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By Terry S. Cory

This report is a comprehensive summary of the results of the propagation measurements program conducted for the US Bureau of Mines under Contract H0366028. Data was gathered in the MF frequency range from a cross sample of six mines representative of the industry having typical wireless requirements. From the raw data which was gathered, a logical method of data reduction is presented which culminates in a set of average attenuation characteristics for all mines visited. These characteristics define a typical MF wireless system when the communication range requirements are known. Direct through-the-earth propagation and the range enhancement mechanism due to coupling on and off conductors are evaluated and related to the planning of a typical wireless MF communications system.

Jan 1, 1977

By J. Bruce Clemmer, M. F. Williams, B. H. Clemmons, Carl Rampacek, R. H. Stacy

"INTRODUCTION This report is the first of several dealing with the application of flotation methods for beneficiating the calcareous and siliceous red iron ores and ferruginous sandstones of the Birmingham district. The flotation study was part of a general investigation of the concentratability of various iron ores of Alabama and other Southeastern States undertaken by the Southern Experiment Station of the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama, Tuscaloosa, Ala.Batch testing and pilot-plant flotation testing of the calcareous red ores of the Birmingham district have been in progress for several years, and although some phases of the study are not yet completed, enough data are available to indicate that many of the ores will yield marketable-grade concentrates with good recovery.The first flotation tests on the calcareous red ores employing conventional methods either the iron oxides or the siliceous gangue materials failed to give the desired results. The inferior separations obtained or prohibitive reagent requirements made the methods unattractive. Other more effective flotation methods were sought. A laboratory study of various reagents was undertaken. It resulted in the development of two attractive methods embracing anionic flotation of the activated siliceous gangue from the retarded iron oxides. The methods were similar in that fatty acid or soap-collecting agents were employed in strongly alkaline pulps to float the naturally activated quartz from the iron-ore pulps. The methods differed, however, in the addition agent employed to retard the hematite or hematite and calcite. By proper choice and quantity of the addition agent, the calcite could be floated with the quartz or retarded with the hematite as desired. Ability to recover or reject the calcite gives added flexibility to the separation. Although the methods have their limitations and cannot be considered ""cure-alls,"" they have given encouraging results on a number of calcareous red ores that heretofore proved difficult to concentrate by conventional flotation procedures."

Mar 1, 1945

By Sigmund Black

Ingersoll-Rand Research, T n c and the Lee-Norse Co. built a Bureau of Mines sponsored, special deep cutting continuous miner under this contract to study the effects of rotational speed and depth of cut on airborne respirable dust. After preliminary tests indicated and later verified that deep cutting - low rotational speed reduces airborne respirable dust, a series of underground tests were performed (9 combinations of rotational speed and depth of cut at 45° bit angle and 4" bit spacing). Additional data was obtained on specific energy, coal sizing and noise. The conclusions reached from the tests results were; a) deep cutting reduces airborne respirable dust generated and specific energy needed to cut coal., b) the greater majority of the decrease occurs in going from 1" to 2" depth of cut, c) lowering rotational speed has a particularly sizable effect of reducing the amount of dust at the operator's location, d) no significant relationship was found for either noise level or coal sizing to rotational speed or depth of cut. Recommendations include. a)) use of specific energy as an indicator of the change in dust level correlating to changes in cutting parameters, b) mine operators should acquire new deep cutting machines., since retrofitting would be selective.

Jan 1, 1977

Objective To develop safety training tools for mine safety and health trainers that can be used for both new-miner training and annual refresher training. Background For the past 3 years, NIOSH has been developing training materials for mine safety trainers in response to gaps identified during stakeholder meetings. Most materials have been directed to the hazards of underground mines, but the recent passage of Part 46 of CFR 30 required new-miner and annual refresher training in aggregate operations. One result was the identification of another audience needing basic information about safety in mining. Trainers characterized trainees in this segment of the industry primarily as young males, many of whom had little work experience. Approach Training specialists from the Arizona State Mine Inspector’s Office approached NIOSH researchers early in2002 about the possibility of a collaborative project to develop safety training materials for new trainees in aggregate operations. A preliminary search of MSHA accident statistics identified over a dozen common hazards that could be targeted in a training video. A storyline was developed for review by safety specialists in the aggregate industry, and a script was written to cover the selected hazards. Although the target audience was primarily new hires, the finished video was also to be relevant to more experienced workers.

