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By A. V. Hooker, E. J. Coggeshall

"The Bureau of Mines for some time advocated the firing of all blasts in coal mines as single shots, and this method of firing is the general practice in American bituminous-coal mines. All single shots can be fired with permissible single-shot units so designed that they will not ignite mixtures of methane and air.If several shots in a face are fired singly it is necessary to return the face after each shot. In some mines having steeply pitching coal seams, this may be dangerous or even impossible, under these conditions shots are usually fired simultaneously.Several shots cannot be fixed simultaneously with permissible single-shot blasting units, and safe types of multiple shots blasters are not readily available. This means that the firing of multiple shots in gassy mines is usually accompanied by the possibility of gas ignition as the blast occurs.Tests have been made at the Pittsburgh Experiment Station to determine the possibility of developing safe types of multiple-shot units suitable for such use, or of applying other type safely in gassy sections of mines where firing shots singly is impracticable.The tests may be divided into the following four groups:1. Tests to demonstrate hazard in the use of existing types of multiple-shot units of the portable generator type.2. Tests to show the electrical characteristics of multiple-shot generator units relative to the possibility of preventing igniting sparks and of modifying the design and application of such units in furthering safety."

Mar 1, 1935

By Norman G. Foster

The mass spectra of four tertiary butyl substituted thiophenes are reported. A comparison and contrast with earlier structure correlations made by API-RP48 mass spectroscopists is presented. The fragmentation routes of these types of molecules are discussed and explained in terms of existing theories in mass spectrometry. Low ionization voltage data are presented to support the mechanistic picture developed. Structures are inferred about some of the ions, and these are correlated with existing theories. Metastable peaks in the spectra are used to support the fragmentation paths. The presence of doubly charged ions in the spectra is noted and the possible implications toward mechanisms discussed. The general picture of simple, small fragments leaving the ion moiety upon further fragmentation is developed in detail. Some suggestions are presented for further work utilizing isotopically labeled molecules to establish firmly the general picture of fragmentations of the alkylthiophenes.

Jan 1, 1966

By T. M. Barczak

A primary objective of the Bureau of Mines geomechanics research program is to develop a better understanding of support behavior and interaction of supports with the strata so that supports can be more closely engineered to the geological conditions in which they are employed. Four longwall shield supports were instrumented with an eight-transducer instrumentation array to measure leg, canopy capsule, and compression lemniscate link forces from which resultant shield loading was determined. The instrumented supports were monitored over a 4-month period, producing over 75 shield cycles of resultant shield loading. Resultant loading is the true measure of support resistance, providing both roof-to-floor and face-to-waste support reactions as well as the location of the reaction on the shield canopy. Observed roof support reactions were analyzed, with particular emphasis on horizontal shield loading, since it is the least understood design parameter. Average, peak, and change in shield loading during the mining cycle are discussed. Correlations among data parameters are examined, as is the distribution of support loading at the headgate and midface. Conclusions are drawn as to the effectiveness of the shield support at this installation. Recommendations are made for further research needs.

Jan 1, 1987

By F. S. Boericke

"INTRODUCTION The mineral found in natural-chromite deposits is never pure Fe0.Cr203, but rather one in which the Fe0 and Cr203 are in part replaced by Mg0 and A1203, respectively. The purest gravity concentrates from many domestic de¬posits consist of a mineral referred to as ""picotite,"" in which this isomorphous replacement is such that the ratio of chromium to iron is low. The Bureau of Nines has investigated methods of chemically beneficiating ores that contain too much iron to be classed as ""high-grade"" chromite 3/ Early investigations 4/ demonstrated that high-iron chromite or picotite ores can be roasted with carbon to obtain selective reduction of the contained iron, and that most of this reduced iron can be removed by acid-leaching the roast products to produce residues of higher chromium-to-iron ratios. tests 5/ indicated that commercially acceptable reaction rates cannot be obtained at roasting temperatures below 1,3000 C., using solid carbon as reducing agent. By this high-temperature reduction and subse¬quent acid-leaching, however, all ores investigated, regardless of the original composition, readily yielded residues considerably better than the minimum specifications for high-grade chromite.In an effort to obtain satisfactory reduction of chromite at lower temperatures, liquid and gaseous seducing agents were tested with varying success. Of the several reducing agents used, methane appeared to be the most promising and was shown to be highly effective at temperatures between 1,000º and 1,100º C., roughly 300º below the roasting temperatures necessary in solid carbon reduction. Further experiments indicated that mixtures of methate with some diluent (hydrogen or other nonoxidizing gas) gave better reduction than did methane alone."

