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By Janet Torma-Krajewski, Pauline Lewis, Paul Gust, Lisa Steiner, Kean Johnson

Since 1990 and the publication of the Ergonomics Program Management Guidelines for Meatpacking Plants by the US Occupational Safety and Health Administration, numerous reports of companies implementing ergonomics program have been published. However, despite these numerous reports, no examples of implementing an ergonomics program in the mining industry have been reported. In 2000, NIOSH initiated a long-term project to demonstrate the implementation of an ergonomics process designed to identify and reduce exposures to ergonomic risk factors found in mining. The mine selected for this project was the Jim Bridger Mine, a surface coal mine located 35 miles northeast of Rock Springs, Sweetwater County, WY. This paper discusses how a large, surface coal mine implemented an ergonomics program and the lessons learned while doing so.

By John J. Sammarco

As part of a project to automate coal extraction, computer control of a continuous mining machine test bed has been developed and tested by the Bureau of Mines. A computer system and control software were developed for accurate positioning of the conveyor elevation and swing, stabilizer jack, gathering head, and shear elevation. Tramming actions are also controlled by the computer. The computer system was designed to access data from sensors installed on a continuous miner and to interface with the existing control circuits of the miner. Testing in free space was used to characterize the operation of the machine. From this information, control algorithms were written and stored in the computer. The ability to control each function of the continuous miner with a high degree of accuracy and stability was successfully demonstrated in a series of tests in free space and in mining a block of simulated coal. In the mining of simulated coal, the cutting drum was instructed to position the shearer at the top of the block and shear down to the bottom under closed loop control. The cutting drum came within 0.27 in of the top and within 0.49 in of the bottom of the block for this shearing test.

Jan 1, 1988

To perform comprehensive economic evaluations on both existing and proposed mineral operations. Approach A comprehensive computer model was developed which is capable of evaluating the economics of an entire mineral recovery operation, including exploration, acquisition, infrastructure, mining, milling, smelting, refining, transportation, taxation, and return of and on capital. How it Works The MINSIM (MINe SIMulator) economic evaluation concept was developed by the Bureau of Mines in 1967. The initial versions used a continuous discounted cash flow rate-of-return (DCFROR) to measure the effect of changes in expected revenues and costs. Subsequent enhancements to the program have expanded and strengthened MINSIM, especially the addition of an option which determines total production cost (i.e., the commodity selling price that a mineral recovery operation would require in order to obtain a target rate of return), an expanded capacity for evaluating by-products from a mineral property, and significantly broadened taxation determining capabilities. The MINSIM computer program uses essentially the same procedures and calculations that are performed in a manual economic evaluation, although the program accomplishes its tasks much more rapidly and accurately, An experienced mineral economist may require a week to evaluate a single mining operation with the same detail and consistency provided by MINSIM in a matter of seconds of computer time.

Jan 1, 1983

Roof falls continue to be the greatest single safety hazard faced by underground coal miners. During 1996-99, 44 coal miners lost their lives in rock falls, and nearly 2,400 were injured. In addition, nearly 6,000 noninjury 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). The purpose of these proceedings is to provide the mining community with a comprehensive survey of coal mine roof supports. Drawing on many years of research undertaken by the NIOSH Pittsburgh and Spokane Research Laboratories, this volume describes what types of 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, material handling considerations, and longwall mining through recovery rooms. This proceedings volume also contains information on several important new technologies, which are described here for the first time: •Guidelines for selecting roof bolt length, pattern, and capacity that were derived from statistical analysis of the roof fall experience at 37 underground mines; •A new design method for longwall tailgate supports; and •A technique for measuring loads developed within cable bolts. The papers in these proceedings were presented at open industry briefings conducted by NIOSH on New Technology for Coal Mine Roof Support. The briefings were held in Norton, VA, Charleston, WV, Evansville, IN, Tuscaloosa, AL, Price, UT, Glenwood Springs, CO, and Washington, PA. The papers were also presented at the Mine Safety and Health Administration (MSHA) Preventative Roof-Rib Outreach Program (PROP) Seminar, which was held at the National Mine Health and Safety Academy near Beckley, WV.