Jan 1, 2003

By C. E. Lapple

To improve mine health and safety conditions, there is need for a portable instrument that mine inspectors can use routinely for rapidly checking concentrations of dust in mine atmospheres. On October 23, 1969, Stanford Research Institute was authorized by the U.S. Bureau of Mines to conduct a study aimed at developing such an instrument under Contract No. H0100186. The results of that study are reported in Technical Report No. 1, "Development of Portable Instrument For Measuring Coal Mine Dust Concentration," August 1970. In that study it was demonstrated on bench-scale that a near-forward optical scattering device gives a linear correlation between mass concentration and optical readout over a range of 2 to 200 mg/m3 with excellent reproducibility. The same correlation was obtained for the Respirable* dust fraction of three different coal dusts within ± 10% and an extreme spread of ± 30%. Based on these results a prototype instrument was designed which was expected to meet all the necessary requirements of a portable instrument for mine use. Because of the excellent results obtained, a further study was authorized by the Bureau of Mines on May 10, 1971 under Contract No. H0111688. The prime objective of this study was to build, calibrate, and deliver to the Bureau of Mines two prototype instruments based on the design previously developed. The emphasis was to be on providing instruments which would meet certain minimum standards of size, weight, response time, sensitivity, ruggedness, reproducibility, permissibility, and cost (ultimate); optimization of the design was to be considered only insofar as it would not significantly delay the development. One instrument was to be delivered after initial calibration of both instruments with Coal Dust PGH. The second instrument was to be used for further calibration with a number of other coal and rock dusts and for assessing other relevant performance characteristics. This report summarizes all the results of this second study.

Jan 1, 1972

By William J. Douglas

This document describes the development of a conventional mining equipment data base, and an approach for conducting industrial engineering studies of arbitrary mining systems employing network techniques. Data was acquired through underground time studies. Each member of a four-man field team was assigned to a specific machine during each shift for which observations were conducted. Using digital wrist watches and networks describing the man-machine interactions, all events occurring luring the course of each shift were recorded on cassette tapes. The tapes were transcribed, coded, keypunched, and validated using computerized editing techniques. The resulting data files were processed to provide statistics relating to activity durations and event frequencies. The results were used to evaluate operator, machine, and system performance for each section which was observed. Equipment, reliability, and maintainability analyses were conducted using the industrial engineering data files in conjunction with historical information collected at the mine site.

Jan 1, 1976

By R. A. Cattell

The conditions under which the researches of the Bureau of Mines on petroleum and natural gas were conducted in 1952 were little changed from those indicated in the last report,2/ which dealt with activities during 1951, immediately after crossing of the 38th Parallel by the North Korean Army. Although only a small part of the program was classified in the military sense, there was a feeling of the clash of world forces which called for even cheer scrutiny of the research problems so that the emphasis could be placed without delay where the greatest needs for na¬tional defense seemed to be. The reports of the work accomplished were so directed as to have the greatest immediate value to persons charged with supply planning for the military forces and included information on the availability and characteristics of a wide variety of crude oils, fuels, and other petroleum products. Actually, the approach, direction, and conduct of the work do not differ greatly under the two circumstances, as has been pointed out in earlier reports; only the tempo changes.

Jan 1, 1953

By T. C. Moore

This report describes the feasibility test of an electromagnetic method for locating boreholes, with or without casing, that have been drilled in conjunction with mining operations but whose location with respect to the tunnel is not precisely known. The first tests were conducted with the cooperation of the Kerr-McGee Corporation, Church Rock Mining Operations, New Mexico, in September 1977. These tests demonstrated that accuracies of better than ±5% of range and ±1° of bearing can be achieved with a simple system and setups. Subsequent tests, in January 1978, on a horizontally drilled pipe line river crossing application, by Titan Contractors of Sacramento, California, demonstrated that accuracies of better than one-half percent of range and a few tenths of one degree of bearing can be achieved by using refined techniques. The demonstration tests were done at ranges on the order of 100 to 200 feet but the method is capable of working at much greater distances.

