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By C. M. K. Boldt, R. L. Levens, A. D. Marcy

Researchers at the U. S. Bureau of Mines conducted investigations to evaluate the potential for ground water contamination by mine waste used as backfill. Samples of cemented waste backfill and water discharging from drillholes and seeps were collected to use in chemical analyses and laboratory tests to determine the physical and chemical factors that control release of heavy metals to ground water. Greater water retention by cemented backfill (as compared to uncemented sandfill) reduces the surface are aexposed to oxidation, which in turn reduces the amount of acid produced. The acid is neutralized by the cement and minerals contained in the backfill. The grain-size distribution of tailings used for backfill affects the structural integrity of cemented backfill under attack by acidic water; breakdown of the backfill structure releases neutralizing materials faster. Backfilled stopes in rock with low hydraulic conductivities will constitute preferential flow paths after mine flooding; however, the rate of flow through backfill will be much slower than when the stope is partially saturated during mine operation. Considering all factors, acid generation and release of metal ions from cemented backfill should be less than in uncemented sandfill.

Jan 1, 1995

By James E. Hill

The Bureau of Mines has been carrying on an extensive diamond- drilling program during the past 7 years on deposits of strategic and critical minerals . Often the project reports and the drill-hole logs describe the findings only in terms of the mineral being sought at the time . Then , too , results may not always be interpreted alike by several mining engineers , and the cores therefore provide a permanent tangible record to complement the project reports . The cores from projects in the eastern divisions are being stored at the Mount Weather Testing Adit . Core from a representative hole ( or skeletonized sections from several holes , if these are more representative ) is selected at each project and shipped to Mount Weather for permanent storage . At the Testing Adit an underground room was prepared and storage racks were installed . Wooden core trays designed to accommodate cores of various sizes were purchased .

Apr 1, 1947

By Lloyd A. Morley, Robert Stefanko

This report was prepared by The Pennsylvania State University, College of Earth and Mineral Sciences, ' Department of Mineral Engineering, University Park, Pennsylvania, under USBM Grant No. GO-133077. The grant was initiated under the Coal Mine Health and Safety Research Program. It was administered under the technical direction of the Pittsburgh Mining and Safety Research Center with Mr. G. J. Conroy acting as the technical project officer. Mr. J. A. Herickes was the grant administrator for the Bureau of Mines. This report is a summary of the work recently completed as part of this grant during the period 19 June, 1973 to 17 June, 1975. This report was submitted by the authors on 18 July, 1974. This technical report has been reviewed and approved.

Jan 1, 1974

By R. V. Ramani, V. T. Burgos, J. A. McClay

Cost Data Library The data retained in the Cost Data Library is of a semi¬permanent nature in that it is held in storage for immediate use with the program although its contents may require periodic evaluation to maintain it in a current status. The library is composed of six arrays containing both technical and cost data. The following description of the library input system provides the information necessary to maintain an active storage file. Array POWERA: FORMAT (8F10.0) - contains the step groupings of the power rate schedule for power cost computations. Four input data cards are required to fill this storage area. Card Column 1 1 - 10 Demand in Kilowatts for the First Step of the Demand Rate Schedule 11 - 20 Demand in Kilowatts for the Second Step of the Demand Rate Schedule y 41 - 50 Demand in Kilowatts for Fifth Step of the Demand Rate Schedule 51 - 60 Maximum Demand Level for this Rate Schedule 61 - 70 Percent Power Factor for this Rate Schedule 71 - 80 Unassigned 2 1 - 10 First Step Demand Charge, $/Kw 11 - 20 Second Step Demand Charge, $/Kw 4¬ 41 - 50 Fifth Step Demand Charge, $/Kw

