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By S. J. Page, J. A. Organiscak

Dust surveys were conducted around small truck-mounted rock drills operating at surface coal mines to assess their airborne respirable dust generation and in-service dust control methods. Of four out of seven drills sampled, respirable dust concentrations measured around the drill deck ranged from 8.68 to 95.15 mg/m with3concentrations ranging from 1.37 to 2.69 mg/m at distances 12.2 to 30.5 m downwind of these drills. The other3drills had noticeably lower respirable dust concentrations measured around the drill deck at or below 1.30 mg/m.3Rotoclone-type dry dust collectors were commonly used with dust being emitted from around the drill deck shroud, collector exhaust, and collector fines dumping. Wind speed and direction was also a factor in the dust concentrations measured on the bench. Dust control modifications were made to three rock drills to reduce their airborne dust emissions. Dust controls tested included water injection into the Rotoclone exhaust, Rotoclone exhaust extension, improved sealing of drilling deck shroud, shrouding the Rotoclone hopper dump process, and wet drilling. These control techniques showed noticeable improvement in dust concentrations measured around the drills. Finally, repositioning the drill operator showed that operator dust exposure can be improved by avoiding the dust cloud around the drill.

Jan 1, 1995

Provide reasonably priced, reliable fire protection for AN-FO haulers. Approach An automatic fire sensing and suppression system for AN-FO haulers was developed and on-vehicle tested. How It Works The system works in two ways to protect personnel from dangerous and unpredictable AN-FO fires. First the system senses and suppresses fires on the truck before they spread to the AN-FO in the bunker. This design was chosen because AN-FO truck fires generally start when combustible liquids (such as diesel fuel, hydraulic fluid or lubricating oils) are ignited by hot surfaces mainly on three areas: the engine, the transmission or the power take-off. These fires are quickly sensed by a linear temperature sensor strung throughout these three areas. The system then warns the operator and automatically suppresses the fire by discharging 30 pounds of multipurpose dry chemical extinguishing agent through a network of fixed hoses and nozzles. Second, this system includes six spot thermal sensors mounted inside the bunker on the truck to monitor the AN-FO temperature in case a fire does spread to the bunker area. If the bunker temperature rises to 190° F, a loud siren is sounded to warn nearby per-

Jan 1, 1981

By G. E. Rennick, F. E. Armstrong, J. Pasini, J. R. Abrams

An oil well penetrating the Pittsburgh bituminous coalbed in northern West Virginia was plugged and safely mined through 3 months later. A sensitive chemical tracer, introduced into the oil reservoir before the test, was not detected in the mine air following the plugging and during mining of the pillar and penetration of the well. Effectiveness of the plugging in preventing reservoir gas from entering the mine through the well hole was verified by continuous monitoring of the mine air for indications of sulfur hexafluoride, an inert gas detectable in amounts as minute as 112 part per billion. Expand- able cement and fly ash-gel-water slurry were utilized to seal the well above and below the coal seam. Three other wells were also plugged using various techniques.

Jul 1, 1972

By T. M. Kohler, G. L. Finfinger, D. M. Hyman, A. T. Iannacchione

The Bureau of Mines measured methane emission rates from an advancing salt face ranging from 15 to 56 ft3/ton (0.5 to 1.8 m3/t). Small room size, use of a continuous miner, and a well-defined ventilation system made possible air velocity and methane concentration measurements, These measurements, representing data from 18 production days, were con- ducted in an area of abnormally low grade salt, Methane emissions occurred primarily during the advance of the salt face by continuous miner.

Jan 1, 1982

By Joel M. Modd, Stephen P. Holt

"INTRODUCTION Nickel is one of the seven metals designated as strategic by the Army and Navy Munitions Board in 1939, when Congress appropriated funds for the investigation of domestic sources of supply of war minerals. The Mertic nickel lode at Punter Bay, Admiralty Island, Alaska, owned by the Admiralty Alaska Gold Mining Co., was investigated as part of this program.During the period 1919 to 1928, the property was examined the following engineers; L. S. Robe, W. E. Dunkic and S.E. Conbest of the Alaska Treadwell Cr., A, F. Buddington of the Federal Geological Survey, and H. C. Boydell. Henry M. Eakin, in the capacity of consulting geologist, examined the deposit in 1928 and later reviewed data resulting; from exploration recommended by him. In 1936, A. Hoogbom, of the Geological Survey of Sweden, made a very brief report on the deposit based upon information furnished by J. S. Pokovich.A comprehensive study by the Geological Survey of the Punter Bay area, including the Mertic lode, was made during the field season of 1937, with brief examinations in 1936 and 1938. 4/Miyaki, representing the Mitsubishi Company, visited the property in 1937 and in the course of his examination took six samples. G. W. Powel examined the deposit in 1937 and took five samples in the Mertie adit.This report describes the results of the Bureau's work and gives information collected from other sources."

