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By Howard E. Parkinson

A brief description is given of various Bureau of Mines research activities that have begun since July 1974 and are not being reported on by others at the Third West Virginia University (WVU) Conference on Coal Mine Electrotechnology. An essential feature of the various projects is that they are pragmatic. The projects are applied research and are carried out both by the Bureau in-house research group and by other research groups through contract research. Projects have been directed toward wired-type communications with a special effort to modify the wired systems so as to be more effectively used. The projects are in three groups: Pager phone systems, trolley line phone systems, and guided-wire wireless communications. Also, a brief sketch is given of research that is essential for further developments in mine communications. From the early results of these various projects, the Bureau has good reason to project that there will be improved performance of existing communication systems and that communications will be extended to other individuals working in areas that are excluded from present mine communication systems.

By J. M. Stuve

This Bureau of Mines investigation measured the low-temperature heat capacities of FeOC1(c) and FeC13(c) in the temperature ranges of 6 to 305 K and 4.6 to 300 K, respectively. The standard entropies (S°, 298.15 K) of FeOCl(c) and FeC13(c) were derived as 19.73±0.03 cal/deg-mole and 35.33±0.07 cal/deg-mole. A large lambda transition was observed in the heat capacity of FeC13(c) at 8.4 K. The standard enthalpy of formation (?H°f, 298.15 K) of FeOC1(c) was determined to be -98.23±0.22 kcal/mole by HC1 solution calorimetry. High-temperature enthalpy measurements (H-H298.15) of FeOC1(c) were determined to 700 K by precision drop calorimetry. Standard thermodynamic formation data and related functions were tabulated at various temperatures for FeOC1(c) and FeC13(c).

Jan 1, 1980

By Harry Dobroski, Larry G. Stolarczyk

Medium-frequency (MF) techniques have been successfully .[pplied] to the problem of radio voice communications in both coal and metal and nonmental mines. Long range is achieved by taking advantage of existing mine conductors that carry and propagate the signal over vast areas. It is very likely that in the near future such systems will become the referred method for general mine communications. MF techniques can also be applied to the areas of in-mine control and monitoring. Preliminary work in this area is described. In a western mine, locomotives are being operated under MF remote control in a loading operation. In several eastern mines, MF has been evaluated as a method for monitoring the status of devices in remote areas of the mines. All control and monitor information uses existing mine conductors.

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal Workers Pneumoconiosis is the leading cause of death due to occupational illness among coal miners. This disease is caused by miners’ exposure to respirable coal mine dust. A Personal Dust Monitor has recently been developed to provide near real time feedback to miners regarding the number of milligrams of respirable coal mine dust in the air they breathe. This paper was prepared by the National Institute for Occupational Safety and Health to document coal miners’ reactions to this new device, and how they make use of the information it provides. Structured interviews were conducted with 30 coal miners at four mines. A four-stage conceptual model of miners’ decision processes with respect to how they interpret and respond to the dust exposure numbers from their personal dust monitor is proposed. The stages are: Diagnosis, Action Planning and Intervention, Evaluation, and Institutionalization. The interview responses provide considerable support for the model. Most miners paid attention to Personal Dust Monitor feedback and made efforts to reduce their dust exposure. Their efforts included: changing where they positioned themselves, making ventilation system improvements, and using respirators more often. The 29 miners who reported having experience wearing both the old and new type of dust monitors were asked which dust sampling system they preferred. Eighteen (62%) preferred the new monitors, 7 (24%) preferred existing monitors, and 4 (14%) had no preference. The most frequently cited advantage of the new monitor is its ability to provide relatively quick feedback on dust exposure. Miners provided several suggestions for improving the design of the instrument.

By Daniel N. Tallman

To provide technology for achieving more efficient water filtration systems for the mineral industry, the Bureau of Mines performed demon-stration filtration tests at three iron ore mines and one steel mill. A comparison of equivalently sized magnesium oxide (MgO) and sand filters showed that MgO had a higher capacity and could operate at higher fil-tration rates than sand. In demonstration tests when alum (AlK(S04)2) was the coagulant, suspended solids breakthrough occurred even though the pressure across the filter (head loss) was 7 psig or less. Under these circumstances, the MgO demonstrated 20 to 100 pct greater filtra-tion capacity, defined in terms of the volume of water filtered before breakthrough. When an organic floccu1ant was used at one location, head loss was the run-limiting factor; the filters essentially plugged with-out any solids breakthrough.

Jan 1, 1985

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of three samples collected from the Kidney seam, in the Northern Field of the anthracite region. Removal of the sink 1.70 specific gravity material from the samples collected would result in greatly reduced ash contents at yields in excess of 90 percent. The Kidney seam, in the locations sampled, proved to be a low-ash anthracite containing an unusually high percentage of float 1.45 specific gravity material.

