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By Roy Greenfield

Estimates are given for the distance from a seismometer at which a miner can probably be detected. The procedure in making these estimates was to first establish the natural noise levels at the output of a surface seismometer for the 25 to 100 Hz frequency passband. The noise levels give the range of values which may be expected in areas with no man-made noise. For each noise level, we give the detection threshold which, when exceeded, indicates that a signal has been received. Based on the signals recorded by Westinghouse, curves are given which show the peak signal amplitude as a function of source- to-receiver distance (slant range). Curves are given for the Westinghouse seismic thumper, a 50-pound timber, and a sledge. For a given type of source, the receive signal strength depends more strongly on slant range than on any other factor. However, there is approximately a five-to-one scatter in the amplitudes. Thus, further study of factors affecting the signal amplitude might allow better estimates to be made for any particular geological setting. Combining the signal amplitude with the detection thresholds for the different noise conditions gives the distances at which a miner should be detected. These are given in Table l* below. [ ] The text also gives the increase in detection ranges which should occur if steps are taken to increase S/N by 10 dB. We feel that 10 dB is a conservative estimate of the improvement possible. During an actual rescue operation, the seismic crew and system should be capable of making on-site estimates of their detection capability, based on measurements of the site noise, and upon the best available estimates of the

Jan 1, 1974

By Albert E. Long

Diamond-bit performance and cost data accumulated in core-drilling sandstones reveal significant trends of economic interest. Large-size, AA-Grade drill bort suffered less diamond loss per foot drilled than any other size or grade of diamonds assessed. Detailed analyses of the factors that affect diamond-bit performances -diamond size, diamond quality, bit size, bit type, percentage of core recovered, and physical characteristics of bit matrices -are assessed in the tables, graphs, and discussion. INTRODUCTION Since 1945 the Bureau of Mines has been compiling detailed performance records on diamond bits used in core drilling throughout the United States and Alaska. Analytical reports covering bit performance in various rocks are issued as in-formation on a significant number of bits used in anyone type of rock is accumulated. The first three such reports analyzed bit performance in gneiss,2/ schist,3/ and lime-stone and dolomite.4/ This report evaluates diamond-bit performance in sandstone. Data obtained from 627 bits, which drilled 42,665 feet on 45 different projects, are presented. The geographical distribution of the projects is shown in figure 1.

Jan 1, 1958

By W. K. Sawyer

In this Bureau of Mines investigation, one-and two-dimensional gas reservoir simulators were combined in such a manner that pressure distributions both in an induced vertical fracture and in the surrounding formation, could be determined as a function of time for any specified well production rate. The technique used consisted basically of the alternate ust of one-and two-dimensional algorithms for obtaining new pressure distributions in the fracture and in the reservoir, respectively. The pressures at adjacent reservoir and fracture nodes were used to calculate flow rates from the formation into the fracture, which provided source terms for both algorithms. The combination model developed provides the only known means of simultaneously simulating transient gas flow in a vertical fracture and the surrounding formation. Thus, the technique developed would be useful in locating wells in a gas storage field in that the effects of both fracture length and conductivity could be considered prior to drilling and fracturing operations. In addition, it will be helpful in analyzing pressure drawdown tests in a vertically fractured gas well since the entire test can be readily simulated for a wide range of reservoir and fracture properties.

Jan 1, 1974

By D. N. Nilsen

The Bureau of Mines is developing a method to recover Ni, Co, and Cu from laterites containing less than 1.2 pct Ni and 0.25 pct Co. The method consists of the following basic unit operations: (1) reduction roasting, (2) leaching, (3) solvent extraction, and (4) electrowinning. The method reflects three Bureau of Mines objectives: (1) recovery of critical minerals that are domestically in short supply from low-grade domestic laterites, (2) lower processing energy requirements, and (3) solution recycling. This report deals with the extraction of cobalt and the preparation of a suitable cobalt electrolyte by solvent extraction from liquor produced by this method. Nickel and copper are coextracted with LIX64N from an ammoniacal ammonium sulfate leach liquor containing about 1.00 g/l Ni, 0.30 g/l Co, 0.03 g/l Cu, and 0.02 g/l Zn. Cobalt (III) in the nickel-copper barren raffinate is reduced to cobalt (II) with cobalt metal. Reduction of cobalt (III) to cobalt (II) greatly aids subsequent extraction. Commercially available XI-51 extracts about 94 pct of the cobalt from the treated raffinate in one stage in a laboratory mixer-settler continuous circuit. Ammonia loaded on the solvent is removed in two washing steps. About 94 pct of the cobalt then is stripped from the XI-51 in one stage with spent cobalt electrolyte containing about 77 g/l Co and 18 g/l sulfuric acid (H2S04), Electrolytes containing less H2S04 also may be used. Preliminary data indicate that coextracted zinc may be removed from pregnant cobalt eletrolyte containing 3 g/l or less H2S04 with di-(2 ethylhexyl) phosphoric acid (D2EHPA).