Nov 1, 1946

By T. E. Bernard

The CO2-absorbent canisters used in four approved rescue breathing apparatus were investigated. A breathing machine was used to simulate human expiration with gas flow rates of 26, 37, and 48 1/min of 3.5% CO2 in air. The exit gas CO2 concentration, the pressure drop across the canister, and the exit-gas temperature were monitored. The absorbent capacities of the packed-bed canister designs were found to be dependent on flow rate within the range studied, while the capacities of the other designs were less affected. The radial canister had the least resistance to breathing while the complex bed design proved to be the most effective in utilization of the chemical. The overall results indicated that LiOH (lithium hydroxide) has the highest capacity for CO2 absorption among the absorbents tested. It can be used in a simple packed-bed design while maintaining acceptable levels of resistance and exit-gas temperature. Examination of oxygen supply with respect to CO2-absorption capacity suggested that it is desirable to closely match CO2-absorption capacity with the avail-able O2 supply to minimize the size and weight of rescue breathing apparatus.

Jan 1, 1979

By Henry M. Harris

Low-carbon shales from 65 deposits and 11 sources of coal-mine waste in western Oregon and Washington were tested in a rotary kiln for their suitability as raw material for expanded aggregate. Shales from 41 sources bloated enough to produce crushed, expanded aggregates, weighing less than 65 pounds per cubic foot in the preliminary tests. The samples were judged on the basis of processing qualities, physical properties, and size and uniformity of the source. Nine low-carbon shale deposits and three coal-mine waste sources were selected for more extensive bloating tests and for examination of the expanded aggregates in concrete shapes. Composite samples from these 12 sources and from 2 commercial operations, when processed for testing in concrete shapes, had bulk densities ranging from 37.S to 72.9 pounds per cubic foot. Damp-cured concrete shapes made with these aggregates had bulk densities ranging from S6 to 119 pounds per cubic foot, and all but three of the lightweight concretes had crushing strengths ranging from 3,270 to 6,810 p.s.i. Properties of the lightweight concretes were compared with those of concrete shapes made with commercial aggregates, and with sand and gravel.

Jan 1, 1962

By E. C. Lane

This report on properties of commercial motor fuels is the twelfth in a series made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the United States Department of the Interior. The first report contained data on motor gasolines sold during the winter of 1935-36.3/ The -present report, covering the summer of 1941, presents analytical data for 1,857 samples, representing the products of approximately 135 companies. -As in previous surveys, these companies include both large and small suppliers. In addition, the Pacific coast is represented by data averaged by the Pacific Coast Technical Group before being submitted, and these data are published exactly as they were received. Conforming to previous surveys, the data cover three groups of samples -- regular-price, premium-price, and third-grade gasolines -- and each group has been aver aged separately. The number of samples, items, and brands comprising each group, exclusive of those of the Pacific coast, are as follows: Regular price, 1,010 samples, 291 items, and 86 brands; premium price, 577 samples, 263 items, and 78 brands; third-grade gasoline, 270 samples 159 items, and 74 brands. The meanings of these terms as used in the surveys are as follows: Sample: The individual supply of gasoline obtained at the filling station and analyzed in the laboratory.

Jan 1, 1942

By Daryl E. Radcliffe

The Bureau of Mines studied the displacement of the roof in a portion of the Bear coal mine near Somerset, Colo, Horizontal-and vertical-displacement gages were installed in a five-entry section during normal room-and-pillar mining procedures. Monitoring of the roof continued until this section was mined out. Displacement measurements in combination with known time lapses between mining and bolting operations indicate that once support is achieved, the length of unsupported time does not appear to affect long-term roof stability in the mine under investigation.

Jan 1, 1978

By Frank J. Weibelt

In accordance with provisions of the Strategic Minerals Act of 1939, the Bureau of Mines surveyed the chromite occurrences in California. The Seiad Creek deposit afforded excellent opportunity for developing reserves that could be used by the nation in case of critical shortages of the mineral. Subsequently an exploration and development program was undertaken in April 1941, which was concluded in October of the same year. Work included road construction, diamond drilling, drifting and crosscutting, surface trenching, and sampling.

