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Continuously monitor air-borne radon daughters that are a hazard to underground miners. Approach A beta detector continuously counts beta activity collected on a filter paper to allow calculation of exposure in working level units. How It Works At each Site a constant flow pump draws mine air through a fiberglass filter located in front of a beta detector (pancake type Geiger Mueller tube), Radioactive particles (products of the radon 222 gas emanating from the mine walls) collect on the filter and decay, releasing alpha and beta particles as well as gamma rays. A portion of the beta particles penetrate the Geiger tube window and create electrical pulses in the tube. These pulses are then amplified and sent by a coaxial type or shielded electrical cable to a central monitor located some distance from a working level detector. At the central monitor incoming Signals are amplified and fed into two channels, (See the block

Jan 1, 1979

By J. D. Sargent

Selenium might be described as a paradoxical element, being a metal or a nonmetal, a conductor or nonconductor, amorphous or crystalline, colorant or decolorant, and a hydrogenator or dehydrogenator. Selenium was discovered in 1817 by the Swedish chemist, Berzelius, while studying flue dust from the lead chambers of the sulfuric acid works at Gripsholm, Sweden.

Jan 1, 1954

By Arthur E. Goddard

Radio propagation measurements were conducted in a coal mine at UHF (200 to 1000 MHz) and VLF (1 to 50 kHz) to characterize the transmission loss of intra-mine paths. The basic experimental parameters included frequency, polarization, path orientation and distance. Further tests evaluated the performance of roof-bolt vs. loop antennas at VLF and parasitic reflectors at UHF. Measurement results are summarized in a series of transmission loss curves. Examples are presented to show the use of these curves in predicting the performance of radio communication systems in mines.

Jan 1, 1973

By Philip C. Tully

The Bureau of Mines, in a continuing effort to improve processes and methods of helium purification, has developed a differential distillation method for removing helium-3 from helium-4. Differential distillation at 4.2 to 1.6 K was used to reduce the helium-3 in helium-4 from about 200 to less than 1 part per billion. The results from four stills ranging in size from 1 to 25 liters are reported. The method has the potential to be adapted to commercial-scale separations.

Jan 1, 1975

Information Circular (IC) 9453 Roof falls continue to be the greatest single safety hazard faced by underground coal miners. During1996-99, 44 coal miners lost their lives in rock falls and nearly 2,400 were injured. In addition, nearly 6,000 non injury roof collapses were reported. Roof supports are installed to protect the miners, but support system failures contributed to most of these incidents. Reducing the terrible toll taken by ground falls continues to be a major goal of research by the National Institute for Occupational Safety and Health (NIOSH).During 2000-01, NIOSH conducted a series of open industry briefings on New Technology for Coal Mine Roof Support in Norton, VA, Charleston, WV, Evansville, IN, Tuscaloosa, AL, Price, UT, Glenwood Springs, CO, and Washington, PA. Drawing on many years of research undertaken by the NIOSH Pittsburgh and Spokane Research Laboratories, the proceedings describe what types of coal mine roof support are available, how they work, and when they should be used. The major subjects covered include roof bolts, standing roof supports, cable supports, and longwall shields. Some special topics are also addressed, including an analysis of roof fall accident statistics, techniques for better skin control, and material handling considerations. The proceedings volume also contains information on several important new technologies, which are described for the first time, e.g., guidelines for selecting roof bolt

