Search Documents

In order to reduce waste and improve resource conservation, mine planning, and development, the U.S. Bureau of Mines is investigating the effects of multiple seam interactions associated with longwall coal mining. Field investigations were conducted at a mine located in Boone County, WV, where a longwall panel was operating subjacent to room-and-pillar workings in an overlying seam. To assess the effects of overlying workings on longwall headgate stability, the Bureau gathered various geotechnical information at this minesite. Headgate pillars and entries were instrumented and monitored to study their behavior during side-abutment loading as the longwall panel approached and passed beneath the overlying room-and-pillar developments. The two operations are separated by 800 ft of interburden, and although interactions between operations separated by this distance are uncommon, geomechanical measurements indicate the occurrence of an interaction. These measurements show that convergence on the headgate entries was most adverse subjacent to barrier pillars in the overlying mine. Pillar measurements indicate that side-abutment pressure increases were slightly greater than predicted values. Several factors related to both geology and mine design, believed responsible for this large interactive distance, are discussed.

Jan 1, 1990

By Ronald S. Conti

This U.S. Bureau of Mines (USBM) report describes various fire-fighting resources available to the mining industry and examines the fire preparedness of four western coal mines. Information regarding fire-fighting equipment indicates that an inadequate maintenance program may cause component failure of fire extinguishers, damage to waterhoses is usually a result of improper care, and foam may be a convenient means of conveying water to the fire. Performance data relative to water nozzles (throw distance) and specific practices to improve the state of preparedness in many of these areas are discussed. Studies also indicated that a high-expansion foam plug, will travel down an entry, with a 1% rise in elevation, 207 m (680 ft) before a plywood stopping separating the generator and plug failed. The advance rate of the foam plug decreased when the entry is dry, requiring more foam concentrate and as the foam spread further down the entry. An examination of the mines showed state-of-the-art monitoring systems were common at the minesites. Fire safety was also stressed, including early detection and rapid response of the miners to evacuate the mine. However, the mines placed little emphasis on performance of water nozzles, or personal protective clothing for the underground firefighters.

Jan 1, 1994

By A. Sainato, S. J. Schatzel, D. M. Hyman, J. C. LaScola

The Bureau of Mines determined the gas contents of 135 oil shale samples obtained from approximately 630 ft of core drilling. Drilling was done within a projected mining zone of the Cathedral Sluffs Mine, located in the Piceance Basin of western Colorado. Methane contents were determined by the modified direct method, which can measure the volumes of several gases released from or reacted with mine rock without destructive sample treatment. Over the duration of the test, nitrogen was largely unreactive, CO2 increased slightly, oxygen decreased markedly, and methane increased more than the total increase of all contained gases. The gas volumes were normalized per unit sample mass and are given in cubic centimeters per gram. Common time irzdices for test duration of 3, 40, and 125 days were used to compare methane desorption among samples. The means of the sample populations for these indices were 0.0316, 0.114, and 0.195 cm3/g, respectively. These quantities are lower than those reported in a Bureau emissions study at the Horse Draw Mine in the Piceance Basin. Oil shale samples that were gas enriched beyond the mean methane contents frequently contained bitumens and pyrite.

Jan 1, 1987

By W. E. Webb

This report describes a method the Bureau of Mines devised for measuring the dielectric constant and loss tangent of low-loss minerals at microwave frequencies. Determina-tion of these properties makes it possible to predict the effects of using microwave heating in potential mineral processing applications. The method uses a test cell and radio-frequency (RF) impedance analyzer with automated data acquisition and analysis. In this initial phase of microwave heating research, the Bureau measured dielectric constants and loss tangents at frequencies between 100 MHz and 1 GHz. The objective was to establish a reliable data base for use in predicting the effects of microwave heating on minerals. Comparison with previously measured data showed the Bureau's measurement method to be accurate to within ± 3 pct. This report describes the method and discusses the preliminary results of the Bureau's investigations. Typical comparative data are included.

Jan 1, 1986

By Wallace W. Roepke

The Bureau of Mines tested new designs of drag bit cutters with sintered diamond inserts instead of standard tungsten carbide tips. The bits were tested for orthogonal cutting forces, primary dust generation, and incendivity, with a standard plumb-bob type conical cutter (600 included tip angle) as the reference. Preliminary wear and impact-failure testing were also done. The results were mixed. Two new designs had forces similar to those of the reference bit, but one new design had about twice the normal force. This same design had almost twice the specific energy during shallow cutting but generated an equal or slightly lower amount of primary dust than did the reference bit. Incendivity was eliminated for two radial designs. One conical design had ignition only after more than 15 impacts, but the other conical design was incendive. Impact failure occurred, but not so quickly as anticipated. Over 7,500 impacts on a sandstone face, with a total cutting distance of more than 1,981.2 m, only scuffed the leading edge of the sintered diamond cutting face but put hairline cracks in the substrate mounting pad. Additional design and testing are needed to develop an optimum cutter, but prospects look good for this material.

