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By Miklos D. G. Salamon, Jim M. Galvin, Bruce K. Hebblewhite

A series of mine design accidents in the late 1980s resulted in a major research program at the University of New South Wales, Australia, aimed at developing pillar and mine design guidelines. A database of both failed and unfailed Australian underground coal mine pillar case studies was compiled. A procedure was developed to enable the effective width of rectangular pillars to be taken into account. The database was analyzed statistically using the maximum likelihood method, both independently and as a combined data set with the more extensive South African database. Probabilities of failure were correlated to factors of safety. It was found that there was less than a 4% variance in pillar design extraction ratios resulting from each of these approaches. There is a remarkable consistency between the design formulas developed from back-analysis of the two separate national pillar databases containing many different coal seams and geological environments.

Jan 5, 1999

By Launa Mallett, Charles Vaught, Kathleen M. Kowalski, Michael J. Brnich

This paper reviews research from the U.S. mining community to define issues relevant to an evolving national and international workforce and to relate them to the emergency response population. The authors further explore and relate the key problem of an aging workforce to the resultant changes and emerging physical and psychological needs of emergency workers. Finally, the authors cite examples from the mine emergency response community and mine rescue experiences to suggest practical recommendations that include both organizational and individual formats, with an emphasis on new approaches to training this changing workforce.

By J. M. Stuve

Calorimetric data for the dissolution of scandium sesquioxide and scandium trichloride in 4.360 molal hydrochloric acid were used to evaluate the standard heat of formation of ScCl3(c). The heat of reaction for Sc(c) + 1.5Cl2(g) = ScCl3(c) at 298.15° K was computed as -225,440 ±340 cal/mole.

Jan 1, 1965

Four catalytic converters for diesel exhaust systems were tested to determine their effectiveness in reducing the amount of harmful substances discharged into the air. Tests were conducted with four different catalytic converter designs, using two diesel engines as exhaust gas generators. (Of the four noble metal catalytic converters, three are commercially available.) Testing showed that the catalysts varied widely in oxidation efficiency at light to intermediate engine loads, but that all were very effective in reducing emissions of CO, HC, aldehydes, and odor intensity at heavy loads (engine operating modes resulting in high exhaust temperatures). Particulate loading, particulate size, and NOx emissions were generally unaffected by any of the catalysts. The catalysts had one ad-verse effect on exhaust quality--increased sulfate emissions. Because of the potential problem of sulfate emissions, the exclusive use of catalytic reactors for emissions reduction does not appear to be satisfactory. However, when used with a means for subsequent removal of sulfates, a catalyst can function as a key component in an emissions control system for diesel engines operated in underground mines.

Jan 1, 1978

By E. J. Gleim

"Information gathered during recent months by field men of the U. S. Bureau of Mines shows that in one State alone there have been 71 fatalities from electrical causes during the last 51/2 years, of which 55 were from contact with mine trolley wires operated at 250 volts or less, direct current. The 1928 law relating to the guarding of trolley wires in the-mines of this particular State reads: ""All trolley wires carrying a voltage of class 2 must be properly shielded except where the same are at least 61/2 feet above top of rail."" Class 2 voltage is defined as being ""between 300 volts and 600 volts direct current, or 240 volts and 480 volts alternating current."" From this it may be inferred that no guards are required, for 250-volt trolley wires, and the natural conclusion to be drawn is that the lack of guards or shields must be held responsible for these fatalities. To prevent fatalities from this source, it has been advocated that every foot of trolley wire in mines should be guarded. While some such drastic step may appear to be amply justified, a closer examination of the records shows that lack of guards is not entirely responsible but rather that carelessness and neglect in the observance of certain well-established simple rules concerning installation and location of trolley wires must also bear a share in the responsibility. In -other words, if trolley wire is installed carelessly and its maintenance neglected, failure may be expected of any guards that have been put up.There are a-number of factors affecting safety as related to trolley wires in mines, among which the following may be enumerated.1. Installation relative to track and passageways.2. Guarding.3. Maintenance.4. Discipline.Acknowledgment is made to D. Harrington and K. L. Marshall of the safety division of the bureau for assistance given in securing data on cost of installing guards for trolley wires.The statement that fatalities should not be charged in every case to lack of guards is supported by the following example: A man operating a locomotive was electrocuted when the trolley wheel jumped the 250-volt trolley wire and allowed it to sag against his shoulder. He was sitting in the regular place provided in the locomotive, but the wire was 11 inches inside of the rail and only 39 inches above it where the wire touched him, or 11 inches from the roof at a distance of 12 feet from the nearest hanger. The accident occurred between two hangers 44 feet apart, and the trolley wire was inside the rail over the entire distance, being 2 inches inside at one hanger and 10 inches inside at the other hanger. A bolt in the roof indicated that there had been a hanger at one time between the two on the 44-foot span.This example is a violation of good practice in the installation and maintenance of trolley wire. In the first place the wire should have been outside instead of inside the rail. In the second place there should have been at least one intermediate hanger so that the span would not be so great and the sag would be reduced. Furthermore, it is possible that the wire was not taut enough even when the intermediate hanger was in place.To provide a degree of safety for men in the mines certain coal-mining States, recognizing the need, have enacted laws to regulate the installation of trolley wires. These limit the distance that the wire must be kept outside and above the rail. Thus, the 1927 mining laws of Ohio specify that:"