Jan 1, 1949

By Everett A. Sondreal

Material and energy balances for stockpiled lignite were calculated by computer simulation techniques to determine the occurrence of spontaneous heating. Data on properties of lignite which affect spontaneous heating were required. In some cases, best values from reported data were utilized; in other cases, new data were developed. These include specific studies on the rate and conditions that influence oxidation, heat of oxidation, heat of wetting, specific heat, thermal conductivity, and permeability of stockpiles to air. These data are presented and discussed in detail for possible application to other studies. Results of computer simulations confirm past field experience on the storage of lignite containing as-mined moisture, and predict a greater risk of heat occurrence in stockpiles of dried lignite where experience is lacking. Successful storage was predicted for dried lignite of 20 pct moisture content, if it were cooled after drying and compacted to an interparticle void fraction of 9 pct (bulk density of 67 lb/cu ft) compared to 10 pet void fraction (72 lb/cu ft) for as-mined lignite.

Jan 1, 1974

By Robert R. Stein, Roy C. Bartholomae, William W. Aljoe

This Bureau of Mines report describes in detail the design and operation of a test apparatus for measuring the sound power levels of drills used by the mining industry. The two major components of the test apparatus are a computer-controlled automated drill test fixture (ADTF) and a large (45,000-ft3) reverberation chamber that houses the ADTF. Design specifications and performance capabilities of the ADTF and the reverberation room are given. Initial test results for three types of drills--a pneumatic percussion drill, a hydraulic percussion drill, and a pneumatic rotary drill--are given to illustrate the types of experiments that can be conducted with the test appartus.

By John Durkin

This report discusses the configuration and system deployment for the postdisaster surface seismic system for detecting and locating trapped miners. It analyzes the results of 15 field tests to define a signal model, background noise levels, and subarray performance. A waveform modeling procedure is described and compared with observed waveforms. The resulting similarity indicates that the major factors affecting the signal amplitude, waveform, and spectral character are understood. A model is presented which gives the sig-nal amplitude as a function of source type, source depth, and horizontal off-set between source and receiver. Using this model a curve is presented which gives the range at which a signal will be detected for different signal and noise levels. Finally, and most important relative to the mission of the system, the ability of the system to detect signals on one or more subarrays is put into a probabilistic framework. For a strong source it is almost certain that a subarray directly over the source will detect the signal. After signal processing, it is highly likely that signals will be detected on sufficient subarrays to locate the trapped miner. Location errors have been found to be less than 100 ft in the majority of cases. Techniques have been used that can reduce the location errors to this level even when soil layer variation between subarrays is severe.

Jan 1, 1981

By E. C. Baker

The Bureau of Mines estimated the economic feasibility of investing in a directional hole methane drainage project in the Pittsburgh coalbed for 5 yr in advance of mining. This report estimates the capital investment and operating cost of recovering 325 MMft3 of methane gas per year and the selling price of approximately 317 MMft3 of gas per year. The labor, equipment, and supply requirements were determined from those of a previous directional hole drilled at the Emerald Mine, near Waynesburg, PA. The cost of equipment, materials, services, and labor are in third quarter 1982 dollars. They were obtained from vendors, contractors, and the U.S. Department of Labor. Findings indicate a total capital investment of $1,381,160. Annual operating cost amounted to $167,690. At a wellhead price of $2.05 per thousand cubic feet, the sale of approximately 317 MMft3 of gas per year results in a rate of return on investment of approximately 25 pet.

Jan 1, 1984

By A. B. Hooker

Gassy mines require daily inspections with methane detectors to test for the presence of methane. Although in many manes it may be sufficient to know that there is no methane present or that its percentage is below a certain amount, it is desirable and often necessary to determine definitely the percentage of methane at the working faces and in the various air currents. The Bureau of Mines recognizes two general types of portable methane detectors, namely; 1. Methane detectors by which the presence of methane may be detected and its approximate percentage estimated.