Jan 1, 1983

By L. J. Defferding

This report documents the work performed by Battelle-Northwest and its sub-contractors in Phase I of a project to develop a cross pit conveyor system for the Bureau of Mines. The conveyor system description includes details of the conceptual design as well as system and component specifications. The selection of primary and back-up sites for system demonstration is discussed. Maneuvers and operating sequences required for mining the selected demonstration site are described and illustrated in detail. Economic viability of the cross pit conveyor system was analyzed by estimating the cost of overburden removal per ton of coal using the Battelle-designed concept and comparing these costs to the cost of an available state-of-the-art 30-yd3 dragline operation. Testing and trade-off studies conducted are documented and the results presented. Alternate designs considered in developing the selected cross pit concept are included for completeness. Based on the evaluation of the selected concept, it was concluded that the cross pit conveyor system proposed by Battelle is a technically and economically feasible overburden handling method with a good potential to improve western coal mining efficiency.

Jan 1, 1976

By Edward G. Cunney

Track in underground bituminous coal mines was investigated and technology was taken from other industries in order to obtain information on conditions that impair the safety and efficiency of the track and to develop guidelines and useful information on the construction, inspection and maintenance of mine track. Volume 1 contains information on the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features, such as gage; descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. It does not repeat the summary or? derivations. Volume 3, Inspection Handbook, summarizes recommended standards and procedures from Volume II and provides related information for ready reference by inspectors in the mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.

Jan 1, 1977

By James Spiers

This paper describing the mining practice at the Central-Eureka mine is one of a series of similar papers being prepared by the United Staten Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The mining practices described in this paper are illustrative of the methods employed in the exploitation of comparatively low-grade gold ores under the extremely heavy and swelling ground conditions which occur in the Mother Lode belt of California. The Central-Eureka Mining Co. comprises a group of adjoining mines in Amador County near Sutter Creek. The principal mines of the consolidated group are the Central-Eureka, formerly known as the Summit mine, and the Old Eureka mine, which is also known as the Hayward Quartz mine. The group is situated in the most productive part of tae main Mother Lode belt, the 10-mile portion which lies between the towns of Plymouth and Jackson. The three largest producing mines of the entire belt at the present time are the Argonaut, Kennedy, and the Central-Eureka; these lie within a radius of less than 1-1/2 miles.

Jan 1, 1931

By W. L. Dare

This information circular is one of a series the Bureau of Mines plans to publish describing the methods and costs of mining uranium on the Colorado Plateau. The Temple Mountain mining district is unique among the uranium-producing areas on the plateau. This relatively isolated mining district is in Emery County, Utah, on the eastern flank of the San Rafael Swell, about 35 miles southwest of the town of Green River. The district lies just within the eastern escarpment of the San Rafel Reef - a rampart of rugged and tilted sandstone cliffs that encircles the highly eroded core known as the Sinbad Country. The presence of petroleum matter found associated with the ore deposits, the occurrence of uranium in various formations, and the structural deformation caused by collapsed features have aroused a great deal of geologic interest. Mine development on Calyx Flat is distinctive, in that the ore deposits are worked through 36-inch calyx-drill holes.

Jan 1, 1957

By R. J. Evans

The generation and disposal of solid waste from electric utility plants using a lime or limestone wet-scrubbing system and the potential effects on the environment were estimated for 1975 and 1980. The study indicated that in 1975 approximately 5.8 million tons of desulfurization solid waste (50 percent solids) will be generated. In 1980, when it is estimated that desulfurization will become commercially accepted, approximately 71.4 million tons of this material will be generated for disposal and/or utilization. The desulfurization waste material when combined with lime, fly ash, and water may have potential for use as a roadbase material, landfill reclamation, and synthetic aggregate.

Jan 1, 1974

By B. D. Nash

The Bureau of Mines continued its research into the recovery of fluorine by the phosphoric acid acidulation defluorination of phosphate rock concentrates. A small process development unit with a capacity of about 10 kilo-grams of charge per hour was operated, and concentrates from both Idaho and Florida were processed. Over 80 percent of the fluorine was evolved and recovered as a dilute fluosilicic acid solution. Phosphate extraction from the concentrates always exceeded 98 percent. The fluorine was converted to a synthetic fluorspar product (3CaFa?SiOa) suitable for use as a slag conditioner in electric furnace steelmaking operations.