Apr 1, 1932

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 Maria I. De Rosa

This report analyzes mine fires for all U.S. underground and surface metal/nonmetal mining categories during 1990–2001 by state and six successive 2-year time periods. Injury risk rates are derived, and ignition source, methods of detection and suppression, and other variables are examined. Fires involving contractors are also included in the analysis. The data were derived from Mine Safety and Health Administration (MSHA)mine fire accident publications and verbal communications with mine personnel. The analysis will provide the National Institute for Occupational Safety and Health, MSHA, and the mining industry with a better understanding of the causes and hazards associated with mine fires and an increased awareness aimed at preventing and reducing fire hazards. It will also form a basis for future fire research programs.

Jan 11, 2004

By Irven A. Jacobson

The thermal reactions of l-methylindole were studied in the temperature range of 525° to 627° C in a flow reactor. The major products consisted of 2-methylindole, 3-methylindole, indole, quinoline, hydrogen, and methane. 2-Methylindole is formed from 1-methylindole by an irreversible isomerization reaction. The 2-methylindole isomerizes in a reversible manner to 3-methyl-indole, the equilibrium favoring the 3-methyl isomer. Indole is formed directly from 1-methylindole. Quinoline is formed from l-methylindole, 2-methylindole, and 3-methylindole.

Jan 1, 1971

By L. H. Johnson

"INTRODUCTION The Pennsylvania anthracite industry produced 53 million net tons of anthracite during 1945. Fifty-one million tons was prepared for the commercial market (3), 3/ and 2 million tons (consisting of fine sizes) was used for colliery power consumption. Of the number of tons prepared for market, 17 million tons (33 1/3 percent) was prepared by the use of acid mine water treated with lime.Mine water from underground workings is pumped, drained, and stored in huge quantities. The mine-drainage systems in the anthracite region handle over 200 billion gallons of water annually, of which 150 billion gallons is pumped to the surface. More than 69 billion gallons of water is impounded in underground pools (1). Much of this water is employed for breaker use, dust-control installations; hydraulic backfilling, combatting mine fires; and aiding in the transportation of anthracite in gently dipping places where sheet iron is used Roos(4) estimates that 1,100 gallons of mine water is utilized in the preparation of anthracite mined."

Nov 1, 1946

To reduce front-end loader (FEL) collision accidents by detecting obstacles in the rear blind area. The Problem Federal regulations require an audible backup alarm to activate when an FEL is backing. Since the device is constantly being activated, the warning soon becomes a normal part of the mine environment and is less effective as a warning device. Also, when several machines are working together, it is difficult to detect by ear alone just which machine is backing. Approach The Bureau defined the location for hazard detection to include an area extending 15 to 20 ft behind the rear bumper of an FEL. Then, existing surveillance and detection technology was assembled, ruggedness, and applied to the FEL's rear blind area to form a new discriminating backup alarm system employing either infrared light, ultrasonics or radar

Jan 1, 1986

By Doris M. Hyde

Belize remained relatively insulated from the social and political turmoil that affected some of its Central American neighbors. This stability encouraged new foreign investments that assisted the economy, especially in tourism and agriculture. The mineral sector remained limited to construction-oriented materials. Oil exploration efforts continued by the various concessionaires.

Jan 1, 1987

By Paul W. Johnson

An evaluation is made of a lime-soda sinter process for extracting alumina from anorthosite. In this process, alumina is extracted by sintering anorthosite with soda ash and limestone, and then leaching the sinter with a dilute sodium carbonate solution. The sodium aluminate solution formed during leaching is separated from the residue and treated with lime in autoclaves to remove dissolved silica before alumina trihydrate is precipitated with carbon dioxide. The trihydrate is then calcined to a-alumina. Two options, dry grinding and wet grinding, are used in the sintering step. For plants producing 1,000 tons of alumina per day for the dry grinding and wet grinding options respectively, the estimated operating costs are $75.40 and $74.36 per ton of alumina when charging $2.50 per ton for anorthosite and $1.00 per ton for limestone. The fixed capital costs based on a Marshall and Stevens chemical equipment index of 240.0 are $76 million and $70 million respectively. This process, when treating anorthosite, using either option, is not competitive under current economic conditions with the Bayer process treating bauxite to produce alumina.