Jan 10, 2000

By K. O. Bennington

The thermodynamic properties of pollucite [(Cs0.650Na0.185Rb0.028)(AlSi2) (05.8630H0.137)?0.19H201 were determined by the Bureau of Mines in collaboration with the Argonne National Laboratory. The standard enthalpy of formation determined by hydrofluoric acid calorimetry is ?Hf°298 = -3,098.52 ±3.63 kJ mol-1. The standard enthalpy of formation from the oxides is ?H298 (from oxides) = -209.50 ±2.38 kJ mol-1. Low-temperature heat capacities were determined by adiabatic calorimetry from 5.0 to 306.1 K. The derived standard entropy is S°298 = 207.24 ±0.43 J mol-1k-1. Enthalpy increments above 300 K were measured by copper-block drop calorimetry from 349 to 674 K. Various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of measurements. Standard enthalpies of formation and Gibbs energies of formation are given as functions of temperature. The Gibbs energy of formation is ?Gf°298 = -2,919.9 W mol-1

Jan 1, 1983

By Basil Dimitriades

Five recently developed methods for determining nitrogen oxides in automotive exhausts have been evaluated from the standpoint of accuracy and applicability in current exhaust studies. Results showed that methods requiring conversion of nitric oxide to nitrogen dioxide as a part of the analytical procedure are subject to errors introduced by the instability of NO2. The extent of some of these errors has been determined and procedures have been developed to minimize undesirable influences. On the basis of the results obtained from this study, recommendations are made regarding procedures for batch type or continuous measurement of nitrogen oxides in exhaust streams.

Jan 1, 1968

By Robert C. Gabler

The extraction of metals from coal ash was investigated by the Bureau of Mines in an effort to produce a more environmentally acceptable waste and offset waste disposal costs with recovered metal values. The research was conducted in two steps: determination of the parameters that affect extraction of metals from coal ash and development of extraction-recovery procedures. Data obtained indicate that the major parameter affecting the extraction of metals from coal ash is the calcium content of the ash. Other parameters such as furnace type and operating temperature had much smaller effects on metal extraction. Two procedures were studied for metal extraction: an acid leach procedure for high-calcium ashes and a lime sinter-acid leach procedure for low-calcium ashes. An alumina product was recovered that, with sufficient washing, meets Hall cell specifications. The leach residues pass the EPA EP Toxicity Test and are thus nonhazardous wastes available for a variety of uses.

Jan 1, 1983

By M. J. Kovalik

Illinois No.6, a high-volatile B coal of low fluidity, was blended with fluidized-bed char and coke breeze to improve the strength of the coke obtained from carbonizing this coal. Twenty-one tests, selected from those made in the small-scale Hanson carbonizer, were carbonized in the BM-AGA 13-inch-diameter, cylindrical retort, with a coal charge of about 90 pounds; the strength of the cokes was determined by the standard ASTM tumbler test. Using the same procedure, 10 tests were made with High Splint, a high-volatile A coal from Harlan County, Ky. Carbonization of the blends produced larger and stronger cokes than did the Illinois No.6 coal singly. The optimum blend contained 6 percent each of char and coke breeze. Further improvement in coke strength was realized by either preheating this blend prior to carbonization or by adding a small pro-portion of a premium blending coal. The former method could possibly eliminate the use of premium coking coals in blends with Illinois No. 6 coal to make an acceptable metallurgical coke. Except for no improvement in coke strength by preheating, results for High Splint coal showed behavior similar to that of the Illinois No.6 coal.

Jan 1, 1973

To develop a system which will effectively detect and extinguish fires in underground fueling areas while also providing a warning for nearby miners. Approach A system involving optical fire sensors. automatically-released dry chemical and aqueous film-forming fluid (AFFF) fire suppressants, and automatic alarms was designed from off-the-shelf, state-of-the-art components, and was in-mine tested at two mines in the two typical underground fueling area situations: fuel transfer areas and fuel storage areas. How It Works As mines become more mechanized, the number of fire hazards increases since fueling areas are more abundant. Fire hazards are especially serious in deep mines, since escape time is longer. To help solve this growing problem, the Bureau of Mines, in cooperation with the Mine Safety and Health Administration (MSHA) and the National Fire Protection Association (NFPA), has developed and in-mine tested a cost-effective fueling area fire protection system. The system was designed to be rugged enough for reliable, long-term use, yet to utilize state-of-the-art, off-the-shelf components to maintain cost-effectiveness. The system consists of cross-zoned, ultraviolet flame sensors used for quick response to fire, and a dual-agent fire suppression subsystem. A dry chemical is used for fast fire -knockdown," and AFFF (or "light water") is used for long-term, fire-securing capability. The basic components of the system are shown in the schematic illustration.

