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By Bernard J. Steblay

Two instruments have been constructed that extend microseismic data collection and processing capability for Bureau of Mines research in rock burst, coal bounce and outburst, and roof fall monitoring. The first instrument is a 13-channel tape-triggering system. This system allows better utilization of instrumentation tape recorders by collecting data digitally, turning the tape on only when valid data are present, and increasing the dynamic range of the recorder by using digital data. A digital-to-analog converter is used to provide analog output of the recorded digital data. The instrument records a much larger time slice of transient events than do current commercial devices. The second instrument is a microseismic energy measurement device. This device uses recent developments In integrated circuits to overcome the dynamic range and accuracy limitations of previous instruments. The analog signal is converted to a digital one, and then high-speed multiplication techniques are used to square the amplitude value in real time and integrate it.

Jan 1, 1983

By Paul Biggs

This Bureau of Mines report provides information on 138 waterflood projects in Wyoming. Injection was in 25 producing zones and 65 fields. Specific data presented include field location, discovery and development, water supply and injection, oil and water production, estimates of oil in place, and oil recoveries by primary and secondary methods. The 138 projects studied will, if successful, recover about 800 million barrels of secondary oil. Almost all of the injection water is from deep water wells.

Jan 1, 1970

By R. L. Grayson, L. L. Probert

"A three-year project focusing on the depth profiling of respirable coal mine dust particles using scanning electron microscopy coupled with energy dispersive X-ray analysis resulted in the development of statistically classified particle-behavior models. The models depict the changing silicon fraction for particles at 5-, 7-, 9-, and 11-keV accelerating voltages, thereby giving a clear indication of the nature of various types of mineral particles. This paper focuses on the results for respirable quartz particles sampled from five underground coal mines across the US. Through statistical analysis of results the relationship between the fraction of surface available quartz in respirable dust samples and coal rank is established for three Pennsylvania coal seams. IntroductionThis is the last in a series of papers detailing the results of SEM/EDX-based analyses of respirable coal mine dust particles collected from field sampling. Previous papers have detailed preliminary results and the statistical validity of the methodology (Grayson, Andre, and Simonyi, 1990; Grayson, 1991). This paper presents the final results of the analysis of respirable dusts from five coal seams with a range of coal rank:• Lykens Valley seam (anthracite), eastern Pennsylvania• Brookville (A) seam (mid-vol bituminous), central Pennsylvania• Pittsburgh seam (high-vol B bituminous), western Pennsylvania• No. 6 seam (high-vol C bituminous), Illinois• Wadge seam (sub-bituminous A), ColoradoSEM/EDX-based techniques were applied to try to clarify the role of quartz as an etiologic agent in coal workers' pneumoconiosis (CWP). It was hypothesized that previous studies were hampered by the restrictions of bulk analysis techniques and that particle-level analyses were needed to answer a number of questions concerning the role of quartz in CWP and its progression.Since 1985, a large number of the respirable dust samples submitted to MSHA are analyzed for free silica (Tomb, Parobeck, and Gero, 1986). Our reasearch shows that conventional bulk analysis techniques may not give a true indication of the biologically available, or active, quartz in mine dusts. Analytical evidence indicates that respirable dust samples may contain many quartz particles that are occluded, or coated, resulting in a bulk analysis for ""free silica"" that may not be indicative of the biologically available quartz surface."

Dec 1, 1996

By Oliver Bowles

Enormous quantities of limestone are used for metallurgical purposes. Approximately 23 million tons were so used in the United States in 1925 chiefly for smelting iron ores in the blast furnace. Smaller amounts are used in basic open-hearth steel manufacture, and in smelting lead, copper and antimony ores. Most limestone producers lave little knowledge of the way in which their stone is used in metallurgy. Maximum tolerances of silica, alumina, sulphur and possibly magnesium; and minimum content of calcium carbonate may be arbitrarily fixed for the guidance of the producer, but aside from these requirements little information is available to producers on the manner in which their stone is used, the office it performs in smelting, or the effects of impurities. More complete [wledge] of utilization would enable limestone operators to solve their production problems more intelligently.

