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By G. F. Kuncir

The funding tables included in this report were defined in support of an evaluation of the Advancing Oil Sale Mining Technology Program undertaken by The Aerospace Corporation. Because of the sensitive nature of the fiscal planning information, the tables have been separated from the main analysis report and given a limited distribution.

Jan 1, 1977

By C. P. Mangelsdorf

This report deals with the efforts to develop a portable device suitable for underground use for the purpose of measuring the frequency of vibration of the horizontal chords of Birmingham roof trusses. Four devices are investigated and evaluated. An approximate emperical expression developed from a mathematical analysis provides a means of converting the frequency into tension. The method appears to be effective in mines with shale roof but requires some modification for other roofs.

Jan 1, 1983

By R. B. Tippin

Research investigations conducted on five ore samples show the applicability of heavy liquid separation (HLS) techniques to mineral processing. Under proper operating conditions, semicontinuous tests in small fluid cyclones yielded 90 percent sink-float concentrates with recoveries exceeding 90 percent on minus 35-mesh ore samples of kyanite, potash, spodumene, fluorspar, and beryl. Although none of the ores were examined in detail, their response to this novel concentration method provides basic examples that are typical of the process. Various aspects of cyclone design and operational characteristics of heavy liquid cyclone circuits were studied which demonstrated the flexibility of HLS by using multiple units connected in series. A comparison of two heavy liquid solutions, tetrabromoethane and methylene bromide, exhibited their individual advantages and limitations. Unique problems relative to this process are discussed including liquid viscosity, mineral composition of the ore, toxicity, and material handling hazards.

Jan 1, 1968

By Michael J. Gallagher

Diamond-bit performance data accumulated by the Bureau of Mines in core-drilling limestone and dolomite show that the physical characteristics of the diamonds and the sizes and types of bits used are economically significant. An analysis of the data establishes one trend of particular significance to those engaged in core drilling: Bits set with small, low-quality drill bort are the most economical. Detailed analysis of the factors that affect diamond-bit performance, such as size and quality of diamonds, sizes and types of bits, percentage of core recovered, and physical characteristics of bit matrices are assessed in the tables, bar charts, and discussion.

Jan 1, 1958

By D. R. Tesarik

An instrumentation and numeric modeling study was conducted by the Bureau of Mines at the Magmont Mine in Bixby, MO. An isolated section of this room-and-pillar mine was monitored with borehole and closure extensometers during a pillar recovery program to determine stress redistribution. In situ stress measurements were taken in the rib before pillar extraction began. Sample cores from the boreholes were taken for analysis of the properties of the host rock in the laboratory. The extensometers recorded no measurable displacements during most of the operation. Two-dimensional, finite-element; three-dimensional, finite-element; and three-dimensional displace-ment discontinuity codes were used to model the area of study. The finite-element models were run with two initial stress conditions, i.e., stress due to gravity only and stress obtained by in situ measurements. Horizontal stresses in the models reduced the calculated factor-of-safety in the mine back by up to a factor of 10, but did not have a significant effect on calculated pillar stability.

Jan 1, 1989

Reduce dust on long wall faces by using a gob curtain to lower air leakage Into the gob and raise the airflow along the face. Approach A brattice curtain (gob curtain) Is hung between shield #1 and the rib in the headgate entry forcing the ventilating air stream to make the 90° turn and stay on the face side of the shields rather than leaking into the gob. How It Works Air leakage is greatest in the headgate area because the gob behind the first few shields remains open due to the roof bolts in the headgate entry. In addition to the open gob, there is a large gap between shield #1 and the rib. Prevention of air leakage behind the shields is accomplished by the Installation of a curtain between the first shield and the rib extending from the roof to the bottom. The curtain Is advanced with the shield line each pass and is helpful In maintaining a sufficient air quantity along the face. The biggest Improvement due to this curtain is seen in the first 25-30 shields where the Increased air volume lowers dust concentrations through dilution.

Jan 1, 1981

By D. E. Kirby

In the preparation of beryllium-copper alloys by fused-salt electrolysis, beryllium was electrowon from beryllium oxide dissolved in fluoride electrolytes and deposited on copper cathodes. At 880° to 1,030° C, deposition was on solid cathodes. Beryllium deposited on the copper, forming a liquid alloy that dripped from the cathode. Dripping alloys containing 3 to 4 weight-percent beryllium were produced with as high as 90 percent cathode current efficiency, by electrolysis at 910°.C. To prepare alloys of higher beryllium content, attempts were made at depositing beryllium on liquid copper cathodes. These efforts were generally unsuccessful, although alloys containing as much as 12 percent beryllium were prepared by this method. At temperatures of 1,100° to 1,300° C, requisite to maintaining beryllium-copper compositions as liquids, the beryllium reacted with cell structures.