Jan 1, 1968

By Raja V. Rarnani, Robert L. Frantz

"The Generic Mineral Technology Center for Respirable Dust (GTCRD) was created at The Pennsylvania State University and West Virginia University by a congressional initiative in 1983 responding to recommendations in the 1980 National Academy of Sciences study on the Measurement and Control of Dust in Mines. Many of these recommendations dealt with the need to initiate focused fundamental research for further professional progress in dust control. Long-term, sustained support was emphasized to develop expertise in respirable dust research. In creating this Center, Penn State and West Virginia University were specifically recognized for their expertise in and facilities for research on coal mining and medicine. Today, the Center includes the Massachusetts Institute of Technology, the University of Minnesota, and the Michigan Technology University. The Respirable Dust Center is the only organization that coordinates and integrates the medical, scientific, and engineering aspects of respirable dust disease. The Center works with the U.S. Bureau of Mines (USBM), Mine Safety and Health Administration (MSHA), the National Institute for Occupational Safety and Health (NIOSH), the United Mine Workers of America (UMWA), and the U.S. coal industry in defining the research priorities for the programs of the Center to enhance research synergism.The Center's mission is to enhance the health, safety and productivity of miners by advancing the fundamental understanding of all aspects of respirable dust associated with mining and milling and the interaction of dust and lungs to reduce the incidence and severity of respirable dust disease.All Dust Center activities are focused to be responsive to this mission, which is shared by the several federal agencies closely associated with the GTCRD. While significant progress has made mine atmospheres cleaner and healthier, respirable dust-related disease remains the nation's most pernicious industrial hazard.The goals of the GTCRD were formulated with recognition of the diverse scientific, engineering, and medical aspects of respirable dust, in addition to a need to enhance researcher interaction, as well as education and technology transfer efforts, in the respirable dust area. These goals reflect the needs of the mining industry as determined by the National Academy of Sciences Committee on Measurement and Control of Respirable Dust study done in 1980. The report of this committee encouraged the Bureau of Mines to redirect its research efforts ""...toward obtaining fundamental understanding of the origin, transport and characteristics of respirable coal mine dust."" The GTCRD's goals, detailed in chapter three of this document, were formulated to mesh with NAS recommendations."

Jan 1, 1995

By William C. Laubengayer, Robert R. Godard, Harry Dobroski

A whole mine, computer-controlled communication and monitoring system for both normal and emergency use is installed and operating in the U.S. Steel Robena Mine complex near Uniontown, Pa. Portions of the system, including the coaxial cable and the key underground and surf ace phones, have been operating for over a year and a half. During this time the basic concept has been modified and new line amplifiers with directional switches have been developed to eliminate some problems in implementing the loopback feature. The quality of the audio and the availability of the system have been outstanding. Since early summer almost all subsystems have been completed. The experience with the telephone system itself, the pocket-pager call alert, section wireless radio, hoistphone, television, environmental monitoring, control and monitoring of equipment, voicedownlink/code uplink post disaster communications, post disaster through-the-earth monitoring, and the system center failure diagnostic routines are reviewed.

Determine safe practices for surface mine blasting near pressurized gas, oil, and water transmission pipelines. Background Surface mine blasters regularly have to address the issue of how blasting affects transmission pipelines that run near and sometimes through their permit areas. Regulatory approaches to blasting have ranged from no regulation at all to strict limits intended to prevent cosmetic cracks in plaster interior walls of homes, but they have not directly addressed the impact of blasting on nearby pipelines. Concerned with both productivity and safety, the mining industry and its regulators have requested guidance on safe practices for mining near pipelines. The Pipeline Research Group of the American Gas Association has sponsored studies of the effects of small close-in blasts because of vibration concerns related to the installation of new pipes into existing pipeline right-of-ways. By contrast, the recent study in which the U.S. Bureau of Mines (USBM) took part is the first addressing large-scale mining blasts.

Jan 1, 1995

By Fred N. Kissell

The new MSHA diesel rules have stone mine operators looking hard at pos¬sible upgrades to their ventilation systems. There are existing methods to reduce diesel engine emissions (MSHA, 2001)(Head, 2001b),but many operators will decide that a ventilation upgrade is necessary is well. NIOSH hay several stone mine ventilation projects underway, but in the meantime a good information resource is the work done by the U.S. Bureau of Mines in the 70's and 80's on ventilation for oil shale mines. The Bureau conducted this research because oil shale mines were projected to be gassy and would, therefore, require a lot of ventilation air. The focus of this oil shale work was on the use of jet tans for lace area ventilation, and on stoppings that would he low Lost and leak-tight. The work also considered changes in mine design to reduce the number and size of stoppings. The findings are still applica¬ble to stone mines.