Jan 1, 1929

By Anthony Iannacchione, Christopher Mark

Residents of Maxwell Hill, a suburb of Beckley, West Virginia, reported from January until March of 1988 a series of earth tremors. The tremors rattled dishes, and the noises associated with tremors were sometimes loud enough to wake people at night. These events were puzzling because Beckley is in an area of low seismic activity. Maxwell Hill is located above abandoned coal mines, though no direct subsidence damage to surface structures has been documented. A research program was initiated to determine whether subsurface ground movements associated with the abandoned mines could be responsible for the seismic activity experienced at the surface. A hypothesis is proposed which states that seismic disturbances can be caused by abandoned mine failure when two conditions are met. First, some instability must exist at the mine level. The most likely cause of instability is the failure of pillars of coal that were left for support at the time of mining. Second, subsurface movements can result in significant seismic activity only when the rock above the mine contains at least one very strong and brittle layer that is prone to fail violently through rupture or fault slip movement. Analysis of the data indicates that both hypothesized conditions for mine-related seismicity appear to have been satisfied in the case of Maxwell Hill. It has therefore been concluded that the earth tremors experienced by Maxwell Hill residents probably are related to the abandoned mines. Analysis of the potential magnitude of these events indicates that they are unlikely to cause significant surface danlage. The probability that future events will disturb the residence of Maxwell Hill should be quite low based on the identified mechanism.

By J. A. Zimrner, R. J. Tirnko

The roles of main mine fans in underground mines are to induce airflow and continuously re- move hazardous gases and dust. While most larger mines use multiple fans to accomplish these tasks, many smaller mines employ only a single fan. This paper concentrates on those mines having only one fan to provide ventilation needs. If this fan should cease to function, it is likely that methane concentrations will in- crease in some areas of the mine. As a safety precaution, Federal Regulations require that personnel must be- gin evacuating the mine within fifteen minutes after fan stoppage. Powered haulage can be used to transport workers to the mine portal as long as travel is through areas where hazardous levels of methane are not expected. To determine where methane will accumulate along haulageways during a fan stoppage, air samples must be taken at specific areas and analyzed for hazardous gases. During this study, procedures were developed for measuring methane levels along the haulegeways that are used to exit a mine following stoppage of the main mine fan. Methane levels were measured in four different mines at selected underground locations during four planned fan stoppages. In these mines the measurements taken only at the specified locations showed that, if workers had used electrically powered haulage to exit the mine following a fan stoppage, the methane accumulated along haulageways during fan stoppages would not have significantly increased the risk of an ignition.

By Walter T. Lewiecki

Bauxite was first discovered in-the United States near Rome, Ga., in 1887, Approximately 400,000 tons of bauxite ranging from 46 to-62 percent alumina were mined in the area from 1888 to 1930. In February 1943, The Republic Mining & Manufacturing Co. installed a dryer and began mining and reworking dumps from the old bauxite mines. Some 3,000 long tons were dried and shipped to the chemical industries from March 1943, to June 30, 1943. In 1941 and 1942, representatives of the Bureau of Mined and the Federal Geological Survey/ visited this area and proposed an exploratory project that at first was to be confined to the Heritage district northeast of Rome (see fig; I). The Bobo district, southwest of Rome, was to be explored after work .1n the Hermitage district was completed. The Hermitage district comprises an area of about 50 square miles in the northwest quarter of Bartow County and the adjacent portion of Floyd County. It is bounded on the north by the Gordon County line, on the east by U. S. Highway 41, on the south by U. S. Highway 441, and on the west by State Highway 53.

Jan 1, 1949

By T. E. Gray

This report describes the preparation characteristics of the most significant coal beds in Wise County, Va. It is one in a series of reports planned to determine coals suitable for the production of metallurgical coke, either as mined or after beneficiation. Wise County produced approximately 6,600,000 tons of coal in 1955, of which about 2,110,000 tons was cleaned mechanically. The Federal Geological Survey has estimated that 1,341 million tons of measured and indicated coal reserves remained in the county as of January 1, 1951.

Jan 1, 1958

By Thomas M. Barczak

The U.s. Bureau of Mines is conducting research to optimize the utilization and design of mine roof support systems. This report describes methods to evaluate resultant loading on longwall shields, defined as external resultant vertical and horizontal force acting on the canopy and base. Four models are considered: two rigid-body models, an elastic model, and a numerical model. The rigid-body models equate measured internal shield forces to unknown external resultant shield forces (loads) through rigid-body analysis of static equilibrium requirements. The elastic model develops a solution to shield mechanics by evaluation of the load-displacement relationship and stiffness characteristics of the support structure. The numerical model is a two-dimensional finite-element representation of a shield structure. Model determination of resultant shield loading is compared to controlled loading of a shield in the Bureau's mine roof simulator. Parameters investigated are shield height, canopy contact configuration, canopy and base horizontal constrainment, and boundary conditions imposed by vertical and horizontal shield displacements. It is concluded that rigid-body models are most applicable to in situ measurement of shield loading. Applications requirements and potential error sources are discussed.

Jan 1, 1990