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By H. Kenneth Sacks

The Bureau of Mines has developed hardware for electromagnetic (EM) detection and location of miners trapped in underground coal mines. This report describes a technique for using the developed equipment for locating uncased boreholes underground. Results of several field and laboratory experiments are described.

Jan 1, 1978

Determine the effectiveness of remining operations in reducing contaminant load (acidity, iron, and sulfate) of discharges emanating from abandoned surface and underground coal mines. Background Until the implementation of remining initiatives, most States had regulations that held the operator remining an abandoned site responsible for preexisting acid mine drainage (AMD) discharges. For example, if a mining. company wanted to remine an area hydrologically connected to an existing AMD discharge, the company became responsible, as soon as the site was activated, for treating that discharge to meet effluent standards. If the mining operation improved the quality of the discharge, but the discharge failed to meet effluent standards, the company was held accountable for perpetual treatment. Because of this regulation, most mine operators avoided abandoned sites with minable coal reserves and AMD discharges. However, changes in remining legislation allow coal companies to be released from treatment liability as long as the post-remining pollution load does not exceed the pre-remining level. If remining can improve water quality through improved mining and abatement techniques, abandoned mine land (AML) areas that previously were liabilities could become

Jan 1, 1994

By T. M. Ruff

A prototype mucking machine designed to operate in narrow-vein stopes was developed by Foster-Miller, Inc., Waltham, MA, under contract with the U.S. Bureau of Mines. The machine, called a compact loader-trammer, or minimucker, was designed to replace slusher muckers in narrow-vein underground mines. The minimucker is a six-wheel-drive, skid-steered, load-haul-dump (LHD) machine that loads muck at the front with a novel slide-bucket system and ejects it out the rear so that the machine does not have to be turned around. To correct deficiencies of the tether-remote-control system, a computer-based, radio-remote-control system was retrofitted to the minimucker. Initial tests indicated a need to assist the operator in guiding the machine in narrow stopes. An automatic guidance system that used ultrasonic ranging sensors and a wall-following algorithm was installed. Additional tests in a simulated test stope showed that these changes improved the operation of the minimucker. The design and functions of the minimucker and its computer-based, remote-control system are reviewed, and an ultrasonic-sensor-based guidance system is described.

Jan 1, 2010

By L. Cheng, M. S. Seehra, P. S. Raghoottama

The four major IR bands of a-quartz at 1080, 797, 693 and 488 cm-1 are studied at room temperature by FTIR-Photoacoustic Spectroscopy. Using Rosencwaig-Gersho theory, equations for the PAS signal q for the thermally thin and thermally thick cases are derived and it is shown how thin to thick transition occurs and leads to saturation as the sample mass is increased. For sample mass < 2 mg, q is proportional to sample mass thus defining the region for quantitative analysis. The dependence of q on the chopping frequency f is found to vary as q f-n with n ? 0.9 for quartz, in good agreement with the RG theory.

Jan 1, 1989

By Michael D. Fenton

The modest mineral industry of Afghanistan continued to suffer adversely from internal disorders that were essentially the result of the continued presence of elements of the armed forces of the U.S.S.R. Despite press reports near yearend intimating that the Soviets might reduce troop strength in Afghanistan, there were no indications of any significant numeric reductions. Indeed, there were clear demonstrations of heightened military actions along the Afghani-Pakistani border, including bombing raids on settlement sites for Afghanis within the territorial limits of Pakistan, actions hardly demonstrative of conditions indicative of Soviet withdrawal.

Jan 1, 1988

Improve the reliability and accuracy of subsurface images using constrained tomography with enhanced ray-tracing capabilities. Background Geophysical tomography is a technique for imaging the structure of a rock mass using seismic or radio waves, in the same way that medical CAT scans image human tissue using X-rays. Tomography has found numerous practical applications related to mining, including lithologic and structural characterization, fracture detection and fluid monitoring, void detection, and evaluation of stress state and integrity of mine structures. Problems Two fundamental problems have largely prevented geophysical tomography from enjoying the tremendous success achieved by medical tomography. The first is a consequence of practical limitations on the placement of sources and receivers of wave energy: ideal resolution can be attained only when the region being imaged is entirely surrounded by sources and receivers, so that it is crossed by rays traveling in all possible directions. When such coverage is impossible or impractical, the inversion becomes underdetermined: there id not enough information in the measured data to provide a mathematically unique solution. The second major problem in geophysical tomography is the necessity for detailed ray tracing. Commercial software, as well as previous U.S. Bureau of Mines (USBM) software, employs a ray-shooting algorithm that may be unable to model some ray paths when velocity contrasts are larger than about 100%. These ?shadow zones" result in loss of data and degradation of reconstructed images.