Jan 1, 1982

By Terry J. Close

The Gates of the Mountains Wilderness study area is underlain by intrusive and sedimentary rocks, mainly limestone. No limestone has been produced from the study area; suitable material is more readily available elsewhere. Small amounts of gold, sapphires, and corundum were produced from a placer deposit along the banks of the Missouri River. The remaining gravel contains low mineral values. Other alluvial deposits along the Missouri River and Beaver Creek contain no identified economic resources other than sand and gravel. Some deposits could provide suitable construction material for local use.

Jan 1, 1984

Reduce longwall shearer operators' dust exposures by more effectively suppressing the dust generated by the upwind cutting drum. Approach Direct more of the shearer water supply to the upwind drum, thus reducing the shearer operator's exposure to respirable dust while making more efficient use of water. How Proportioning Permits More Efficient Use of Water On most longwall mining operations, the cutting action of the shearer drums is the primary source of dust. Al-though the amount of dust generated is directly related to the amount of coal and rock cut by the drum, the exposure or the shearer operators to dust depends more on their work position relative to the upwind drum. When cutting with the airflow, the upwind drum, cutting bottom coal and floor rock, is the primary generator of dust reaching the operators. The lead drum is downwind of both shearer operators and is thus of less concern. (See diagram). When cutting against the airflow, the lead drum is upwind-taking a full cut, including roof rock-and both shearer operators may be exposed to very high levels of respirable dust. Currently, water sprays mounted on the cutting drum provide the most effective method of controlling dust from longwall shearer drums, and all longwall mining operations use some type of bit flushing or cavity filling water spray system on the cutting drums. Bureau surveys of longwall operations, conducted as part of its research program to reduce respirable dust, have indicated that six longwalls with better than average compliance records use higher than normal water flowrates to the cutting drums. The average water flow to the shearers at these six operations was approximately 60 gpm-about 50 percent more water than is normally supplied to double-drum longwall shearers.

Jan 1, 1982

By George H. Johnson

An evaluation of the diamond-bit-performance data accumulated from core-drilling cherty limestone and cherty dolomite reveals that the percentage of core recovered and the physical characteristics of the bits and diamonds used are economically significant. One of the established trends, of particular interest to those engaged in diamond drilling, is that bits set with small, low-quality, West African drill bort are the most economical. Detailed analysis of the factors that affect diamond-bit performances, such as diamond size and quality, bit size and type, percentage of core recovered, and the physical characteristics of the bit matrices are assessed in the tables, charts, and discussion.

Jan 1, 1958

By James H. Aase

Selected glacial lake clay deposits in Minnesota were sampled, tested, and evaluated to determine their suitability for use as a bonding agent in iron ore pellet manufacturing. Preliminary tests conducted on clay samples obtained from five ancient glacial lake basins identified the clays in the Lake Agassiz glacial lake basin near Cook, Minn., as having the greatest bonding potential. An auger drilling program was conducted to obtain substantial quantities of representative material for detailed testing. The drilling indicated the presence of large clay reserves in excess of 500 million tons within the 12-square-mile area investigated. Bench scale tests indicated that the bonding properties of Cook area clays, when activated with relatively small quantities of sodium carbonate monohydrate (Na2C03?H2O), imparted excellent strength characteristics to iron ore pellets. Larger scale continuous pelletizing tests were made to confirm the bench scale results. These tests indicated that use of 1 percent activated clay alone as binder gave the iron ore pellets an overall strength slightly lower than with 0.75 percent bentonite, considered the industry standard. Use of 0.5 percent activated clay plus 0.5 percent bentonite produced better pellet strength qualities than use of 0.75 percent bentonite alone, without increasing the silica plus alumina content. The data from both bench scale and larger scale continuous tests suggest that the Cook, Minn., clays can be utilized after activation either alone or in combination with bentonite at an economic advantage over present pelletizing practice with bentonite.

