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By Gary L. Mowrey, William D. Monaghan, George F. Persetic, Gregory M. Molinda

Ground penetrating radar (GPR) has been investigated by the U.S. Bureau of Mines Pittsburgh Research Center for its potential to determine rod hazards in underground mines. GPR surveys were conducted at four field sites with accompanying ground truth to determine the value of GPR for roof hazard detection. The resolution of the current systems allows detection of gross roof fractures (>6A mm (>0.25 in) zone) or rider beds in coal measure roof. Data quality is not yet sufficient to detect small bed separations or subtle lithologics changes in the roof. Differences in data quality are discussed, as well as suggestion for collecting improved data.

Jan 1, 1996

By James Rowland, Isaac Zlochower, Richard Mainiero, Michael Sapko

The National Institute for Occupational Safety and Health (NIOSH) carried out exploratory laboratoryscale studies to identify factors that may contribute to nitrogen oxides (NOx) production associated with non-ideal detonation of blasting agents. Explosive admixture with drill cuttings, loss of fuel oil in ammonium nitrate and fuel oil (ANFO) from wicking, ammonium nitrate dissolution with water, degree of explosive confinement, ANFO density, and critical diameter were identified as contributing factors to increased NOx production under the laboratory test conditions. Experiments were also conducted to examine the effectiveness of various additives in reducing the NOx production from ANFO, emulsion, and ANFO/emulsion blends. Aluminum powder, coal dust, urea, and excess fuel oil in ANFO formulations were tested and were found to reduce both the nitric oxide (NO) and nitrogen dioxide (NO2) production. Fumes measurements were obtained in the NIOSH underground closed chamber from the detonation of 4.5-kg (10 lbs) charges in schedule 80 seamless steel pipe and from detonations in light weight galvanized steel stove pipe. Some exploratory tests were also conducted with 0.8-kg (1.8 lbs) charges of pulverized ANFO initiated with 0.08-kg (0.18 lbs), 50/50 (Pentolite) boosters (in the NIOSH 12-ft (3.7-m) diameter steel sphere) to measure the degree of fumes production associated with post-detonation oxidation. Ammonium nitrate, emulsion and Pentolite boosters were also detonated in an oxygen-poor environment.

By Thomas O. Llewellyn

Laboratory semicontinuous and continuous heavy liquid cyclone separation pilot plant tests were made to determine the feasibility of producing a high-grade kyanite concentrate from a kyanite-quartz rock sample from Graves Mountain, Ga. Use of a three-stage heavy liquid cyclone circuit demonstrated that a 96.4-to 99.0-percent kyanite concentrate could be obtained with recoveries of 95.5 to 96.7 percent. The test work showed that by steam stripping with 6.9 tons of steam per ton of ore and two stages of detergent scrubbing the residual TBE content of kyanite cyclone products was 0.22 pound per ton of ore.

Jan 1, 1971

By D. A. Hill

Introduction The fields of an infinite line source in the presence of a conducting half-space have been examined by Wait and Spies (1971). In any real communication link using a current-carrying cable for the transmitting antenna, the cable is of finite length. Here we examine the fields of a finite length cable carrying a constant current in the presence of a homogeneous conducting half-space. The constant current assumption is valid at sufficiently low frequencies when an insulated cable is grounded at the end points (Wait, 1952; Sunde, 1968). Here we examine both surface and buried cables since both downlink and uplink communication links are of interest. Also, we examine both frequency and time solutions since either CW or pulsed communications may be used. Finally, it is necessary to include both magnetic and electric field solutions since reception could be with either loops or dipoles. Since the finite cable solution is more complicated than both the infinite line source and the short dipole solutions, we explore under what conditions a cable appears to be either infinitely long or very short. Some special cases, such as- the low frequency limit, permit analytical solutions which exhibit the dependence on various parameters, such as cable length, quite clearly. Frequency Domain Subsurface Fields The geometry of a line source of length 2[l] located on a conducting half-space with the observer in the half-space is shown in Figure 1. The fields