Jan 1, 1927

By Robert C. Dyni

The use of techniques and equipment designed to pneumatically place backfill into an underground mine opening through boreholes for subsidence abatement has historically met with limited success, largely due to the inability to directly monitor the placement of the backfill in the opening. The success of a backfilling project cannot be guaranteed if it is not known whether the underground opening has been completely filled with backfill material. To overcome the inability to directly monitor backfill placement, the U.S. Bureau of Mines developed a pneumatic backfilling system that allows for direct viewing of the backfill as it is placed in an underground mine opening. This system utilizes a recently developed pneumatic nozzle coupled with an instrumentation package that allows for real-time observations and measurements of backfill placed in an underground opening through a borehole. The nozzle utilizes a high-velocity airstream to redirect backfill falling through a pipe in the borehole and directly in front of the nozzle; the airstream redirects and propels the backfill horizontally into the .mine opening at over 100 ft/s. The instrumentation package, mounted directly to the nozzle, contains a video camera, high-intensity lamps, laser-rangefinder, electronic compass, and water sensor.

Jan 1, 2010

By W. J. Boone, Will E. DeVaney, Lowell Stroud

This report is the fifth in a series presenting equilibrium vapor - liquid data for helium- bearing natural gases . It covers a 0.41 - mole - percent - helium natural gas that may be processed in the Department of the Interior's longrange helium conservation program . A Bureau of Mines phase equilibrium apparatus was used to obtain 139 samples of equilibrium vapor and liquid phases at 85 experimental conditions at temperatures from 0 ° to -299 ° F and at pressures from 100 to 500 psia . An appendix covers phase data at 100 , 200 , and 300 psia and at temperatures from -125 ° to -275 ° F for the dehydrated gas containing its original concentration ( 0.2 mole - percent ) of carbon dioxide , and the effect of a preliminary hydrocarbon trap upon subsequent vapor - liquid compositions .

Jan 1, 1964

By M. M. Fine

This Bureau of Mines report describes the theory, experimental procedures, and the results obtained to date in the development of the Bureau's process for magnetically roasting iron ores using scrap iron as a means of reduction. Since magnetic separation is an operational step common to magnetic taconite plants, the preliminary research studies emphasized only the novel magnetic roasting step. The studies included the use of automobile scrap, ferrous reductants such as borings and turnings, and prereduced pellets. Technical feasibility of the process was demonstrated both on a bench- and pilot-scale. Quality magnetic concentrates with recoveries of over 90 percent were obtained from a direct shipping ore containing 59.5 percent Fe and from fine grained semitaconites with about 30 percent Fe.

Jan 1, 1966

By T. E. Green, E. F. Spano, W. J. Campbell

A combined ion exchange X- ray spectrographic method was evaluated for the determination of 11 metallic elements in high - purity tungsten : Aluminum , calcium , chromium , cobalt , copper , iron , magnesium , manganese , nickel , titanium , and zinc . Copper , nickel , and manganese in the 5- to 100 - microgram range ( 1 to 20 parts per million based on 5 - gram samples of tungsten ) , calcium in the 10- to 100 - microgram range , and cobalt in the 5- to 20 - microgram range can be determined within an accuracy of ± 10 percent of the amount present . Limits of detection of these elements are 0.05 to 0.14 microgram . The overall method was unsatisfactory for the determination of aluminum , chromium , iron , magnesium , titanium and zinc in tungsten .

Jan 1, 1964

By Deborah A. Kramer

This Bureau of Mines report presents a cost estimate of the Bayer process, which is used for virtually all cell-grade alumina production. The report will serve as a reference point to determine the economic merits of processes that have evolved from Bureau of Mines investigations on technology for producing alumina from domestic nonbauxitic raw materials. The Bayer process involves dissolving the alumina present in bauxite in a caustic solution at high temperature and pressure. After the un- dissolved impurities are removed, the solution is seeded to produce an alumina trihydrate precipitate. This precipitate is filtered, washed, and calcined to produce the cell-grade alumina product. This cost estimate is for a plant producing 1 million tons of alumina per year. The estimated operating cost is approximately $250 per ton of alumina.