Aug 1, 2001

By L. C. IlsLey

A specially recommended cable is a rubber-sheathed cable that has met the minimum performance requirements for cables as set forth in Schedule 20. The first in the series of recommended cables was listed September, 1930, by an ad- vance notice published as Information Circular 6375 which described the conditions under which the cable tests were made. Since that time six additional cables have met the test re- quirements and have been specially recommended. The complete list of specially recommended. cables is as follows: Specially recommended-cables Cable Symbol No. Hazacord No. 2 BM1 Stranding 19 x 7 Hazacord No. 3 BM2 do. Hazacord No. 4 BM3 do. Super-service No. 3 BM4 7 x 19 Super-service No. 2 Super-service No.. 4 BM5 do. BM6 do. Super-service No. 4 BM7 7x 7 Manufacturer Hazard Insulated Wire Works (division of the Okonite Co.) Do. Do. Rome Wire Company (division of the General Cable Corporation) Do. Do. Do. The cables listed were all twin (parallel duplex) cables having outer belts or cov- erings of approximately -inch high-grade rubber compound, and have the same general appear- ance and relative dimensions as the types of twin cables in general use. The cables were tested under conditions designed to show their approximate perform- ance under mine conditions. Only twin-type cables have met these test conditions. Although the recommended trailing cables are much better and safer for mine use than other cables and withstand being run over by a 7-ton car, they should not be considered as 100 per cent safe. The 7-ton car test represents the minimum limit requirement effective at present under Schedule 2-C, but the test car operates on a straight and level track, and thus does not represent the more severe conditions of mine use such as might result from uneven and curved tracks.

Mar 1, 1931

By Peter. PH. D. Cain

Smoky River Coal Ltd. mines low-volatile metallurgical coal by surface and underground methods in the foothills of the Rocky Mountains of Alberta, Canada. Current underground operations are confined to the 5B-4 Mine. Development of 5B-4 began in January 1998; production from depillaring sections commenced in July 1998. This paper describes the history of underground mining on the Smoky River property in terms of extraction methods and pillar design. The development of the present pillar design guidelines is discussed in this context. Recent work to prepare a number of case histories for back-analysis using the Analysis of Retreat Mining Pillar Stability (ARMPS) method is described, along with the modifications developed for calculating the ARMPS stability factor for retreat extraction of thick seams. The design criteria are described, as well as the geotechnical program implemented in order to verify its applicability.

Jan 5, 1999

By K. K. Kelley

"In an earlier consideration of the vapor pressure of iron 3/ it was found necessary to estimate the specific heat of gaseous iron to write satisfactory free-energy-of-vaporization equations for the several forms of iron. That the specific heat of gaseous iron will exceed greatly the classical value of Cp = 4.967 calories per gram-mole per degree is evident from even a cursory Lamination of its spectrum. The two lowest energy states are separated by only 416 cm-1, which is small enough so that the second state is effective, theoretically, at below room temperature. Such phenomena are by no means uncommon, but, while they have been recognized with substances that ordinarily are encountered as gases, classical gaseous specific--heat values still are used, often without question, for the vapors of metals and other elements that are solids under ordinary conditions. The following calculations for iron and copper gases are presented to illustrate the sort of deviations from classical values that are encountered with metal gases.The methods employed in calculating from spectroscopic data of thermodynamic quantities such as specific heat, entropy, and free energy have been described, in detail by Giauque 4/ and others. These will be briefly reviewed here. It is customary to separate the translational energy of a molecule from the rotational, vibrational, and electronic energies. In the case of monatomic gases, only translational and electronic Energies are involved. The classical expression for the specific heat of a mona¬tomic gas, Cp = 4.967, deals only with energy stored in the molecule as translational energy and consequently is valid only in temperature ranges in which no appreciable number of molecules undergoes a change in electronic state."