Jan 1, 1970

By George E. Fasching

The Bureau of Mines has developed a pulse counting system with improved energy resolution and having dual channels to process pulses at different rates and a pulse pileup detector for channel selection. Pulse input is delayed until the detector determines if any pulse is so closely followed by a second pulse as to constitute pulse pileup. If no pulse pileup is detected, the slower channel is selected; this clips the pulse to a wide pulse width to retain good energy resolution. If pulse pileup is predicted, the fast channel, with correspondingly shorter pulse width, is selected to improve resolution with respect to time. Output of the two channels is transmitted to a pulse height analyzer for interpretation. The pulse processing system can process count rates above 300,000 counts per second with little loss in energy resolution.

Jan 1, 1974

By Gordon H. Dechman

This Bureau of Mines report presents an iterative approximation method for microseismic source location that was developed to adapt microseismic techniques for rock structure analysis to investigations of surface problems, such as slope failure in an open pit mine. The source location method and two derivative location algorithms are described in detail, and the speed and accuracy of the two algorithms are compared.

Jan 1, 1977

By Ralph B. Adair

The Bureau of Mines conducted laboratory and small-scale, continuous tests of weathered mica-pegmatite ores from Randolph County, Ala., to determine the feasibility of recovering commercial-grade mica concentrates by flotation. Two flotation methods were used in continuous tests for recovery of mica. One method utilized acid-cationic flotation for the recovery of coarse mica and alkaline-anionic-cationic flotation for recovering fine mica. This method yielded mica concentrates containing 98.6 percent mica with a recovery of 85.9 percent. The other method was based on the Bureau-developed alkaline-anionic-cationic method, and yielded concentrates containing 97.5 percent mica with a recovery of over 90 percent. In both methods, preconcentration of the ground ore on a Humphreys spiral was employed to reject over half of the feed in a product virtually free of mica.

Jan 1, 1968

By Wilbur I. Duvall

The borehole deformation gage and overcoring techniques developed by the Bureau of Mines form one of the primary methods of determining in situ rock stress. This report describes a least squares method of calculating the average rock stress components in the horizontal plane from more than three diametral deformation measurements in a vertical borehole. This least squares analysis provides a means of determining the multiple correlation coefficient, the variance, and the scatter for a set of deformation measurements. From this information, confidence limits can be calculated for the secondary horizontal principal stresses and their directions. The material presented in this report can be used as a guide to the development of least squares solutions for stress measurement techniques other than the borehole deformation method. Since the statistical information that results from the least squares method is extremely useful in the interpretation of results, it is recommended that a least squares analysis be used on stress measurement data whenever possible.

Jan 1, 1979

By C. H. Elder

An experimental degasification program using a vertical borehole and vacuum pump to drain gas from the gob area of a longwall panel was successful at Bethlehem Mines Corporation, Cambria Division, No. 33 coal mine. Sixty-one million cubic feet of methane has been exhausted during a 9-month period. Daily production time in the panel increased as a result of lower methane levels in the returns. Removal of large quantities of methane in this way and the exclusion of it from the ventilating system will provide reduced cost in mine ventilation and provide a safer environment for the mine.

May 1, 1969

Develop a method for mapping planar geologic features in deep underground mines where the presence of metal interferes with compass readings. Background A fundamental problem of mapping planar geologic features in deep underground mines is the presence of metal (water and air pipes, track, equipment, etc.), which affects the accuracy and consistency of compasses. Present geologic mapping methods include use of transits or theodolites, both of which are cumbersome and time consuming to use. To complicate the mapping, process each planar feature must be surveyed, and if that feature is not apparent on the opposite wall, it cannot be mapped. Another method of mapping is to stretch a tape measure between two survey spads and place a string along a planar feature on one wall and out into the opening until it intersects the tape measure. This method, in addition to being time consuming, is also inaccurate. Because detailed mapping of planar geologic features deep underground involves many repetitive measurements, a quick, accurate, and reliable method for making such measurements was necessary. The geolaser was developed to make such measurements in deep underground mines where metal interferes with conventionally used compasses.

Jan 1, 1990

To reduce the possibility of injury to operators and damage to equipment caused by collision of mining vehicles during coal loading. Approach An energy-absorbing bumper was developed and tested underground on a continuous miner. How It Works The bumper, a long box-like weldment backed by five energy absorbers, is attached to a continuous mining machine by a hinge behind the cab. See Figure 1. When a shuttle car collides with the bumper, or when it is otherwise struck, the energy absorbers are compressed. This absorbs and dissipates part of the kinetic energy of the colliding vehicle, thereby reducing or eliminating its destructive effects. Each energy absorber consists of two chambers separated by a freely-moving piston. One chamber (Figure 2) contains hydraulic fluid. The second chamber contains a gas. When a collision causes the absorber to compress, the hydraulic fluid in the first chamber is forced past a metering pin and through an orifice. The hydraulic fluid then pushes against the piston, compressing the gas in the second chamber.