Jan 1, 1983

By Frank A. Peters

The Bayer process treating Jamaican bauxite was evaluated from an economic standpoint, using standard estimating methods and published data, to present a reference point for cost estimates for nonbauxite alumina processes. The estimated operating cost for a plant producing 1,000 tons of alumina a day is $47.96 per ton of alumina when charging $8 per ton for bauxite and $2.30 per hour for direct labor. The estimated fixed capital cost is $46 million.

Jan 1, 1966

By Robert W. Gordon

This report describes the results and conclusions of the further development of a lightweight probe drill for use in anthracite mines. Improvements to the drill previously developed under Contract H0282044 were made and tested at an Eastern Pennsylvania mine. These improvements were: 1. Better hole cleaning due to the development of an air-water mist flushing system. 2. The application of roof drill bits to allow drilling through rock seams and lenses. 3. The development of a quick coupling drill system which reduced total steel change time. 4. Adaptation of a swivel to the drill anchoring system which greatly reduced set-up time between holes. With these improvements the probe drill demonstrated its ability to drill the required 11 holes in one shift. It also gained miner acceptance as a viable underground working tool. The probe drill proved to meet all of the design requirements of portability, low weight drilling controllability, structural integrity and reliability. In addition to its ability to drill the required probe pattern, the probe drill has the capability of drilling long holes. By drilling several holes over 80 feet deep the probe drill has demonstrated a potential for use in robbing pillars and for methane drainage.

Jan 1, 1981

By Oliver Bowles

From the most remote periods of civilization, stone Las been used to perpetuate the memory of individuals or to immortalize their noble achievements. Ancient memorials ranged from simple piles of stone (cairns) or single markers to great obelisks and pyramid or magnificent mausoleums. The Taj Mahal at Agra, India, built of white marble by Shah Jehan in memory of the Empress Mumtaz Mahal, is one of the most beautiful and costly memorials ever built. It was erected between 1632 and 1050 at a cost estimated at a: high as $50,000,000, and it is today an object of unusual attraction for travelers. Other magnificent memorials, both ancient and modern, are to be found in many lands. Memorials of varying design have characterized the passing centuries and have found an important place in the New World. In early days, monuments were chiefly imported into America, but gradually an extensive memorial stone-manufacturing industry developed on this side of the Atlantic. Sales value of domestic memorials, f.o.b. quarry or mill, attained a maximum of $17,488,755 in 1920, and retail sales, of course, reached a much higher figure. Modest markers and tombstones are to be found in almost every rural community in the United States, and there are many elaborate and costly monuments in and near urban centers.

Jan 1, 1938

By Harry R. Nicholls

Preliminary tests on presplitting rock in the presence of an in situ static stress field were undertaken to study the influence of a horizontal static stress field on the creation of a vertical presplit fracture plane. These tests indicated that it is easier to fracture the rock parallel to the in situ maximum compressive stress than in other directions. Instrumented shots indicate that the interaction of stress waves generated by the detonating charges is probably responsible for starting tensile fractures between shotholes and that expanding gases may propagate these initial cracks by a wedging action. The hole spacing for presplitting appears to be equal to the half wavelength of the stress wave. However, wider hole spacing appears feasible if the initial fracture is started by closer hole spacing.

Jan 1, 1966

By L. A. Haas

The Bureau of Mines conducted bench-scale leaching tests with recycled spent copper electrolytes and copper-nickel mattes produced from the Minnesota Duluth Complex concentrates. This report describes the first stage of an overall two-stage leach operation. The objective of this research was to determine the matte-leach technology required to convert spent copper electrolyte into an enriched nickel liquor suitable for a nickel refinery and there-fore essentially free of copper, iron, and sulfuric acid. The experimental variables investigated were matte composition, particle size, spent electrolyte content, pulp concentration, oxygenation, temperature, and time. The time required to produce an enriched purified nickel liquor decreased with increasing pulp concentration, temperature, and oxygenation, but increased with increasing particle size and electrolyte copper and acid content. Nickel-rich (about 50 g/l) liquors at a pH of about 4 and containing less than 1 g/l of copper and iron were produced at 70° C by leaching minus 325-mesh low-iron (less than 5 pct) matte for 8 hours with spent electrolyte containing 22.4 g/l Cu, 28.9 g/l Ni, less than 0.1 g/l Fe, and 50 g/l H2S04 at a pulp concentration of 1 kg of matte per liter of spent electrolyteo Varying the nickel content of the spent electrolyte from 11 to 101 g/l appeared to have no appreciable influence on the matte leaching characteristics.

