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By P. C. McWilliams

Theoreticians in soil mechanics have been pursuing a probabilistic approach to the factor of safety of an embankment or darn for the past 10 years. The motivation for this work is in contrast to the current practice of deterministically computing a factor of safety and treating it as an absolute with no regard to its inherent statistical variability. Basic to the probabilistic approach is the selection of an appropriate statistical model to represent the histogram or probability density function (PDF) of the factor of safety values, Rather than simply assuming which PDF is appropriate, the Bureau of Mines collected data at two waste disposal embankments for consideration, This report addresses three candidate models, using the techniques of nonlinear curve fitting, and identifies the "best" model. A propagation of error formula for estimating the variability of Fellenius? factor of safety is also discussed.

Jan 1, 1983

By Norman L. Wimmler

Active placer mining in Alaska began near Juneau in 1880, but the first gold rush did not start until 1896; then the discovery of the Klondike brought gold seekers from all parts of the world. A few of the newcomers were experienced miners, but the majority knew nothing whatever of placer mining. Even those who were placer miners of much experience found entirely new conditions, notably frozen ground, that presented many difficult problems. As a result, numerous methods of mining and of thawing frozen ground were tried. From these trials the practice described in this bulletin has been developed. All known placer fields in Alaska have been mined to some extent, and some have been virtually exhausted. In most districts, however, there remain large quantities of low-grade gravel and also some small isolated areas of comparatively rich gravels which could not be successfully mined because of adverse physical conditions. These districts are now the scene of most placer mining, including dredging, hydraulicking, drifting, mechanical methods of open-cut mining, and ground sluicing (or booming) followed by " shoveling-in."

Jan 1, 1927

By Donald P. Tuchman, Robert P. Vinson, Steven J. Page, Linda J. McWilliams, Gerald J. Joy, Steven E. Mischler, Jon C. Volkwein

The National Institute for Occupational Safety and Health (NIOSH), through an informal partnership with industry, labor, and the Mine Safety and Health Administration, has developed and tested a new type of instrument known as the personal dust monitor (PDM). The dust monitor is an integral part of the cap lamp that a miner normally carries to work and provides continuous information about the amount of respirable coal mine dust in the breathing zone of that individual. Testing was conducted on 25 prototype instruments in the laboratory to verify the instruments’ accuracy as received from the manufacturer and after a period of underground use. The laboratory testing verified previous work; there is a 95% confidence that the individual PDM measurements were within ±25% of reference measurements. In-mine testing determined the precision, durability, and miner acceptance. Data from the mines showed a field precision of 0.078% relative standard deviation for the PDM and 0.052% for the recognized standard—the coal mine dust personal sampler unit. The PDM had about 90% availability for collecting valid information in over 8,000 hr of underground use. Anecdotal comments by miners indicated that they found the PDM more convenient to wear for sampling than currently used instruments because of the integration of the sampler into the normally worn cap lamp. The means of the instruments’ pre- and postmine accuracy verification test values were statistically equivalent. Additional data were collected to measure the equivalency of the PDM to the U.K. Mining Research Establishment sampler, as required by U.S. law. However, analysis of the data was more complex than originally anticipated because the variance with increasing concentration required use of a more sophisticated statistical model. Explanation of and results from this work will be the subject of a second publication. Under the broad range of test conditions covered in this work, the PDM functioned as well as the current sampler in terms of availability for use, accuracy, precision, and miner acceptance.

Jan 1, 2006

General economic conditions continued to improve in the second quarter of 1984 as real gross national product advanced at an annual rate of 7.5 percent (table 1). This followed an even larger first quarter annual rate increase of 10.1 percent. The slower second quarter growth was greeted as a sign that the economy is not over-heating. The signs of slowed growth in some sectors suggest that the recovery may continue well into 1985 without the inflation symptomatic of a rapid recovery. Most of the slowdown in growth was absorbed by business inventories, personal consumption of durable goods, and residential fixed investment. Business inventories grew by only 68 percent as much as in the first quarter, personal consumption for durable goods grew by 58 percent of the first quarter rate, and residential fixed investment slowed to only 44 percent of the first quarter growth. Sectors with accelerated growth in the second quarter included personal consumption of nondurable goods and of services, which increased at annual rates of 9.6 percent and 3.8 percent, respectively, and Federal purchases of goods and services, which increased at an annual rate of 47.9 percent.