Jan 1, 1968

By S. C. Tadolini, T. M. Barczark

Mines in the western United States have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the earl v 1990s provided an effective alternative, (lilt/ it remains the dominant form of tail¬gate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled to¬gether; provides more capacity than (m equivalent sized Call support and improves transport efficiency. However the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but the \' have not been proven in high deformation en¬vironments. This paper compares the performance characteristics o f these various support systems.

By John C. Edwards

The Bureau of Mines has developed a time-dependent droplet vaporization model (in the absence of forced convection) that can be applied to the vaporization of liquid Halon 1301 droplets (vapor pressure at 300 K = 14 atm) sprayed from an extinguisher. It was found that rapid surface vaporization quickly lowers the droplets' surface temperature very near to the boiling temperature, and the vaporization becomes diffusion controlled. Although the lifetime of the droplet is proportional to the square of the initial radius of the droplet, the elapsed time prior to complete droplet vaporization is not proportional to the square of the droplet radius, as an equilibrium model would indicate.

Jan 1, 1982

By Larry G. Stolarczyk

1.0 FRAMEWORK FOR COMPARISON This document describes the decision factors that bear on the selection of the modulation process for the wireless underground medium frequency (MF) communication system. The selected modulation process must satisfy the Bureau of Mines stated objective of improving general communications within an underground mine. The improvement being sought includes the development of a wireless communication technology of measurable benefit to both mine safety and mine productivity. The improvement will allow wireless communications paths to exist between roving miners. The wireless communication paths will also be made compatible with the existing underground telephone system to extend paging and voice communication throughout the underground mine. The new wireless equipment will include man-pack, vehicular, repeater, and base station transceivers. Repeaters and base stations will feature coupling networks for interfacing with the existing telephone circuits. Frequency modulation (FM) and single sideband (SSB) modulation processes are analyzed in view of the special conditions associated with underground mining. Of primary importance is the tremendous electrical noise generated in an operating mine that could adversely affect communications quality. High noise coupled with high attenuation rate of near field signals forces the communication system to be inherently short range. Fortunately, near field signals can propagate over great distances on underground wires and cables. The framework for comparison is generated by presenting all factors that

Develop an environmentally feasible method of mining shallow oil sands without removing overburden. Approach Oil sands are extracted through a single borehole by cutting into the sands around the borehole with a high pressure water jet, and pumping the resulting slurry to the surface. Although oil can be extracted from shallow fields by open-pit mining methods, this type of mining may create significant environmental impacts, including; (1) disruption of the surface, (2) accumulation of waste rock piles, (3) accumulation of tailings, (4) damage to the ground water quality, and (5) surface water pollution. The borehole mining system developed and successfully field tested by the Bureau of Mines offers a method for extracting oil from oil sand with minimal disturbance to environmental quality. (For examples of other applications of borehole mining, see Technology News Nos. 95, 63 56, and 48.) How It Works Prior to the start of mining operations, baseline conditions for ground subsidence and ground water quality are established at the test site so that the degree of subsidence and changes in ground water quality can later be determined. Oil sands mining is conducted using the Bureau of Mines borehole mining system. The borehole mining tool consists of a 12-inch-diameter pipe string and accessories capped with a three passage swivel terminated with a mining section. The mining section has an auger at the bottom. Four slurry inlet holes and an eductor are located above the auger, and a single cutting nozzle is located near the top of the mining section. The tool generates a high velocity water jet that erodes and slurrifies ores. The slurry is drawn into the inlet of the eductor which lifts the slurry to the surface where it is deposited into a slurry discharge sump. To detect evidence of subsidence, surveys of the land surface are made at regular intervals during, and until 30 days after, the termination of the mining operations. Samples of ground water from the borehole and two adjacent monitor holes are taken on alternate days during the mining operations, and are later analyzed to determine if any ground water contamination has occurred.