Jan 1, 1981

By Thomas H. Dubaniewicz

Fiber optic systems are being deployed in locations where explosive gas atmospheres are normally present or are present under fault conditions. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory (NIOSH, PRL) conducted a study of laser safety in potentially flammable environments. Researchers conducted experiments to estimate the mean and standard deviation of laser powers needed to ignite 6% methane-air atmospheres using single mode optical fiber tips covered by two types of iron oxide (Fe304 and (FeMn)203) mixed with a ceramic adhesive. The iron oxides, heated by a 1064 nm continuous wave laser, ignited the methane-air mixtures ,at similar powers. The minimum igniting power and maximum non-igniting power (10 tests) were 407 and 350 mW, respectively, using a 62.5 pm fiber. Laser beams guided by 125 and 80 pm diameter cladding single mode fibers produced similar methane-air igniting powers. Ignition was not observed using coal particles at powers that produced ignition with the iron oxides. Threshold ignition delays using the single mode fiber were approxinlately proportional to the inverse square of the igniting power. Ignition delays were significantly longer than the reported activation time for a comnlercial fiber optic power limiter. Comparisons are made with the results of other researchers. Published by Elsevier Ltd.

By M. M. Wong, J. E. Klosterman

Scrap beryllium chips ( nominally 96 to 97 percent Be ) were electrore fined in a prototype cell with 408 lb of electrolyte composed of 52.4 mole - percent LiCl , 36.3 mole - percent KC1 , and 11.3 mole - percent BeCl2 . The cell temperature was 500 ° C. In a typical 10-3 /4 - hour deposition cycle , 0.415 pound of metal was produced ; the metal contained impurities in parts per million as follows : C , 700 ; 0 , 610 ; Al , 34 ; Ca , 32 ; Cu , 20 ; Fe , 25 ; Mg , 9 ; and Mn , 23 . Operation of the prototype cell for 2 years demonstrated that adapting the electrorefining process to an enlarged scale of operation presented few difficulties in mechanical functions , maintenance of optimum operating conditions , and control of product purity . After the spent anode feed was leached in a 5 - percent nitric acid solution and the fine - sized particles were removed , it was recycled in some tests . The metal produced was somewhat higher in impurities than metal from the fresh scrap chips .

Jan 1, 1964

By Thomas C. Atchison, Joseph M. Pugliese

Six explosives were compared by measuring their strain- producing abilities in limestone . Peak strain , e , varied with scaled distance , R/Ro , according to the following equation : € = Kc (R /R 。)- ". The distance exponent , n , was a constant of the rock and did not depend upon explosive . The strain intercept , Ke , increased with increasing detonation pressure of the explosive . The strain intercept also depended upon the explosive- to - rock impedance ratio . For impedance ratios from 0.53 to 1.38 , the strain intercept was approximately proportional to the medium stress , Pn , as calculated from the explosive detonation pressure , P , and the explosive - torock impedence ratio , Z , by the simple elastic theory relation : P = 2P / ( 1 + Z ) . PD However , the data indicated that , at lower values of impedance ratio , the strain intercept is relatively larger than would be expected from the simple elastic theory . The results presented provide a simple method for predicting the relative effectiveness of different explosives in breaking limestone from the detonation pressures and characteristic impedances of the explosives .

Jan 1, 1964

By Paul L. Russell

Because of the increasing demand for fluorspar , investigation of the deposits of the Gila district in Grant County , New Mexico , was undertaken by the Bureau of Mines in 1943 with the cooperation of the Federal Geological Survey . It was the purpose of the investigation to assist owners and lessees to develop their properties and to attempt to estimate ore reserves that might be available to supply a 300- ton mill that was under construction at Gila . Field work was begun June 14 , 1943 , and ceased August 16 , 1943. Seven veins were trenched and sampled .

Feb 1, 1947

In 2007, a total of 7,199 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 ? Sand and gravel mines were the largest mining sector, comprising 48.4% of all mining operations. ? Sand and gravel mines were found throughout all 50 states and Puerto Rico.

Aug 1, 2009

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining the potential for reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/ lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978