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By M. P. Ristenbatt

A new automated post-disaster signaling system, intended to use through-the-earth EM propagation, was demonstrated in the laboratory at an input SNR of -34 dB. The system presently available requires an input SNR of +6 dB, and uses a human-ear detector. The work here demonstrated coherent integration, for the automated system, in multiples of 17 s, up to 1088 s (18 minutes). A repeating pseudorandom (or pseudonoise) signal is used, which offers an ideal auto-correlation at the receiver matched-filter output. A novel decision-variable algorithm achieves the estimate of noise level by using those matched-filter output samples that occur between the signal auto-correlation peaks. This work included corraboration that the received signal power decreases as distance to the tenth power, for through-the-earth propagation. Thus, the above 40 dB reduction in required input SNR permits an automated system to have a range 2.5 times that of the present system. In addition, an automated system permits the possibility of operating receivers around-the-clock; this would reduce the initial-detection-time from a few hours (present system deployment time) to a few minutes (signal processing time).

Jan 1, 1981

By F. W. Wood

The Bureau of Mines has sought clarification of the Ti-TiN system by studying the phases formed by diffusion reactions between titanium and titanium nitride. Reaction couples were prepared by embedding pockets of TiN powder in arc-melted buttons of titanium. Specimens were vacuum annealed at nominal temperatures of 800°, 950°, 1,200°, and 1,500° C. Metallographically mounted cross sections from reacted specimens and from some that were not annealed were examined optically, with an electron microprobe, with an election microscope, and by X-ray diffraction. Each annealed specimen contained a segregated core primarily of d-phase material, an ?-phase diffusion layer, an a-phase diffusion layer, and host metal. On the basis of corresponding microprobe analyses, and considering results of certain other research, a new phase diagram is proposed. It contains no qualitative innovations, only quantitative adjustments. Results were also analyzed from the viewpoint of diffusion behavior. Diffusion coefficients calculated for the ? phase were sufficiently scattered that the parameters are very tentative. Nevertheless, the diffusion behavior reported is in reasonable agreement with one of two prior studies if it is assumed that the earlier investigators were mistaken in their identification of the nitride phase in which the diffusion occurred.

Jan 1, 1974

By W. P. Yant

A previous report of the Bureau of Mines dealt with the toxicity of dichlorodifluoromethane5, a new refrigerant that has a remarkably low toxicity. Continued research by the Prigidaire Corporation6 and toxicological experiments performed in the Laboratory of Applied Physiology of the University of Cincinnati7 revealed another organic fluoride, dichlorotetrafluoroethane, whose toxicity also appeared to be of a very low order and whose physical-and chemical properties make it suitable for refrigeration purposes. In addition to low toxicity, safety in its use is further enhanced by its physical properties, which permit the design of equipment that operates at comparatively low pressures and hence mitigates the dangers and problems of leakage. The investigation described in this report was performed by the Bureau of Mines at the request and with the cooperation of the Frigidaire Corporation.

Jan 1, 1932

By Duane L. Abata

Toxic gases produced by the detonation of six explosives were measured in an underground hardrock metal mine during actual mining operations. The six explosives included two semi-gelatin dynamites, three slurry explosives and an ammonium-nitrate, fuel-oil/ammonia dynamite combination. Explosives were detonated at the face of a drift and the toxic gases produced by the detonation were trapped to the end of the drift by a bulkhead located a short distance away from the face. Toxic gas concentrations were then measured with direct readout instruments and together with the containment volume, the toxic gas volumes per mass of explosive were calculated. Toxic gas measurements were found in the following ranges (ft3/lbm): N02 0.010-0.035; N02, 0.003-0.019; CO, 0.08-0.30; S02, 0.00-0.05; and C02, 0.7-1.8. Results showed that toxic gas production (ft3/lbm) correlated with the densities (kg/m3) and energy densities (kJ/kg) of the explosives tested.

