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The question of earth models has repeatedly arisen in our work. An accurate representation of the seismic properties is required for three reasons: 1.To be able to determine from a set of received arrival times, the location of a seismic source in the earth, and secondly the degree of accuracy required in the model used for calculating source location from the set of arrival time differences. 2. To be able to determine the expected arrival times at an array of geophones produced in response to a hypothetical source in the earth. 3. To be able to estimate received signal strengths more accurately. The work reported here on earth models is based on information from sever- al consultants and from others who expressed an interest in the problem and supplied information to us. II. COAL MINE GEOLOGY On one of our earlier assignments for the Bureau of Mines, Earth Science Research Inc. of Cambridge, Massachusetts prepared for us a short description of the lithology to be expected at coal mine sites. This description follows, together with the ranges of compressional seismic velocities (Figure I*) associated with typical materials comprising the layered structure of a coal mine area. Coal is primarily associated with fresh water sediments including sandstones, shales, and clays, and occasionally may be metamorphased to varying degrees. In the Appalachian Basin the coal beds occur within cyclical sequences of non-marine shales, sands tones, conglomerates, limes tones, and clays. The beds range in thickness from a few inches to 60 feet, averaging between 2 feet and 10 feet. They have generally broad areal extent, occasionally up to 5,000 square miles, and have an overall tabular or lens-like shape. Within a particular lens, local changes in thickness are normal.

Jan 1, 1974

By D. K. Dysinger

In this U.S. Bureau of Mines study, neodymium metal of 99.8 pct purity was prepared by electrolysis of Nd203 salts dissolved in a molten fluoride electrolyte. The metal was electrowon in a molten state at current efficiencies of 50 to 60 pct. Oxygen and carbon were the major impurities detected in the product. During operation of the small-scale laboratory cell, a number of technical problems including anode effect, low oxide solubility in the electrolyte, high neodymium metal solubility, reactivity of the metal with the cell materials, and back reaction of the metal with the anode gases were encountered. Approaches to improve cell operation and prospects for commercial adoption of the electrolytic production of neodymium metal are discussed.

Jan 1, 2010

By James R. Coldwell

Mining and processing cost analyses were conducted by the U.S. Bureau of Mines on stratiform zinc-lead-silver, coal, and stratiform barite deposit types that are found in the Colville Mining District. Reserves and gross revenues which would allow these deposits to be minable were modeled. A 15% Discounted cash-flow rate-of-return economic threshold was selected as the minimum acceptable return on investment for the three deposit types. The economic modeling indicated combinations of grades and tonnages for stratiform sulfide deposits that could be economically viable for orebodies ranging in size from 25 to 130 million metric tons. The gross revenues for a surface mine range from $200/mt for a 5,000 mtpd operation using the proposed South corridor to $140/mt for a 17,000 mtpd mine using the proposed North corridor. The economic modeling indicated underground coal mining was subeconomic for deposits ranging in size from 42 to 250 million metric tons. The required gross revenues ranged from $300/mt for a 2,200 mtpd mine to $21 D/mt for a 13,000 mtpd mine. The economic modeling indicated supplying projected in-state barite demand was subeconomic for the three seasonal surface mines modeled. The required gross revenues ranged from $600/mt for a 90,000 mtpy mine to $840/mt for a 6,000 mtpy mine.