Feb 1, 1946

By Manuel Gomez

The Bureau of Mines used data from 31 core samples to develop prediction equations for evaluating chemical and carbonization properties of six seam units in a lignite deposit approximately 2 miles wide and 8 miles long in the Wilcox Formation of central Texas. Statistical response surfaces, based on core analyses, were computed for 14 parameters indicative of lignite quality. These computed surfaces, and their mathematical equations, can be used to predict values of the selected properties of the lignite seams at any desired surface coordinate position between core hole locations. The wide range of application shown by this study indicates that the methods of statistical regression analysis may be useful to evaluate large deposits of lignite or higher rank coal.

Jan 1, 1969

By W. E. Dennis, M. M. Fine

"INTRODUCTION During peacetime, the United States uses less than 3,000 tons of chemical-grade celestite annually. The war need, however, was estimated to exceed 15,000 tons a year.Hitherto; most of the required chemical-grade ore has been imported from England, Mexico, and other foreign countries. If foreign sources do not find it possible to meet the demand for ore of chemical grade (plus 92 percent SrSO4), it is expected that requirements could be satisfied by concentrating low-grade domestic ores. Celestite deposits on Brown, Nolan, Fisher, and Coke Counties, Texas, are considered to be possible sources of supply for this low-grade material. The Bureau of Mines explored the most important deposits to determine the grade and amount of ore available and conducted ore-dressing tests to obtain a suitable method of concentration.The exploratory work, consisting of test pitting and sampling, was carried on under the direction of W. E. Dennis, one of the authors of this paper, from October 8, 1942, to January 30, 1943. The ore dressing-tests described herein were conducted at the Bureau of Mines Laboratory at Rolla Mo.In this report, a particular deposit is referred to by the name of the landowner on whose .property the .deposit lies. The location of the deposits investigated is shown on figures 1, 2, 3, and 4.The celestite deposits were previously studied by the Bureau of Economic Geology of the University of Texas, and the results of its investigation are published in Mineral Survey Circular No. 46."

Feb 1, 1947

By William Porter

Hand scaling is a physically demanding job and is responsible for numerous overexertion injuries in mining. This experiment studied rib scaling from an elevated bucket to examine force generation capabilities and electromyographic responses to a prying subtask. Subjects exerted force using two bars (steel and fiberglass) at five target heights. Work height significantly affected peak prying force during scaling activities with highest force capacity at the lowest level (p = 0.0188). Bar type did not affect force generation (p = 0.7843): However, use of the fiberglass bar required significantly more muscle activity to achieve the same force (p < 0.05). It was concluded that miners should scale points on the rock face that are below their knees, and reposition the bucket as often as necessary to do so. Additional research is needed to fully understand the impact of bar type on the physical demands of an entire scaling task.

Jan 1, 2006

By Kray Luxbacher, Mario Karfakis, Erik Westman, Peter Swanson

Three-dimensional velocity tomograms were generated to image the stress redistribution around an underground coal longwall panel to produce a better understanding of the mechanisms that lead to ground failure, especially rockbursts. Mining-induced microseismic events provided passive sources for the three-dimensional velocity tomography. Surface-mounted geophones monitored microseismic activity for 18 days. Eighteen tomograms were generated and high-velocity regions correlated with high abutment stresses predicted by numerical modeling. Additionally, the high-velocity regions were observed to redistribute as the longwall face retreated, indicating that velocity tomography may be an appropriate technology for monitoring stress redistribution in underground mines.

By Dale W. Richardson

Ductile hafnium was not obtained consistently by the conventional Kroll process. The bimetal reduction modification produced a more ductile hafnium by lowering the impurities, especially oxygen, in the sponge metal. Hafnium oxide was chlorinated in the presence of carbon to form anhydrous hafnium tetrachloride, which was reduced by sodium and magnesium in an inert atmosphere to produce sponge hafnium metal. After vacuum distillation to remove the byproducts, the sponge was arc-melted into ingot and rolled into strip. Metallic impurities were decreased by evaporating the hafnium tetrachloride from a fused salt. An excessive amount (over 1,200 parts per million (p.p.m.)) of aluminum was contained in some of the hafnium oxide, much of which remained as aluminum chloride in the hafnium tetrachloride during chlorination. Evaporation of the hafnium tetrachloride from a fused NaCI-KCI mixture during the Mg-Na reduction greatly lowered its aluminum content, as most of the aluminum and some of the other metallic impurities were retained by the fused salt.

Jan 1, 1961

This report was limited to a search of available literature on under- ground methods to combat acid water pollution. From this review it is evident that very little work has been done in this specific area. It is also evident that there are specific areas of mining engineering and mining related hydrology and geology that need further research efforts to solve the many water problems. They are: (A) Composition, variation and availability for oxidation of sulfur in strata. (B) Rate of oxidation of sulfuritic materials. (C) In situ limestone and its influence on underground acid drainage. (D) Structural, stratigraphic and hydrologic character of old mining areas as a basis to make decisions about adjacent new mining areas. (E) Operational changes in mining methods to prevent pollution. (F) Sealants for underground coating to exclude water from contact with pyrite to inhibit formation of the contaminants. Such a program has been initiated on refuse piles. The prime purpose of this report is to investigate those practices which have been used to regulate or control water accumulation and prevent harmful mine drainage. A supplemental purpose is to indicate those areas which need further research to prevent underground mine water pollution.