Jan 1, 1978

Significantly reduce respirable dust exposures of longwall shearer operators when cutting out at the headgate. Approach As a result of Bureau research, a ventilation curtain is recommended to be mounted between the stage loader and the coal rib to more effectively prevent the ventilation air from blowing across the shearer drum as it cuts out at the headgate. Some mine operators already employ this method of reducing dust, but a vast majority do not. How It Works One source of extreme concentrations of respirable dust for longwall shearer operators is the shearer headgate drum as it cuts through into the headgate entry. As the drum cuts into the entry, it is exposed to the primary ventilation airstream. The high velocity air passes through and over the rotating drum, picking up large quantities of dust.

Jan 1, 1982

Eliminate accidental tramming of a cleanup tractor. Approach A switch was installed in the operator's seat cushion to pre-vent the cleanup tractor from tramming without an operator in the driver's seat. How It Works The operator must be seated, and the Forward/Reverse Switch (that controls tramming direction) must pass through the NEUTRAL position before the vehicle will tram. See Figure 1. A pressure-sensitive seat cushion switch, a solid-state relay, and a double-contact relay were added to the control circuitry of an S & S BMUAT -88 cleanup tractor to create this tramming interlock. The weight of the operator on the cushion closes the seat cushion switch (Figure 2, A). This activates the solid-state relay (B), which completes the initial circuitry. Moving the For- ward/Reverse Switch (C) to NEUTRAL energizes the coil in the double-contact relay (D) and closes both contacts. One contact completes a sustaining circuit which keeps the double-contact relay energized. The second contact transfers power to the remaining contacts within the Forward/ Reverse Switch. These circuits are shown in greater de- tail in Figure 2.

Jan 1, 1978

To produce industrial-grade titanium castings by processes that are nonpolluting and lower cost than the currently used rammed-graphite process. Approach Foundry-grade zircon and olivine sands, bonded by waterglass or bentonite, are used to make shell or rammed molds which require relatively low-drying temperatures and do not generate noxious fumes during drying or casting. Procedures Three separate processes have been developed which meet the stated pollution and cost goals. These are: 1. Waterglass-bonded rammed zircon or olivine sand molds are dried at 480°F, zirconia washed, redried, and used in an inductoslag or skull-casting furnace. 2. Waterglass-bonded zircon or olivine sand shell molds are formed at 560°F, cured at 620°F, zirconia washed, dried at 480°F. and used in an inductoslag furnace. 3. Rammed zircon and olivine sand molds are bonded with western bentonite, zirconia washed, dried at 980°F, and used in an inductoslag or skull-casting furnace.

Jan 1, 1981

By Robert P. Vinson, Fred N. Kissell, Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

Provide an inexpensive, simple means of supporting highly yielding ground In underground mines. Approach The Bureau of Mines developed a high capacity support post made from standard steel pipe which, when using a 60-inch post configuration, has a 45-ton capacity and a yield length of 24 inches. How It Works The post mechanism is a three-piece unit consisting of a top and bottom leg (made from standard steel pipe) and a separate foot bracket. During installation in the mine, the bottom leg is placed on a relatively flat surface on the mine floor and the top leg is placed over it until its flared end contacts an expansion ring attached to the bottom leg. As the roof and floor converge, the flared end of the top leg is forced into the expansion ring, causing the walls of the top leg to be deformed radially and along the axis. The mechanism will yield until the unit bottoms out after about 24 inches of yield.

Jan 1, 1987

By T. O. Llewellyn

The Bureau of Mines conducted laboratory batch beneficiation tests on a waste granite sludge from New Hampshire to determine the feasibility of recovering a reusable silicon carbide product. The granite sludge responded to attrition scrubbing, desliming, and flotation in either alkaline or acid circuits using fatty acid as a collector. Recovery of over 80 percent of the contained silicon carbide at grades of up to 96 percent SiC was obtained.

Jan 1, 1975

By R. Unger, L. Mallett

The use of virtual reality (VR) technologies to train miners is an evolving area in research and development. In July 2006, representatives of 14 international organizations met to discuss current VR-related efforts and explore ways to employ VR in the future. This paper gives an overview of the various approaches presented at the meeting and discusses directions for future implementation. An example of a training package that teaches mine map-reading skills is presented. The meeting was the first step to building collaborations for furthering VR applications for mining. Planning has begun for a 2008 meeting open to broader participation. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.