May 1, 1937

This chapter details the perspective from which collected data have been examined. The first part, intended primarily for lay readers, discusses several topics related to mining as an enterprise. Initially, the organizational functioning of atypical large mine will be described. It is the formal structure above a miner that decides the conditions of his or her work. A second point of concern is the technology itself An underground coal mine is a sociotechnical system, with workers and machines organized in particular ways during production. Third, general conditions and dangers underground will be described in detail. The physical environment of an operation is a powerful factor in the work life of miners. Fourth, a discussion of the process of formal training is given. During this training, a new worker is taught what the organization expects of him or her in the role of safe, productive, coal miner. Next, there are outside organizations that act as significant forces in the workplace. Examples include the Mine Safety and Health Administration (MSHA), State agencies, and the United Mine Workers of America (UMWA). The roles of these entities will also be examined. The second part of this chapter will depict each study site as a concrete setting, so that findings can be interpreted in their proper context. The Organizational and Technical Nature of Mining A coal mine is a complex system. It is defined as all parts of a mining plant's property (both underground and surface) that contribute, under one management, to the extraction or handling of coal [American Geological Institute 1997]. As suggested, many functions that must be carried out at an operation are only indirectly related to coal mining and processing. Even the jobs that are di¬rectly related tend to be numerous and varied [Wallwork 1981]. According to Palowitch [1982], the chief reason for this sophistication is that "after more than two centuries of exploiting our coal resources, today's coal industry finds itself saddled with a horrendous legacy of human impairments and environmental damages which society demands be corrected." Now, the effects of government regulation are evident in every aspect of the mining industry. Any operation, if it is to survive, must be administered with an eye for social efficiency and accountability. Long-range planning is needed to ensure that the mine produces coal in a cost-effective manner. One of the first things that must be considered is location and method of access. To extract coal from an underground mine, a coalbed (or "seam") must be reached from the surface. The term "portal" is generally given to any entrance that provides access to a coal mine. In hilly terrain, such as is found in Appalachia, the coal may "outcrop" on a hillside. This allows direct

Jan 1, 2000

By Fred N. Kissell

In This Chapter [Early indicators of a gas problem How the methane hazard is reduced Ventilation principles for gassy tunnels Monitoring for gas Eliminating ignition sources and The all-important human factors component] This chapter gives guidelines for preventing methane gas explosions during tunnel construction. Emphasis is placed on assessing the hazard potential, on ventilation principles, and on monitoring for gas. The chapter also emphasizes the importance of human factors in reducing explosion risk. Ensuring safe conditions is much more than just good engineering design. It also involves the every-day vigilance of those working underground. This does not imply that the engineering design can be ignored, only that the job of providing safe conditions has just begun with design. EARLY INDICATORS OF A GAS PROBLEM For the engineer planning a tunnel project, reliable early indicators of methane are scarce. How-ever, the local geology can often provide some information.2 Carbonaceous rocks and tar sands are a likely methane source. Gas is also a distinct possibility if it is known to be present else-where in the same sequence of geologic formations. Swampy areas, sewerage systems, and landfills are also candidates because the decomposition of organic materials produces methane. The gas in a tunnel can originate in the strata being excavated, or it can migrate a considerable distance from adjacent strata. Test borings at the project site can also serve as initial indicators of gas. Methane has no odor, but may be emitted along with gases that do. If gas is emitted from the borehole, a sample may be collected by inserting a tube into the hole as far as possible and pumping the gas out. The gas sample should be collected in a sampling bag or canister for later analysis by a chemical laboratory.3

Jan 6, 2006

By J. Wade Watkins

One potential peaceful application of nuclear explosives is stimulating the production of liquid or gaseous hydrocarbons from essentially nonproductive deposits of petroleum, natural gas, oil shale, and tar sands. Within the United States the appreciable difference between producible proved reserves and ultimate reserves and resources of hydrocarbon deposits is of such magnitude that much petroleum, natural gas, shale oil, and bitumen will not be produced unless significant technological progress is made in production techniques. The shattering effect of contained nuclear explosives and, to a lesser extent, the heat produced, have been considered as stimulative forces when the thickness, depth, and nature of such deposits permit considering the use of nuclear devices. Mechanical production problems would be less in an oil or gas reservoir than in an oil-shale or tar-sands deposit. Also, tar-sands resources in the United States may not be adequate to warrant serious consideration of applying nuclear-explosives stimulation. Gas reservoirs should present the least-radioactive-contamination problem. The technical feasibility of using nuclear explosives cannot be evaluated fully at present. Additional information is needed on the effects of pressure, heat, and radioactivity on the solids and fluids of hydrocarbon deposits, the nature and extent of induced fractures in different rock media, and the possibility of isolating and confining or removing radioactive contaminants. Final technical feasibility can only be determined by a field test. If technical feasibility is established, economic feasibility will depend upon the comparative cost of producing hydrocarbons by nuclear explosives and by conventional means. It is probable that an economic comparison would favor nuclear stimulation only where devices of relatively high yield could be used practicably and safely.