Jan 1, 1972

By M. Terry Hoch, George J. Karabin, James M. Kramer

This paper introduces the fracture mechanics approach—a unique way to predict the stability of a coal mine panel. The technique uses analytic equations to calculate the stress, strain, and yield characteristics of coal support systems. It uses fracture mechanics to model almost every type of mine support structure. Another feature is a method that incorporates field-tested knowledge into the analytical analysis. For example, this technique can model the yield characteristics of a coal seam by combining empirical pillar strength equations into the analytic analysis. It may be possible to simulate multiple-seam mining by incorporating subsidence methods into the analysis. The method is simple and quick, which makes it attractive for stress analysis software. It should be more accessible to those in the mining industry who do not have expertise in rock mechanics or numerical modeling. Although the purpose of this research is for modeling coal mines, it should be adaptable to any mine in a tabular deposit.

Jan 1, 1999

By Edward F. Divers

This Bureau of Mines report describes the results of a laboratory evaluation of a mechanical dust collector (scrubber) suitable for underground coal mine applications. The scrubber was developed by the Mining Research and Development Establishment (MRDE), Burton-On-Trent, England, and tested at the Federal Bureau of Mines Pittsburgh Mining and Safety Research Center (PMSRC) as part of a technical exchange program. The 2,000-to 8,000-cfm scrubber consists of an electrically driven vane-axial fan, water sprays, a 2-inch-thick, loosely knit stainless steel wire filter panel, and a water droplet eliminator. The dust-laden airstream travels axially through the water sprays, filter panel, fan, and eliminator. Slurry water drains into a sump where a belt-driven pump recycles it back to the sprays. Fractional breakdown tests showed a maximum dust collection efficiency of 96 pct of respirable-size (less than 7 µm) coal dust at 2,000 cfm. Efficiency decreased with increasing airflow; for example, to 91 pct at 6,000 cfm. Following these tests the original wire panel was replaced with a similar but smaller panel developed at PMSRC; a marked improvement in dust collection occurred at all flow rates tested.

Jan 1, 1979

Provide blasting-resistant, quickly reusable stoppings for large mine openings. Approach Stoppings are assembled using roof-to-bottom panels of brattice held together by Velcro seams that peel open when struck by a strong air blast. How It Works The Velcro seam is designed to open when exposed to forces lower than would normally damage the brattice. When the seams partially open, they relieve the blast air overpressure to prevent damage to the brattice panels and their anchoring devices. A stopping is returned to service by reclosing the Velcro seams. To hang a brattice panel, its top is stapled to a board, and wrapped once or twice around it. That assembly is then attached to the roof with bolts. The length of the board should be a foot less than the width of the panel to allow for the sealing seam on each side of the panel. The boards are installed end-to-end in an approximately straight line across the roof of the mine opening.

Jan 1, 1979

By Marvin L. Whisman

A radiotracer technique developed by the Bureau of Mines extends to the parts-per-billion range the sensitivity for determining contributors of deposits formed in stored and thermally stressed jet fuels. The method depends upon measuring radioactivity associated with thermally induced deposits from fuels containing one labeled compound. The technique was applied to 88 test blends, representing 12 fuels and nine carbon-l4 labeled fuel constituents or fuel additives, or both. Data from results of these tests are included in this report. With this radiotracer technique, the contribution of fuel components and additives to thermally induced deposits in a variety of fuel environments was estimated before and after storage.

Jan 1, 1969

This chapter describes the adverse health effects associated with exposure to respirable coal mine dust. Epidemiological studies of underground and surface coal miners in the United States and other countries are discussed. Also discussed are animal studies that add to our understanding of particle deposition and retention in the lungs and associated disease responses. This chapter emphasizes studies that (1) were performed since the passage of the Federal Coal Mine Health and Safety Act of 1969 [P.L. 91- 173], (2) used standardized methods of exposure monitoring and disease classification, and (3) investigated exposure-response relationships between respirable coal mine dust exposure and disease. Several published review articles contain further discussion of health effects studies of coal miners [Attfield and Wagner 1992b; Petsonk and Attfield 1994; Cotes and Steel 1987; Merchant et al. 1986; Morgan and Lapp 1976; Morgan 1975].