Jan 1, 1995

By N. S. Dalal, X. Shi, V. Vallyathan

"INTRODUCTIONThis paper summarizes our recent investigations of the potential role of silicon-oxygen based free radical species in the biochemical mechanism of the lung injury caused by the inhalation of freshly fractured silica. The impetus for this study came from the following observations. Inhalation of crystalline silica is associated with the development of acute and chronic silicosis. Chronic silicosis is characterized by the development of sharply marked concentric fibrotic nodules in the lung. This occurs over a period of several decades with the development of progressive respiratory impairment. In contrast, acute silicosis is manifested by the filling of the alveoli with an amorphous lipoproteinaceous exudate within a short period after exposure, and rapid development of respiratory disability often leading to fatality. Most studies on the pathogenesis of silicosis have focused on the elucidation of cellular mechanisms of cell injury and the development of chronic silicosis. Because pulmonary responses to crystalline silica are distinctly different for · the acute and chronic silicosis, we hypothesized that the acute response is associated with some unique properties of ·freshly formed silica particle surfaces, due to the formation of some reactive chemical species caused by the rupturing or the silicon-oxygen bonds. In occupations involving drilling, tunneling and sandblasting operations acute silicosis can be correlated with this unique surface reactivity of silica. The formation or reactive species was demonstrated, using electron spin resonance (ESR) spectroscopy (Dalal et al., 1986; Fuibini et al., 1987; Hochstrasser and Antononi, 1972). Grinding of quartz crystals under ultra high vacuum (10-10 torr) leads to the formation of Si- and SiO• radicals and these radicals are quenched by exposure to air and other gases (Hochstrasser and Antonini, 1972). ESR signals have also been reported from micronized quartz samples that were evacuated at 413 K (Bolls et al., 1983). In order to find a more direct relationship of such radicals to acute silicosis, we made ESR measurements on quartz dusts freshly ground in ambient air and found- that indeed grinding under ambient environment leads to the formation of the Si• and SiO• type of radicals which decay on storing the dusts in air or in biological buffers (Dalai et al., 1986; Vallyathan et al., 1988). The Si• and SiO radical formation on grinding has also been reported by Fubini et al. (1987). In addition, we recently found that •OH radicals are generated in aqueous suspensions of freshly ground quartz (Dalai et al., 1988; Shi et al., 1988; Vallyathan et al., 1988). We have subsequently carried out detailed cytotoxicity and biological assays on freshly made as well as aged quartz dusts. As summarized below, the results provide new insight into the biochemical mechanism of acute silicosis."

Jan 1, 1988

By R. V. Ramani, K. V. K. Prasad, M. Swaminathan

"Engineering design involves, in addition to numerical calculations, considerable amount of expertise and judgement. The expertise and judgement is required to conceptualize and idealize the problem, select a suitable mathematical model for the problem and to interpret the model results in terms of stipulated design constraints. In recent years, knowledge based systems (KBS) have provided the capability to integrate the qualitative experiential and expert knowledge with ~he quantitative knowledge for improved analysis and design of systems. A possible KBS architecture for mine ventilation system design was discussed by Ramani and Prasad · (1987). The expert system (ES) component of the KBS supports the analysis and interpretation phases of the ventilation design process with an algorithmic program used for the solution of alternate designs. The purpose of this paper is to discuss the data and knowledge needs for developing such a system and a formal means of their representation on the computer. A number of ES shells were evaluated to explore possible development and delivery environments for the system. A brief summary of this evaluation is also provided.INTRODUCTIONLuxbacher and Ramani (1979) have discussed the design process of mine ventilation systems and have provided the interrelationships that exist between ventilation, strata control, drainage and material handling systems and mining methods. They have also outlined the importance of correct analysis of the problem, choice of the right solution method and a rigorous interpretation of the solutions. The expertise required for analysis and interpretation phases was identified as the key element in developing effective and efficient ventilation system designs. Such expertise is embedded in the right choice of questions to be asked of the user as well as in directing the user to a wide array of alternative methods that may satisfy the design requirements. With advances in artificial intelligence applications in recent years, particularly expert systems, the integration of expertise into traditional mine planning and design algorithms has been facilitated. These planning and design aids, employing the integration of numeric and symbolic logic and called coupled systems, are powerful tools for engineers to tap the benefits of experts (Kitzmiller and Kowalik, 1985; Fenves, 1985). The purpose of this paper is to discuss the means of representing knowledge for the design of mine ventilation systems through the use of a coupled system. The KBS is visualized as consisting of the following components:"