Jan 1, 1980

By Eugene T. Sheridan

This report presents statistical data on individual plants in the fuel- briquet and packaged-fuel industries circularized by the Bureau of Mines, United States Department of the Interior, in its 1957 annual survey. This survey revealed that 17 briquet and 23 packaged-fuel plants were active part or throughout the year. The annual production capacity of the fuel-briquet industry was 3,088,000 net tons, a decrease of 17 percent from 1956. The decline in capacity was caused in part by the permanent retirement of 4 plants and also by the reduction in capacities of 4 other plants. The rate of production of briquet plants also decreased as the industry operated at 35.8 percent of capacity compared with 40.9 percent in 1956. Every operating plant in 1957 had an annual capacity exceeding 25,000 tons.

Jan 1, 1958

By T. W. Goodman, J. Cervik

The Bureau of Mines conducted studies to compare the effectiveness of the cross-measure borehole system with that of surface gob holes on two successively mined retreating longwalls in the Lower Kittanning Coalbed. Only the cross-measure system was in operation on panel A; on panel B, both systems were in operation. In addition, the cross-measure bore-holes on panel B were drilled parallel to the face, whereas those on panel A were drilled at a 45O angle with respect to the longwall axis. The studies show that the cross-measure system captured 71 pct of the methane generated by longwall mining on panel A. On panel B, the sur- face gob hole dominated over the cross-measure system for about 700 ft (213 m) after it was intercepted. Beyond that point, the cross-measure system dominated. About 93 pct of the methane generated on panel B was captured by the two systems. Cross-measure boreholes that were drilled parallel to the face were as effective as boreholes oriented 45" with respect to the longwall axis. In addition, they are shorter and require less drilling time. Comparison between observed gas pressure differentials in boreholes and calculated values indicate that boreholes can be shortened further to 140 ft (43 m). Additional studies are needed to verify these calculations.

Jan 1, 1986

By F. Garcia, J. Cervik

The cross-measure borehole technique has been shown by the Bureau of Mines to be an effective method of controlling methane liberated by fracturing the roof strata in longwall gobs where overburden is less than 750 ft (229 m). Boreholes are drilled into roof strata before mining operations affect the roof strata. Longwall mining fractures the roof strata and releases methane from source beds. Surface exhausters or vacuum pumps are used to draw the gas to the surface through an underground pipeline and vertical exhaust hole. The captured methane is thus prevented from entering the mine's ventilation system. About 71 pct of the methane produced by longwall mining in the Lower Kittanning Coalbed was captured by the cross-measure boreholes. Borehole spacing is an important factor affecting the performance of the technique. Interference tests and measurements of methane flows in return air indicate borehole spacing in the Lower Kittanning Coalbed should be limited to about 200 ft (61 m) except on the first 600 ft (183 m) of the longwall, where spacing should be reduced to about 100 ft (30 m) to capture the large quantities of methane released when the first large roof fall occurs. Comparisons between measured and calculated gas pressure differentials on boreholes indicate borehole length can be reduced from 280 to 140 ft (85 to 43 m), which reduces drilling costs significantly. Additional experimentation is necessary to verify the calculations.