Jan 1, 1978

By R. F. Randolph, R. S. Fowkes, J. J. McClelland, G. H. Schnakenberg

Between 1986 and 1992, there were268 deaths and 54,642 severe injuries to workers in underground U. S. mining operations. Clearly, this level of health and safety risk is not acceptable. While most underground coal mining jobs are dangerous, some are much more dangerous than others. Many jobs in an underground coal mine are clustered around the working face—the place where machinery digs coal from the surrounding rock. The hazards in this area are numerous: When the coal is removed, the ground around it becomes unstable and can cave in on the workers. The mining machines used there are large, heavy, powerful, and move in many different directions in a very confined space, presenting danger to workers. Also, the machines churn up coal dust that causes black lung and other ailments. Figure1 shows a modern radio remote controlled continuous mining machine and its operator. In a typical mine, the jobs with the greatest exposure to hazards involve operation of machinery that cuts tunnel-like passages into the coal (the continuous mining machine) and machines that insert supportive steel bolts into the rock above the work area (roof bolting machines). The workers who endure these hazards are at almost twice the risk of death or disabling injury than co-workers in other safer areas of the mine. Of the statistics quoted above, 106 of the 268 deaths and 21,552 of the 54,642 severe injuries occurred in jobs involving equipment at the working face. The operators of roof bolting and continuous mining machines account for only 21% of the work force but suffered 40% of the deaths and 39% of the lost-time injuries during1986-1992. These death and injury rates are almost twice the rate for workers in other underground mining jobs (see figure 2). The estimated total cost of the 106 fatalities and21,552 lost-time injuries was $327 million from 1986-1992. On average, each fatality cost over $1 million and each lost-time injury costs in excess of $9,000.

Jan 1, 1994

By E. D. Calvert

The Bureau of Mines, in its effort to promote greater utilization of domestically abundant materials, conducted reasearch on an alternate mold material that has commercial potential for titanium investment casting. Using variations of the conventional lost wax molding process, investment shell molds were formed entirely of fused, calcia-stabilized Zr02 and a Zr02-forming binder. Optimization of binder/slurry properties', stucco grain size and dis¬tribution, and curing practices resulted in a structurally sound investment shell that was distortion free and thermally stable. Small titanium castings, weighing up to 10 pounds, were prepared in unheated molds by both static and centrifugal casting techniques. Microstruc¬tural examination of the castings revealed that mold fill and surface quality were enhanced by centrifugal casting, although good results also were obtained from the statically poured molds. Microstructural and electron microprobe examinations showed that excessive, brittle case formation could be avoided by curing the dried shell molds in air for at least 2 hours at 1,400° C. Increasing curing temperature and time above these levels yielded added bene¬fits. Molds fired in vacuum at 1,500° C for 4 hours yielded castings essen¬tially free of case formation. The tensile properties of as-cast test specimens (no surface conditioning performed) id the chemical composition of representative metal samples showed that castings produced were comparable to Grades C-1 and C-2 unalloyed titanium This indicated that no sifnificant degradation of metal properties resulted from mold/metal interaction.

Jan 1, 1981

By Oliver Bowles

This paper is the third of a series of reports on asbestos prepared by the Bureau of Mines. The reports already issued contain general information, including descriptions of deposits throughout the world.3/ The present paper deals chiefly with milling and marketing. Many grades of asbestos are marketed, and an important phase of milling is the grading of fiber; these subjects therefore are related so intimately that contiguity in their treatment is fully justified. Although the Bureau of Mines is interested primarily in the mining and preparation of raw materials, the fabrication of asbestos products has attained such importance in the United States that brief reference to processes of manufacture is included. CLASSIFICATION OF FIBER Canadian asbestos fibers are divided into three main groups - crudes, mill fibers, and shorts. The term "crude" is applied to fiber of spinning grade measuring three eighths inch or longer, that is. hand-cobbed and not passed through a mill. Mill fibers are obtained by crushing and beating the fiber-bearing" rock, until the, asbestos is freed and, then removing the fiber from the rock by screening or air separation. Shorts are the lowest grades of mill products.