Jan 1, 1970

Develop a user-friendly, personal computer-based numerical modeling program that performs structural analyses of underground tabular deposits, making these readily available to the mining industry. Background When ore is extracted from an underground mine, the overburden weight is redistributed to unmined areas, recompacted gob zones, and artificial structures such as packwalls and/or cribs. This redistribution of stresses continually changes throughout the mining cycle and can be especially complicated when multiple-seam mining is involved. Numerical mine structural analysis methods provide a way of calculating the redistribution of overburden stresses and the resulting loading for any given area of an underground mine, thus enabling engineers to design safer and more productive mines. In 1973 Crouch and Fairhurst developed a mine structural analysis computer program called MINSIM. This computer program was based on the three-dimensional displacement-discontinuity approach, a subvariation of the boundary-element method. In 1979 Sinha expanded MINSIM&apos;s capability to provide an analysis of parallel multiple seams. Sinha called his program MULSIM. During 1984 and 1985, the Bureau of Mines upgraded and completely restructured MULSIM into what is now called MULSIM/BM.

Jan 1, 1990

By E. J. Gleim

During the past 10 years the Bureau of Mines has had a broad experience in the tasting and inspection of electric motors for gaol-cutting machines, cowl drills, storage-battery locomotives and other equipment Which is used in mines where explosive mixtures of methane and air may be encountered. From this experience the Bureau&apos;s engineers have reached the conclusion that the most satisfactory method of protecting a motor so as to prevent any sparks resulting from rough commutator, loose contacts or short-circuits in it, from igniting he surrounding atmosphere, is to totally inclose the motor with a substantial casing; having flanged joints. These joints should be metal-to-metal contact so that the shortest path from the interior to the exterior Of the casing is not less than one inch in length. On account of this experience with mining machinery, the Bureau has been asked whether an equal or loss degree of protection would be sufficient for motors for service in or about places such as refineries, gasoline filling stations, cleaning establishments and pumping stations, or in any place where there is liklihood of explosive mixtures of gasoline or naphtha vapors and air accumulating.

Jan 1, 1922

By Robert B. Fisher

[The purpose of this paper is to acquaint manufacturers of various types of asbestos product&apos;s, particularly those that specialize in materials used for sound deadening, vibration damping, and filtration, with a recently invested depth deposit of paligorskite, a type of asbestos usually called mountain leather. In the past this mineral has been only a museum curiosity but it possesses characteristics that may adapt it to industrial uses. The deposit is on Lemesurier Island, near this entrance to Glacier Bay, in the northern portion of southeastern Alaska, at approximately latitude 58° 17? N., longitude 1360 05&apos; W. The island is about 4 ½ miles in east- west length and miles in width. The property on which the deposit occurs is owned by the locator Joe Ibach, end it was brought; to the attention of the Bureau of Mines by Col. George B. Norris. A Bureau of Mines engineer, accompanied by the owner and Chris Ellingen, visited the property sand examined the open-cuts from May 7 to 10 in 1944. The purpose of the examination was to determine the approximate extent of the occurrence and to obtain samples of the material for identification end study of its utilization.]

Jan 1, 1945

By Daniel R. Babich, Jeffrey R. Vipperman, Eric R. Bauer

Prolonged exposure to loud noise can cause permanent damage to the auditory nerve and/or its sensory components. Despite regulations and efforts by government and industry to reduce noise-induced hearing loss (NIHL), it is still a problem in the U.S. coal mining industry. The Mine Safety and Health Administration noise standard (30 CFR3 62), which was enacted in September 2000, is aimed at reducing NIHL in the mining industry. To address NIHL in various aspects of coal mining and provide the necessary information to effectively implement control technologies, the National Institute for Occupational Safety and Health conducted a cross-sectional survey of noise sources and worker noise exposures. Noise surveys consisting of full-shift worker noise exposure (dose) determination, time-motion studies (task observations), and equipment and/or area noise profiling were completed in 8 underground coal mines, 10 surface coal mines, and 8 coal preparation plants. The studies revealed that more than 40% of all workers monitored were subject to noise exposures above 90 dBA TWA8. A summary of these studies is presented, their application to administrative and engineering controls is discussed, and exposure reduction methods are reviewed.