Jan 1, 1997

By Charles C. Boley

The Bureau of Mines dried and carbonized two wood wastes, one softwood (redwood) and one hardwood (oak), using continuous, vertical entrainment techniques previously developed for use with coal. It was demonstrated that these techniques are readily applicable to wood waste and that appreciable changes in the yields of carbonization products can be obtained by varying operating conditions. A limited amount of experimental work was done on briquetting the char-coals. Firm briquets were formed with oak charcoal, although greater quantities of starch binder than used commercially for kiln-produced charcoal were required. Redwood charcoal did not briquet successfully under the test conditions employed.

Jan 1, 1969

By E. Chin

Natural gas was Bangladesh's only significant exploited mineral. A few other minerals or mineral-based commodities were produced for local consumption. The most valuable were nitrogen fertilizer, salt, cement, and clay for brick.2 The most important mineral industry development of 1987 was the start of modest production of crude oil, the first discovered and produced in the country. PRODUCTION AND TIADE Production of natural gas from the nation's huge reserves continued to increase but was limited by the lack of residential and industrial demand. Gas reserves of 7 trillion to 16 trillion cubic feet were sufficient for far more production than the country could efficiently utilize for many years. The country's consumption-to-reserves ratio was one of the lowest of the developing nations. Mineral exports have been insignificant, comprising a small amount of nitrogen fertilizer. Nitrogenous fertilizer exports could become important when planned new capacity comes on-stream. Mineral imports were dominated by crude petroleum.

Jan 1, 1989

By David P. Lindroth

The heat content above 25.0° C up to 1,000° C was measured for six rock types: St. Cloud Gray Granodiorite, Holston Limestone, Sioux Quartzite, Rockville Quartz Monzonite, Salem Limestone, and the basalt at Dresser, Wis. The calorimetric data were obtained with an isothermal jacket-copper block calorimeter. The experimental heat content data for each rock type are presented, along with specific heat data obtained from the temperature derivative of the heat content. For the six rock types the maximum deviations of the specific heats at a given temperature were within 10 percent below 575° C and within 34 percent above 5750°C. The increase in the values of specific heat range from a minimum of 13 percent for the basalt at Dresser, Wis. (temperature range, 100° to 1,000° C) to a maximum of 46 percent for Holston Limestone (temperature range, 100° to 870° C).

Jan 1, 1971

By Mark Larson, Steve Iverson, Brian G. White

The authors hypothesize that excavation-induced extension fractures are caused by elastic shearing displacement that in turn causes tension oblique to a propagating shear zone. Such extension is manifested as tension on scales larger than that of microcracks. En echelon fracture patterns are a common result. FLAC modeling confirmed that localized tension is created near the corners of mine openings. In the model, tension was concentrated at the leading edge of a simulated fracture in a pattern that could promote the formation of an en echelon fracture. Particle Flow Code models confirm progressive formation of en echelon tensile failures with distance from an opening. The elastic displacements and the resulting fractures facilitate reduction in applied load at the expense of shear deformation and lateral dilation. Understanding the mechanics of fracture and deformation is vital for designing more effective ground support practices, a major objective of ground control research being conducted at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health.

By A. J. Rambosek

An evaluation of diamond-bit performance data accumulated from core drilling in quartzite shows that core recovery and physical characteristics of drill bits and diamonds have economic significance. Relatively inexpensive, low-quality, small Congo diamonds will perform as well as, or better than, other diamonds used as drill bart. M-type bits set with oriented Congo diamonds provide those engaged in core drilling with near optimum combination. Various factors that affect bit performance, including size of diamonds, size and type of bits, grade or quality of diamonds, and percentage of core recovered, are evaluated by means of tables, charts, and discussion.

Jan 1, 1958

By A. W. Hall

A neutron meter was developed for monitoring the sulfur content of coal streams. Neutrons from 80 micrograms of californium-252 penetrate the coal, producing thermal neutrons that are captured by atoms of elements present in the coal. The excited atoms emit prompt gamma rays with energies characteristic of the capturing element. These gamma rays are detected with a 6-by 7-inch sodium iodide detector and processed by electronic equipment to produce a gamma ray energy spectrum of the elements. Tests of the meter at a commercial coal preparation plant showed that sulfur in moving coal can be determined to a precision of 0.05 percent sulfur within 2 minutes. Based on this report by the Bureau of Mines, reliability of the coal-handling system proved inadequate for long-term operation, however, and improvements are planned.