Jan 1, 1994

By Thomas E. Marshall, Timothy Batchler, Anthony T. Iannacchione

As the amount of new fractured surfaces or "damaged rock layers" within roof rock increases, the stability of the rock mass decreases. While direct measurements of this phenomenon are not easily made, there is good circumstantial evidence to support this hypothesis. For example, it is common to observe increased cracks or fractures in the immediate mine roof rock before a roof fall. Likewise, roof drill holes placed in areas that later fail often reveal increased numbers and/or separations of fractures within the rock column through time. And finally, the frequency of microseismic activity, representative of rock fracturing, increases before a roof fall. For this study, more than 700 microseismic emissions were collected from two underground limestone mine roof fall areas in southwestern Pennsylvania. Microseismic events were located and magnitudes determined using the moment magnitude technique. Moment magnitude is based on the event seismic moment, which is a measure of the seismic deformation. The amount of new fracture surface length was calculated based on the stored strain energy within the rock prior to fracture. In the two case studies presented, a significant amount of microseismic activity was observed as much as two days before the first signs of failure in the roof fall areas. Additionally, results from this analysis reveal much about the behavior of strata prone to failure and allows for the construction of hazard maps based on microseismic emissions. The potential use of this technique as a means of anticipating roof falls is analyzed and discussed.

By Yael Miron

Ammonium nitrate-fuel oil (AN-FO) mixtures are used as blasting agents in mining pyrite-bearing ores. The temperature of these ores can increase by the continuous, though at times slow, oxidation weathering of the pyrites. At elevated temperatures, AN-FO reacts exothermally with pyrite, and the reaction becomes self-sustained at 120° C ± 10° C. The Bureau of Mines has conducted an investigation to determine the reactivity of mixtures of AN-FO with pyrite containing ferrous sulfate. The results of tests in a heated vessel simulating a hot borehole demonstrate that small amounts of ferrous sulfate, a major product of pyrite weathering, initiate a self-sustained exothermic reaction with AN-FO at 80° C. Five pct by weight of urea was found sufficient to prevent a reaction among the three ingredients, at least within the limits of the test, which reached 180° C. Smaller amounts of urea and of potassium oxalate slowed down the reaction and delayed its onset to higher temperatures, but did not prevent it.

Jan 1, 1979

By H. K. Sacks

The Bureau of Mines has improved a mine dust incombustibles analyzer originally developed at the Bartlesville Energy Research Center (BERC). This analyzer provides quick, accurate analysis of the percentage of incombustible material present in dust samples taken from mine ribs, roof, and floor so that costly overdusting may be eliminated while still maintaining a proper level of incombustibles. The changes being effected on the present design of the BERC model IV rock dust analyzer should simplify its operation and calibration procedures, resulting in increased accuracy.

Jan 1, 1976

By William P. Diamond

A 3-inch pilot hole was directionally drilled to intercept the Freeport coalbed horizon horizontally at Mather, Pa., as part of a Bureau of Mines degasification project. The original concept was to continue the horizontal drilling into the coalbed, after the initial intercept, with a total of three horizontal holes eventually being completed. However, the erratic thickness (0.0 to 4.3 feet) of the Freeport coalbed at Mather was not sufficient to support the horizontal drilling degasification technique, and the site was abandoned after six attempts to locate adequate continuous coal thicknesses. The drilling of coreholes in the immediate vicinity of proposed well paths to evaluate coal thickness is essential prior to future slant hole operations. Although mechanical failures of the new directional drilling equipment, mud pump and rig breakdowns, directional control problems, and exploratory horizontal drilling in the Freeport horizon more than doubled the anticipated cost of the pilot hole, continuing improvements in directional drilling equipment and techniques should significantly reduce the time and costs of future drilling operations.

