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By Richard Hammer

Various alternating current (ac) methods can localize faults in mining power cables. Several methods considered by the Bureau of Mines in this report are the Murray loop for short circuits, wherein a bridge provides proportional distance to the fault; capacitance measurements for open conductors; inductance measurements for shorted conductors; phase comparison, high speed recordings of voltage and current in the faulted state are compared with normal voltage and current with the difference being a function of impedance change and impedance change being a function of fault location; and standing wave measurements, detecting the resonance of the length of cable to a fault (either short or open). Portable capacitance bridges are presently available for the second method, and the fourth method is well developed for use on large power distribution systems. Because it utilizes pulses rather than ac, the time domain reflectometer (TDR) method of fault locating was not included in this investigation. However, a comparative evaluation between this versatile method and the Murray loop might prove advantageous in locating high resistance faults.

Jan 1, 1977

Provide the National Park Service (NPS) with guidelines for closing abandoned mine openings such as shafts and adits. Approach The NPS needed alternative methods of closing a variety of abandoned mine openings on National Park lands. Because the U.S. Bureau of Mines (USBM) has a long history of mining-related experience, the NPS requested that the Bureau provide them with technical mine closure information. USBM engineers compiled information on various types of mine closures and prepared technical illustrations of those closure techniques. Multiple closure options, by type of opening, were prepared as one-page field guides to assist NPS field personnel in determining the most appropriate closure method for a given situation and detailing the construction of the closure method. Results Guidelines provided to the NPS included a description of the method, use applications, construction techniques, technical illustrations, and technical support information. The following provides a brief description of 11 mine closure techniques identified for use by NPS personnel. Most of the closure methods, except the backfill methods, allow for construction that can provide access to the mine. However, providing access makes the closure susceptible to vandalism. Most closure methods require periodic monitoring for subsidence and corrosion or deterioration of construction materials.

Jan 1, 1994

By Thomas A. Gray, Lynn M. Crayne, Michael A. Trevits, Phil Glogowski

Mine seals can be remotely constructed in underground coal mines, through vertical boreholes, when direct access to a fire is impossible or considered to be too dangerous. This method has great merit because boreholes can be drilled to specific mine areas and seals can be positioned close to a fire zone. The technology however, can be largely ineffective if the constructed seals do not provide effective barriers to airflow or cannot be used to impound water and other inert materials. Unfortunately, no viable alternatives exist to sealing the entire mine at the ground surface. Full-scale remote mine seal construction research is being conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Lake Lynn Laboratory (LLL). Under this effort, Howard Concrete Pumping Company and GAI Consultants, Inc. have joined forces to evaluate a potentially significant improvement to the current state-of-the-art. This paper will cover development of novel technology for remote mine seal construction, evaluation of the materials used, construction practice, and follow-up testing.

By Herbert R. Appell

Urban refuse, cellulosic wastes, and sewage sludge have been converted to heavy oil by heating under pressure with carbon monoxide and steam. Conversions of the organic matter to oil, water, and gas have averaged near 90 percent at temperatures of 250° to 400° C and pressures of 1,500 to 5,000 psi. The yield of oil, based on the dry organic matter of the waste materials, is usually near 40 percent. This is the equivalent of more than 2 barrels of oil per ton of dry, ash-free waste material. The oil from urban refuse and cellulosic wastes has a sulfur content near 0.1 percent. This low sulfur content makes the oil from refuse a desirable source of fuel oil.

Jan 1, 1970

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

8. Refuge Chambers 8.1 Refuge Chambers - Technical Discussion 8.1.1 Introduction As a part of the overall escape system, refuge chambers can provide a last resort when existing escapeways are blocked. These chambers are intended to provide both protection from toxic gases and a life supporting environment for a period of time before external rescue or further escape efforts can be carried out Escapeways may be blocked physically (due to cave-ins, etc), by fire, or by the presence of a toxic or oxygen deficient atmosphere. In the first two cases, the trapped miners would most likely await external rescue efforts, and hence the design of the chamber will have to consider the time durations that such efforts may take, It is also possible, in the second case, for fire fighting and fire protective equipment to be stored in the chamber so that miners may attempt their own escape. In the third case, it should be recognized that a compact, beltmounted 1-hour self-contained breathing apparatus has been developed(9), and that other, less compact equipment is available for up to 4 hours of self-contained breathing supply. If such equipment were stored in the chambers, then miners could escape by travelling from chamber to chamber, taking temporary refuge in each before proceeding to the next. 8.1.2 Background The concept of "barricading" has long been recommended for those emergencies where miners are trapped inby a fire. Barricading, which is the construction of a makeshift shelter in a crosscut or deadend, protects the entrapped miners from toxic gases and enables them to conserve a supply of air. In this manner, they can survive two or three days--hopefully enough time for them to be reached by rescue teams. In the past, many lives have been saved with this technique.