Jan 12, 2006

By Philip E. Niebuhr

A procedure, which can be performed in the field by nonanalytical personnel, is given for sensitive spot tests for detecting tellurium or selenium. The expressed need of a field test for detecting small amounts of tellurium, which may be accompanied by relatively large amounts of selenium, has led to the development of this method. Tellurium search has been impeded by the lack of a satisfactory test from the standpoint of sensitivity and specificity. A quantitative laboratory method exists, but it is expensive and relatively laborious. Several other qualitative tests are known, but they require unstable solutions, which must be freshly prepared for use, and a greater variety of laboratory equipment. The particular advantages of the test described are its simplicity and the stability of the reagents required, there-fore is is well adapted for field use. Also, this test was found to be of practical use in the analytical laboratory when screening samples, thereby reducing analytical costs. The roughly quantitative interpretation of the results can save time by indicating the approximate size of the sample taken for a quantitative determination.

Jan 1, 1962

By Larry G. Stolarczyk

1.0 FRAMEWORK FOR COMPARISON This document describes the decision factors that bear on the selection of the modulation process for the wireless underground medium frequency (MF) communication system. The selected modulation process must satisfy the Bureau of Mines stated objective of improving general communications within an underground mine. The improvement being sought includes the development of a wireless communication technology of measurable benefit to both mine safety and mine productivity. The improvement will allow wireless communications paths to exist between roving miners. The wireless communication paths will also be made compatible with the existing underground telephone system to extend paging and voice communication throughout the underground mine. The new wireless equipment will include man-pack, vehicular, repeater, and base station transceivers. Repeaters and base stations will feature coupling networks for interfacing with the existing telephone circuits. Frequency modulation (FM) and single sideband (SSB) modulation processes are analyzed in view of the special conditions associated with underground mining. Of primary importance is the tremendous electrical noise generated in an operating mine that could adversely affect communications quality. High noise coupled with high attenuation rate of near field signals forces the communication system to be inherently short range. Fortunately, near field signals can propagate over great distances on underground wires and cables. The framework for comparison is generated by presenting all factors that

By R. A. Cattell

A technologic group such as the Petroleum and Natural Gas Division of the Bureau f Mines, which conducts research on many of the complicated and frequently interrelated problems f extracting crude oil and natural gas from the ground, transporting them to market or to daces for subsequent treatment, and manufacturing products, should report progress from time to time. Engineers and others who apply the results obtained by this division are closely associated with its personnel, because many of the problems are attached cooperatively with groups in industry. Some of this cooperation is formal, as exemplified by work now in progress under cooperative agreements with the States of Oklahoma, Kansas, and others, but much of it is informal, prompted by the desire to be mutually helpful in the public interest. Furthermore, the published reports of the Bureau on subjects pertaining to petroleum and natural-gas technology come to the direct attention of a relatively large number of persons, whose interest in results and appreciation of the value of this type of work have caused them to be kept currently informed regarding available data.

Jan 1, 1940

By R. A. Cattell

A technologic group such as the Petroleum and Natural Gas Division of the Bureau of Mines, which conducts research on many of the complicated and frequently interrelated problems of extracting crude oil and natural gas from the ground, transporting them to market or to places for subsequent treatment, and manufacturing products, should report progress from time to time. Engineers and others who apply the results obtained by this division are closely associated with its personnel, because may of the problems are attached cooperatively with groups in industry. Some of this cooperation is formal, as exemplified by work now in progress under cooperative agreements with the States of Oklahoma, Kansas, and others, but much of it is informal, prompted by the desire to be mutually helpful in the public interest. Furthermore, the published reports of the Bureau on subjects pertaining to petroleum and natural-gas technology come to the direct attention of a relatively large number of persons, whose interest in results and appreciation of the value of this type of work have caused them to be kept currently informed regarding available data.

Jan 1, 1940

By Jacqueline A. McClaskey

The U.S. Bureau of Mines (USBM) Information and Analysis Directorate collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. The USBM&apos;s data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority for the USBM survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress). This act strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1995

By Carl Rampacek

The conversion of dilute sulfur dioxide gas into sulfuric acid by autoxidation in mechanical cells of the flotation or gas absorber types was investigated. Bench-scale tests were made with sulfur dioxide-air mixtures to determine the influence of several factors on autoxidation of sulfur dioxide, using iron and manganese salts as catalysts. The laboratory investigation subsequently was extended to pilot plant acid-making tests, using a modified turbomixer gas absorber having a 12-inch-diameter impeller. Sulfur dioxide gas was produced for the tests by roasting pyrite in a fluidized-bed reactor. In the better tests, made with manganese sulfate as the catalyst, the equivalent of 1,000 pounds of anhydrous H2SO4 was produced per 24 hours as a 10-percent solution; power consumption was 0.2 kwhr per pound of equivalent anhydrous acid synthesized. The batch and continuous tests demonstrated the technical feasibility of producing dilute sulfuric acid by autoxidation of sulfur dioxide gas in mechanical cells when converting pyrite roaster or waste smelter gases.

Jan 1, 1963