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By C. C. Shale

Electrical resistivities for various coal ashes in air and in a nitrogen atmosphere are given over the range 100° to 1,500° F. Resistivity of low-carbon ash in air is very high at low temperature, rises to a maximum at about 250° F, decreases very rapidly with increasing temperature to about 800° F, then decreases gradually to approach an asymptote at 1,500° F. Resistivity of high-carbon ash in air follows this same general trend at values which are much lower and are proportional to the carbon content. After the carbon has been burned off, resistivity of the remaining ash approaches the high values corresponding to low-carbon ash of similar chemistry. Two factorial experiments show the effects of temperature, particle size, chemical content, and compressibility on the resistivities of four fly ashes of widely different chemical composition in the temperature range proposed for coal-fired turbines. Resistivities of all low-carbon ashes tested fall in the range 106 to 107 ohm cm at 1,500° F and should be removable by electrostatic precipitators. Ashes containing carbon in excess of about 8 percent, however, have low resistivity (as determined in nitrogen), especially at high temperatures. Therefore, high-carbon materials may not be collectable in precipitators because the resistivity is below the minimum value necessary for precipitation. Consequently, high carbon residues from partial combustion of coal probably could not be removed effectively at high temperatures.

Jan 1, 1968

By D. B. Dow

The study of oil production methods with reference to the amount of oil originally pressent in the oil-bearing, formations has developed the fact that-ordinary methods-of production remove only a part of the oil actually present. In fact, it is generally realized that when a field is abandoned more oil remains in the sand than has ever been removed. As a consequence of this realization, the petroleum engineer has devoted considerable tine in recent years in devising methods for increasing the percentage of recovery. His studies have indicated that in most cases the total production of a field is dependent upon the available gas rather than upon the available oil. Mien the gas in the sand is exhausted, oil production ceases even though there may be enormous quantities of oil remaining unrecovered. Consequently, any method of conserving the gas or increasing the supply of gas will increase the ultimate recovery from a field. The practice of producing oil under vacuum increases the effectiveness of the gas remaining in the sand, as well as furnishing more gas by evaporating the light fractions of the crude. Pumping ' compressed gas or air down selected wells of a lease has been found to increase the production of oil from the surrounding wells. Studies of oil and gas ratios have indicated that much of the available gas has been wasted as far as its effectiveness on oil production is concerned. his has led to the development of "stop cocking"3 and the practice of producing under back pressure3, which methods aim, to obtain more effective work from the gas with reference to the amount of oil delivered to the well.

Jan 1, 1926

By C. E. Jordan

Domestic cobalt resources are relatively large, but low grade. The full potential for cobalt production from domestic sources is at least 19.4 million lb of cobalt per year exclusive of offshore resources. A summary of the cobalt processing technologies for the major domestic resources is presented in this Bureau of Mines report. The processing technologies for the Blackbird, Madison Nine, Duluth Gabbro, iron ore pyrite, laterites, and manganese sea nodules are nearly complete, but the economics are not favorable. Research on these resources should be limited to approaches that promise to cut the total processing costs by at least 50 pct. The most promising sources of cobalt are the spent copper leach solutions and siegenite from the Missouri lead ores. Research on cobalt processing from these two sources needs to be completed.

Jan 1, 1988

Although the Stamler feeder/breaker has been used for coal crushing in underground mines for many years, it has only recently been applied to other crushing operations. Two companies presently using Stamler feeder/breakers for rock crushing were contacted regarding their experiences with the units in actual field use. In both cases information was obtained directly from the individuals responsible for field operation and maintenance of the units. White Pine Copper Co. has been using Stamler feeder/breakers for over two years to crush copper ore. They now have fourteen 450-ton-per-hour units on line. The ore has a compressive strength of from 18,000 to 28,000 psi and is extremely abrasive. Maintenance is performed on a tonnage basis. The breaker shaft is replaced every 250,000 tons (requiring about 4 hrs) and picks are replaced about every 1500 tons by the operator (requiring about 2 min per pick). Very little unscheduled maintenance has been required. Crushing costs are fairly high (estimated at 13 to 15t per ton including maintenance and operation) because of tale extreme abrasiveness of the material. A new Stamler feeder/breaker with Ultramet wear surfaces was put or line in June 1976. Ultramet was found to increase the life of belt transfer station surfaces by up to 400 percent and it is hoped that it will do the same for the feeder/breaker. At this time it is still too early to evaluate the performance of the Ultramet unit. If it does improve abrasion resistance, crushing costs could be greatly reduced. White Pine is very pleased with the units and the service provided by Stamler.