Jan 1, 1981

Control respirable dust in underground coal mines through selection of optimum water spray pressures. Approach Through underground trials at longwall and continuous mining operations, the relationship between operating water spray pressure and respirable dust levels at the machine operator's location was determined. Defining the Application Water sprays are used for two significantly different control applications. On longwall mining machines, sprays are commonly installed both on the body of the machine and on the cutting drum. Sprays on the body of the machine are used to redirect dust which has already become airborne away from the machine operator. Each spray acts as a small fan, directing the primary airflow over and around the machine and towards the face, away from the operator. The energy of this system is directly related to the spray pressure. Higher pressures move more air, but care must be taken not to cause turbulence and boilout into the walkway. Sprays mounted on the drum are, effective at suppressing the respirable dust at the bit/coal interface and preventing it from becoming airborne. Again, these sprays must not impart excessive energy to the dust particles thus stirring up more dust than they suppress. While mounting sprays on the shearer drum is standard industry practice, there is no reliable technology available to successfully mount water sprays on the cutting drum of continuous miners. Instead, sprays are mounted on the machine body, close to the drum, and directed at the cutting head. This allows the water to reach the bit/coal interface and mix with the cut material. Here again, care must be exercised to prevent these sprays from imparting excessive energy to the dust particles and stirring up more dust than they suppress. These sprays can also cause dust "rollback" from the face, toward the operator, if operated at too high pressures.

Jan 1, 1986

By Ronald D. Hill, Elmore C. Grim

The cost of reclamation can vary widely, depending on the primary objectives of the restoration activities. statistics in this study originated from State files, publications, and personal communications relating to restoration and pollution control measures for previously mined lands (orphan lands) and active mines. Reclamation of orphan lands is generally considered a public burden and constitutes an economic problem. All work reported here was completed under government contract, by the lowest bidder, with money coming from State and/or Federal funds. Cost would have been substantially lower had the reclamation been concurrent with mining. Several persons connected with some of the projects have observed that costs could probably be reduced by at least one half, if the reclamation had been conducted along with the mining. The expense of clearing and grubbing of volunteer vegetation, disposal of buried trees and brush, loosing of compacted spoil, and re-establishing access to areas could be saved. In addition, a contracting firm doing the work for a government agency would have mobilization costs and receive a profit. Mining companies also are profit conscious and would consider these costs in anticipating their profits (e.g., overhead would be less if reclamation is integrated with mining). The data presented here should serve as a guide for estimating and determining cost ranges, however, it should be recognized that variations exist. Adjustments may be necessary from the standpoint of physical conditions, economic conditions, price changes, and more restrictive requirements of recent surface mining laws. Reclamation conditions, procedures and successes in the eastern United States, particularly in Appalachia, have no bearing on conditions to be expected in the western United States. The situations are wholly different. Reclamation in the West differs from th t in the East, primarily because of aridity especially a during the summer months 1). Because of the many variables and differences between reclamation in eastern and western areas, they will be discussed separately.

Jan 1, 1974

By Maria I. De Rosa

Table 1 and figure 1 show the number of fires and fire injuries that occurred in underground metal/nonmetal and stone mines by state during 1990-2001. Table 1 also shows the injury risk rates, employees' working hours, and lost workdays. Overall, 65 fires occurred in 20 states; these include 2 fires and no injuries for contractors. Six of the fires caused nine injuries. The yearly average was 5.4 fires and 0.75 injury. Forty-one fires with 2 injuries occurred in metal mines, 14 fires with 7 injuries occurred in nonmetal mines, and 10 fires with no injuries occurred in stone mines. The underground mine fires required 25 mine rescue team interventions and 30 mine/section evacuations. The Ewhr value was 260 x 10° hr (Irr = 0.007), and the LWD value was 83. Idaho had the most fires (eight fires and no injuries), followed by Louisiana (seven fires and two injuries), Michigan (six fires and six injuries), and Missouri (six fires and no injuries). Of these states, Michigan had the highest injury risk rate value (Irr = 0.146). Table 2, partly illustrated in figure 2, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires during the six time periods show an increase during the fourth period followed by a sharp decrease during the fifth period and a sharp increase in the last period. The number of fire injuries show an increase followed by a decrease during most of the periods, accompanied by a decline in employees' working hours during most of the periods; an increase is seen during the third and fourth periods. The In values follow patterns similar to those shown by the injury values. Tables 3-8 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 3 shows the major variables related to fires for 1990-2001. Table 9 shows the number of fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004