However, when a metallic conductor is stretched along the gallery the electromagnetic characteristics of the latter are considerably modified and the effect of the cut-off frequency disappears; this is due to the fact that the gallery equipped with such a conductor works like a coaxial cable where the conductor serves as the outward conductor and the wall of the gallery as the return conductor. This is the principle of the monofilar waveguide cable which has been perfectly studied by Gabillard. Two mean characteristics of the monofilar mode are as follows: first of all, when the cable is suspended in the middle of the cross section of the gallery, the electromagnetic field occupies all the space between the wire and the walls of the gallery. When the wire is close to the wall, the electromagnetic field tends to become concentrated between the wire and the wall, with the consequence that, with the given monofilar mode power, the aerial of a receiver standing somewhere in the tunnel will capture a weaker and weaker signal. Secondly, owing to the fact that the mode of monofilar propagation uses the ground as return conductor, its power of propagation is considerably diminished; the closer the wire is to the wall the higher the attenuation, for only a very small part of the wall is utilized as return conductor. To cover great distances, everything else being equal, two or more conductors must be placed in the gallery. If the distance between two conductors of a cable is much smaller than the distance between one or other of the conductors and the walls; or again if one of the conductors surrounds the others and forms a screening, two sorts of modes appear: on the one

Jan 1, 1973

This book has employed miners' narratives to illustrate basic concepts about the escape process. One of the most powerful means by which people make sense of their experiences is through the telling and internalization of stories [Bruner 1990]. By couching one's own and others' motives and actions in terms of a coherent narrative, a person is able to learn from mistakes and plan future behaviors that may help ensure survival. A growing body of research suggests that decision-making skills used to deal with emergency situations can be taught and assessed by simulations based on narratives from the real world [Bransford et al. 1986; Brecke 1982; Brener 1984; Connolly et al. 1989; Halff et al. 1986; Jones and Keith 1983; Lacefield and Cole 1986]. Such techniques have been used to address the decision-making of medical personnel, civil and military flight crews, and even people involved in broader life events such as political and military situations [Babbott and Halter 1983; Dugdale et al. 1982; Farrand et al. 1982; Gilbert 1975; McGuire 1985; McGuire et al. 1976; Flathers et al. 1982; Giffin and Rockwell 1984; Jensen 1982; Janis and Mann 1987]. Given the validity of this method of study and the promise it holds for helping people improve the quality of their responses to nonroutine occurrences, it is perhaps surprising that there have been no studies of emergency decision-making among blue-collar workers prior to those conducted by the present authors and their colleagues. The purpose of this chapter is to describe underground coal miners' decision-making performance on a table-top simulation whose problem structure is derived from interviews with a group of eight miners who escaped from the 5 Left section at Brownfield Mine. The exercise was constructed by a panel of domain experts (mine safety and rescue personnel) with the assistance of an educational psychologist. The simulation includes actual predicaments with wise and unwise decision alternatives that, in the opinion of these domain experts, are characteristic of such escapes. Results reported in this chapter are the scores of a sample of experienced mine workers who completed the simulation. Because the exercise is a series of objective performance tasks coupled with detailed and immediate feedback, this simulation can be used to teach and refresh critical escape skills, as well as to provide data concerning the proficiency of miners at the time of exercise administration.

Jan 1, 2000

Improve the safety of mine workers by developing a means of forecasting impending roof falls in underground mines. Approach The Bureau of Mines, through in-house and contract research, has developed the Roof Fall Warning Device. This battery-operated, portable electronic system forecasts roof falls by detecting and interpreting high-frequency rock noise, The technology has shown potential for detecting stress-related failures in a variety of underground environments. How It Works All geologic materials produce high-frequency acoustic emissions when they encounter an increase in stress. These ultrasonic frequency range events ( >20kHz) are well above the audible range of human hearing, very small in amplitude and duration, and can only be detected with sophisticated electronic equipment.