Jan 1, 1976

By T. A. Henrie, D. C. Fleck, D. G. Kesterke

Uranium metal was electrowon from uranium dioxide dissolved in fluoride melts . The UO₂ was fed directly to the cell in a continuous manner . Electrolysis was performed at 1 , 200 ° to 1,300 ° C in electrolytes composed of UF4 , LiF , and BaFa . A single regulus of metal was collected in a confined area of the crucible . Product purity of 99.8 percent was attained . Carbon was the major contaminant . Compartmented cells were studied as a means of confining the oxide feed to the vicinity of the anodes .

Jan 1, 1964

By M. K. Larson, B. G. White

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are investigating the causes and mechanisms of roof failure in underground mines. It is expected that a better understanding of these causes and mechanisms will lead to better layout and support designs that will help prevent accidents and fatalities associated with fall of ground. Two numerical experiments were conducted by NIOSH researchers using the Fast Lagrangian Analysis of Continua (FLAC) computer modeling program with a strain-softening continuum to simulate fracture zones. Two models, one of a round hole in a plate and one of a rectangular opening, were constructed and boundary conditions were applied to simulate far-field shear. The Particle Flow Code in Two Dimensions (PFC2D) computer program was used to look at the effects of far-field shear in generating fractures around an underground opening, but these models are preliminary until boundary conditions, strengths, and stiffnesses are matched to the FLAC models. Results showed that shear zones propagated from the opposite corners of openings in directions that appeared to be determined by opening shape and far-field stress. Tensile failures also formed and extended away from these shear zones. The consistent direction of shear deformation with respect to far-field shear provides a plausible explanation for preferred directions of shear as seen in geologic environments.

By Ernest R. Rodriguez, Allen D. Look

"INTRODUCTION The underground mine of the Miami Copper Co. has operated since 1927 without a fatality from blasting or the handling of explosives. To improve safety and efficiency, electrical blasting has been used exclusively since 1934. During the period January 1, 1934, to December 31, 1948, inclusive, over 4,000 tons of explosives were used to produce 60,925,071 tons of ore with 896,760 feet of development footage and 2,591,788 square feet of undercut area.The purpose of this paper is to recount the company's precautions to insure safe handling of explosives at this operation, where safety involves careful planning rather than ""trial and error.""GENERAL INFORMATIONThe Miami Copper Co. operates on underground mine in a large, low-grade, Porphyry copper deposit near Miami, Ariz. The deposit contains numerous fractures and planes of weakness, which contribute to ease of working the ore bodies by the block-caving method of mining.An individual stope-caving method is used with stoles 150 feet by 200 to 300 feet and 30- to 50-foot pillars between stapes. After the stope is undercut, the ore is drawn through the draw raises on the grizzly level, and thence through the transfer raises to the ore chutes on the haulage level.Access to the mine is by four active shafts, three of which are primarily for ventilation. No. 5 shaft is used for both hoisting and service. There are four operating levels in the mine. The elevations of the grizzly levels are governed by the contour of the bottom of the ore body and therefore vary in different locations in, the mine.Grizzly levels are on the 850, 900, and 975 levels. The 1,000 level is the haulage level. This mine operates in very low-grade ore and requires economical handling of large tonnages safely and efficiently."

May 1, 1950

By P. Yant, A. C. Fieldner

"IntroductionIn its investigations relative to reducing the hazards of carbon monoxide poisoning, the Bureau of Mines recently had its attention drawn to a compound2a sold under a trade name for which claims are reported to have been made regarding its efficacy in reducing that type of poisoning in automobile garages. Accordingly, some of the product was obtained and analyzed for its power to absorb, oxidize, or destroy carbon monoxide; and the results are herein reported.Description of ""Compound"" (quoted from manufacturer's circular)While the circular does not actually state that the ""compound"" protects against carbon monoxide, the inference is therein, because each of the two following quotations is below these respective headings; ""Carbon-Monoxide Poisoning,"" and ""Chronic Gassing Among Garage Workers.""The ""compound"" holds chlorine and oxygen gases in solution with formaldehyde, which unites with the hydrogen to form hydrochloric acid., giving an over-supply of oxygen which burns up carbon just as a piece of wood is burned in the fire. The formaldehyde in the composition of the ""compound"" is a great affinity for ammonia and hydrogen sulphide."