Jan 1, 1976

By W. P. Yant

The hazard to health from contamination of air by a noxious gas depends not only on the potential harmful response attending exposure., but also on the warning properties, which in effect may be termed the "accompanying warning response," This warning may be manifested as an odor, taste, irritation of the eyes, nose, or throat, or perhaps headache, vertigo,, or nausea. These manifestations may be painful and even slightly harmful, but to a much lesser degree than the primary injury of exposure. The warning response mitigates hazards directly in proportion to the degree of intolerability which -accompanies injurious exposure, and accordingly its absence augments hazards. This accounts for the fact that the actual health hazards from a nonodorous or non-irritating gas or vapor of comparatively low toxicity sometimes equal or exceed the hazard from a considerably more toxic substance, but one which possesses a marked odor or produces eye, nose, or throat irritation in advance of harmful exposure. When a substance lacks the properties for giving warning, it is often possible to impart them by the addition of a small amount of another substance which has an exceedingly high warning intensity. The vapors of this substance, commonly termed a "warning agent" or "tracer gas," escape and mingle with the gas or vapor which lacks warning properties and thereby apprises persons of the latter's presence. The amount of the warning agent added is that which will give adequate warning in advance of serious physiological harm from the dangerous gas or vapor.

Jan 1, 1930

By G. E. McClelland

As part of its mission to assure an adequate domestic supply of metals essential to the Nation's welfare, the U.S. Department of the Interior, Bureau of Mines, investigated a particle agglomeration technique as a means for improving the flow of leaching solution through heaps of clayey or finely crushed, low-grade, gold-silver ores. Bench-and pilot-scale experiments showed that the percolation rate of cyanide leaching solution was markedly enhanced by mixing the ore with a portland cement binder, moistening the mixture, and mechanically agglomerating and aging the feed prior to heap building and leaching. The rate of gold and silver recovery markedly increased because of the increased, uniform percolation of leaching solution through the agglomerated feed. The use of concentrated cyanide solution instead of water during the agglomeration procedure decreased the leaching time required to obtain maximum recovery. Results of bench-and pilot-scale experiments are discussed.

Jan 1, 1981

By J. T. Schimmel

The purpose of this investigation was to obtain complete information on some of the uses of a 24-inch-diameter auger in the underground mining of pitching anthracite beds. The auger was placed in operation early in 1958 to drive ventilation connections between coal gangways driven by a continuous miner. Although designed to drill rise holes only, it was used also to drill dip holes. The latter holes were drill id from an adjacent gangway to avoid interference between the auger and the continuous miner. These holes established immediate ventilation returns when intersected by the continuous miner. Bureau participation in the project covered 361 working days. The auger was used on 288 shifts, usually one 7-hour shift per day, and drilled 3,246 feet, of which 493 feet were reamed. The longest hole was 87 feet; hence the maximum drilling depth of the machine (rated at 100 feet) was not required. Holes drilled normal to the strike of the bed ranged from 30 to 66 feet deep, averaging 45 feet. The continuous miner drove gangways on 575 shifts. Thus, the auger worked one shift for each two worked by the continuous miner and was used on less than 80 percent of the workdays. The auger drove 24-inch holes 10 times faster than the larger, conventional openings could have been driven by usual mining methods and exceeded the workload for which it was purchased. Augering eliminates exposure to the hazards encountered in driving chute-work by conventional methods and provides adequate circular ventilation openings, which are strong in self support and are adaptable to reaming when required. With alterations, the auger may have limited use as a production machine in thin-bed pitch mining but cannot compete with established methods of thick-bed pitch mining.