Jan 1, 1990

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

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

Jan 1, 1985

Develop a safe, efficient filter for removing diesel particulate matter (soot) from the exhaust of underground mining machines equipped with water scrubbers. Approach The Bureau of Mines and the Donaldson Company, Inc., jointly developed a low-cost, disposable, pleated-media filter (PMF) system. The system is intended for use on Part 36 permissible equipment or other machines equipped with water scrubbers. The PMF is installed downstream of the water scrubber to take advantage of the cool exhaust produced by the water bath. This demonstration system was tested on three Jeffrey 4114 Ramcars and a Wagner LST-5 scoop at Utah Fuel Company's Skyline mine near Scofield, Utah. Figure 1 illustrates a clean filter element being inserted into the canister on the Ramcar. How It Works The PMF system consists of a water trap, an optional over-pressure relief valve, filter canister, and PMF Under normal operations exhaust from a vehicle equipped with a water scrubber is heavily laden with water, especially on immediate startup of the engine. The water trap is designed to remove most of the water droplets from the exhaust before they enter the PMF, thus improving PMF performance. The over-pressure valve is designed to limit the exhaust backpressure by venting off some exhaust gas before the: filter. It is attached to the water trap upstream of the PMF. Figure 2 illustrates and shows a break out sectional view of the location of the PMF on the Ramcar.

Jan 1, 1991

To recover metals as sulfide concentrates from contaminated waste streams using hydrogen sulfide (H2S) generated by the bacterial digestion of waste organic materials. Approach The goal of this research is to develop a treatment method for metal mine effluents that will rival the cost and convenience of conventional lime treatment, and that will provide better effluent water quality, result in less expensive sludge disposal, and allow for the selective recovery of metals.

Jan 1, 1993

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal workers’ pneumoconiosis is the leading cause of death due to occupational illness among U.S. coal miners. This disease is caused by miners’ exposure to excessive levels of respirable coal mine dust. A personal dust monitor (PDM) has recently been developed to provide near real-time feedback to miners regarding the level of respirable coal dust in the air they breathe. The main objective of this report is to document coal miners’ reactions to this device and how they make use of the information it provides. It summarizes a field study by the National Institute for Occupational Safety and Health that documented the opinions of 30 miners at 4 underground coal mines concerning the use of PDMs.

Jan 2, 2008

By Charles L. Kimbell

This study is intended to serve three roles. First, it is an extension of the previous works under the same title that have been the overview and summary chapter of the international volume of Minerals Yearbook since the inception of that volume. Following the traditional format of past chapters, the basic statistical presentations herein deal chiefly with 1989, and in some instances with 1988, the latter only because more recent, comprehensive global statistics for 1989 are simply not yet available owing to delayed 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 on the world's mineral industry that have occurred between the end of 1989 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, 1992

By Joseph A. DeCarlo

This information circular presents data for 1960 on individual coke plants in the United States. All oven-coke plants in existence, whether active or idle at the close of the year, are listed in this report. With two exceptions, only beehive plants on which reports were submitted to the Bureau of Mines are included. Although the Bureau was unable to obtain reports from these two active plants in 1960, the number of ovens and annual coke capacity are estimates, based on previous reports filed with the Bureau of Mines. Accordingly, there were 73 oven-coke plants in existence at the end of 1960 of which 70 were active. Reports were received on 44 beehive plants of which only 13 were in operation at year end. Oven-coke plants are listed alphabetically by States in table 1 which shows the name and address of the company, location of plant, classification or type of ownership, number and type of ovens, annual coke capacity, and coal-chemical materials produced. The terms "furnace" and "merchant" plants used in this and all other reports of the Bureau of Mines designate the type of ownership. Furnace plants are those owned by iron and steel companies whose main business is production of coke for use in their own blast furnaces. Merchant plants are those associated with chemical companies, gas utilities, as well as those that produce for sale on the open market metallurgical, industrial, and residential-heating grades of coke and coal-chemical materials. The annual coke capacity shown for each plant in this table is based on the minimum coking time necessary to produce coke with qualities suitable for its intended use. Therefore, the annual capacity of a plant may change from year to year, depending on age and condition of ovens, the character and quality of coal carbonized, the grade of coke required, and other factors. For example, annual coke capacity of a coke plant primarily making foundry coke with longer coking cycles would be lower than one making blast-furnace coke. Also some ovens must be operated at slightly lower than normal flue temperature because of the condition of the refractories and maximum capacity would be somewhat lower than designed capacity. For this reason, the capacity reported to the Bureau of Mines may differ from the designed or rated capacity estimated by the coke-oven builders at the time of construction. For example, if the generally accepted standard coking rate of one inch per hour were used on all ovens to calculate total annual capacity, it would have been 80.4 million tons or 2 percent higher than the capacity reported to the Bureau. Because of the factors mentioned above, the annual coke capacity shown in this table is believed to be a reliable measure of the practical operating capacity of the industry.