Jan 1, 1973

By Mark Larson, Doug Tesarik, Joe Shoemaker, Brad Seymour

In cooperation with Cyprus Twentymile Coal Co., researchers from the National Institute for Occupational Safety and Health (NIOSH), Spokane Research Laboratory, conducted a study at the Foidel Creek Mine, an underground coal mine near Oak Creek, CO, to evaluate the stability of underground working conditions as a longwall advanced through a series of backfilled cross-panel entries. Instruments installed in the cross-panel entry pillars, backfill, longwall panel, and adjacent headgate entry were continuously monitored by a computerized data acquisition system as the longwall approached and advanced through the backfilled section of the panel. Data collected from these instruments were analyzed to determine the magnitude and direction of the secondary principal stress changes ahead of the longwall face, deformation and closure of the headgate entry, and stability of the cross-panel entry pillars and backfill. A three-dimensional, boundary element model was calibrated to accurately predict mining-induced stress changes and the distance they occurred ahead of the longwall face. As the longwall advanced through the backfilled entries, most of the mining-induced load was supported by the cross-panel entry pillars. The backfill provided stability for the roof and floor of the in-panel entries and also confined the entry pillars significantly improving their load-carrying capacity. Comprehensive information derived from backfill material property tests, instrument data, underground observations, and numeric modeling results document the safety and stability of the 8-Right mine through and should provide beneficial case study information for other longwall backfilling applications in the future.

By G. R. Friggens

A nuclear method for continuously monitoring the coalbed and ash levels and void formation in commercial-scale, fixed-bed, pressurized gas producers is proposed. Measurement of gamma ray transmission through the coalbed is the basis of the method. The coalbed level is monitored by detecting the trans-mission of gamma rays from a 1 to 2 Ci Co-60 source positioned on the outside wall of the vessel. Coal bridging or, alternatively, ash level is monitored by a 10 Ci Co-60 source at the center of the coalbed. Source activities and geometries are calculated for a 12-foot-ID producer designed to operate at 350 psi. Source capsule and detector specifications and operational safety are also discussed.

Jan 1, 1973

Provide an instrument for continuous remote monitoring of carbon monoxide concentration in underground mines. Approach A carbon monoxide fixed? point continuous monitor consists of two modules. A line-powered control module is designed to power a remote transducer module; provide continuous readouts, visual and audible alarms, operational checks; and activate fans and equipment shutdown circuits if preset CO concentration levels are exceeded. How It Works The control module must be used in conjunction with a single transducer module. Developed under contract. the control module is a wall-mounted Instrument which contains a readout and alarm capability and power supply

Jan 1, 1981

By Donald R. Irving

THIS CHAPTER is new to the Minerals Yearbook and will appear regularly hereafter. Its purpose is to present statistics that reflect technologic trends in the minerals and metals industries (except fuels). Much useful information has been collected annually through the Bureau of Mines mineral commodity and employment and injuries canvasses. However, these data must be supplemented by further data to permit evaluation of the type, direction, and rate of technologic change, which are vitally important in long-term mineral planning. In addition to, and fully as important as, expanding the available data is the need to ascertain that the various items collected are obtained from identical reporting units, to enable direct comparisons to be made.

Jan 1, 1960

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 Doug Tesarik

The study of neutrinos?particles infinitesimally smaller than atoms?would be significantly advanced if a deep underground facility were available that would filter out unwanted cosmic radiation. Encouraging progress has been made in satisfying the criteria for such a facility with the selection of the Homestake Mine in Lead, SD, by the National Underground Laboratory Committee as the recommended site for a National Underground Science Laboratory (NUSL). The Homestake Mine is America?s oldest and deepest underground mine, and its well-maintained infrastructure to depths of 2438 m below the surface makes the mine an excellent site for such a laboratory. The investigation reported here is an initial study of the stability of the first of the proposed chambers. A cylindrical room with a dome-shaped roof and floor was analyzed in three dimensions using the finite-difference program FLAC3D. The results were compared to recommended support requirements based on Barton?s Tunneling Quality Index, Q. Based on model results and observations from previous mining studies, large rooms with 50-m roof spans can be constructed and will remain stable at 2141 m below the surface in the Poorman Formation when the rock is reinforced with cable bolts. Construction may be possible at lower levels in the Yates Formation if more extensive laboratory strength tests confirm initial results.