Jan 1, 1989

By Blair Burwell

This paper describing the method of mining a deposit of vanadium ore near Rifle, Colo., is one of a series of similar papers on metal-mining methods and costs being issued by the United States Bureau of Mines. This vanadium deposit probably is the largest yet found in North America. It is situated 12 miles northeast of Rifle, Colo. (see fig. 1), on the southern flank of tae White River plateau, and is at an altitude of 6,500 feet. Between 150 and 200 tons of ore are mined daily and trucked to the mill at Rifle. The product of the mill is fined vanadium oxide, which is shipped to the company's plaits at Columbiana, Ohio, and Niagara Falls, N. Y., for the electric manufacture of ferrovanadium. HISTORY The deposit was discovered about 1909 by men prospecting for carnotite. Its outcrop on the bola cliff of Rifle Canon had been known to stockmen for many years.

Jan 1, 1932

By R. L. Schmidt

Research conducted over the past 20 years in France, Great Britain, and the United States on the use of the large-hole burn cut has established cer¬tain advantages for this system. Advantages include longer pull and more complete fragmentation from blast rounds. However, research is needed to establish a set of parameters for optimum performance. As part of the Bureau of Mines Advancing Mining Technology for Marginal Resources program, the Twin Cities Mining Research Center, Twin Cities, Minn., acquired a horizontal rotary drill capable of boring holes up to 24 in. in diameter. This was used for a series of underground experiments at White Pine mine, White Pine, Mich., during 1973. Exceptional results were obtained with a 12-1/4-in void hole that yielded up to 18 ft of pull in a 10- by 20-ft drift, Fragmentation was excellent, and the compactness of the muck pile facilitated loading.

Jan 1, 1975

By Daryl E. Radcliffe

The Bureau of Mines studied the displacement of the roof in a portion of the Bear coal mine near Somerset, Colo, Horizontal-and vertical-displacement gages were installed in a five-entry section during normal room-and-pillar mining procedures. Monitoring of the roof continued until this section was mined out. Displacement measurements in combination with known time lapses between mining and bolting operations indicate that once support is achieved, the length of unsupported time does not appear to affect long-term roof stability in the mine under investigation.

Jan 1, 1978

By A. B. Hooker

Since man first mined underground, there has been need for adequate illumination; this need has never been fully supplied. At first, suitable lamps were not available. Gradually they have been developed, but along with that development the need for better and better lamps has continued owing to the following conditions and factors: 1. Increasing hazards from gas and dust ignitions. 2. The speeding of operations with mechanized mining, which necessitates greater visibility. 3. A demand that cleaner coal be loaded, which requires higher levels of illumination. 4. The cost of compensation for injuries that has created a demand for better illumination and safer lamps. Use of better lamps has been retarded by: 1. Prejudice and resistance to change on the part of the workers in some districts. 2. The cost and upkeep of the lamps. 3. The present types of lamps, while a great improvement over the old lamps, do not entirely fulfill the requirements for a safe and efficient light for underground workers.

Jan 1, 1938

By L. W. Higley

Procedures were developed for reclaiming high-temperature alloy scrap in the form of standard cobalt-base alloy. A cobalt-base, multicomponent, high- temperature alloy, such as S-816, can be successfully melted from scrap, and its specified chemical composition can be retained. Induction furnace melting in a controlled atmosphere was used to obtain ingots that were subsequently fabricated by impact forging to provide specimens for heat treatment and testing. Of the numerous metal elements in S-816 alloy, only small quantities of molybdenum were lost in the melting operation as finally developed. Test results indicated that the scrap material, after melting, forging, and heat treatment, was equivalent in room-temperature tensile strength, in high-temperature creep and stress-rupture properties, and in chemical composition to commercially produced S-816 alloy made from virgin material.