Jan 1, 1964

By H. V. Makar

An aluminizing dross which is accumulating as a waste material in substantial quantities was tested for possible use as a steel deoxidizer. This material, consisting mainly of aluminum, silicon, and iron, was used to deoxidize laboratory-scale melts ranging from 7 to 100 pounds. Oxygen analysis showed that the aluminizing dross was effective in reducing oxygen levels in steel. A direct comparison with aluminum wire showed the dross material to be at least as effective. Under similar test conditions with 7-pound melts, 3 grams of aluminum reduced the oxygen concentration from 210 to 175 ppm, while 4 grams of aluminizing dross (equivalent to approximately 2 grams aluminum) reduced the oxygen concentration from 250 to 170 ppm. An additional 4 grams of aluminizing dross produced a final oxygen concentration of 140 ppm.

Jan 1, 1972

By Dean H. Ambrose

This paper presents an approach for representing and analyzing random motions and hazardous events in a simulated three-dimensional workplace, providing designers and analysts with a new technique for evaluating operator-machine interaction hazards in virtual environments. Technical data in this paper is based upon a project striving to reduce workers' risks from being hit by underground mining machinery in a confined space. The project's methodology includes human factors design considerations, ergonomic modeling and simulation tools, laboratory validation, and collaboration with a mining equipment manufacturer. Hazardous conditions can be analyzed in virtual environments using collision detection. By simulating an operator's random behavior and machine's appendage velocity, researchers can accurately identify hazards, and use that information to form safe design parameters for mining equipment. Analysts must be discerning with the model and not read more from the databases than what the simulation model was designed to deliver. Simulations provided an interesting approach to data gathering in that there was no need for live subjects and logistics - test sites and costs associated with experiments-became insignificant. Collisions versus speed, operators' size, and risk behaviors proved the versatility found in the data obtained from the model. Preliminary results show that response time significantly affects the number of collisions experienced by the virtual subject. Also simulation data suggests that more mishaps occur with hand-on-boom-arm risk behavior.

By J. Wade Watkins

One potential peaceful application of nuclear explosives is stimulating the production of liquid or gaseous hydrocarbons from essentially nonproductive deposits of petroleum, natural gas, oil shale, and tar sands. Within the United States the appreciable difference between producible proved reserves and ultimate reserves and resources of hydrocarbon deposits is of such magnitude that much petroleum, natural gas, shale oil, and bitumen will not be produced unless significant technological progress is made in production techniques. The shattering effect of contained nuclear explosives and, to a lesser extent, the heat produced, have been considered as stimulative forces when the thickness, depth, and nature of such deposits permit considering the use of nuclear devices. Mechanical production problems would be less in an oil or gas reservoir than in an oil-shale or tar-sands deposit. Also, tar-sands resources in the United States may not be adequate to warrant serious consideration of applying nuclear-explosives stimulation. Gas reservoirs should present the least- radioactive-contamination problem. The technical feasibility of using nuclear explosives cannot be evaluated fully at present. Additional information is needed on the effects of pressure, heat, and radioactivity on the solids and fluids of hydrocarbon deposits, the nature and extent of induced fractures in different rock media, and the possibility of isolating and confining or removing radioactive contaminants. Final technical feasibility can only be determined by a field test. If technical feasibility is established, economic feasibility will depend upon the comparative cost of producing hydrocarbons by nuclear explosives and by conventional means. It is probable that an economic comparison would favor nuclear stimulation only where devices of relatively high yield could be used practicably and safely.