Jan 1, 1975

To provide safer and more efficient mine operations by improving the operational performance of underground trolley line communication systems. Approach The dc trolley line provides a convenient means of In-mine communication since it can carry signals to each phone on the system whether the phones are in mine vehicles or in a fixed location such as that of a dispatcher. In many cases, however, the system does not perform satisfactorily. Short communication range, noise, and dead spots commonly interfere with effective communication. These problems are inherent with the trolley line, which was designed to transmit power and not communication Signals. As a power line, the trolley line is connected to rectifiers and feeds many loads such as motors, water pumps, track block lights, etc. Each of these devices represents a low impedance radio frequency (RF) shunt that seriously reduces carrier communication Signals. Performance is therefore often poor and can be improved only if the effects of the various shunts can be reduced. The Bureau of Mines has developed numerous methods applicable to either existing or planned phone systems which can improve communication range and reduce the shunting effects of the various loads.

Jan 1, 1983

By Robert C. Ellman

The Bureau of Mines studied lignite pulverization in a laboratory ring-roller mill. Both moisture content and the source of lignite were found to be important factors in pulverizer operation. Reduction of moisture content increased capacity and reduced power consumption, but predrying is more effective than in-the-mill drying in improving pulverizer operation. A combination predrier-crusher system produced significant improvements but other efforts to improve in-the-mill drying in the test mill were unsuccessful. Pulverization of frozen lignite was found to seriously reduce pulverizer capacity and increase power requirements.

Jan 1, 1972

By J. E. Pahlman

As part of its goal to minimize the requirements for mineral commodities through conservation and substitution, the Bureau of Mines is conducting research to determine the resistance of alumina refractories to corrosion by alkali-containing slags that could result from burning of the abundant Western lignites in metallurgical operations. Static corrosion tests were performed at 1,000° to 1,350° C and dynamic tests were performed at 1,400° to 1,600° C to investigate the stability of refractory specimens in slag environments. In general, the degree of refractory attack increased with decreasing alumina content in the refractory and with increasing alkali content of the lignite ash. The parabolic kinetics observed in static tests suggested that a reaction product layer is formed through which ionic diffusion must occur to sustain the reaction with the refractory material. The linear kinetics observed in dynamic tests in high-viscosity slags indicated a shearing of the reaction product layer by viscous slags. The observed lesser attack of refractories by low-viscosity slags can be explained on this basis. Two 99-percent-alumina refractories and two 90-percent-alumina refractories formed an expanded protective layer with the more viscous slags but not with the less viscous slags. Corrosion of 90-percent-alumina refractories increased exponentially with temperature. In refractories with the same nominal alumina content, those that contain a combination of a-Al203 and mullite (3A1203?2Si02) have better corrosion resistance than those containing a combination of a-Al203, cristobalite (Si02 mineral), and mullite. In alkali environments (1,300 to 1,400° C), 90-to 99-percent-alumina refractories are recommended for use as furnace linings.

Jan 1, 1980

By Robert M. Becker

A thick-wall cylinder solution applicable to the evaluation of anisotropic elastic parameters is derived for the interpretation of stress relief data. For a restricted class of problems, a special relationship among certain orthotropic moduli yields stress distributions for the plane orthotropic problem that are identical to the corresponding isotropic case. A ring or hollow cylinder with these specialized anisotropic properties subjected to uniform radial loads is one of the problems in this class. Consequently, known stress solutions are used to develop the strains and displacements for a specialized orthotropic thick-wall cylinder under uniform pressures. The results are consistent with anisotropic equations used in the evaluation of in situ rock stresses.

Jan 1, 1968

By T. Christos

The explosive oils, nitroglycerin (NG) and ethylene glycol dinitrate (EGDN), were extracted from dynamites by a halocarbon solvent and were then determined by high-pressure liquid chromatography. Separation was achieved by liquid-liquid chromatography on a column packed with Durapak-Carbowax 400/Corasil II and the eluted NG and EGDN were detected with a double-beam ultraviolet detector.