Jan 1, 1963

By J. T. McCartney

Thin sections of coal have been prepared for many years either by cutting on a microtome (1,2)5 or by grinding and polishing (2,1). Specimens of most coals had to be demineralized in hydrofluoric acid and softened in caustic solutions before they could be successfully cut with a conventional microtome. Some lignites could be cut without pretreatment. Jeffrey (1) obtained sections from coals of all ranks, although long and tedious pretreatment was required for anthracite. His sections were less than 1 cm.2 in area (probably much less for high rank coals) and about 5 microns thick. Thiessen (2) also cut sections of softened coals, mostly of low rank. His sections were a few square millimeters in area and about 3 microns thick. However, Thiessen preferred ground and polished sections for detailed studies because they were larger and had not been chemically attacked by softening media. He prepared ground sections as large as 4 cm.2 in area and usually 5 to 10 microns thick. Thousands of such sections, covering complete column samples of many coal beds, were studied for a number of years (4). With the development of the electron microscope and increased interest in quantitative optical studies of coals, a need for much thinner sections arose. However, no suitable technique for preparing such sections was known until Fernández-Morán developed a diamond knife for cutting ultrathin sections of hard materials (5). Workers at the Centre d'Etudes et Recherches de Charbonnages de France applied this new tool to the cutting of coal sections and have recently described their technique to the Burg, of Mines. Using their methods, with some modifications, researchers of the Bureau of Mines have succeeded in cutting ultrathin sections of coals ranging in rank from lignite to

Jan 1, 1961

By Raymond M. Stateham

Microseismic noise rates and slope movements were measured in an unstable area along the north wall of the Tripp-Veteran pit, Kennecott Copper Corp., Ruth, Nev. Low-noise, wide-band microseismic geophones were located at various points in the wall, and the change in distance across open fractures, resulting from instability, was determined by repeated measurements between fixed points set on each side of the fractures. The microseismic noise rate increased and decreased with corresponding increases and decreases in the rate at which the fractures opened. The microseismic noise rates and changes in width of the fractures show excellent agreement, and the two types of measurements complement each other in monitoring the progress of pit wall failure.

Jan 1, 1971

A major hazard to workers in underground mines is fire and the resulting contaminated air. Fire reaches miners thousands of yards away with carbon monoxide gas and other toxic fumes. The same ventilation system that furnishes fresh air to miners can also be the vehicle to carry contaminated air to remote locations. To reduce these problems, the U.S. Department of the Interior's Bureau of Mines entered into Contract H0242016, "Mine Shaft Fire and Smoke Protection System," with FMC Corporation, Santa Clara, California, to evaluate mine shaft fire and smoke hazards and to develop and demonstrate a low-cost, reliable mine shaft fire and smoke protection system that would be applicable to a majority of metal and nonmetal mine shafts, including raises and winzes, especially in deep mines.

Jan 1, 2011

Part Two of this report is based upon six working memoranda prepared during the first half of 1972 at an early stage in our work for the Bureau of Mines. This work presents preliminary performance estimates of baseband voice and narrowband through-the-earth electromagnetic communications systems of principal interest to the Bureau for operational/ emergency mine communications applications. The calculations were prepared to obtain early indications of the feasibility and governing parameters of such communications systems. They are based on limited, but pertinent, coal mine electromagnetic noise data acquired to-date by Bureau of Mines contractors; on theoretical signal-attenuation characteristics for two transmitter antenna types of present interest to the Bureau and on semi-empirical models which describe the intelligibility of voice communications as a function of the frequency variations of the signal-to-noise ratio across the voiceband. This work examines the cases of baseband voice and narrowband communications for uplink and downlink transmissions, for frequencies up to 3kHz. Downlink transmissions are via a horizontal wire antenna, and uplink transmissions via a vertical-axis loop antenna, for typical mine depths of 300, 600, and 1000 feet. Representative coal-mine overburden conductivities of 10-2 mhos/meter (moderate and common) and 10-1 mhos/ meter (high) were used; the former figure for both voice and narrowband calculations and the latter for narrowband calculations only. Examples of high, moderate, and low, surface and subsurface, harmonic and broadband-impulsive noise conditions were taken from NBS and Westinghouse (WGL) mine noise data, together with examples of high- and low-levels of ELF atmospheric noise taken from M.I.T. Lincoln Laboratory data. The effects of simple voice spectrum shaping techniques on the intelligibility of through-the-earth voice communications are examined, and indexes of intelligibility more broadly based than signal-to-noise ratio are discussed. Finally, a means of overcoming the affects of 60 Hz noise and its harmonics which are the largest contributors to typical audio frequency in-mine noise, is suggested. These feasibility calculations are not intended to serve as definitive and complete treatments, but as a starting point: to establish first-order estimates of the magnitude and variability of transmitter power requirements under different noise, overburden conductivity, and mine depth conditions; to identify relationships, conditions, or frequencies that are likely to limit or enhance system performance; to reveal items requiring further investigation and data still required; and to suggest practical methods for optimizing system performance. These objectives were met by the calculations. Simple experiments to support these calculations can and should be carried out; together with more detailed investigations of specific modulation, coding, noise-suppression, voice-compression and signal-conditioning techniques, aimed at producing through-the-earth operational/emergency mine-communication systems that are not only effective, but practical and economically sound.