Jan 1, 1977

By H. H. Schrenk

One phase of the Bureau of Minest work in the field of health and safety is the promotion of safe, satisfactory, and reliable respir atory protective devices. To insure that such devices will be available, the Bureau has established schedules of what it considers the minimum re- quirements for oxygen breathing-apparatus,3 gas masks, hose masks,5/ and mechanical filter-respirators (a schedule of requirements for hose- type supplied-air respirators is being prepared). Approval of oxygen breathing-apparatus is given by the Safety Division; approval of other types of respiratory equipment is given by the Health Division, both divisions being in the Health and Safety Branch, Manufacturers of respiratory protective devices may submit their equipment to the Bureau for approval under the requirements of these schedules. As a prerequisite to submitting a device for approval, the Bureau requires a statement that the device is completely developed and of the design and material that the manufacturer believes suitable for a finished marketable device; that the device has been

Aug 1, 1937

By Kenneth H. Johnston

Information and data necessary for research on improving methods of oil recovery from low-permeability reservoirs and for comparison and evaluation of performance of such reservoirs with those producing from more permeable sands were obtained. Core analyses, well logs, production tests, well stimulation techniques, primary and secondary production records, and data on two water-flood projects were examined for wells producing from the Bartlesville sand, West Avant field, Osage County, Okla. Overall recovery from the study area was generally poor with only 9.0 percent of the pore volume recovered to January 1, 1968. Larger fracture treatments (8,000 to 12,000 gal) could have resulted in an increase in primary oil recovery. Secondary recovery by water-flooding accounted for only 1.9 percent of the pore volume because of the inability to control the large volume of injection fluid that escaped from the flood patterns and the excessive volumes of water produced with the oil. Future waterflood development in other low-permeability reservoirs should include the drilling of new input wells, use of injectivity surveys to locate possible natural fracture systems, or zones of high permeability, and control of injection fluids by altering flood patterns and/or plugging of the more permeable zones.

Jan 1, 1968

The Federal Mine Safety and Health Act of 1977* defines respirable dust as dust measured with a device approved by the Secretary of Labor and the Secretary of Health and Human Services [30 USC 842(e)]. The approved sampler for respirable coal mine dust is the coal mine dust personal sampler unit (CPSU) [30 CFR 74; Jacobson 1971; Jacobson and Lamonica 1969]. The CPSU is generally called the 10-mm nylon cyclone, although the 10-mm nylon cyclone is actually just one component of the CPSU. The CPSU may either be mounted on a worker (with the sampling head positioned in the breathing zone for personal exposure monitoring) or in a fixed location for area sampling [Tomb 1990]. The CPSU consists of a pump unit, a sampling head assembly, and a battery charger if rechargeable batteries are used in the pump unit [30 CFR 74.2]. The sampling head assembly contains two stages. The first stage is a 10-mm nylon cyclone, which has collection characteristics similar to an elutriator. The amount of dust penetration depends on the flow rate [Jacobson and Lamonica 1969]. The second stage is a membrane filter (vinyl, pore size 5 pm) that collects the dust passing through the cyclone. The dust collected on the membrane filter is weighed to a precision (standard deviation) of 81 pg [Parobeck et al. 1981], and the respirable dust concentration in the mine atmosphere is then determined from the mass of dust collected and the volume of air sampled [Tomb 1990].

Jan 1, 1997

By Andrew J. Fergus

A study of the flotation characteristics of columbium-tantalum minerals was made by contact-angle and microflotation methods, and the findings were confirmed by flotation of two natural ores. In the contact-angle study conditions for collection of columbite, pyrochlore, and tantalite were determined for (1) sodium oleate with a sulfonate; (2) sodium isooctyl phosphate; (3) a short-chain primary amine; (4) a long-chain primary amine; and (5) a quaternary amine. These conditions were confirmed in microflotation tests. Information about collector action on common gangue minerals was also obtained by these two methods. In batch flotation tests on a pyrochlore ore and a columbite ore, it was demonstrated that collectors selected on the basis of contact-angle and micro-flotation studies would float columbium minerals from a complex natural ore. However, multiple cleaner and scavenger flotation steps will be necessary to produce commercial concentrates. From a pyrochlore ore containing 0.54 percent Cb2O5, a 44.4 percent Cb2O5 concentrate was made containing 36.4 percent of the total Cb2O5. For a columbite are the corresponding values were: 4.35, 54.6, and 67.1 percent. During the batch flotation study, wetting agents were found to aid in the gangue-ore mineral separations.