Jan 1, 1935

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the fourteenth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned & name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled except the deep holes drilled to test geophysical anomalies. The locations of those holes are shown on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By G. S. Rice, H. P. Greenwald, H. C. Howarth

"""Rock-dust barriers""5 as they are termed in this country, are for the purpose of confining a coal-dust mine explosion to the limited area in which it originates. These barriers were first tested in 1910-1911, with favorable results under the conditions of test, at the French official gallery which was then at Lieven, Department of Pas-de-Calais. Shortly afterwards the Bureau of Mines in the course of its investigation of all practical explosion-prevention methods tried barriers in the Experimental Mine near Bruceton, using the primary form of simple fixed cross shelves 20 inches wide extending over the passageway and laden with rock-dust. The Bureau termed them “Taffanel barriers"" in honor of the director of the Lieven testing station. The trials were made in conjunction with tests of explosibility of different coal-dusts.Experience showed that although the principle of barriers had merit when they were used for secondary defence, the primary form was uncertain in effectiveness. This led the senior author to design mechanically discharging barriers to be operated by the compression air waves which precede the flame of an explosion. For the better understanding of the principal involved, it is pointed out that the advance air waves are what make a coal-dust explosion possible by stirring up the coal-dust from the walls and floor of the passageway. If a barrier can throw inert dust into the air to form a cloud as dense or denser than that formed by the coal-dust, it will neutralize the explosiveness of the coal-dust, and the flame of the explosion will be extinguished. When the flame ceases, the pressure dies away in a short distance if the 'area that had been traversed by the explosion is not large."

Jan 1, 1930

The STATE MINERAL SUMMARIES publication provides estimated data and summaries of mineral activities at the State level for 1991. Most of the estimates are based on nine months data. Individual State summaries are published separately as State Mineral Industry Surveys and copies can be obtained from the appropriate State mineral officer or Bureau field office specified in each State summary.

Jan 1, 1992

By S. J. Hussey

This Bureau of Mines report presents a discussion of the statistical approach to the design of experiments and indicates, by concrete examples, how and when statistical design is essential for obtaining meaningful data with a minimum number of experiments. Every research worker plans his work and designs his experiments in a manner which, based on his experience, seems most rational to him and which he believes will produce the information essential for resolving the problems. If the results obtained are open to multiple interpretations and are not of definitive reliability, the failure of the experiment design to produce the desired information may be due to several causes, These include faulty judgment in selecting the factors to be tested, ignoring the importance of interaction between factors, failure to adequately control test variables, and assuming that meaningful trends in the results can be identified without comparison to a predetermined experimental error. An experienced researcher probably will deduce from the nature of the data obtained that the design is faulty and may by trial and error ultimately arrive at the correct solution to the problem. Statistical methods of planning research minimize the chance of faulty experiment design, embody concrete procedures for testing the validity and reliability of the test data and for indicating mandatory changes in the design, and enable the researcher to obtain meaningful information with the least number of tests.

Jan 1, 1963

6889. Aslakson, C. I., and Swick, C. H. Gravity Observations in Peru and Colombia. Coast and Geodetic Survey,-Special Pub. 233, U. S. Government Printing Office, Washington, D. C., 1943, 18 pp. (Price, 10 cents.) In accordance with the policy of cooperation among American republics, the-United States Coast and Geodetic Survey in 1941 made gravity surveys in Peru and-Colombia. The information was desirable for determining the figure of the earth for geophysical purposes and for studying the relationship between intensities of gravity and deflections of the vertical. The survey instrument was the Brown pendulum apparatus. 11 gravity stations were established in Peru and 13 in Colombia. The results obtained at these stations are given in a table covering observed gravity, theoretical gravity, and anamalies. - V. S.