Jan 1, 1974

By R. D. Currie

Many coal companies have a system for checking men into and out of the mine , and generally such systems appear to be perfectly sound and adequate . However , when the real test comes at the time of a mine disaster , too often the system is found to have failed , and hours and sometimes days pass before it is known how many men are in the mine and who they are . Most of the systems in use , when properly maintained , are adequate for the routine work of the mine , and some of them may prove adequate at the time of a mine disaster . All systems , however , depend upon proper supervision and strict adherence to the system .

Jun 1, 1930

By John Redington

This paper describing the milling practice at the Coniaurum Mine is one of a series of papers on milling methods, practice, and costs prepared in cooperation with an published by the United States Bureau of Mines. The 500-ton will of the Coniaurum Mines (Ltd.) is located at approximately the center of the company's property and a little more than a mile from the town of Schumacher, Ontario. The main shaft through which all the ore is heisted is adjacent to the mill so that the ore hoisted in a 3-ton skip is dumped directly into a 15-ton bin at the crusher.

Jan 1, 1931

By E. J. Gleim

Contact with trolley wire in the mines of the United States has taken a considerable toll of life throughout the years that trolley locomotives have been employed as a means of' transportation. A study3/ of the records over a 15-year period for one State alone showed that, of 98 fatalities resulting from contacts with electrical circuits and equipment, 75 were caused by direct or indirect contact with unguarded trolley wire in coal mines. The law relating to guarding trolley wires in the mines of this particular State, as amended in 1935, reads in part as follows: "All trolley wires carrying 220 volts or more, and less than six feet six inches above top of rail, must be guarded at all points under which men and animals are required to pass***,'" The natural conclusion to be drawn from such records is that lack' of guards or shields must be held responsible for these fatalities. As a preventive measure, it has been advocated that every foot of trolley wire in mines should be guarded. Although some such drastic steps may appear to be amply justified, closer examination of the records nor this and other coal-mining States shows that absence of guards is not entirely responsible; but rather that other factors, such as carelessness and neglect it the observance of certain well-established simple rules concerning installation and location of trolley wires, also are responsible. In other words, if trolley wire is installed carelessly and its maintenance is neglected, it should not be expected that the mere installation of guards will overcome such carelessness and neglect. This publication discusses Various types of guards that have been used in Coal and metal mines of this country, together with related steps bearing upon the problem of 'preventing shock and fatalities from contacts with trolley wire. The material herein contained is taken largely from Information Circular 6577,4/ now out of print, and has been revised to include some types of guards that have been used in metal mines, together with a discussion of guard materials not covered in that publication.