Apr 1, 1924

By Suzann C. Ambrosio

Crude petroleum, the only commercially exploited mineral resource in Cameroon, continued to dominate developments in the mineral industry sector. International mining concerns have expressed interest in developing Cameroon's bauxite and iron and steel potentials. Domestically, the mineral industry focused on production of fertilisers for agricultural development, infrastructure construction, and hydrocarbon development, through the nearly self-sufficient production of fertilizer materials, cement, and crude oil. The mineral sector contributed 5.6% to the estimated 1981 gross domestic product (GDP) of $6.5 billion.2 Petroleum exports accounted for approximately 4.5% of the 1981 GDP and exceeded coffee and cocoa exports for the second consecutive year. The trade gap widened during the fiscal year ending on July 80, 1981, owing to a 21% increase in exports and a 25% increase in imports. Offsetting these balance-of-payments difficulties, typical of developing countries' early economic stages, were increases in foreign exchange reserves to $71 trillion by May 1983.

Jan 1, 1983

By Roy H. Grau, John C. LaScola

This Bureau of Mines report contains a tabulation of methane emissions during 1980 for all coal mines located in the United States with emissions greater than 0.1 MMcfd. Listed for each mine are methane emission quantity, location, and coalbed. The report also compares records of 1975 and 1980 and describes relationships between emissions in 1980 and the Bureau's coalbed gas content data on 11 mines.

Jan 1, 1984

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove, grindability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions 2 issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1970

By N. F. Le Jeuns

For a number of years the Bureau of Mines has conducted semi-annual surveys to determine the changes in motor gasoline being sold in the United States. It was pointed out in the previous survey that there was an apparent tendency toward greater uniformity in the character of gasoline marketed in the United States. This practically uniform tendency which continued from April, 1917 to January, 1923, has been interrupted in the, present survey, as shown by an examination of the column marked "Difference," as given in Table 1. The figures in this table were obtained by averaging the end points of the least volatile and most volatile samples of gasoline. For example, of 850 samples analyzed in 1919, the 10% ,(85 samples) having the highest end points and the 10% having the lowest end points mere grouped, and the end points of each group averaged. These averages are represented in the table as the "Maximum 10%" and the ?Minimum 10%? respectively. The same process was used on the other surveys.

Jan 1, 1923

By M. L. Whisman

The Bureau of Mines developed a radiotracer method for detecting the contribution of selected components and additives to thermally induce deposits of turbine aircraft fuels. Fuels were examined before and after 52 weeks of storage at 130° F. Of particular concern was the influence of aromatic hydrocarbon fuel constituents on thermal-stability quality of jet fuels during storage. A microfuel coker test apparatus was used to thermally stress the test fuels and blends, and the resultant contribution to deposits of selected fuel components, labeled with carbon-14, was determined by radioactive-counting techniques. Ninety-one blends of five test fuels with carbon-14-labeled fuel additives or components were prepared, tested, stored for 52 weeks at 130° F, and reanalyzed for deposit-forming tendency. These additives included two anti-oxidants, a metal deactivator, and a corrosion inhibitor. Of the labeled hydrocarbon fuel systems studied, the greatest reaction was observed in blends containing methyl-and ethyl-substituted indenes. Other aromatic types also showed some contribution to the deposits. Three of the additives showed a marked tendency to degrade and react during storage and thermal stress. A cresol antioxidant, however, barely contributed to deposit formation. Oleic acid interacted with cadmium present in aircraft fuel systems and produced deleterious effects upon the thermal-stability quality of the fuel.

Jan 1, 1971

By Thomas E. Marshall, Roy H. Grau

The U.S. Bureau of Mines has developed an acoustic test for determining if a rock salt sample is from a "normal" nongassy salt face or from a gassy face where an outburst has the potential to occur. The test is based on the observation that a salt sample taken near an outburst-prone zone produces an audible popping sound when it is dissolved in water. The sound is produced when pressurized gas that is trapped in salt samples is released. In the acoustic test, the sound is electronically measured, digitized, and transmitted to a microcomputer; the output is an average decibel value that classifies the sample as "normal" or "outburst." The acoustic test procedure and equipment are described, and raw test results and data analysis are shown. Results are also shown for several salt samples that were analyzed using a laser Raman microprobe.

Jan 1, 1990

By James A. West

THE South Asian countries of India, Ceylon, Pakistan, Afghanistan, Nepal, Bhutan, and Sikkim have a large variety of mineral resources; however, in spite of mineral industry growth during 1964, development of resources remained far short of possible development, and, in terms of value of trade in minerals, the area remained a sizeable net importer. India's mineral industry is by far the most significant; its minerals production in 1964 accounted for more than 90 per cent of the total value of all minerals produced in the area. The total value of all minerals produced in South Asia in 1964 was only about 1 percent of the area's estimated gross national product of $55,125 million. Despite the rather small current contribution of minerals to the economy, development of mineral resources figures prominently in plans for the industrial development of the nations of this area.