Jan 1, 1961

By R. Pakalnis, C. A. Dreesbach, L. A. Martin

Instrumented cable bolts developed at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health were used in conjunction with existing ground control systems to monitor rock mass loads at Tg Soda Ash’s trona mine, Granger, WY. Axial and shear loads were determined to levels of strain gauge accuracy of ±5 N or ±5 microstrain. These gauges were embedded in a remanufactured king wire that replaced the conventional king wire. Cable bolt performance, quality of grout, and installation techniques were also assessed. By using instrumented cables, a mine operator can determine axial load along the cable at predefined gauge locations. These data provide necessary input for an operator to design a safer working environment for miners.

Produce an annotated bibliography to serve as a comprehensive source of published information available on the use of soil amendments in coal mine reclamation and the characterization of coal mine soils. The Problem There is a substantial amount of information available tin coal mine reclamation and revegetation, particularly on the use of soil amendments to ameliorate site conditions and aid vegetation establishment, growth development, and productivity. Additionally, site characterizations based on chemical, physical, and mineralogical properties have been thoroughly researched. This information, however, is widely disseminated throughout various professional and scientific journals, State and Federal documents, proceedings of conferences, theses, and other technical writings. A critical need exists for a comprehensive and up-to-date summary of published information concerning the uses, methodologies, and types of soil amendments that arc necessary for reclamation success.

Jan 1, 1991

By Julie Mitchell, Robert King, Len Eros

The Bureau of Mines has studied the Deserado Mine computerized monitoring and control system, located in Rangely, Colorado, to acquire knowledge about the overall costs and benefits of mine monitoring systems. The Deserado system is a complex system monitoring environmental parameters, electrical power, and operation of all mine equipment, and controlling the entire conveyor haul age system. This paper discusses the evaluation of the Deserado monitoring system from initial design through system installation and operation. It also examines the costs, benefits, and performance of the monitoring system.

By J. W. Horne

The quantitative determination of salt in petroleum ins generally divided into two steps - (1) extraction of salt from the oil and (2) accurate measurement of the extracted salt. This paper presents a method used by the Bureau of Mines for quantitatively extracting the water-soluble chloride salts4/ from petroleum and discusses important details attendant on the success of the method. Among these details are homogeneity in the dispersion of salt crystals, emulsified brine and other impurities in the oil sample, complete solution of the salt, and total extraction and titration of all the aqueous phase. Recently, the chlorides of sodium, calcium, and. magnesium produced with and present in various oils have developed growing problems of salt deposition and corrosion in the petroleum industry. Therefore, a technical study of various emulsions and salts that accompany petroleum is being made by the Bureau of Mines in cooperation with the State of Oklahoma. One report (5)5 reviewing the literature pertinent to the study has been published.

Jan 1, 1940

By C. M. K. Boldt, R. L. Levens, A. D. Marcy

Researchers at the U. S. Bureau of Mines conducted investigations to evaluate the potential for ground water contamination by mine waste used as backfill. Samples of cemented waste backfill and water discharging from drillholes and seeps were collected to use in chemical analyses and laboratory tests to determine the physical and chemical factors that control release of heavy metals to ground water. Greater water retention by cemented backfill (as compared to uncemented sandfill) reduces the surface are aexposed to oxidation, which in turn reduces the amount of acid produced. The acid is neutralized by the cement and minerals contained in the backfill. The grain-size distribution of tailings used for backfill affects the structural integrity of cemented backfill under attack by acidic water; breakdown of the backfill structure releases neutralizing materials faster. Backfilled stopes in rock with low hydraulic conductivities will constitute preferential flow paths after mine flooding; however, the rate of flow through backfill will be much slower than when the stope is partially saturated during mine operation. Considering all factors, acid generation and release of metal ions from cemented backfill should be less than in uncemented sandfill.