Jan 1, 1977

By Guy E. Dent, Hugo E. Kuehn

"SUMMARYFor making a comparison of magnetic surveys measured from the ground and from the air, Worcester County, Maryland, was chosen as a proving ground. Vertical magnetic intensities were observed on the ground, and total magnetic intensities were observed from the air. A comparison of the two magnetic maps reveals similar large magnetic features, but these are displaced in some instances by distances greater than a mile. Magnetic terrane in the two charts is of the same type but often differs greatly in respective characteristic features.The sacrifices in accuracy that may be expected from the use of different systems of diurnal magnetic corrections on ground observations constitute a part of this report.INTRODUCTIONThe value of magnetic surveys for gaining information concerning the crystalline basement is recognized increasingly. That this topography is often reflected to a major degree in the overlying sediments with certain offsetting is well understood. Even where such sediments are deep, the surface topography of upper formations often reflects this bedrock topography to a certain degree."

May 1, 1947

By W. P. Diamond, J. R. Levine

The explosion hazard of methane-air mixtures has become an increasingly serious mine planning problem, and an advance assessment of methane gas potential can therefore be essential for a safe and economic mine development pro- gram. As part of its coal mine health and safety program, the Bureau of Mines has developed a simple, inexpensive test to measure the methane content of coal samples obtained from exploration cores. The gas content of coal per unit weight as determined by the direct method test can be used as a basis for a preliminary estimate of mine ventilation requirements, and to determine if degasification of the coalbed in advance of mining should be considered. Since the Bureau began measuring the gas content of coal samples in 1972, experience has led to equipment and procedural changes, the most significant of which has been the development of a ball mill for crushing the coal sample to release the residual gas at the end of the desorption test period. This revised procedure replaces the crushing box and graphical methods described in earlier Bureau publications. The results of 583 direct method tests are summarized in tabular form. These results include data on the gas content of 125 coalbeds in 15 States.

Jan 1, 1980

By John C. Machisak

The Nation's mining and quarrying industries have again met the annual challenge to their ingenuity--that of reducing disabling work injuries among their employees. The effectiveness of management in facing this problem and in meeting this responsibility is evident from the results of the 1961 National Safety Competition. Three hundred ninety-three or 45.3 percent of the mines and quarries participating in the competition established a new record number of participants operating throughout the competition year without a disabling work injury. Another record established in the 1961 contest was the number of participants (868) enrolled in the competition. This annual safety competition was begun in 1925 and is conducted by the Bureau of Mines, U.S. Department of the Interior. It provides for six bronze Sentinels of safety trophies which are awarded each year to the winning participant in each group. Since its inception, the competition has exerted a strong influence in the field of safety promotion. The statistical record of its accomplishments over the years gives strong support to the theory that well-organized and well- administered safety programs are effective tools to be used to reduce the number of disabling work injuries. It stimulates and holds the interest of employees and management in accident prevention. Because of this, mines and quarries participating in the contest have a more favorable safety record than those operations not enrolled.

Jan 1, 1963

By M. G. Zabetakis

Benzene and toluene are the first two members of an important homologous series whose general formula is CnH2n-6. The members of this series differ in composition from benzene by some integral multiple of CH2; they can all be prepared in the laboratory by the Wurtz-Fittig, Friedel-Crafts and Grignard syntheses. Because 'of the industrial importance of these-hydrocarbons, the limits of flammability of eight members of the series have been determined at 100° C.-(A temperature of 1000 C. was chosen because the determination of the upper limit of flammability of p-cymene requires an apparatus temperature. of at least 90° C. As elevated temperature data are available for other combustibles at 100° C. but not at 90° C., all data were taken at 100° C. in order to obtain comparable results.) Minimum ignition temperatures of these combustibles have been determined at laboratory-pressures.