Jan 1, 1966

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 J. J. Bourquin, S. H. Katz

"Three types of respiratory apparatus namely, gas masks, hose masks, and self-contained oxygen-breathing apparatus - are now commonly used for protection from noxious gases, vapors, and smokes or ristes, but no particular type can be selected as best for all conditions. Many factors must be considered in connection with each situation, so that each must be considered as a problem in itself. Following are concise statements for comparing the types:Gas masks are the simplest and easiest to wear, also the least cumber-sore; but they protect only in comparatively low concentrations of noxious gases and should never be used where the air contains less than 16 per cent of oxygen. Special masks give protection from one gas or class of gases, but may give no protection against another gas or class of gases.Hose masks protect in any irrespirable atmosphere, but are somewhat cumbersome, the length of hose limiting the distance a wearer may go from fresh air. They are serviceable also where a supply of pure air moves with the wearer, as where a locomotive engineer in a smoky tunnel is using a hose mask supplied with air from the compressed air line of the locomotive. Hose masks consume no chemicals or materials and so are not limited in the time they may be used.Self-contained oxygen-breathing apparatus protect in any irrespirable atmosphere, but their weight is cumbersome, they can be used only by trained men, and frequent attention must be given them to maintain good working condition. On the other band they are the only safe means for exploring mines and other places filled with irrespirable gases in high concentrations."

Jun 1, 1923

By J. F. Barkley

"In the course of the Government's Fuel Economy Survey of its own power plants, studies and tests have been made of various oil-burning equipments under power-plant boilers. There are now many types of burners being offered in the relatively limited field of power-plant use. The majority of the types used may be grouped into two general classes- those using steam to effect the atomizing of the oil, and those using mechanical means.Burners using steam have had the most prominence in this field for a long period. The mechanical atomizing type of burner successfully applied on shipboard, however, pointed to a possible betterment in land work. The vision presented itself of a burner that would need no steam for atomizing that would permit of air inlets or registers compactly arranged as a part of the entire burner, and that would only require the natural stack draft usually available in land boiler furnaces. Hence, rather recently there has been much development along this line, resulting in various types of burners.In Table 1 are grouped test items chosen from many tests showing representative analyses of the products of combustion obtained with various burners installed in various types of furnaces. In all these tests the burners were handled by experts and represent practically the best attainable for that particular arrangement. The boiler efficiencies ranged from 70% to 80%. It will be noted that the burners using steam for atomizing were able to secure slightly better 002 and less 02 without the presence of CO."

Feb 1, 1926

By Berenice B. Mitchell

THE STATISTICAL tables in this chapter present, country by country, the mineral production of the world in 1949-50. The figures are on a mine basis, unless otherwise indicated, except for cement, coke, and steel, which are measured at the processing plant. The tables are essentially a retabulation, by countries, of the 53 commodity world tables appearing in the various chapters of this volume. For lack of comprehensive information, data for the following minerals are excluded: Andalusite, aplite, asphalt, boron, bromine, calcite (optical), calcium chloride (natural), carbon dioxide, clay, columbium (niobium), diatomite (kieselguhr), dumortierite, emery, garnet (abrasive), gem stones (other than diamonds), germanium, greensand, grindstones, helium, indium, iodine, kyanite, lithium, magnesium compounds (other than magnesite), meerschaum, mineral pigments, monazite, natural gas, natural gasoline, oil shale, olivine, perlite, pumice, quartz crystal, radium, sand and gravel, selenium, sillimanite, sodium salts (other than common salt), stone, strontium, sulfur (byproduct), tantalum, tellurium, thallium, topaz (industrial), tripoli) uranium, vermiculite, wollastonite, and zirconium. In addition, a few minor geographic areas for which no statistics are available, are also omitted from the tabulation; it is believed that no significant quantities of minerals are mined in any of these areas. The statistics in these tables were derived principally from questionnaires sent, in cooperation with the United States Department of State, to the governments of each country. Supplementary sources were United States consular reports, the Imperial Institute's Statistical Summary of the Mineral Industry of the British Commonwealth and Foreign Countries, other official publications of various countries, the United Nations Statistical Yearbook, the Year Book of the American Bureau of Metal Statistics, Minerais et Metaux, business magazines, and company reports. Where official data were not available, esti-

Jan 1, 1953