Jan 1, 1995

By J. B. Janus

This Bureau of Mines publication updates a series of reports on the quality of coal purchased under specifications for Government use. Listed are analytical data on the composition and quality of tipple and delivered samples of coal collected during the period July 1975 through September 1976.

Jan 1, 1977

Reduce the airborne dust generated in a longwall coal face. Approach Reduce the rotational speed and increase the depth-of-cut of the longwall shearer. How It Works An Anderson-Mavor AM500 double-ended ranging drum shearer was fitted with drums specially designed to accept the large picks required for this testing program. Change gears In the shearer allowed rotational speeds of the drums to be set at 35, 45, 55, or 70 rpm. As deep cutting removes larger coal fragments, the specific energy requirements of the operation are reduced and less surface area results. Dust generation and shearer power consumption are also reduced. The lower rotational speed minimizes the fanning action of the cutterheads and thus reduces the amount of coal fines that become airborne.

Jan 1, 1981

To improve a miner's chance of survival during an emergency by providing immediately avail-able breathable air and protection from toxic gases until a longer-duration breathing apparatus, stored nearby, can be reached. Approach: A belt-carried apparatus which can provide a closed-circuit atmosphere for ten minutes breathing has been developed under a Bureau of Mines contract. How It Works: Water vapor and carbon dioxide in the user's exhaled breath are removed, and oxygen is supplied, by chemical reactions. When the user exhales into the mouthpiece, water vapor in his breath reacts with potassium superoxide (KO2) stored In the canister to produce oxygen. The other product of this reaction (KOH) reacts with carbon dioxide and removes it from the air. The oxygen-enriched air then flows from the canister into two breathing bags. When user inhales through the mouth, that air is drawn out of the bags, makes a second pass through the chemical-containing canister, and flows into the mouthpiece tube. A nose clip is worn to seal off the nasal passages.

Jan 1, 1975

By J. W. Horne

The quantitative determination of salt in petroleum ins generally divided into two steps - (1) extraction of salt from the oil and (2) accurate measurement of the extracted salt. This paper presents a method used by the Bureau of Mines for quantitatively extracting the water-soluble chloride salts4/ from petroleum and discusses important details attendant on the success of the method. Among these details are homogeneity in the dispersion of salt crystals, emulsified brine and other impurities in the oil sample, complete solution of the salt, and total extraction and titration of all the aqueous phase. Recently, the chlorides of sodium, calcium, and. magnesium produced with and present in various oils have developed growing problems of salt deposition and corrosion in the petroleum industry. Therefore, a technical study of various emulsions and salts that accompany petroleum is being made by the Bureau of Mines in cooperation with the State of Oklahoma. One report (5)5 reviewing the literature pertinent to the study has been published.

Jan 1, 1940

Develop a down-hole replaceable diamond core bit that will reduce overall drilling costs and increase total available drilling time per hole. Approach A one-piece diamond core drill bit of unique geometric shape has been designed, fabricated and field tested. The bit can be withdrawn (or replaced) from the bottom of the well-bore without removing the drill rods from the hole, saving a significant amount of non-productive drilling time. How It Works The replaceable bit system consists of two basic subsystems: the removable core bit, and the equipment necessary to replace the wornout bit without pulling the drill rods out of the hole. The geometric configuration of the bit is that of a one-piece diamond studded cutting element created by "slicing off" two parallel sides of a conventional diamond cone bit. This geometric configuration, along with some minor modifications to the outer core barrel, allows the bit to be rotated in two planes and, with the retraction-insertion tools, raised or lowered through the interior of the drill rods using a conventional wire-line system. For example, to retrieve the bit, a retraction tool is lowered through the drill rods using a conventional wire-line system and at the hole bottom, the tool automatically orients itself within the outer core barrel.

Jan 1, 1981