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To quickly and more reliably measure the alignment and deflection of mine guides used to run skips and cages into a mine shaft. The Problem Conventional mine guide alignment measuring systems require the use of a plumb bob and tape measure. This method is not only laborious, but it is time consuming as well. Approach Aware of the drawbacks of the current measuring method, the Bureau of Mines designed a self-contained instrument system that can accurately perform vertical guide alignment and deflection measurements by remote control. How It Works The Bureau-developed instrumentation system, called the Guide Alignment Measuring System (GAMS), is based on conventional mechanical electronics using inclinometers and displacement transducers. The instrumentation system is attached to an operating skip or cage where it functions as a completely self-contained measurement system, operating in conjunction with nor-mal travel of the skip or cage. An on-board tape recorder or a mini-computer with memory can be used to record all telemetry.

Jan 1, 1987

By John C. Edwards

To have the capability to predict the development of localized spontaneous heating within a porous coalbed that is subjected to forced air ventilation or in an otherwise quiescent environment in which buoyancy develops, the Bureau of Mines developed three time-dependent mathematical models, which were used to calculate the temperature increase associated with chemisorption of oxygen by the coal. In each model, spontaneous heating is driven by an Arrhenius first-order reaction between the oxygen and coal. Two models are two-dimensional, and one is one-dimensional. In the first two-dimensional model, a constant-velocity forced convection airflow is specified; and in the other, buoyant flow is allowed to develop in the absence of forced convection. The third model evaluates the airflow from Darcy's law and a specification of the pressure at the surface of a one-dimensional porous coalbed. Numerical computations demonstrated how each model could be used to predict the onset of spontaneous heating when the porous coalbed was subjected to constraints of an imposed internal heat source or a high- temperature airflow. The effects of particle size and coalbed compaction upon spontaneous heating were examined with the third model.

Jan 1, 1990

By B. T. Brady

Results of a study are presented of the effect of low radial reinforcement pressure on the postfailure characteristics of two types of granite, a sandstone, and marble. The low radial reinforcement pressure is applied to the rock surface by a gooch rubber sleeve. The gooch rubber sleeve provides a radial pressure of less than 1 psi pressure to the rock surface. This method of support gives an average strength increase of approximately 8 percent to the fractured rock sample.

Jan 1, 1973

By Henry E. Blake

The purpose of this Bureau of Mines investigation was twofold. The first phase of the work was to determine the technical and mechanical feasibility of defluorinating low-grade siliceous fluorspars on an intermediate scale by high-temperature pyrohydrolysis in a rotary kiln. The second phase was to react the liberated hydrogen fluoride (HF) offgas with alumina monohydrate to produce commercial-grade aluminum fluoride (85 percent AIF3). The two phases of the work were to be integrated into a single continuous process. Evaluation of the data shows that low-grade siliceous fluorspars can be successfully defluorinated, either in a solid or a molten state, in a gas-fired rotary kiln in the presence of water vapor at 1,250° to 1,350° C. The water produced by combustion of propane was sufficient to yield defluorinatians of 75 to 85 percent.

Jan 1, 1962

By Fred Leighton

The Bureau of Mines monitored a rock-burst-prone pillar in a metallic ore vein, up to and through failure, to measure its reactions to increasing loads, as it was mined. Three parameters were monitored: the stress changes at chosen points within the pillar, the displacement characteristics of the drift above the pillar, and the micro-seismic activity in and around the pillar. In descending order of effectiveness, the microseismic technique, vibrating wire stress measurements, and displacement measurements reflected the pillar reactions, and all showed good correlation to one another. A major rock burst in the pillar, which destroyed about 100 feet of drift above the pillar, occurred at the end of this study. This burst was preceded by a large anomaly in the microseismic activity in the failure area.

Jan 1, 1982

By Richard J. Bielicki

Poor mixing of methane and air at coal mine working faces causes fluctuating methane concentrations. If these fluctuations are large enough, methane levels can periodically exceed safe limits, even though the time average methane concentration may be satisfactory. Concentration fluctuations measured underground can result both from variations in methane emission rate and poor mixing. The present paper reports on a statistical analysis of fluctuations at a constant methane emission rate, that is, on fluctuations due only to poor mixing. A full-scale model of a working face was used. Both peak heights and elapsed times between peaks were evaluated. Good mixing was indicated by normal, Poisson, and exponential distributions while poor or incomplete mixing was indicated by log-normal or gamma distributions.