Jan 1, 1985

By Michael G. Zabetakis

The process of ?gasfreeing? has been defined3/ as "* * * the removal of oil and vapors from tanks, pipelines, and compartments to render such spaces safe for the intended work," Generally, part or all of a vessel is gasfreed for one of several reasons: Periodic cleaning; tank inspection or repairs; shipyard overhaul or major repairs; or change of cargo, Curing the gas- freeing, flammable or explosive4/ mixtures (mixtures through which a flame can propagate after ignition by an open flame, heated object, electrical charge, or other means) may be produced. These mixtures create an explosion hazard, as the pressures produced after their ignition are often great enough to completely demolish the vessel and kill all those aboard, This paper outlines a study by the Federal Bureau of Mines of the gas explosion hazards likely to be encountered while gasfreeing a vessel compartment. To better understand these hazards it will first be necessary to review the language used in gas- explosions work. This language is considered in the following sections. Inert gases such as carbon dioxide, nitrogen, water vapor, and others can be used to decrease the range of combustible-vapor concentrations in which flammable mixtures are formed. Sufficient quantities of such gases can often be added to cause a mixture that originally was flamable to become nonflammable. Unfortunately, the use of water vapor in this application is complicated by the fact that elevated temperatures are required to keep the water in the vapor state. In practice, it may be difficult to maintain these elevated temperatures throughout the space (such as a cargo tank) to be inerted for any length of time. Accordingly, where other inert gases are not available, it may be desirable to gasfree a Lank by using heated air. To do this, the combustible vapors should be flushed as quickly as possible from the space to be gasfreed. In a properly designed system, large tanks were gasfreed with a littlee as 6 volumes of air per volume of tank capacity.

Jan 1, 1961

By H. B. Freeman, E. J. Gleim

During the 12 months ended July 1, 1931, engineers of the Bureau of Mines examined electrical equipment in 80 bituminous-coal mines. The purpose of these examinations was to ascertain the condition of such equipment with respect to possible hazards of gas and dust ignitions, also of shock. Although only 3 of the 80 were being worked with open lights and therefore did not use explosion-proof equipment, there were others where electric cap lamps were used by the men but where it was apparently assumed that conditions as to gas and dust did not require equipment designed to give protection against ignitions. Early in its history the United States Bureau of Mines originated certain standards covering the construction and testing of electrical equipment in order to minimize the dangers of ignitions from exposed electric sparks and flashes ; accordingly, it is comparatively easy to determine wherein a machine built to these standards falls short of continuing to meet them if damaged or neglected. Many so-called flame-proof and dust-proof machines, however, have not been built to any standard comparable with that developed by the Bureau of Mines. In addition, certain machines have parts which pass Bureau of Mines tests, but do not satisfy the full requirements in other respects, and others make no pretense of inclosing the spark-producing parts. It is not uncommon to find two or more of these various types in the same mine with " permissible " machines, the type that has been built to conform to the Bureau of Mines standard. Consequently, inspection of nonpermissible machines becomes somewhat difficult without a standard of comparison. Because of its unprotected condition obviously open-type electrical equipment must be used with great care, if at all, in a mine where precautionary measures are adopted in guarding against gas and dust ignition. The unsafe nature of such equipment is widely recognized. For that reason it is to be installed only where there is no likelihood of gas being present. It is not apparent to some, however, why flame-proof and dust-proof equipment and equipment having tested parts should not be regarded in the same light as permissible equipment.

Jan 1, 1932

By Robert H. Lambeth

The Madison RARE II study area has four prospects with identified resources. These are listed in table 1 and are described in the following text. A high potential for Sillimanite exists at the Placer Creek occurrence (fig. 1, no. 7) and potential for phosphate rack in all areas underlain by the Phosphoria Formation. Some prospects exhibit minor potential for copper, lead, zinc, silver, and gold in the southern portion and very minor potential in the northern portion. Deposits in the northern end also have low potential for rare earth, asbestiform anthophyllite, or kyanite group minerals (including sillimanite).

Jan 1, 1982

By J. R. Thoenen

[Since the publication of the preliminary report on this subject in July, 1927, (The Wire Saw in Slate Quarrying, Preliminary Report, Serial No. 2820, by Oliver Bowles) the wire saw has been in constant daily operation at the quarry of the Colonial Slate Company. Luring this time between twenty end thirty successful cuts have been made varying in length from forty-five to ninety-two feet and in depth from six to ten feet. No accurate time records have been kept on these cuts but they have totaled over 12,000 sq. ft. of area and required 19,000 lineal fact During these cuts the average speed of cutting has risen from the 12.8 sq. ft. per hour obtained in the original recorded tests to between 15 and 20 sq. ft. per hour, with the present rate running very close to 20 sq. ft. per hour at this quarry.]