Jan 1, 1968

Develop a training program to help mine workers effectively fight small fires in underground Goal mines. Training would enable miners to make rapid judgments on whether to attempt extinguishment, and how best to use the firefighting equipment on hand. Approach Fire reports were analyzed to define and delineate physical and behavioral variables which affect firefighting activities, and to determine effective procedures for extinguishing small fires. A course was then designed to train miners in such procedures. Finally, the course was reviewed by industry experts and administered to a group of miners to determine needed revisions and to validate the course. How It Works Analysis of fire data showed that six items should be emphasized in teaching proper fire response: 1. Alertness to fire potential. 2. Immediate power cutoff. 3. Internal, external communication. 4. Teamwork in fighting fires. 5. Role of ventilation and position of men inby the fresh air side. 6. Effective use of fire suppressant materials.

Jan 1, 1983

This report describes magnetic field measurements in the Helvetia Coal Co. Lucene #8 Mine for purposes of deriving a mapping of the magnetic field strength covering the major haulageways which contain conductors. The measurements were performed by Terry S. Cory, P.E. under U.S. Bureau of Mines purchase order P0372716. Assisting in performance of the measurements were personnel from the Bureau of Mines, PMSRC, and Helvetia Coal Co. Acknowledgement is given to Engineer Tom Strong of Helvetia Coal Co. who accompanied the measurement team and who lended support in performing the measurements and in supplying valuable engineering information for use in evaluation of the results. The results of the testing at medium frequency show that coverage of the entire mine area containing conductors can be achieved employing wireless radio techniques whereby radio signals are coupled into and are carried by these conductors. These results confirm earlier qualitative testing of the Collins Mine Wireless Radios in this mine. These results, performed over the frequency range 71-2890 KHz, illustrate the effect of frequency on the radio propagation with the conclusion that the best overall coverage is obtained at frequencies approximating 1000 KHz. This report presents all the raw data and the reduced data in the form of magnetic field strength contour maps. Sufficient information is provided to enable independent reduction of the data. A summary of observations which can be made directly from the contour maps is given.

Jan 9, 1977

By F. E. Griffith

Cost data are given for five methods of secondary backfilling of strip mines previously partially backfilled. The operations were conducted in north-central Pennsylvania; an average of 600 linear feet of highwall were backfilled in each trial. Major obstacles and the relative merits of the methods are discussed.

Jan 1, 1966

By David M. Hyman

Outbursts are sudden and violent releases of gas and coal that result from a complex function of geology, stress regime, and gas pressure and content. The Bureau of Mines has reviewed methods for prediction and mitigation of such outbursts in use worldwide, as an aid in selecting the proper techniques for use in specific mine environments. Outburst-prone coal may be distinguished from normal coal by its sorption-desorption velocity. Three types of methods used to characterize the kinetics of sorption-desorption are described; all are based on the ability of outburst-prone coal to release, through desorption, methane or carbon dioxide much more rapidly than normal coals. Other prediction methods, based on borehole samples, are also described. Various mitigation methods described and evaluated include (1) working the least stressed, less disturbed, lowest gas content seam in multiple-seam areas; (2) mine opening geometry; (3) inducer shot firing; (4) water infusion; (5) localized stress relief, using boreholes or by cutting a reliever slot in the longwall face; and (6) other gas drainage methods.

Jan 1, 1987

By A. May

Florida has accumulated about 400 million tons of phosphogypsum, a mineral process waste generated in the production of fertilizer, and is adding 30 million tons to this annually. To minimize storage of this waste and reduce potential environmental effects, the Bureau of Mines conducted research into utilizing the phosphogypsum, by identifying and developing high-volume uses for this material. Admixtures of phosphogypsum, fly ash, and lime that could produce a coarse aggregate suitable for road construction were investigated. Using phosphogypsum with asphalt, cement, cement-kiln dust, silica, clays, and oxychlorides to pro-duce aggregate was also examined.

Jan 1, 1985

By B. Dimitriades

The Bureau of Mines measured the reactivities of 19 hydrocarbons known to be prominently present in automotive exhaust and ambient air in a smog chamber. Results agreed well with those obtained using two other smog chambers. Reactivity scales were developed for hydrocarbons and aldehydes using the results of this work and those of a previous study. Application of the reactivity scales to automotive exhaust samples gave fair agreement between predicted and observed rate-of-N02-formation values; however, predicted and observed ozone yields were neither in agreement nor did they correlate well. This lack of correlation for ozone yield was attributed to the inappropriateness of (1) the individual component reactivity data, (2) the reactivity classification scheme used, and (3) the linear summation method. In seeking to understand this problem and to develop more appropriate reactivity scales, the data were examined from a reaction mechanism standpoint, and further studies were suggested.

Jan 1, 1975