Jan 1, 1974

By Tobias W. Goodman

The U.S. Bureau of Mines used a contact drilling strategy with short-collared assemblies in order to rotary drill long horizontal methane drainage holes in the Beckley Coalbed near Glen Daniel, WV. By decreasing the thrust, and increasing the rotation of the drill bit when in contact with the roof and floor rock, assemblies with 1-ft (0.3-m), 10-ft (3- m), and 144 (43-m) long collars were made in deflect and stay in the coalbed. Successful application of this procedure resulted in holes drilled full length in coal with the original assembly including bit. The test assemblies deflected away from the original bearings of the holes during drilling and arced. Four holes were drilled to depths ranging from 478 ft (145.7 m) before the strategy was developed, to 4,034 ft (1,230 m) when the strategy was applied. Total length of the holes in coal was 8,590 ft (2,618 m). After 577 days the total methane captured by the holes was 221,600,000 ft? (6,276,000 m3). The methane flow rate peaked at 805,000 ft3/d (22,798 m3/d), then decreased to stabilize at 670,000 ft?/d (18,974 m3/d) after 6 months.

Jan 1, 1989

Abandoned Mme - A mine that a not producing any mineral and will not continue or resume operation Abatement - The lessening of pollution effects Acidity - A measure of the extent to which a solution is acid Acid Mme Drainage - Any acidic water draining or flowing on, or having drained or flowed off, any area of land affected by mining

Jan 1, 1975

By James J. Hanslovan

Stresses that damage coal mine trailing cables were investigated to obtain a quantified description of cable-stress locations, magnitudes, and frequency of occurrence. Stresses occurring in operating mining sections were measured and observed. Answers to questions that arose during the underground investigations were pursued under controlled conditions, both in the field and in the laboratory. Cable-handling suggestions that minimize or eliminate the stresses are summarized in the form of recommendations to mine operators.

Jan 1, 1979

Provide a means through which members of the mining community can easily and readily access information on human factors/ergonomics as it relates to mining. Approach As part of a research study aimed at reducing human error accidents in mining the Bureau of Mines developed a computerized information retrieval system which provides relevant human factors or ergonomics information on 19 mining-related special interest categories.

Jan 1, 1988

By J. Torma-Krajewski, M. Lehman

In 2005, NIOSH and Badger Mining Corporation entered a partnership to implement ergonomic interventions, including a systematic process, to address exposures to risk factors that may result in musculoskeletal disorders or other types of injuries/illnesses. As a result of this partnership, an ergonomics process was integrated with the existing safety and health program to promote an on-going application of ergonomic principles, and over 40 task-specific interventions were implemented during the first year of the process. This paper presents details of the process integration, and several examples of task-specific interventions that reduced exposures to risk factors.

By D. R. Forshey

The recent occurrence of fatal accidents in copper mines, presumably due to premature ignition of loaded holes by the heat from reacting ammonium nitrate-fuel oil (AN-FO) and pyrite-bearing ores, has led to an examination of this reaction. The reactivity of prilled AN-FO mixtures with pyrite-bearing ores and the effects of water, dilute sulfuric acid, and potential inhibitors on reactivity of the mixtures were evaluated. Initiation of an exothermic reaction was observed as low as 150° F with acid in the absence of inhibitors. Low concentrations of urea, calcium carbonate, zinc oxide, and magnesium oxide were effective in inhibiting the reactivity of the mixtures. The temperatures produced during the reaction of mixtures of AN-FO and pyrite-bearing ores, in the absence of inhibitors, always exceeded the temperature at which electric blasting caps are thermally initiated.

Jan 1, 1968

By R. V. Lundquist

Past reports by the Bureau of Mines have described the extraction of alumina from numerous aluminum silicate materials by the lime-soda sinter process. The results from pilot-plant investigations of six materials, with alumina-to-silica mole ratios from 0.3 to 8.7, indicated a relationship between the alumina-silica ratios and the processing characteristics of the sinter. A series of laboratory tests was conducted to define this relationship. Sinter and leach tests determined that an alumina-to-silica mole ratio of 0.90 or greater resulted in the best alumina and soda recoveries while leaving the leach slurries practically free from any tendency toward gelation. The widely different chemical and mineralogic properties of the various aluminous materials used in compounding the mixes had no perceptible effect on the leaching characteristics of the sinter. The blending of low-cost, high-alumina materials with aluminum silicate materials to give an alumina-to-silica mole ratio of 0.90 or greater would improve alumina and soda extraction and minimize operating problems in the lime-soda sinter process.