Jan 1, 1975

By E. J. Gleim

"Information gathered during recent months by field men of the U. S. Bureau of Mines shows that in one State alone there have been 71 fatalities from electrical causes during the last 51/2 years, of which 55 were from contact with mine trolley wires operated at 250 volts or less, direct current. The 1928 law relating to the guarding of trolley wires in the-mines of this particular State reads: ""All trolley wires carrying a voltage of class 2 must be properly shielded except where the same are at least 61/2 feet above top of rail."" Class 2 voltage is defined as being ""between 300 volts and 600 volts direct current, or 240 volts and 480 volts alternating current."" From this it may be inferred that no guards are required, for 250-volt trolley wires, and the natural conclusion to be drawn is that the lack of guards or shields must be held responsible for these fatalities. To prevent fatalities from this source, it has been advocated that every foot of trolley wire in mines should be guarded. While some such drastic step may appear to be amply justified, a closer examination of the records shows that lack of guards is not entirely responsible but rather that carelessness and neglect in the observance of certain well-established simple rules concerning installation and location of trolley wires must also bear a share in the responsibility. In -other words, if trolley wire is installed carelessly and its maintenance neglected, failure may be expected of any guards that have been put up.There are a-number of factors affecting safety as related to trolley wires in mines, among which the following may be enumerated.1. Installation relative to track and passageways.2. Guarding.3. Maintenance.4. Discipline.Acknowledgment is made to D. Harrington and K. L. Marshall of the safety division of the bureau for assistance given in securing data on cost of installing guards for trolley wires.The statement that fatalities should not be charged in every case to lack of guards is supported by the following example: A man operating a locomotive was electrocuted when the trolley wheel jumped the 250-volt trolley wire and allowed it to sag against his shoulder. He was sitting in the regular place provided in the locomotive, but the wire was 11 inches inside of the rail and only 39 inches above it where the wire touched him, or 11 inches from the roof at a distance of 12 feet from the nearest hanger. The accident occurred between two hangers 44 feet apart, and the trolley wire was inside the rail over the entire distance, being 2 inches inside at one hanger and 10 inches inside at the other hanger. A bolt in the roof indicated that there had been a hanger at one time between the two on the 44-foot span.This example is a violation of good practice in the installation and maintenance of trolley wire. In the first place the wire should have been outside instead of inside the rail. In the second place there should have been at least one intermediate hanger so that the span would not be so great and the sag would be reduced. Furthermore, it is possible that the wire was not taut enough even when the intermediate hanger was in place.To provide a degree of safety for men in the mines certain coal-mining States, recognizing the need, have enacted laws to regulate the installation of trolley wires. These limit the distance that the wire must be kept outside and above the rail. Thus, the 1927 mining laws of Ohio specify that:"

Apr 1, 1932

By Carla A. Kertis

Because coalbed discontinuities often pose serious economic and safety problems in underground coal mines, criteria were documented for the recognition and prediction of discontinuities in advance of mining. Pennsylvanian strata in Indiana and Armstrong Counties, PA, were deposited as part of fluvio-deltaic complexes with channel-phase sandstones as the predominant type of coalbed discontinuity. Coalbed isopach maps constructed for this study delineated numerous want areas (areas of no coal) with elongate to linear geometries. A comparison of coalbed isopach and corresponding sandstone isolith maps of the study area revealed many examples of a thick-sandstone, thin-subjacent-coalbed relationship. Nearly 60 pct of the want areas in the study area were found to lie subjacent to thick (> 20 ft [6 m]) sandstone accumulations. In addition to erosion of the coalbed, channels may contribute to coalbed splitting, coalbed thinning over paleotopographic highs, abnormal coalbed thick- nesses, and deterioration of coal quality. If these features are considered, then approximately 80 pct of all interruptions in the economic coalbeds in this area result from channel activity. By using the criteria developed in this study and described in this Bureau of Mines report, the occurrence of coalbed discontinuities may be predicted and anticipated in advance of mining.

Jan 1, 1985