Jan 1, 1962

By C. L. Chaney

Investigations were conducted to develop spectrochemical methods capable of determining 0.01 to 100 micrograms of metals in 50 milliliters of solution. The use of gallium hydroxide (Ga(OH)3) as a carrier-precipitant to concentrate metallic ions is described. A porous-cup graphite electrode is used to collect the precipitate. A specially designed plunger permits the electrode assembly to serve as the sample-containing electrode in the subsequent spec-trographic analysis. Analytical curves are presented for antimony, arsenic, beryllium, and zinc. Sensitivities of detection are given for 13 elements. The techniques were applied to identify impurities separated from tungsten, to determine trace impurities in solutions containing high concentrations of magnesium, cobalt, or nickel, and to identify trace impurities in hydrofluoric acid. Laboratory glassware was a serious source of contamination when low levels of zinc were determined.

Jan 1, 1963

By D. D. Dornenburg

The effect of changes of atmospheric pressure on methane emissions from extensive worked-out areas of coal mines in several Midwestern States has lone caused concern to State and Federal mining departments, as well as to the operating companies involved. Common mining and ventilation methods employed in mines in these States have resulted in large sealed and unsealed worked-out areas in which considerable quantities of methane are emitted alone both intake-and return-air courses. The common practice is to watch barometric changes very closely and take special precautionary measurer during periods of low barometric pressure. Although the hazard is recognized, mining officials have different opinions concerning the effect of barometric pressure variations on the emission of mine gases. These opinions are based upon scattered personal observations, as no records exist of actual studies to establish such effects.

Jan 1, 1955

By V. E. Erwin, W. W. Adams

"INTRODUCTION This report presents statistics of accidents at coke ovens in the United States during the calendar years as 1933, the twenty-first year for which data of this kind are available, 1913 being the first year for which accident reports were collected from the operating companies by the Bureau of Mines. The present report is presented in mimeograph form because insufficient funds are available for printing it. The first report of the Bureau of Mines that contained statistics of accidents for the coke-mining industry in the United States covered the two calendar years, 1913 and 1914. While the figures presented therein related both to beehive and by-product ovens, the original returns from the operating companies were not classified so as to permit the presentation of accident statistics for each class of ovens separately. Beginning with 1915, the accident reports from the operating companies have shown the general type of ovens to which the reports related; therefore, since that year, separate statistics for each of the two classes of ovens have been given in the Bureau's yearly reports of accidents at coke ovens.The coke-making industry in the United States established a safety record in 1933 almost equal in merit to that which it achieved in 1932, when the accident-frequency rate was the lowest and therefore the most favorable that the industry has known. Credit for the achievement is due almost entirely to companies operating byproduct ovens. (See table 8.)"

Mar 1, 1935

By F. W. Lane

[The rapid expansion of the petroleum industry, the steadily growing use of oil fuel or steamships, the increasing transportation of oil in tankers and the extensive use of petroleum oils for many land industries, has resulted in pollution of our coastal eaters by these oils. On account of the great importance of this problem to the petroleum and shipping industries its, the Bureau of Mines, in cooperation with the American Petroleum Institute and -he American Steamship Owners Association has undertaken to ascertain the extend of petroleum oil pollution along the coasts of the United States and to indicated the principal so arcs of such pollution. Certain typical methods and devices in use and proposed for the separation of oil from water, and for the disposal of oily castes from ships and industrial plants have been studied. An attempt has also been made to point out the nature of the fire hazard resulting from oil pollution and to indicate the effect of such pollution on bathing beaches.]

Jan 1, 1924

By Joan T. May

Anhydrous methods were tested for the extraction of beryllium from low-grade source materials. The purpose of the investigations was to find new extraction processes that are applicable to domestic ores. Beryl, helvite, and phenacite materials containing from 0.1 to 2.8 percent BeO were used as starting materials for direct halogenation tests and pretreatment followed by halogenation. The results of the investigations showed that direct fluorination and carbide-chlorination are two practicable methods that can be applied to low-grade concentrates. Treatment of concentrate-carbon mixtures with anhydrous hydrogen fluoride extracted 99 percent of the beryllium in the concentrate; the soluble fluoride product, converted to an oxide, contained 70 percent BeO. Chlorination of beryllium-silicon carbide, prepared from low-grade concentrates, extracted beryllium into the volatile chloride product.