Jan 1, 1978

By D. Harrington

The record of fatalities from mine explosions in the United States during the past 3 years has been the best in the history of the mining industry. During these 3 fiscal years, mine explosions have resulted in an average of 4I0 deaths per year, as compared with an average of 153 deaths per year for the preceding; 5 years; an average of 542 deaths per year for the 3-year period 1907-09, inclusive, just before the organization of the U. S. Bureau of Mines; and a yearly average of 265 deaths per year for the 20-year period prior to 1929. This remarkable reduction in deaths from mine explosions demonstrates clearly that mine explosions can be controlled; in fact, they can be prevented when or if the mining people of the United States see fit to take the readily available precautions necessary to bring about this desirable objective. Several large coal-producing States, which in the past have had numerous disastrous explosions, have been free from such disasters for continuous periods of as much as 6 years or even longer. The bituminous mines of Pennsylvania, the largest coal-producing State, give a good example of what can be done to prevent explosions; this State has had only one major explosion (and it resulted in 7 fatalities) during the past 6 years, and no explosion occurred in the several hundred bituminous-coal mines of the State during the past fiscal year. This is a truly remarkable record when compared with past performance in any year in the operation of coal mines in Pennsylvania.

Jan 1, 1936

By Fred E. Fiedler

A demonstration project investigated the feasibility and effectiveness of two management interventions, Management Training and Organization Development, for improving productivity and safety in metal/non-metal mines. The management training intervention was conducted at Texasgulf Company's trona mine, using three nearby trona mines as controls. The Organization Development intervention took place in Hecla Mining Company's Lucky Friday mine, using the highly similar Star Mine as control. The two management interventions seemed about equally effective in reducing accidents and injuries, as well as MSHA citations, and the management intervention at the Texasgulf mine also appeared to have led to substantial improvement in mine productivity.

Jan 1, 1983

By Steven W. Schmauch

The U.S. Bureau of Hines conducted e mineral resource survey of approximately 232,000 acres in part of the Humboldt National Forest, Nevada, during 1989. About 7S percent of the study area was covered with mining claims. About 1,800 samples were collected end analyzed for 16 elements. Geologic structure, including thrust faults, is the most important factor in the localization of mineral deposits in the study area. The Independence mine (formerly Jerritt Canyon), Big Springs, and Wood Gulch are the most well known active properties, all developed on large, low-grade, disseminated gold deposits. These deposits have produced almost 3 million ounces of gold and are known to contain more than 8 million ounces of gold. At least 10 barite deposits in the south end of the range have had significant past production and contain 0.2 million tons of resources. Numerous precious and base metal targets have been identified and in some cases quantified during this study.

Jan 1, 1992

These proceedings consist of papers presented at two Bureau of Mines Technology Transfer Seminars for the purpose of disseminating recent advances in mining technology related to coal mine fire and explosion prevention. Primary, although not exclusive, emphasis is placed on underground coal mining. The papers address research accomplishments ranging from methods for detecting mine fires to remote sealing systems for extinguishing coal mine fires. Each paper represents the current state-of-the-art in the respective research categories. Presentations include research occurring from both Bureau in-house and contract efforts.

Jan 1, 1978

The general nature of the special constructional features that are required to provide safety from explosion hazards on machines approved as permissible by the Bureau of Mines is fairly well known to mining men who are at all interested in safety. These requirements are outlined in the schedules, under the provisions of which the investigations of such machines are conducted. Also, the method of conducting inspections and. tests of such machines has been described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine Type Electrical Equipment for Permissibility, published in 1929. A more detailed knowledge of the special safety features of a particular machine is often useful and sometimes essential for inspectors, safety engineers, maintenance men, and engineers in selecting machines for a particular application. Three bulletins that give information of this nature have been published by the bureau, viz., Bulletin 313, Permissible Storage-Battery Locomotives and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 382, Permissible Coal-Cutting Equipment.

Jan 1, 1937

By Albert W. Deurbrouck

The percentage of coal cleaned mechanically has increased greatly in the past 30 years. This technological change in preparation methods, accompanied by mechanical innovations in most phases of coal mining, has enabled the industry to supply quality coals at competitive prices. The Bureau of Mines has contributed to this progress by conducting research on coal-preparation problems, by evaluating the performance of domestic-and foreign-made preparation equipment, and by recording advances as they occur in industrial coal-cleaning practices. The Bureau's work in this field is recorded in the more than 150 technical and scientific publications listed in this volume. These reports, published by the Bureau over the past half century, document the Nation's progress in a vitally important phase of fuel technology.