Jan 1, 1964

By John J. Henn

An evaluation is presented for an ammonium sulfate leaching process designed to extract manganese from Cuyuna, Minn., and Aroostook, Maine, deposits. In this process the manganese and iron in the ore are reduced to MnO and Fe 3 0 4 in a shaft furnace; the reduced ore is then leached with ammonium sulfate solution forming soluble manganous sulfate while leaving most of the iron undissolved. After filtration, the manganese and some impurities are precipitated from solution as carbonates which are then pelletized and calcined to form a product composed mainly of Mn3O4. The plants are designed to produce 100 tons per day of manganese contained in a product that is suitable for the production of ferromanganese. A byproduct credit, together with the extra processing cost, is included for the Cuyuna ore processing plants because Fe2O3 may be recovered for use in blast furnaces. The estimated operating costs per ton of manganese, excluding income taxes and return on investment, are: [ ] The process with or without byproduct recovery, when treating Cuyuna or Aroostook ores, is not economically competitive with ores available at $71.43 per ton of contained manganese.

Jan 1, 1968

To develop a business case that promotes adoption of noise controls by reducing barriers to industry acceptance and enhancing drivers that foster their implementation. Background Over 75% of the U.S. mining workforce is exposed to hazardous noise, putting them at risk of noise-induced hearing loss (NIHL). Consequently, coal miners suffer high rates of hearing impairment that increase to 70%-90% by retirement age. To address the noise problem for coal miners, researchers from the National Institute for Occupational Safety and Health (NIOSH) first determined that the continuous mining machine (CMM) ranked first among machines associated with reported coal noise overexposures. Further studies found that most CMM noise is generated by three component systems on the machine: dust collection, cutting, and conveying. Of these systems, the on-board chain conveyor was found to be a dominant noise source. Noise generated by the conveying system was addressed through the development of a urethane-coated flight bar chain. The coated chain, shown in Figure 1, has demonstrated an 8-hour time-weighted average (TWA) reduction of operator exposure by 3 dB(A). It has since been accepted by the Mine Safety and Health Administration (MSHA) as a "technologically achievable" noise control for CMM operators who are exposed to noise that exceeds the MSHA permissible exposure level. Having demonstrated the noise reduction performance of the coated chain, NIOSH has assembled information into a business case that can be used by operations considering adopting the chain at their worksite.

Dec 1, 2009

Determine the extent to which remote-sensing techniques, primarily lineament analysis, can be used to identify geologic structures that may affect the location and migration of subsidence over abandoned underground coal mines in the Colorado Springs, CO, area. Compile data using a geographic information system (GIS) to allow efficient and reproducible comparisons and analyses. Background The basis for evaluating abandoned mine land (AML) sites with remote-sensing techniques comes from past and ongoing Bureau ground control research using remote-sensing data to identify potential hazards caused by geologic structures (faults, joints, etc.) above active underground coal mines. Research showed that lineament (linear feature) analysis of Landsat Multispectral Scanner (MSS) images could indicate locations of fractures and fracture trends that had varying, but significant, impacts on the stability of mine openings. Such geologic structures should be identifiable over abandoned mines as well. If fractures are present, even if they arc not faults, they should represent areas of potential instability over these mines and, therefore, should tend to localize subsidence when it occurs, particularly for deep and moderately deep portions of mines.