Jan 1, 1928

Coal miners, especially roof bolter and continuous miner operators, work in a hazardous underground environment where they are often exposed to poor roof conditions. Nearly 500 rock fall injuries are reported each year, and 99% of them are caused by rocks falling from between the roof bolts. These loose rocks that injure miners are usually just a few inches thick, but on average weigh 280 pounds. NIOSH has found that most rock fall injuries can be prevented by installing roof screen during the bolting cycle. Roof screen is a sheet made of steel wires in a grid pattern. When screen is bolted up against the mine roof, it provides far more coverage than any common surface control used in the mines today. Because more mine roof is covered, there is less chance that a rock will fall and injure a miner. The facts about roof screen are shown in the new NIOSH video entitled “Make It Safer With Roof Screen.” Using extensive underground footage, the 7-minute video shows how well screen keeps loose rock from falling in difficult roof conditions. Techniques for installing screen from both outside-controlled and walk-thru roof bolting machines are shown. The video also provides safe handling tips, best practices, and information about machine technology that can greatly improve material handling. Throughout the video, a coal mine safety manager and a shift foreman talk about the tremendous difference that roof screen has made at their mines. An instructional booklet supplements the video with additional information. It presents compelling data from mines that have practically eliminated rock fall injuries with a roof screening program. Other sections of the booklet discuss in greater detail roof screen installation, tips for manual screen handling, a material handling system for roof screen, and use of the personal bolter screen, which can be easily handled by one person. Screen specification and custom ordering are described, including the sizes of screen, grid sizes, reinforcing (indicator) wires, edge cut options, and screen strength. A list of additional sources of information is also provided. Nearly every mine eventually encounters poor roof. Screen is one of the most powerful control techniques available. This new video will help make mine managers aware of screen, and it can help them in developing a roof screen installation program. It also serves as an information source and teaching tool for safety managers and trainers. The video can easily be integrated into new miner training programs or annual refresher training.

Mar 1, 2005

By C. A. Wilson

The Bureau of Mines started a continuing program to investigate and evaluate analytical techniques to assist governmental agencies to select simple, rapid, reliable methods for crude oil spill identification. Six crude oil samples were analyzed to evaluate gas-liquid chromatography, atomic absorption spectrophotometry, infrared spectoscopy, sulfur and nitrogren determinations, mass spectrometry, nuclear magnetic resonance spectroscopy, and ultraviolet spectrophotometry. Samples were studied from the following selected fields: El Morgan, Egypt; Duri, Indonesia; Minagish, Kuwait; Bachaquero, Venezuela; Gach Saran, Iran; and Prudhoe Bay, Alaska. These samples were chosen to represent high-production fields that are likely to be involved in oceanic transport. Over 50 years of Bureau of Mines analytical research on petroleum served as the basis for evaluation of the experimental results to determine which of the methods are effective techniques to identify crude oil spills. Gas-liquid chromatographic analysis, atomic absorption spectrophotometric analysis, and sulfur-nitrogen determinations are recommended as the most useful of the techniques investigated.

Jan 1, 1975

By Michael S. Wieland

Recognizing the dynamic nature and possible range of toxic concentrations in the impending fume cloud prior to undertaking explosive blasting can reduce potential hazards and mitigate related incidents. The scaled cloud model was formulated to predict the relevant (major) toxic components in fume clouds released by nonideal mining explosives used for surface blasting. Natural turbulence unceasingly disperses the toxic molecules, widening (inflating) the fume cloud while diluting the concentrations, ultimately rendering nonhazardous conditions. The threshold cloud size depends upon the type and quantity of total explosives used and the cloud's thermodynamic condition. Though the scaled theory works for fume clouds with irregular (odd) shape, an equivalent upright cylindrical form is useful for rendering simple riskhazard scenarios. The cylinder's projection downward on the underlying terrain yields a circular 'shadow' marking the region threatened, thereby permitting a rough estimation of the potential hazards, were the cloud to settle down there. Wind causes the cloud to drift while it expands, so the shadow travels while it grows, until the risk hazard process is truncated at the nonhazardous threshold. The overall relative fume toxicity (RFT) is taken from the traditional Russian RFT rule, which utilizes only the two fume components that tend to dominate the resultant toxicity: carbon monoxide (CO) and total nitrogen oxides (NOx). Tabulated constants that characterize the fume spectrum in the cloud model were resolved for ammonium nitrate (94%) with fuel oil (6%), ANFO-94/6, using a refined thermodynamic work-principle. Comparable results were found with the reduction factor technique, when test results from the underground fume chamber were readjusted to reflect nominal field shooting conditions.