Jan 1, 1961

This Bureau of Mines publication consists of an overview of the mine waste management research currently being conducted by the Bureau. The following papers, given at a Technology Transfer Workshop, emphasize the increasing importance of research related to the safety and environmental considerations of mine waste disposal In recent years. Current work related to legislation passed in the last 10 years and their subsequent standards includes the development of adequate monitoring systems, development of stability and seepage prediction and control techniques, control of runoff water, and control of leaching solutions. Selected topics are included here that cover coal mine waste disposal, embankment slope stability monitoring, flow failures of mine tailings impoundments, and controlled burnout of abandoned coal mine fires. The projects described provide a current documentation of problems being addressed.

Jan 1, 1981

By Charles L. Kimbell

The year 1980 on the whole was not a good year for the world's mineral industry. The general upturn of activities in 1979 after a rather poor 1978 showing was not maintained with a number of key measurement standards showing downturns. Most notably, the world's steel and petroleum industries recorded significant reductions in output, the former in response to markedly lower demand levels and the latter partly in response to lower industrial consumption owing to general economic conditions and partly owing to successes in campaigns for the reduction of energy use in general and petroleum product use in particular among major importing nations that were feeling the trade balance pinch of ever-higher oil prices. During 1980, a number of political events-some international in scope, some confined to single nations-had significant influence upon world mineral industry activities and mineral commodity supplies, and other political happenings had the potential to significantly affect the industry in future times.

Jan 1, 1982

By M. G. Zabetakis, T. D. Moore

The use of a partially slotted 6.5-inch-inside-diameter vertical pipe to remove methane from a longwall gob area at a depth of 2,260 feet in the Pocahontas No. 3 coalbed ms investigated. The value of gas removed by such a pipe under free-flow conditions was found to equal the cost of the installation in this case. Approximately 25 percent of the available methane passed through the pipe without the use of an exhauster; an additional 10 percent was removed when an exhauster was employed. The diversion of methane through a vertical slotted pipe to the surface permitted the use of increased mining rates and decreased the ventilation air requirements.

Jan 1, 1972

By P. J. Remington

Field measurements utilizing a seat pad accelerometer were made on 25 underground coal mining machines in order to quantify the vibration levels experienced by the operators. Those data were combined with information on the statistics of the operating times of those machines in order to compare the operator's vibration exposure to the criteria in ISO 2631, "A Guide for the Evaluation of Human Exposure to Whole Body vibration." The comparison showed that about 30% to 40" of all underground coal mining machine operators can be expected to be exposed to vibration exceeding the fatigue decreased proficiency criterion, whereas only 10 to 15% would be expected to experience vibration exceeding the exposure limit. The primary sources of the exposure are shuttle cars and possibly scoop trams. Detailed exposure statistics are presented and the implications of the results are discussed.

Jan 1, 1983

By R. D. Leitch, W. P. Yant, A. C. Fieldner, R. R. Sayers, S. J. Pearce

"The detection of leakage is a recognized problem in the safe and economic distribution and use of natural gas. Natural gas is practically odorless and therefore lacks he property of indicating significant leakage by the sense of smell, the means most widely used by gas employees and consumers for detecting leaks of the more odorous types of fuel eases. In view of the recognized value of the odor of gas for indicating leakage at the time of occurrence the Bureau of Mines has studied' the possibility of adding small amounts highly odorous substances to types of fuel gas (such as blue water gas and natural gas) that lack warning properties. These studies revealed that the mercaptans were promising substances to accomplish this purpose, not only for odorizing fuel gases but for other purposes° where it was desired to give warning through the sense of smell.Since completing the studies mentioned, the Bureau of Mines jointly with the American Gas Association has conducted further investigations dealing with the use of warning agents for fuel gases. The results of this work will be published later.The Bureau of Mines had been desirous of observing the practical use of ethyl mercaptan for detecting leakage of natural gas, particularly to determine whether the odor would permeate the ground and give indication of lea's in underground pipes. Opportunity for making these observations was recently given by E. A. Munyan, manager, gas department, Union Gas t Electric Co., who requested the bureau's cooperation in making leakage surveys of the company's distributing systems at Franklin and Middletown, Ohio."