Jan 1, 2002

By J. P. Rider

Average production from longwall mining operations in the United States has risen from approximately 800 tons per shift in 1980 to over 4,600 metric tons per shift in 1999. Such a large increase in production has the potential to generate significantly more dust. Previous NIOSH research has shown that, on average, respirable dust levels generated by the shearer accounts for 50% of the airborne dust generated during longwall mining. Ventilating air and water are primary controls being used in an effort to reduce longwall dust levels. Longwall operators are applying more air and water than ever before and have expressed concern over reaching maximum practical limits for these controls. Full-scale laboratory tests are being conducted to evaluate the impact on shearer-generated dust levels for changes in face air velocity, water quantity at the shearer, water spray pressure, spray system design, mining height and cutting direction. Results of this research should identify the most appropriate control levels for various operating conditions. In addition, general recommended dust control practices for longwall mining will be discussed. KEYWORDS Longwall, coal dust

Apr 1, 1975

Provide a central source of subsidence reference in formation for industry, academia, and government agencies interested in improving subsidence prediction and analysis under U.S. mining conditions. Approach Develop a comprehensive bibliography about mining related surface subsidence and store this information in a computer file. Make specific references accessible through a key word retrieval program. Supplement these key word identifiers by entry of author's name, title of publication, subject of text, or sponsor of publication. How It Works Requests for subsidence in-formation are made by phone or mail to the Bureau of

Jan 1, 1982

By Robert W. Freedman

This report describes sampling and analytical procedures used for measurement of sulfates in diesel tailpipes and in the diluted exhaust within dilution tunnels. A variety of methods exist for sulfate analysis for such systems, including ion exchange. Two chemical methods used by the Bureau of Mines are described in detail. These are based upon spectrophotometric measurement of chloranilic acid using barium chloranilate. The procedures are rapid and relatively inexpensive. In general, ion exchange is preferred by many analysts for sulfate analysis. However, it is more complex and expensive than chloranilic acid procedures, which are adequate for exhaust analysis.

Jan 1, 1982

In the three years to June 2005, 959 injuries associated with continuous miners (CMs), shuttle cars (SCs), load-haul-dump and personnel transport (PT) were reported by NSW underground coal mines, comprising 23% of all injuries reported. The present paper reports an analysis of the narrative field accompanying these reports to determine opportunities for controlling injury risks. The most common combinations of activity and mechanism were: strain while handling CM cable (96 injuries); caught between or struck by moving parts while bolting on a CM (86 injuries); strains while bolting on CM (54 injuries); and slipping off a CM during access, egress or other activity (60 injuries). For the other equipment considered, the common injury mechanism was the vehicle running over a pothole or other roadway abnormality causing the driver or passengers to be injured (169 injuries). Potential control measures include: monorails for CM services; hydraulic cable reefers; handrails on CM platforms; redesign of CM platforms and bolting rigs to reduce reach distances during drilling and bolting; improvements to guarding of bolting controls; standardisation and shape coding of bolting controls; two handed fast feed; improvements in underground roadway maintenance, vehicle suspension, visibility and seating; and pedestrian proximity warning devices.

By C. B. Manula, R. L. Sanford, R. A. Rivell

A generalized flow diagram is presented in Figure 1, which shows the relationship of major model functions. This chart does not necessarily represent the anatomy of the computer program, but is designed to illustrate the informational interchange between major model functions. The related flow-charts-and computer program are listed in Parts I and II, Appendix A, respectively. Mine Car Stations The mine car stations are the activity centers for the model. The locomotive logic structure is designed to provide these stations with adequate cars and to clear them of car buildup. The model is designed to simulate a three stage haulage situation which suggests the need to differentiate station levels by type numbers. These are: a) TYPE 1 stations - mine cars are loaded here; b) TYPE 2 stations - intermediate stop and storage for mine cars; c) TYPE 3 stations - all mine cars that are stored here leave mine; and d) TYPE 4 stations - mine portal. TYPES 1, 2, and 3 have all loaded cars assigned to an ascending TYPE as their next destination. In input, if single stage haulage is designated, TYPES 1 and 3 do not exist, and if two stage haulage is called for, TYPES 2 and 3 are absent. A motor is not permitted to exchange cars between stations of the same type. Station Status Update. One major model function is to continuously evaluate the status of each mine car station. The major evaluations

Jan 1, 1974

By Alan H. Goode

The advancement of high-temperature drilling fluid technology for application in geothermal environments is part of the Bureau of Mines program for more efficient development of our Nation's energy resources. The bentonite constituent of water-base drilling fluids is sensitive to destabilization by high-temperature and salinity. A substitute material for bentonite, phosphate slime, which is reported to be saline resistant, was considered. These studies show that spray-dried slime suspensions have more favorable rheological behavior, but poorer filtration properties, as compared with bentonite suspensions.