Jan 1, 1962

By C. Kwong, L. H. Rorden, T. C. Moore

This report describes the feasibility test of an electromagnetic method for locating, boreholes, with or without casing, that have been drilled in conjunction with mining operations but whose location with respect to the tunnel is not precisely known. The first tests were conducted with the cooperation of the Kerr-McGee Corporation, Church Rock Mining Operations, New Mexico, in September 1977. These tests demonstrated that accuracies of better than ±15% of range and ±1° of bearing can be achieved with a simple system and setups. Subsequent tests, in January 1978, on a horizontally drilled pipe line river crossing application, by Ti tan Contractors of Sacramento, California, demonstrated that accuracies of better than one-half percent of range and a few tenths of one degree of bearing can be achieved by using refined techniques. The demonstration tests were done at ranges on the order of 100 to 200 feet but the method is capable of working at much greater distances.

Jan 5, 1978

By Joseph S. Coffman

The Bureau of Mines investigated the availability of barite (BaSO4) from 35 U.S. and 41 non-U.S. mines and deposits in 17 market economy countries (MEC's). This evaluation assesses the availability of mud-grade barite, and concentrates consumed by the chemicals and fillers industries. The demonstrated resources defined in this analysis totaled 130 million metric tons (Mmt) of barite (contained BaSO4), yielding a potential 115 Mmt of recoverable barite concentrates. At the 1984 MEC production rate, the evaluated resources would last about 30 yr; however, this would include production costs of up to $100/mt concentrate. An average price needed to cover all costs of production over the life of each operation was determined for both mud-grade and chemical- and filler-grade barite products. Including a 0-pct discounted-cash-flow rate of return (DCFROR), regional weighted- average total production cost ranged from $38/mt for barite concentrates in Asia to $71/mt for U.S. operations. Transportation costs have the greatest impact, contributing up to 60 pct of the total cost of production. Rail transportation costs from the mines to U.S. markets are generally significantly higher than ocean shipping rates on imports.

Jan 1, 1986

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

8. Field Demonstration of the Remote Mine Sealing System in a Coal Mine 8. 1 Selection of Field Test Site Eastern Associated Coal Corporation (EACC) offered its Federal No. 1 coal mine in Grant Town, West Virginia as the site for field testing of the remote sealing system. The choice of Federal No. 1 mine was particularly appropriate as the first attempt at fire control by remote sealing was done in this mine in 1963. EACC provided the men and equipment required for much of the initial preparation. Considerable assistance, advice, and background on coal mining technology was given by Mr. William Laird, Vice President for Research and Development, EACC, and by Mr. Lawrence Jackson, Resident Engineer at the Federal No. 1 mine. District 3 USBM office, the West Virginia Bureau of Mines, the Technical Support Group of the USBM, and Local 4047 of the United Mine Workers of America also cooperated. 8.2 Preparation of Field Test Site 8.2. 1 Underground Site Preparation The underground site chosen for the field testing was in a non-working portion of the mine within a few hundred feet of the main haulage road, as shown in Figure 80. Known as "Seven Switch, " this area was a 20 minute walk or 5 minute "jeep" trip from the man-trip shaft. Ten years having passed since this area was actively worked, considerable effort was required for gob clearing, roof bolting, rock dusting, and rejuvenating the track from the haulage road to the test area. Three primary borehole locations were chosen for the test program. Borehole No. 1 was in a straight passageway