Jan 1, 2002

By Ronald D. Hill, Elmore C. Grim

The removal of overburden often exposes pyritic materials (iron disulfide). As shown in equations 1 and 2, the oxidation of this material results in the production of ferrous iron and sulfuric acid. The reaction then proceeds to form ferric hydroxide and more acid, as shown in equations 2 and 4. [ ] Consequently a low pH water is produced (pH 2-4.5). At these pH levels, the heavy metals such as iron, manganese, copper, and zinc are more soluble and enter into the solution to further pollute the water. Water of this type supports only limited water flora, such as acid-tolerant molds and algae; it will not support fish life, destroys and corrodes metal piers, culverts, barges, etc., increases the cost of water treatment for power plants and municipal water supplies, and leaves the water unacceptable for recreational uses. The amount, and rate of acid formation, and the quality of water discharged are a function of the amount and type of pyrite in the overburden and coal, time of exposure, characteristics of the overburden, and amount of available water(l). Crystalline forms of pyritic material are less subject to weathering and oxidation than amorphic forms. Since oxidation by oxygen is the primary reaction during early acid formation, the less time pyritic material is exposed to air, the less acid is formed. Thus, a positive preventative method is to cover pyritic materials as soon as possible with earth, which serves as an oxygen barrier. In terms of mining, this step is accomplished by current reclamation techniques and small open pits.

Jan 1, 1974

By Dennis R. Dolinar

Screen material in the form of welded wire mesh and geogrids are used in underground coal mines to prevent the fall of small pieces of rock from the roof between roof bolts. Further, if the screen is installed during the production cycle, roof fall injuries can be reduced significantly. Therefore, the National Institute for Occupational Safety and Health (NIOSH), because of the safety implications, conducted an evaluation of screen materials commonly used in U.S. coal mines to determine their support characteristics and identify the parameters that could affect their performance with respect to controlling the fall of rock from the roof surface. To evaluate the load and stiffness characteristics of the screen, a test frame was designed and installed in the Mine Roof Simulator (MRS) at the NIOSH Pittsburgh Research Laboratory (PRL). With this test set up, the screen is bolted at four corners of the frame and a center load is applied. The test set up allows for up to 20 in of screen deflection while the load and screen defection are continuously recorded. A series of tests were conducted to evaluate the effects of various parameters such as bolt tension, the type of load bearing surface and the size of bearing plates on welded screen performance. The most common screen material used in U. S. coal mines is an 8-gauge wire welded in a 4-by-4-in spacing or aperture. The peak screen load was normally limited by wire breakage. The conditions at the bearing plate influence the nature of the wire breakage. However, the screen stiffness was controlled by slippage at the bearing plates, and by weld and wire failure. The size of the bearing plate had a significant effect on the performance of the welded screen. Therefore, the design capacity of the 8-gauge screen is evaluated based on plate size. For a 6-by-6-in bearing plate the average peak load is 2,900 lb with a stiffness of 250 lb/in. For an 8-by-8-in bearing plate, the average peak load is 4,500 lb with a stiffness of 430 lb/in. These test results are based on a 4-by-4-ft bolt spacing. A geogrid mesh was also tested.

By H. C. Ko

As part of the Bureau of Mines effort to provide thermodynamic data for the advancement of mineral technology, the standard enthalpies of formation for ZnO?2ZnSO4 and COS04-6H20 were determined by HC1 acid solution calorimetry. The values are -550.31 ±0.28 and -641.33 ±0.15 kcal/mot, respectively.

Jan 1, 1982

The current procedure for measuring the concentration of respirable coal mine dust is as follows. Each filter is preweighed by the filter manufacturer to ±0.1 mg. Following sampling with the Coal Mine Dust Personal Sample Unit (CPSU) at 2.0 L/min, the filter with coal mine dust is sent to MSHA for weighing. The current MSHA procedure for weighing respirable dust samples uses a Mettler Model AE163 analytical balance in conjunction with an automatic weighing system with a precision of ±0.02 mg [Tomb 19901. Each balance is calibrated twice per day. Quality control for the automatic weighing system includes the systematic weighing of one in eight filters on a second Mettler AE163 balance. Tolerance is set at ±0.1 mg between the two weighings of the same sample. Weights are truncated at the 0.1 mg level (e.g., 3.457 mg is truncated to 3.4 mg) [Bowman et al. 19851. The difference of the two truncated weights is then recorded as the weight of coal dust deposited. The respirable concentration (mg/m3) is computed by multiplying by a correction equal to 1.38 and dividing by the volume of air sampled (2.0 L/min x sampling time [min]).

Jan 1, 1997