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

By G. M. Molinda, J. P. Ulery

Since 1970, abnormally high methane emissions have been observed in eastern sections of the Federal No. 2 Mine operating in the Pittsburgh Coalbed in northern West Virginia. The nature and volume of these emissions indicate a source other than the coalbed. An investigation was undertaken to delineate probable methane sources. Gas well information and stratigraphic correlation of corehole data indicates that a sandstone directly above the main coalbed is an additional source of methane emissions. The sandstone body appears to be an ancient stream channel, infilled with fine-grained sand and organic matter. Coalification of the organic matter produced methane as a byproduct. Additional methane presumably migrated into the sandstone unit from the subjacent coalbeds. The methane became trapped in the porous clasticunit by the surrounding impermeable strata. Mine development near this unit creates a significant pressure gradient, triggering abnormal methane emissions into the mine along naturally occurring fractures. Pre-development methane drainage of the sandstone could be accomplished by completing vertical boreholes along its trend.

Jan 1, 1984

By J. C. Nigro

Hematite-to-magnetite reduction kinetics were investigated mainly in CO-CO2 atmospheres at temperatures ranging from 500° to 1,000° C. Reduction rates were measured with a thermobalance, which recorded the weight loss as the specimen was reduced. Reduction data on both synthetic and natural hematite spheres showed good linearity of ro [1-(1-R)1/3] with time, t, up to over 85 pct conversion to magnetite; the rate coefficient (k[L], cm/min) obtained from the linear portion of the plot was used to characterize the penetration rate of the hematite-magnetite interface. Gas composition, porosity, and silica content were major factors affecting the rate. Temperature dependency of the reaction rate was small, yielding a mean activation energy of about 3 kcal/mole. Silica additions increased the reaction rate, probably through an increase in the effective surface area and diffusion; however, above 900° C, silica can react to form fayalite. Experimental data showed that the linear thickening rate of the magnetite layer, normally evidence of a chemically controlled reaction, can also be indicative of a reaction controlled by both mass transfer and diffusion. Evidence from this study indicates that the dominant rate-controlling factor in the reduction of hematite to magnetite at high temperatures is transport in the gas phase.

Jan 1, 1973

By H. C. George

This report presents a comprehensive tabulation of lifting cost data collected from oil companies in many different fields. These data were collected during the writer's studies of surface equipment and methods of pumping oil wells, in practically all of the important oil fields in the United States and are based on average operating conditions at 57 groups of properties with a total of 4,497 producing wells. Although lifting cost is only a part of the total cost of producing oil, it nevertheless gives a representative cost figure for purposes of comparison.

Jan 1, 1923

By R. E. Morgan, J. F. Barkley

"INTRODUCTION In city smoke-abatement work it is customary to require approval of the sizing of fuel-burning equipment. This is to insure that, with reasonable attention, the equipment can be operated essentially smokelessly, having such features as ample furnace volume and air supply. To answer the many inquiries that come to the Bureau of Mines as to what dimensions are acceptable and standard, the requirements of a number of smoke-abatement ordinances have been tabulated.CONCLUSIONSStudy of these tabulations shows that even after many years of fuel-burning practice and experience there is no common standard. Variations in the requirements for the same type of equipment under the same conditions of operation are great. This causes considerable difference in installation costs. Over-all costs being affected, the competitive positions of different types of fuel-burning equipment are also affected. It is apparent that there is a lack of information as to proper dimensions that is commonly accepted as authoritative.DISCUSSIONTable 1 gives the minimum furnace-setting heights required by various cities for mechanical underfeed stokers installed under H.R.T. boilers. Figure 1 shows a typical installation. The dimension given for each case is the distance from the dead plate of the stoker to bottom of boiler shell, unless otherwise noted. As shown in the table, different cities use different size-classification systems; it is not possible to make complete, exact, direct comparisons. Table la gives a comparison for various cities, showing the approximate percentage difference in H.R.T. furnace-setting heights required from those recommended by the Stoker Manufacturers' Association arbitrarily chosen to serve as a basis of comparison. The percentages are approxi¬mate because they were calculated as if all heights as given were measured from the dead plate of the stoker. In two cases a lower height is permitted, in a number of cases the height may be the same, and in a number of cases the height must be greater. The percentage increase goes to 100 in one case. Lack of uniformity is quite evident."

Mar 1, 1950

By Frank A. Peters

This description of process evaluation techniques used by the Bureau of Mines for studying proposed processing techniques has been prepared to provide those interested in using these studies with an understanding of the methodology. The methods used for preparing both capital and operating cost estimates are described. Each step in preparing the evaluations is described. Types of equipment costs are shown and factors used in the estimates are defined. Uses of the estimates are suggested and several examples are included. The accuracy of various types of estimates is discussed, along with an explanation of the reason for selecting the type used in the Bureau's process evaluation studies.

Jan 1, 1987