Jan 1, 1984

By G. S. Scott

The investigation of the causes, behavior, and control of anthracite mine fires, which the Bureau of Mines has been carrying on has yielded several publications directly applicable to mine-fire problems. 3/, 4/, 5/, 6/, 7/, 8/ As a further step in elucidating the causes of heating in certain anthracites subjected to oxidation, reliable information vial needed relative to the actual amount of heat that is liberated when a unit volume of oxygen combines with anthracite at varying temperatures.

Jan 1, 1939

By Frank E. Chase, John L. Ellenberger, Christopher Mark

The nature of competition in the coal market tends to deplete the most favorable coal reserves first, and forces subsequent development of mines in more extreme ground conditions such as those associated with multiple-seam mining. In fact, 70% of the United States coal reserves are in multiple-seam situations. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop mine design algorithms that will result in safer multiple seam mines. This paper presents an overview of multiple seam issues in the central Appalachian coalfields. To date, more than 50 case histories have been analyzed from 20 operating mines in Eastern KY, Western VA, and Southern WV. Each case history is classified according to the degree of multiple-seam interaction, ranging from no apparent interaction to severe interaction with direct impacts on mine safety and resource recovery. The case histories are also examined with regard to amount and geologic characteristics of interburden and overburden, and design stability factors. The sequence of mining has also been found to be critical when the lower seam is fully-extracted. This paper compares current case histories to traditional rules of thumb. In addition two situations were modeled using LaModel software. LaModel has been upgraded to import pillar grids and topographic data from AutoCAD files. The cases presented demonstrate vertical stress capabilities of LaModel.

By J. S. Stachulak, G. H. Schnakenberg

The objective of the Diesel Emissions Evaluation Program (DEEP)-sponsored project at Inco's Stobie mine was to conduct a long term field evaluation of diesel particulate filter (DPF) systems available to the underground mining industry. Some of the major issues studied were criteria for selecting the filter media, means of DPF regeneration, efficiency of DPF systems and the occurrence of unwanted secondary emissions, and reliability and durability of DPF systems. Nine state-of-the-art diesel particulate matter (DPM) filtration systems have been retrofitted to heavy-duty and light-duty vehicles and have been subjected to extensive long-term in-mine evaluation. Periodic efficiency tests were conducted at various stages of the study (2001, 2002 and 2004) to establish in-use efficiencies and durability of the tested DPF systems. The results were used to assess the effects of the filter systems on the concentrations of particulate matter, nitric oxide, nitrogen dioxide and carbon monoxide in the vehicle exhaust. The variety of filtration systems and regeneration concepts used in this study offered the opportunity to investigate their advantages and disadvantages. This paper also offers a review of selected experiences with the installation and operation of the DPF systems on underground mining vehicles at the Inco Stobie Mine.

By Michael Schmitz, Eugene Ahrenholtz, William A. Heitbrink, Jeanne A. Zimmer, Andrew B. Cecala, Ernest S. Moyer, Earle H. Andrews, Chris C. Coppock, John A. Organiscak

Many different types of surface mining equipment use enclosed cabs to protect equipment operators from health and safety hazards. The overburden removal and mining process can be extremely dusty and can cause excessive dust exposure. To study this issue, a cooperative research effort was established between the National Institute for Occupational Safety and Health, U.S. Silica Co., Clean Air Filter Co., and Red Dot Corp. in an effort to lower respirable dust levels in an enclosed cab on an older surface drill at a silica sand operation. Throughout this research effort, a number of modifications were incorporated into the drill's filtration and pressurization system, as well as in other areas, to improve its design and performance. An average cab efficiency of 93.4% was determined with gravimetric sampling instruments when comparing the outside with the inside cab dust levels on the final design. Although this study considered just one operation, the goal was to identify cost-effective improvements that could be implemented on all types of enclosed cabs to lower respirable dust concentrations. Two critical components for an effective enclosed cab system are having a properly designed, installed, and maintained filtration and pressurization system, along with a method for maintaining structural cab integrity, which allows the cab to be positively pressurized. Another important component is maintaining cab cleanliness. Although this research was originally directed toward the mining industry, it is also applicable to agricultural or construction equipment.

By H. William Zeller, T. E. Westpha1

The U.S. Bureau of Mimes evaluated the effects of two iron-based fuel additives on diesel particulate matter (DPM) emissions. The 5.6-L, six-cylinder test engine is typical of engines used in underground mines. One additive, ferrous picrate, did not measurably affect exhaust emissions. This report is mainly about a ferrocene-based additive that reduced DPM between 4 and 45 pct, depending on engine operating conditions. The report concludes that the DPM reductions were caused by the catalytic oxidation properties of a ferric oxide coating that developed inside the engine's combustion chamber. The ferric oxide coating also decreased gas-phase hydrocarbons and O, but it increased CO, and NO,. The increase in NO,, of about 12 pct, is considered the only adverse effect of the ferrocene-based fuel additive. The results suggest that the effectiveness of ferrocene was partially offset by increased sulfates because of the high-sulfur fuel used. Recommendations for continuing fuel additive research are presented.