Jan 1, 1973

By Edward A. Barrett, Roberta A. Calhoun

Introduction This Instructor’s Copy contains most of the materials trainers will need in order to use Drill Rig Incident (DRI). It includes suggestions for using the exercise, performance objectives for the training, master answer sheets, a scoring key, and a set of discussion notes that provides additional subject information. Four appendices are also included. Appendix A is the complete exercise problem booklet. It may be reproduced so that every person in the training class has one. Appendix B contains answer sheet blanks. The blanks are furnished if you choose to have the invisible ink answers that appear in appendix C printed on them at your location.3 Answer sheets are consumable. One is needed for each group of three to five persons who work the exercise together. An alternative is for each individual trainee to have his/her own answer sheet. Appendix D contains the 24-question pretest / posttest that was used in the field evaluation of the DRI exercise. Acknowledgment The authors thank Linda J. McWilliams, Statistician, NIOSH Pittsburgh Research Laboratory, for her assistance in analyzing the experimental data in this document.

Jan 2, 2005

To reduce air be respirable dust generated from emptying dry dust collectors on small truck-mounted drills used at surface coal mines.

Jan 1, 1995

By Edward D. Thimons

The Bureau of Mines conducted in-mine tests to determine correction factors applicable to low-velocity airflows (below 150 fpm) measured by the smoke cloud, vane anemometer, and oil of wintergreen tracer gas techniques 0 The average correction factors found for these methods of measurement were lower than those reported in the literature for use with higher velocity measurements. All tests measured airflows with controlled average velocities ranging from 50 to 100 fpm. Correction factors averaged about 0.75 for readings taken by the centerline smoke cloud method, remotely controlled and stickheld center" line anemometer, and split traverse stick-held anemometer. For hand-held centerline anemometer and oil of wintergreen tracer gas readings, correction factors averaged about 0.67. Since special anemometers are needed to measure airflows in this low-velocity range, and since proper calibration of these anemometers is difficult and expensive, the use of anemometers for low-velocity measurement is imprac-tical. On the other hand, smoke and oil of wintergreen give results as con-sistent as those obtained with specially calibrated, low-velocity anemometers. Furthermore, they are easy to use and inexpensive.

Jan 1, 1979

By P. W. Jeran, C. M. McCulloch, Maurice Deul

The natural vertical fracture sys tem in bituminous coalbeds is called cleat. Cleat orientation commonly controls the direction of mining with major development paralleling the face cleat. Previous researchers have categorized the origin of cleat as endogenetic, relating the origin of cleat to compaction and coalification, and exogenetic, relating the origin of cleat to tectonic forces. In the coalbeds studied for this report it was found that tectonic forces were the controlling factor of cleat formation. Face cleats were formed as extension fractures during structural deformation, and butt cleats, as release fractures during erosion and uplift. The face cleat of the Pittsburgh coalbed rotates from N 80° W in north- western West Virginia to N 57° W in southwestern Pennsylvania ; the face cleat maintains a perpendicular orientation to the shifting axial trend of local structures . Cleat orientation in other bituminous coalbeds in Virginia, Utah, Oklahoma, and Central Pennsylvania showed a similar relationship to local structure. Directional permeability of coal is directly related to cleat. Holes drilled perpendicular to the face cleat yield from 2.5 to 10 times the amount of gas released as compared with holes drilled perpendicular to the butt cleat.

Jan 1, 1974

By Peter. PH. D. Cain

Smoky River Coal Ltd. mines low-volatile metallurgical coal by surface and underground methods in the foothills of the Rocky Mountains of Alberta, Canada. Current underground operations are confined to the 5B-4 Mine. Development of 5B-4 began in January 1998; production from depillaring sections commenced in July 1998. This paper describes the history of underground mining on the Smoky River property in terms of extraction methods and pillar design. The development of the present pillar design guidelines is discussed in this context. Recent work to prepare a number of case histories for back-analysis using the Analysis of Retreat Mining Pillar Stability (ARMPS) method is described, along with the modifications developed for calculating the ARMPS stability factor for retreat extraction of thick seams. The design criteria are described, as well as the geotechnical program implemented in order to verify its applicability.