Jun 1, 1930

By Francis E. Federspiel

In 1984 and 1985, at the request of the U.S. Forest Service, the U.S. Bureau of Mines examined the 87,720-acre South Boise Yuba study area (formerly known as RARE II Wilderness Recommended area I-4553) to evaluate mineral resources. The study area and additions are in Blaine, Camas, and Elmore Counties, 10, about 60 mi east of Boise. Granitic rocks of the Cretaceous age Idaho Batholith occupy the western two-thirds of the study area. A Tertiary age granitic complex has intruded, and broken into small blocks, Paleozoic age sedimentary rocks in the eastern third of the study area. Tertiary Challis Volcanics overlie both of these rock types. Principal mineralized structures are gold-and silver-bearing quartz veins and shear zones trending northwest to easterly in the Cretaceous granitic rocks. Copper, lead, and zinc are accessory metals in many mineralized structures.

Jan 1, 1987

By E. D. Gardner

This is one of a series of paper's being published by the Bureau of Mines on placer mining; it is written as a supplement to Information Circular 6788, "Placer Mining in the Western United States, Part III", by E. D. Gardner and C. H. Johnson which was published in February 1935. Since Information Circular 6788 was written (1933), considerable advance has been made in the technique of mining placer gravels with power shovels and draglines. Although new washing plants continue to be built in accordance with untried designs the trend of new installations is toward proved equipment. A substantial number of plants are now being operated successfully (1937).

Jan 1, 1938

By Wing G. Agnew, John A. Johnson

"INTRODUCTION This paper is one of a series being published by the Bureau of Mines pertaining to an investigation on the use of stemming in metal mines now being conducted at the Mount Weather Testing Adit. Its purpose is to compare the amount of dust and gases produced as a result of blasting charges of dynamite (1) in drill holes, (2) in bombs, and (3) in mud-cap or adobe shots.ACKNOWLEDGMENTSValuable assistance and advice on stemming were given by members of the staff at the Bureau of Mines, as acknowledged in previous publications. 4/TEST PROCEDUREThe results used for comparison in this report are from dust and gas samples taken after blasting (1) four regular test rounds with no stemming, (2) five bomb shots, and (3) two mud-cap or adobe shots.The four rounds were the standard 26-hole test rounds designed to break 4 feet of rock. The procedure for drilling and blasting these rounds is described in Report of Investigations 3509.Before the regular test rounds were blasted, about 1,200 bounds of fine rock was placed on the steel mucking sheets that covered the end of the adit track; the wails, hack, and floor of the adit were washed thoroughly; and the fine rock on the mucking sheets was completely wetted.Each of the 5 bomb shots consisted of 10 sticks of dynamite tied together and hung at midpoint of the adit, 8 feet from the fall."

Dec 1, 1942

By Ross. C. Barkley

A computer program has been written to simulate ground vibrations induced by multiple-hole surface blasts. The program is an inexpensive and relatively easy to use tool for predicting the principal blast vibration characteristics that determine damage and annoyance potential: peak particle velocity, frequency content and pulse duration. The program generates a complete ground motion history by superposing, at any surface position, the vibrations induced by each individual explosives charge. It requires specification of (hence allows accounting for) the blast geometry, initiation sequence (including random delays), position with respect to blast, pulse characteristics induced by each charge, and propagation laws. A methodology is outlined to determine the necessary variables either on the basis of site investigations (e.g. velocity, attenuation, pulse), or by backcalculation from measured blast vibration records. The latter procedure has been applied to blasts from two coal strip mines. Main difficulties are backcalculating individual pulses, propagation (especially dispersion) parameters and delays. A normal distribution of delays, based on published results, has been shown to influence the results and the response of a single degree of freedom structure significantly. Broadening of the wave types included and additional verifications with field results are required.

Jan 1, 1983

By S. Malhotra

Processes for the recovery of manganese contained in low-grade domestic sources are evaluated. Conclusions are based on analysis of literature, technical evaluation and cost analysis. The Nossen Nitric Acid Process, the Sulfuric Dioxide Process rind the Ammonia Leach Process should be developed further as they offer the hunt opportunity for commercialization.

Jan 1, 1984