Jan 1, 1992

By W. W. Stephens

As part of the Bureau of Mines program directed toward more effective utilization of the mineral resources of the United States, a number of processes for production of sponge iron have been investigated. The use of sponge iron as a raw material for production of steels and other ferrous alloys offers several possible advantages over the conventional pig-iron and scrap process, especially for utilization of the smeller, widely distributed iron-ore deposits of the western United States. Although considerable information has been made available on various processes for production of sponge iron, little information 118.6 been published heretofore on the problems and costs involved in melting the sponge iron for production of steel. The present Paper reports the results of tests conducted at the Bureau of Nines pilot plant at Redding, Calif. in which several different types of sponge iron Were used as charge material for production of steel in a 4-ton-capacity basic arc furnace.

Jan 1, 1949

By D. A. Buckingham

Engineering and economic evaluations were performed by the Bureau of Mines on 14 Frasch sulfur, 1 native sulfur, and 21 metal sulfide operations in 11 market economy countries. The evaluation included discounted-cash-flow rate-of-return economic analyses at 15 pct to determine the average total cost of production of these two commodities and the potential availability of elemental sulfur (8) and pyrite concentrate. The Bureau evaluated the potential availability of elemental sulfur and pyrite concentrate. Approximately 279 million metric tons (Mmt) of pyrite concentrate at 46 pct 8 is potentially recoverable from 422 Mmt of in situ metal sulfide ore. Nearly 89 pct of the total pyrite concentrate is available at an average total cost of production below the January 1984 pyrite concentrate market price ($43/mt). About 185 Mmt 8 is potentially recoverable from 253 Mmt of in situ elemental sulfur. About 99 pct of this sulfur is available at an average total cost of production below its January 1984 market price ($131/mt).

Jan 1, 1986

By Gerald L. Finlinger

This Bureau of Mines publication reviews underground methane drainage programs being conducted in various coalbeds. Equipment used in drainage programs such as drills, underground pipelines, and methane monitoring systems is described.

Jan 1, 1980

By A. L. Worthen

This is one of a series of pacers being published by the United States Bureau of Mines, describing mining and milling methods at crushed-stone plants throughout the United States. These pacers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total production costs. Although the publication of total production cost might not be advisable in some instances, yet a knowledge of operating costs is essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called o this differentiation in order that there will be no misunderstanding of the scope of the cost tabulations. This paper deals with the quarrying and crushing methods used at the Plainville plant of the New Haven Trap Rock Co., which produces annually between 275,000 and 300,000 tons of trap rock, Although pct the largest quarry operated by the company, it typifies the standard methods used by all the quarries in producing crushed stone and has one or two rather unique operating features. The cost of production at this plant is close to the average cost at all quarries of the company.

Jan 1, 1936

By C. W. Whitten

Iron ore deposits in south-central Missouri have emerged as a possible resource for the rare-earth elements. The Pea Ridge Iron Mine is one such deposit. Rare-earth minerals at the Pea Ridge Iron Mine are contained in breccia pipes consisting primarily of silicon oxides and feldspars. These pipes extend up through the magnetite ore body and appear to be alterations and replacement of earlier hematite. The mineralogy of these pipes is very complex and varied, which could complicate the concentration and extraction of the rare-earth minerals. This U.S. Bureau of Mines !eport represents a study by characterization of the mineral phases to assess the amenability and development of concentration and extraction techniques. Previous characterization of rare-earth minerals has been mainly by transmitted light microscopy. This method along with reflected light microscopy, scanning electron microscopy, and X-ray diffraction was used to identify and characterize the rare-earth and associated minerals. The minerals identified were the major ore minerals, magnetite and hematite; the rare-earth phosphates, monazite and xenotime; the rare-earth silicate, allanite; the minor associated minerals, cassiterite, pyrite, and apatite; and the gangue minerals, feldspar, quartz, and actinolite.

Jan 1, 1990

By Harold M. Smith

This report presents a complete qualitative picture of knowledge of the composition of petroleum as of April 1965. The material is presented in detai 1 on two imaginative maps--one, the Hydrocarbon Hemisphere, depicts the hydrocarbons that have been identified in petroleum; the other, the Heterogeneous Hemisphere, shows the sulfur, nitrogen, and oxygen compounds that have been found. All compounds are placed on the maps according to boiling point. The accompanying text illustrates by structural formulas the several types of hydrocarbon and nonhydrocarbon compounds identified, presents some quantitative data, and points out the possible geochemical significance of a number of the compounds. The possibilities of the Petroleum World of the future are discussed as a function of needed research.