Jan 1, 1992

By Dean H. Ambrose

This paper presents a technique for representing and analyzing random motions and hazardous events in a computer simulated three-dimensional workplace, providing machine designers and safety analysts with a new technique to evaluate ways to reduce operator-machine interaction hazards. Technical data in this paper is based upon a project striving to reduce workers' risks from being hit by underground mining machinery in a confined space. By simulating motions of an operator's random behavior and a machine's appendage, researchers can accurately identify hazards, and use that information to form safe designs for mining equipment appendage velocity. Validating the model provided improvements in the operator's optimal viewing area, work task- starting positions, and operator's motions for a more accurate random behavior. Preliminary simulation results provided (1) an interesting approach to research data gathering in that there was no need for live subjects and test sites and costs associated with experiments become insignificant and (2) that the model was versatile by showing it was capable of accurately mimicking the range collision forces versus speed, operators' size, and risk behaviors found in actual industrial situations and showed (I) that response time significantly affects the number of collisions experienced by the virtual subject and (2) that analysts must be discerning with the model and not read more From the databases than what the simulation model was designed to deliver. Keywords: random human-motion, anthropomebics model, machine-operator hazards, mine safety

By Isaac A. Zlochower

This paper presents data on the limiting (minimum) oxygen concentration (LOC), in the presence of added N2, of methane (CH4), propane (C3H8), ethylene (C2H4), carbon monoxide (CO), and hydrogen (H2), and some of their binary mixtures. It also addresses the issue of the flammable concentration (flammability) limits of these pure gases in air. The study is based on spark ignited explosions in large, spherical laboratory vessels (120-L and 20-L) using a 7% pressure-rise criterion for explosion propagation. The results of the study are compared with the older values which used long flammability tubes with a diameter >5 cm together with visual evidence of substantial upward propagation. They are also compared to results reported recently using a 12-L spherical flask with a visual flame propagation criterion. Finally, they are compared to results reported in Europe using more modest flammability criteria and smaller chambers. The findings reported here show excellent agreement between the 120-L and 12-L results, good agreement with the 20-L results, and reasonable agreement with the earlier flammability tube values for the lower flammability limits. They disagree, however, with the more conservative European values. These results and those from the 12-L experiments also feature lower LOCs than are given by traditional flammability tubes. A model for the LOCs of such fuel mixtures based on the Le Chatelier mixture rule for lower flammable limits is seen to reasonably fit the observed results on binary mixtures and can accommodate more complex mixtures as well. One such set of ternary mixtures containing CH4 and 1:1 CO:H2 is well fitted by the model.

Jan 1, 2009

By Lon Santis, Scott Deitchman, John A. Decker

This report describes three cases of carbon monoxide (CO) poisoning in a manhole, including one fatality, from CO migrating through soil after nearby use of explosives. A municipal sewer project involved installation of new pipes and manholes. Work of the general construction contractor was interrupted when a subcontractor detonated 265 pounds of nitroglycerin-based explosive 40-60 feet south of the manhole to break up underlying rock. A construction worker who descended into the manhole 45 minutes after the explosion collapsed within minutes, and two co-workers descended into the manhole to rescue him. One rescuer retrieved the unconscious worker, and the other rescuer died in the manhole. All workers had elevated carboxyhemoglobin levels. In the subsequent NIOSH investigation, air monitoring was conducted with real-time instruments, and air samples were collected in Tedlar bags. Laboratory analyses of the bag samples collected near the bottom showed 1905 parts per million (ppm) CO, 19.5% oxygen, and 3% carbon dioxide. Direct reading instruments showed progressively higher concentrations as the sensor was lowered into the manhole. Subsequent chamber tests on sample explosive yielded 27 liters CO per kilogram detonated. Based on this value, the surface blast at the construction site may have produced about 3,250 liters (114.8 cubic feet) CO. The CO in this incident most likely was released from the nearby explosion and migrated through soil and fractured rock into the manhole. The blasting and construction industries should be made aware of this previously unrecognized CO exposure hazard associated with surface blasting. The extent of CO exposure from explosives used in construction is not known, and additional information on the extent of CO exposure must be collected. In addition, confined space entry procedures (including monitoring confined space atmospheres before entry) should be observed; CO monitoring of confined spaces in the presence of blasting can prevent future incidents such as this one.

Oct 30, 1997