Jan 1, 1943

By Arnold O. Tanner

Tables based on 1985 data, which were not available in time for publication of the "1985 Minerals Yearbook," are included in this chapter; corresponding tables for 1986 are not yet available. Raw nonfuel minerals produced in the United States during 1986 had an estimated value of $23.5 billion, an increase of $0.25 billion over the 1985 value. This is the fourth consecutive year that the value has increased, and except for a de- crease in 1982, the value each year has increased since 1971, or 14 out of 15 years. Industrial minerals growth slowed from a 3% increase in value in 1985 to a 1.5% increase in 1986, reflecting the slow growth in the domestic economy. The value of industrial minerals, more than three times larger than the value of metals, easily offset the less than 0.5% decline in the value of metal mine production. Although the decline was small, this decrease makes 1986 the fourth year in the past 6 years in which a drop in the value of metal mining production occurred in the United States. U.S. production continued to lag behind the growing world production. Overall, the estimated raw nonfuel mineral production rose 1% over that of 1985. Domestic mine production of ferrous metals declined as follows, in decreasing order of production: nickel, iron ore, tungsten, and molybdenum. All remaining domestic primary nickel and tungsten mines had closed down by yearend. Nonferrous metals that similarly declined included titanium, rare-earth metals, lead, silver, zinc, and magnesium. For the second consecutive year, aluminum, produced predominantly from imported bauxite, declined in production, while imports reached record-high levels. Somewhat modest gains were made in beryllium and copper. As has been the case for a number of years, gold was a bright spot in the domestic and internation-al metal mining industry. Gold production was spurred on by the increasing usage and development of heapleaching techniques that make lower grade ores, which were previously uneconomical, profitable. Additionally, various mining companies, the U.S. Mint, individual States, and a number of foreign countries began production of gold bullion and commemorative coins. Gold output in the United States increased from 2.43 million troy ounces (revised) in 1985 to about 3.73 million troy ounces in 1986, a dramatic 54% rise.

Jan 1, 1988

The 1965 Lignite Symposium, the Louth in a series and the third sponsored by the University of North Dakota and the Bureau of Mines, was held at Bismarck, N. Dak., on April 29-30, 1963. These symposia provide a forum for those interested in the technology and utilization of solid fuels, especially lignitic coals. As part of the meeting, a 200-mile field trip was taken including; inspection of (1) the 200-megawatt, pulverized lignit-fired Leland Olds plant of Basin Electric Power Cooperative, under construction near Stanton, N. Dak.; (2) the site of the Glunharold mine of the Truax-Traer Coal Co., Division of Consolidation Coal Co., where a wheel excavator was being assembled; (3) the operating Beulah mine of Knife River Coal Mining Co., subsidiary of Montana-Dakota Utilities Co., near Beulah, N. Dak.; and (4) the 400-megawatt, hydroelectric Garrison Dam powerplant, near Garrison, N. Dak.

Jan 1, 1966

By R. M. Becker

THIS IS a progress report on a study of the application of statistical practice to mine and mineral sampling undertaken by the Federal Bureau of Mines to provide sound theoretical and practical data for use of the mineral engineering professions. One of the problems in mine sampling is determining the reliability of the results. For certain types of sampling data (random data) the reliability of the results can be stated mathematically. For other types of data there is no known means of quantitatively expressing reliability. In applying measures of reliability to a set of random data, some knowledge or assumption of the characteristics of the particular data is necessary. In many fields these characteristics are well known. However, in mining, where the data are in assays, these characteristics are not well known.

Jan 1, 1961

By D. Gearhart

Full-scale tests are conducted on mine roof supports using protocols developed by the National Institute for Occupational Safety and Health (NIOSH) using the unique capabilities of the Mine Roof Simulator (MRS). These protocols simulate the loading conditions that the support will be exposed to in an underground mine to determine the performance capabilities and limitations of the support. Some tests are conducted with rigid boundary conditions, creating uniform contact and near ideal axial loading conditions. These tests are used to determine the ultimate performance potential of a support, including the strength, stiffness, and stability. For prop supports where stability is a critical design issue, tests are implemented to induce buckling by a modified end condition, eccentric contact, or biaxial loading. It is important to determine the cpacity of the support design when the support is subjected to unpredictable loading conditions. This paper examines the effect of end conditions and load profiles on prop support performance and applies a new analysis methodology based on eccentric loading to determine a factor of safety for load capacity. Recommendations for installation practices that minimize eccentricity and therefore preserve capacity are also provided.