May 1, 1965

By A. H. WHITE, PERRY BARKER

In a consideration of the various means whereby more economical and more efficient use may be made of the fuels in the United States, the possibility of obtaining for the production of illuminating gas other and cheaper fuels than the Pennsylvania coals demands attention. For the Government, as well as for private corporations and the householder, there can be no more economical and efficient way of using some coals than through the medium of illuminating gas. In the stove, gas reduces the labor cost of heat production and lessens the drudgery of the kitchen; burned in the Welsbach mantle, it is an excellent and cheap illuminant. In addition, the coke that remains after the gas has been recovered furnishes a smokeless fuel that has about the same heating value as anthracite. Hence any investigations that will indicate how local coals through proper treatment may be substituted for the higher priced and rapidly vanishing Pennsylvania gas coals will bring about lower prices for both gas and coke and will also aid to conserve for use in metallurgical processes the coking coals of Pennsylvania and of ot,her States. The annual drain on the gas-coal resources of this country and the importance of the gas and coke industries are indicated by the fact that 8,390,129 tons of coal were carbonized in retorts in the United States in 1909. The resulting salable products from by-product ovens were 15,791,220,000 cubic feet of coal gas, 6,254,644 tons of coke, and 60,126,000 gallons of tar. The total value of all by-products was about $28,508,637.

Jan 1, 1911

7253. Arkhangelsky, A. D. Geological Results of the General Magnetometric and Gravimetric Surveys of the U.S.S.R. (in Russian). Internat. Geol. Cong., Rep. of the 17th Sess., Moscow-Leningrad, 1937, vol. 1, Moscow, 1939, pp. 241-250. Geophysical methods have been used in the U.S.S.R. to study geological problems. Such is the case of the general magnetometric and gravimetric surveys made jointly by the Main Physical Observatory, Main Office of Geodesy and Cartography, Institute of Terrestrial Magnetism, and Main Office of Geophysical Prospecting. Some institutions supplied the data, others processed them. Geological interpretation was made by the author. (1) Regional magnetic anomalies in the plains of the U.S.S.R. are traceable to the folded substratum overlain by sedimentary rocks; these anomalies promise to yield data characterizing the substratum in respect to strike and depth. Anomalies in European U.S.S.R. suggest that the pre-Cambrian -substratum of the East European plateau consists of elements of different ages. In the most ancient of them, the main strike of the folding is almost latitudinal; in the younger ones, the folding is oriented in the meridian. (2) The Faye and Bouguer gravity anomalies are caused primarily by differences in the density of rocks composing the upper crust and by unknown processes producing changes of density at depth; these processes are not connected with isosiatic movements. The anomalies in the European and adjoining Asiatic U.S.S.R. promise to indicate the volume of the pre-Cambrian massif of the east-European plateau and to clarify the interrelations between the Ural, Tian-Shan, and Donetz Basin folding systems, as well as between the Dnieper-Donetz depression and the mid-European depression. - V. S.

Jan 1, 1944

By Maria I. De Rosa, Charles D. Litton

The National Institute for Occupational Safety and Health (NIOSH/PRL) conducted a series of large-scale experiments to evaluate the effectiveness of optical flame detectors, photoelectric smoke detectors, and combined ionization and photo­electric smoke detectors for rapidly detecting mining equipment cab fires. The detec­tor alarm times were then used to trigger the discharge of a fire inerting system inside the cab to suppress cab material fires. This paper discusses the types of fire detectors tested, the experiments that Were conducted, and the results that were obtained. Con-" elusions are that rapid detection of equipment cab fires can be achieved to trigger the discharge of a fire inerting system inside the cab to protect the operator in the cab.

By Alton Gabriel

During the fall of 1940, J. R. Thoenen of the Mining Division, Bureau of Mines, accompanied by the senior author, surveyed the more important domestic alunite deposits. Although the study was designed primarily as an economic survey, samples from a number of the deposits were collected to investigate the beneficiation of the lower-grade material.

Jan 1, 1942

By Alton Gabriel

During the fall of 1940, J. R. Thoenen of the Mining Division, Bureau of Mines, accompanied by the senior author, surveyed the more important domestic alunite deposits. Although the study was designed primarily as an economic survey, samples from a number of the deposits were collected to investigate the beneficiation of the lower-grade material.

Jan 1, 1942