Jan 1, 1970

By J. H. Maysilles

The Bureau of Mines is examining a variety of low-grade uranium ores because projections indicate that an appreciable percentage of future U.S. uranium production will be derived from resources containing 0.01 to 0.1 percent U308. One possible source is represented by a granitic material from Wyoming; the available samples contained 0.06 and 0.12 percent U308. Tests were conducted to explore the general leaching characteristics of this potential resource. The material responded to both acidic and alkaline leaching techniques. Conventional acid leaching extracted 93 percent of the uranium in 18 hours; the required acid addition was 50 to 100 pounds of H2S04 per ton of ore, and the oxidant addition was 3 pounds of NaCl03 per ton of ore. The acid consumption continues after maximum uranium recovery has been reached; this effect may complicate heap or in situ leaching with acidic solutions. Some variation in reagent requirements was noted between the two ore samples. Conventional carbonate leaching with strong solutions at 85° C extracted 94 percent of the uranium in 24 hours. These granitic materials also showed some response to dilute carbonate solutions, and the results suggest that the material may be chemically amenable to heap or in situ leaching with dilute carbonate solutions.

Jan 1, 1977

By W. E. Anable

A 180° magnetic deflection residual gas analyzer mass spectrometer with a mass range of 2 to 200 amu was used to study the nature of gases evolved during arc and electron-beam melting of certain reactive and refractory metals. The partial pressure of residual gases over molten Mo, Hf, Ti, and Fe, was found to be similar: Water and hydrogen were evolved from the samples and from the furnace components, carbon dioxide and carbon monoxide resulted from deoxidation of some of the melts. Argon and acetone were residuals in the system, and methane was a decomposed organic compound from the oil diffusion pump.

Jan 1, 1969

By Louis D. Dornetto

The effects of electric shocks on man are an important factor in the design of power systems and protective devices. The current levels just below let-go and just prior to the onset of ventricular fibrillation must be known and taken into consideration in the design of power systems and protective devices. Isolated (ungrounded) electrical distribution systems are compared with resistance and solidly grounded systems. The advantages and disadvantages of each are discussed and recommendations are made. Transients on coal mine power systems are a problem that, until recently, have been ignored. Transient voltage levels that can be expected on both the high and low side of the load center and the effects of transients on electronic equipment and personnel are covered.

Jan 1, 1975

By John C. LaScola

The Bureau of Mines repeatedly surveyed a grid of monuments over an active longwall mine panel in southwestern Pennsylvania during a 1-year period. Both conventional ground surveying techniques and photogrammetry were used. The objective of this investigation was to compare elevation measurements of subsidence obtained from aerial and ground survey methods under dynamic ground conditions. The results of a statistical analysis of the survey data show that the mean of the differences between 372 matched pairs of elevation measurements was 0.20 ft (61 mm) with a 95-pct-confidence interval of 0.05 ft (15 mm). The mean of the absolute values of the differences was 0.38 ft (116 mm) with a 95-pct-con-fidence interval of 0.04 ft (12 mm). Ninety-five percent of the absolute values of the differences were less than 1.11 ft (338 mm).

Jan 1, 1988

Identity the difficulties of establishing vegetation on mining-related wastes resulting from adverse chemical, physical, and biological properties; describe the ecological and soil factors affecting the relationship between mycorrhizal fungi (soil microorganisms) and plants; and evaluate the feasibility of establishing vegetation on mine waste by introducing mycorrhizae. Problems in Revegetation Successfully using vegetation to stabilize a situ disturbed by mining-related activities depends on knowing the chemical, physical, and biological characteristics of the site prior to, or at the time of, stabilization. The primary objectives of mine land reclamation are to minimize environmental degradation and to facilitate the re-establishment of a functional plant-soil system. Mining disturbances can significantly alter the physical, chem¬ical, and biological characteristic of a site, thus affecting plant establishment, survival, and growth. The physical disturbance caused by the removal and replacement of soil and overburden, together with the waste material from ore processing, affect the chemical, physical, and biological process within the disturbed soil or waste. Additionally, variability in soil properties results from differences in climate, topography, vegetation, and parent material of the site.

Jan 1, 1993

By P. W. Jeran, C. D. Sullivan, C. M. McCulloch

A series of geological surveys were completed in six coal mines in connection with a Bureau of Mines research program on methane control. The aim of these surveys was twofold: First, to study the overall geology of the coalbed, and second to use the resulting data to evaluate the influence of the geological characteristics of the coalbed on safe and efficient coal extraction. This report explains the advantages of geologic maps and fence diagrams in coal mining, and how the knowledge gained from such geologic investigations of mines can help control many underground problems.

Jan 1, 1975

By David R. Forshey

This Bureau of Mines report presents a quantitative theoretical analysis of a coupled gasdynamics-heat release system involving the kinetics of water condensation in and behind the rarefaction wave in a shock tube using the method of characteristics. The merger of characteristics to form a shock wave is included.

Jan 1, 1977