Jan 5, 1999

By Edward D. Thimons

A remote-actuated stench gas fire-warning system has been designed and tested by the Bureau of Mines. This system makes use of the hard-wire network for the mine's phone pager system, thus greatly reducing the system cost. By locating stench gas canisters with remote-actuation release capabilities near working sections, the fire-warning time can be greatly reduced. In a test of the system in a Missouri lead mine, the time required to warn miners of a fire at two working faces was reduced from about 20min with the conventional system to less than 4 min with the remote-actuated system.

Jan 1, 1984

Mine closing methods should be carefully considered. If not properly sealed, an abandoned mine may continue to produce acid water. Since 60 to 90 percent of the total acid discharged from all coal mines is from abandoned mines,(58) some states require that provisions for sealing be contained in the mining permit application. Closing an operation to prevent harmful mine drainage into nearby runs and streams is a subject of much concern to states as a result of continuing problems from long abandoned mines which were improperly closed.

Jan 1, 1970

By Steven J. Schatzel, Joseph Cervik, Gerald L. Finfinger

Gas drainage through surface bore¬holes has been the conventional means of methane control for U.S. longwall gobs. However, these vertical boreholes are becoming so costly, and the surface rights so difficult to obtain, that the Bureau of Mines is developing underground gob gas drainage as an alternate means of methane control for U.S. longwal..ls. Holes are drilled into the roof over the panel and on retreating longwalls, towards the working face from a location inby the face. As the longwall retreats, an increasing portion of the hole inter¬cepts the fracture system over the caved gob. A surface exhauster maintains a vacuum on a pipeline parelleling the panel and draws the methane mixture out of the mine. Auxiliary systems of gob gas drain¬age during longwall mining will be essen¬tial for an increasing number of coal mines. Deep and gassy mines often find ventilation insufficient for adequate dilution of methane in bleeder entries. Although this cross-measure method of degasification has been used successfully in Europe, some of the European tech¬niques cannot be directly applied to U.S. mines. This is the first study of its kind in this country.

Jan 1, 1982

By Kenneth B. Higbie

Expenditures to advance scientific technology in general reached an all time high in 1965 with some $22.2 billion estimated to have been allocated by government and industry. Federal Government expenditures were estimated at $15.4 billion, with almost 90 percent of the funds devoted to programs involving defense, atomic energy, and outer space efforts. With this massive effort in the United States and a very impressive effort elsewhere in the world, there is little wonder that many new metallurgical developments were announced in the technical press during the year. No effort has been made to cover all aspects of the industry, but a few of the developments are described in this chapter.

Jan 1, 1966

By Launa Mallett

This paper introduces a method for teaching workers to communicate necessary information when giving or receiving emergency warning messages. Research has shown that when an emergency occurs, people may not get the information they need to take appropriate action. Interviews conducted with 48 underground coal miners who had escaped mine fires revealed that the warning information provided was inadequate. In some cases, sufficient information was not provided to the endangered miners. At other times, miners failed to ask for information they needed to plan and execute effective escapes. Researchers from the NIOSH Pittsburgh Research Laboratory have been studying the content of emergency warning messages and have developed an emergency communication protocol. A training intervention that presents the protocol and related mental cues is being evaluated for effectiveness in improving the content of emergency messages. In this paper the protocol is presented and the training package described. The evaluation procedures and a summary of the analyses conducted to-date are also provided. The training package was developed for use with underground coal miners, but could easily be modified for emergency communications training in other settings.

Jan 1, 2000

The Bureau of Mines believes that all coal mines are potentially gassy; for the purpose of administration in the prevention of explosions and fires, the Bureau recommends: That any coal mine wherein methane or other combustible gas can be detected in amounts as much as 0.27 of 1 percent or more by frequent systematic searches shall be classified as a gassy mine. Permissible methane-indicating detectors such as are given in I.C. 7110 or subsequent lists of Bureau approved methane-indicating detectors, or conventional methods of sampling and analysis of required accuracy may be used. The concentration referred to in the decision is percent by volume.

Jan 1, 1941