Jan 1, 1945

By Wilson Blake

The Bureau of Mines used a mathematical model based on the finite element method of stress analysis to calculate stresses and displacements surrounding an open pit mine in a gravity-loaded rock mass. Comparison of the finite element solution for a semicircular notch in a gravity-loaded plate with the theoretical solution for a semicircular notch in a plate under uniform compression parallel to the free boundary demonstrates the inapplicability of the latter method to openings at the free surface of a gravity-loaded medium. High stress concentrations are formed at irregularities along the boundary of an open pit in a gravity-loaded continuous competent rock; however, for this type of rock the magnitudes of the stresses are too low to be considered a major factor in open pit slope stability. High stress magnitudes will occur if, in addition to the gravity stress field, a large horizontal stress field exists.

Jan 1, 1967

By P. L. Loyselle, B. D. Comilsen, D. H. Carlson, J. H. Johnson

"In-mine airborne particulate samples have been successfully collected and the relative amounts of diesel and coal determined using the Laser Raman Quantitative Analysis (LRQA) method. This method allows analysis of filters which have been collected by a method similar to that used to determine the airborne respirable dust concentration in us underground coal mines. Samples were taken near the feeder-breaker, on haulage vehicles, and in the returns. Sampling methodologies were developed for coal-only and diesel-only particulate reference samples with sufficient filter loading for the LRQA method. A statistical analysis of reproducibility has been carried out. Samples have been collected simultaneously at two locations using the LRQA and the size-selective sampling methods. Good agreement between the two methods has been found.INTRODUCTIONThe goal of this research has been to develop the Laser Raman Quantitative Analysis (LRQA) method to measure the composition of respirable particulate, i.e. the fractions of coal and of diesel particulate, in the mine ambient air. In earlier Bureau of Mines sponsored research, we successfully demonstrated that the LRQA method could be used to measure the fraction of Diesel Particulate Matter (DPM) in coal/diesel particulate mixtures which were prepared in the laboratory.(I) 'The immediate objective was to test and refine this LRQA method on samples collected in a diesel underground coal mine.Specific objectives required to meet this goal include:I) Develop in-mine sample collection methods which will insure sufficient particulate loading on filters for LRQA. ,2) Develop methodology for in-mine collection of reference samples (""coal-only"" and ""diesel-only"" filters) which arc required for quantitative LRQA. 3) Analyze precision and accuracy of the LRQA method. 4) Compare composition measurements with another analytical method, i.e. the University of Minnesota/Bureau of Mines size selective sampling Micro-Orifice Uniform Deposit Impactor (MOUDI) method.An advantage of the LRQA method is that it allows analysis of filters which have been collected by a method similar to that used to determine the respirable dust concentration in US underground coal mines. No new sampling instruments and techniques are required. Transfer of sample from collection substrate to analysis substrate is not necessary. Furthermore, other analyses can be made on the same sample since the technique is nondestructive."

Jan 1, 1988

By G. E. McElroy

Economic solutions of problems of mine-ventilation improvement can be found by mathematical analyses of alternative methods of procedure, but, in the case of our older bituminous-coal mines, the airway network is usually so complex that mathematical solutions are too tedious to be practical. Recourse usually is made to extremely costly and uncertain trial-and-error procedures with the existing layout and equipment. The resulting errors often prove costly and sometimes create hazardous conditions. Both the economic and safely aspects of alternative methods of ventilation improvement may be rapidly and cheaply investigation with analogue computers. An electrical analogue computer, designed and built especially for analyzing mine-ventilation-distribution problems, has been placed in service by the Bureau of Mines at its Pittsburgh, Pa., Experiment Station. It is a nonlinear, low-voltage, fluid network analyzer of a type developed by Malcolm S. Mcllroy, professor of electrical engineering at Cornell University. It was designed in close coopera¬tion with Professor Mcllroy and built by the Standard Electric Time Co., Springfield, Mass. It is the seventh unit of this type to be placed in service and the first designed for mine airflow problems. The other six were designed for either water- or gas-distribution analyses. Three are much larger and more expensive units. The largest unit has a capacity of 20 sources, 576 mains, and 180 loads, or regulated-flow paths. The Bureau unit has a capacity of 5 sources, 128 mains, and 48 loads.

Jan 1, 1954