Jan 1, 1951

By R. K. Koch

The normal spectral emissivities of liquid Ti, V, Zr, Mo, and Pt were determined at the fusion temperatures in an electron-beam furnace using a water-cooled copper hearth. The normal spectral emissivities were estimated above the melting points by using adjusted two-color temperatures as approximations of the true temperatures for substitution in Wien's equation. Simultaneous brightness temperatures were determined with a micro-optical pyrometer. The true temperature ranges covered were 1,668° to 1,885° C for Ti; 1,919° to 2,013° C for V; 1,855° to 2,367° C for Zr; 2,610° to 2,751° C for Mo, and 1,772° to 1,990° C for Pt. The spectral emissivities for titanium and zirconium decreased with increasing temperature. At an effective wavelength (?) of 658 mµ the emissivity of titanium ranged from 0.51 to 0.45 and zirconium, from 0.47 to 0.41. The emissivities of vanadium (? = 658 mµ) and molybdenum (? = 657 mµ) were constant at 0.41±0.02 and 0.33±0.01, respectively. The spectral emissivity of platinum (? = 658 mµ) was constant at 0.39±0.02 up to 1,900° C; above that temperature anomalous data were obtained. A mass spectrometric study indicated that platinum was reacting with back-streaming silicon vapors from the diffusion pump when the ambient pressure was greater than 2 X 10-5 torr.

Jan 1, 1973

By P. D. Tracy, M. W. Von Bernewitz

"IntroductionA study of 256 coal-mine explosions, which occurred during the period 1909-1924 killed 4113 men and injured 570 others, reveals the fact that there are the critical times of day when explosions are most likely to occur, and when corresponding care should be exercised to guard against disaster. Of these 256 explosions, 83 straight as explosions, 89 were straight coal-dust explosions, and 81 were mixed gas and dust explosions, while three were undetermined.It has been determined from the times given in these reports (in several cases no times were given,that the critical period in the morning ranges between 6 and 9 o'clock when 83 explosions took place with a peal. at 7;30 o'clock. Of these 55 were straight gas explosions, the remainder being either coal dust or mixed gas and coal dust explosions. The critical period in the afternoon or early ranges between 3 and 7 o'clock, when 113 explosions took place, with a peak at 6 o'clock. Of these, 87 wore straight coal-dust explosions the remainder being neither gas or mixed gas and coal-dust explosions. Between these morning and evening periods is one which might be called the noon period - that is, from 11m to 7. p. m. - when 26 explosions occurred while some of these were normal type of explosions - that is, as to causes - others were of unusual cause and character, and. are discussed later. A number of explosions (29 in all) took place during mid-afternoon, late at night, and early in the morning - that is, after midnight."

Sep 1, 1924

By Gene Asai

The Bureau of Mines investigated the caustic extraction of alumina and soda from retorted dawsonite-bearing oil shale, as part of a program to devise technology for treating alternative domestic sources of alumina for the production of aluminum metal. Colorado oil shale yielding 13 pct oil (35 gal/ton) and containing 12 wt-pct dawsonite (representing about 4 pct extractable alumina) was retorted to obtain oil-free (spent) shale Spent shale was leached with dilute NaOH to determine the effect of particle size, retorting temperature, leaching variables, and storage conditions on extraction of alumina and soda and dissolution of impurities. Maximum alumina and soda extractions were obtained by promptly leaching minus 28-mesh spent shale, obtained by retorting raw shale at about 5000 C, with 0.5N NaOH. Under these conditions, dissolution of impurities such as Ca, Fe, Ti, and P was low. Leaching tests were made on spent shale stored for periods of up to 30 days at 0° to 42° C and at 0 to 100 pct relative humidity (RH). These tests indicated that significant reductions in alumina extraction would occur if spent shale were stored in ambient Colorado air under naturally fluctuating temperature and humidity.

Jan 1, 1983

By Seth C. Schaefer

The Bureau of Mines investigated the standard Gibbs energies of forma-tion AGfo, for NiCr204 (nickel chromite) and CoCr204 (cobalt chromite). High temperature galvanic cells employing stabilized ZrOz (zirconia) as the solid electrolyte were used to measure the open-circuit potentials for the cell reactions ?

Jan 1, 1986

By Charles A. Seitz

This Bureau of Mines report describes a chromatographic method for analyzing impurities in helium that utilizes a helium carrier gas contain-ing 25 to 30 ppm Ne. An example of the effect of trace amounts of nitrogen, methane, and moisture on the detector's response is shown. The added neon in the carrier does away with irregularities of the analysis which were experienced when the carrier contained up to 3 ppm Ne. The addition of 25 to 30 ppm Ne causes a loss of sensitivity, but the re-maining sensitivity is adequate for routine analyses. The high-neon carrier allows positive and more linear responses for eight impurities: neon, hydrogen, argon, oxygen, nitrogen, methane, carbon dioxide, and ethane. Neon concentration levels of 0.02 to 125 ppm in helium carrier gases were studied. The high-neon carrier has been in successful rou-tine use in Bureau of Mines helium facilities since October 1981.

Jan 1, 1985