Jan 1, 1973

By James C. Barker

Gold placer deposits along the upper Yukon River, in the region between the river villages of Circle and Eagle, were investigated by the Bureau of Mines. The investigation was conducted intermittently between 1976 and 1985 as part of an evaluation of mineral resources on lands proposed for inclusion in the National Park System. At least 230,000 troy ounces (tr oz) of gold has been produced in the region, principally from Woodchopper, Goal, and Fourth of July Greeks. The placers are underlain by, or occur downstream of, early Tertiary sediments that have been deposited in the Eagle Trough. Strike-slip displacement along the Tintina Fault is responsible for creation of the trough and may have been a factor in the formation of the present placers. Placers were found to have a close spatial correlation to certain altered fault lineaments of the Tintina Fault trench. Placer concentrates contain several different textural forms of gold, suggesting multiple origins. Geological studies and a survey of 162 panned concentrates throughout the region indicated previously unreported sites of placer gold, and potential exists for the discovery of additional placer and lode gold. Because of nearly continuous soil and vegetation cover, further evaluation of the region will require subsurface sampling.

Jan 1, 1986

By T. T. Campbell

Research conducted by the Bureau of Mines demonstrated the feasibility of preparing columbium and tantalum metals by the application of Kroll-process techniques. Yields in excess of 95 percent were obtained in a modified Kroll-process reduction apparatus constructed from nickel and Inconel.4 Operating conditions during reduction and distillation were determined. Optimum temperatures during sodium reductions ranged from 650° to 750° C and for magnesium from 700° to 800° C with retort pressures ranging from 3 to 7 psig. Undesirable vapor phase reactions occurred when temperatures exceeded 750° C during sodium reductions or 850° C with magnesium. Vacuum distillation at 850° C effectively removed volatile salts and excess reductant from the reduced metals. Calculations based on the results obtained in small scale tests indicate that reaction rates of up to 34 lb/hr could be obtained during columbium reductions and up to 60 lb/hr during tantalum reductions in production scale reac¬tors. The small, laboratory-scale techniques used in this study could be adapted to commercial practice. The reduced powder or sponge metals can be consolidated by conventional arc-melting techniques, and the arc-melted metals can be fabricated into ductile sheet at room temperature. Analyses of arc-melted buttons prepared from Kroll-process tantalum or columbium showed that tantalum of greater than 99.8-percent purity was obtained and that columbium purity exceeded 99.7 percent. A significant purification of the reduced metals occurred when they were consolidated by electron-beam melting, and the purity and ductility of electron-beam-melted Kroll-process tantalum and columbium compared favorably with the commercial metals. After electron-beam melting, the purity of the tantalum exceeded 99.95 percent, and columbium purity was approximately 99.9 percent.

Jan 1, 1962

Research workers from the Bureau of Mines and industry met with other government and industry representatives at the Mont Chateau Lodge, Morgantown, W. Va., on May 30-31, 1973, to discuss the current status of methane control in eastern U.S. coal mines. The opening remarks, the eight technical presentations, and the discussions of the members of a government-industry panel are published here for the benefit of those concerned with the control of methane in coal mines. In addition, an introduction has been added to present the background of work in this field.

Jan 1, 1973

By Charles L. Kimbell

While the statistical summary focuses on 1991 data, this update and outlook section draws on information available to the author as of the date of final preparation in early 1993. For all the press notoriety associated with the shift in the Near East crisis from the defensive posture of Desert Shield to the restoration of Kuwaiti sovereignty through Desert Storm, this was not the dominant event governing global economic thinking in 1991 and the first half and more of 1992. From the global perspective, the momentous political changes in the area that was the U.S.S.R. and in the smaller emerging transitional economy states of Eastern Europe will have even greater current and long-lasting effects on world mineral industry activities than the crisis in the Near East.

Jan 1, 1993

By Noel N. Moebs

Coal mine roof failure is categorized according to character, trend, or pattern of occurrence. Two principal categories of failure are proposed--geology related and stress related. Geology-related failure includes both lithology and structure. Each of several subcategories reflects the probable cause of failure and thereby provides a basis for the selection of appropriate techniques for reducing the incidence of failure. These control techniques, depending on local conditions, may include supplementary support, destressing, reduction of mine air humidity, or a change in the customary support methods.

Jan 1, 1986