Jan 1, 1975

By Uwe Kaulbars

Vibration measurements at the workplace are often complicated and expensive. The assessment of the risk in conformity with EC Directive 2002/44/EC “Vibration” (which lays down the minimum requirements of laws in Europe for occupational safety and health) can therefore be carried out on the basis of an estimate based on information from manufacturers as well as by measurement conforming to ISO 5349. The characteristic values (emission values) determined by manufacturers in laboratory conditions may deviate from the exposure values measured at source at the workplace. Equally, deviations may arise as a result of the delay in the changeover of test methods from the single axis of measurement to the total vibration value for the three axes of measurement conforming to ISO 20643. To prevent faulty estimates, the manufacturer’s information has to be corrected by a tool-related factor in accordance with CEN/TR 15350. By taking the example of masonry and stone working machines, the empirically determined tool-related correction factor is checked and confirmed. Methods Vibration measurements were carried out in accordance with ISO 5349 in practical application conditions on 10 selected typical eccentric and orbital sanders, concrete and disc grinders as well as on wall chasers and stone saws. Results The total vibration value obtained for the investigated tools rangedfrom ahv = 3.6 m/s² to ahv = 11.6 m/s². When the values from the practical measurements are compared with the manufacturer’s vibration values, the underestimation of the risk occurring in some cases can be largely compensated for by the tool-related factors conforming to CEN/TR 15350 (see Figure 1).

Jan 6, 2006

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 David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

7. Hoisting Systems Hoists used solely for emergency escape use should above all, be simple and dependable. The hoist systems' motive power should be independent of all other mine equipment so that only an emergency in the immediate vicinity of the hoist will render it inoperative. The hoist should receive the same high level of inspection as is normal with any other man hoisting system. It should be operated at regular intervals, and must include sufficient safety devices to ensure safe operation when hoisting men. Of equal importance, however, safety devices must be included to safeguard the hoist system from in¬advertant damage due to inspection, maintenance or operator error In an emergency situation the hoist operator will be under considerable stress and the system must be simple and foolproof to operate. Under normal circumstances the hoist will only be operated during the regular inspection cycle. Because of this very low operational use rate, certain requirements, normally associated with man hoisting, can be relaxed. In particular the wire rope installation requirements, in terms of drum and sheave diameter and fleet angles, can be reduced provided that rope inspection during the system life is maintained at a high level. The following section includes recommended guidelines for emergency hoist system design, installation, operation, maintenance and inspection A summary of available hoisting equipment and components is included in Appendix C. Emergency Hoist Guidelines All hoists designated as part of a mine emergency escape system shall meet the requirements of the Emergency Hoist Guidelines. Where these hoists are also utilized for hoisting other than emergency hoisting, the requirements of Title 30, Code of

Jan 1, 1976

By Dave P. Cooper, Tim D. Burgess, Dean H. Ambrose

This paper discusses the application of digital human models (DHM) to examine computer generated forces necessary to move specific joysticks by using roof bolter virtual operators to predict the forces experienced on the operator’s upper extremities. Using DHM and simulations of static movements, investigators analyzed predictions of joint moment and joint force effects on virtual operator’s right wrist, elbow and shoulder and compared them to different body dimensions and work postures. This study exemplifies the ease of estimating upper extremity loads on equipment operators using virtual operators and computer models of equipment and work environment. As expected, comparing results of percentage of joint force and moment reduction using the electronic control and of the mechanical control showed that the electronic control had lower joint forces and joint moments over the mechanical control. The average predicted value of the joint moment on the wrist was 1.84 Nm, elbow 7.85 Nm and shoulder 14.55 Nm and of the joint force on the wrist was 5.06 N, elbow 4.56 N, and shoulder 3.67 N. Because the data illustrates low-level forces to move a joystick, inadvertent actuation of the control is addressed. Regardless of the findings, research is still needed on joysticks in real world situations such as an epidemiological assessment of equipment operators in the field before final recommendations and conclusions can be drawn.

Jan 1, 2007