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By Ronald H. Church

As part of the Bureau of Mines health and safety research program in strata control, a ground-penetrating radar (GPR) system capable of pene-trating approximately 10 ft into the mine roof has been devised to identify anomalistic conditions. The GPR system consists of a transmitter with carrier frequencies of 250, 500, and 1,000 MHz, utilizing a dipole antenna, and a receiver, consisting of a dipole antenna fed into a sampler with a time base housed in a storage oscilloscope. A computer was utilized for data acquisition and data processing. Data analysis by computer enhancement revealed recognizable return ra-dar signatures from the middle man rock and main roof of the test site. These stratigraphic anomalies can be cataloged for recognizable fea-tures, which from the past history of the mine may have been shown to create strata control problems. Early recognition of such features could lead to immediate corrective actions and result in the saving of lives.

Jan 1, 1985

By J. M. Singer

The objective of this investigation was to determine minimum air velocities and entrainment rates for coal and rock dust dispersion in wind tunnel experiments under conditions that simulate dispersion from surfaces in coal mines where airflows are induced by weak gas explosions. Dust deposits were bed-or ridge-shaped; particle sizes were 6 to 80 microns (cohesive deposits) or 100 to 150 microns (free-flowing deposits); and wind tunnels were 7.62 cm wide by 5.08 cm high by 300 cm long, and 2.4 m wide by 1.5 m high by 215 m long. The investigation showed that minimum air velocities (directed at mid-height) of separate, layered, or mixed piles of coal dust and rock dust were within the range 5 to 30 m/sec, independent of size of wind tunnel. This finding considerably facilitates scaling of data to mine-size passageways. Free-flowing deposits dispersed relatively slowly by single-particle detachment; cohesive dusts dispersed faster by the breaking and lifting of large clumps along weak failure flames; particle dispersion occurred in flight. Layered or mixed deposits of coal and rock dust did not disperse selectively. Semiempirical expressions were derived relating minimum air velocities and dispersion rates to dust-pile geometry, cohesion, porosity, and bulk density.

Jan 1, 1972

By R. A. Pallanch

This paper, which describes the milling practice at the Midvale concentrator, is one of a series being prepared by the Bureau of Mines. The Midvale concentrator, a custom lead-zinc selective flotation plant, is in Salt Lake County, Utah, on a flat site several hundred yards east of the Jordan River and about 200 yards south of the Denver & Rio Grande Western Railroad tracks leading to Bingham Canyon. The site is at an elevation of about 50 feet above the river, the highest available location, thus allowing maximum storage of tailings.

Jan 1, 1931

By M. M. Wong

Salt mixtures consisting of KC1, BaC12, and HfCl4 with RbCl or CsCl were investigated as electrolytes for refining hafnium. The presence of RbCI or CsCl in the electrolyte appeared to suppress the volatility of. Best electrorefining was obtained with an electrolyte containing 50.7 percent KCl, 27.l percent BaCl2, 15.7 percent CsCl, and 6.5 percent HfCl4. In this electrolyte, hafnium metal with an average oxygen content of 470 ppm was produced from an anode feed containing l,600 ppm oxygen. All metallic impurities were lowered, except titanium, manganese, and tin.

Jan 1, 1966

By Franklin H. Persse

The Bureau of Mines estimated reclamation costs for 13 surface coal mines in nine States west of the Missisisppi River. With the exception of the Pacific Coast coal province, at least one mine in each of the western coal provinces was studied. Cost estimates were, made using standard estimating procedures from data obtained from company records, interviews with industry personnel, and onsite observations. Estimated costs are presented in four categories which represent the four phases of mined-land reclamation: (1) Design, engineering, and overhead; (2) bond and permit fees; (3) backfilling and grading; and (4) revegetation. Estimated costs as of the first quarter of 1976 are expressed as averages and ranges in terms of per acre, per ton of coal produced, and per million Btu. Total reclamation costs ranged from $860 to $7,200 per acre, from 6 to 84 cents per ton, and from 4 to 35.3 mills per million Btu. A mine in the Northern Great Plains coal province (Region D) showed the highest per acre cost whereas mines in part of the western region of the Interior coal province (Region A) experienced the greatest per ton and per million Btu cost. The high cost of reclamation in the Western United States is reflected in the backfill in and grading category, particularly in the cost of topsoil removal and subsequent replacement as required by individual State reclamation regulations.

Jan 1, 1977

By V. F. Parry

Under the present emergency every consumer should store as much coal as he can. Although there is no shortage of coal, there is likely to be a shortage of labor to mine excessive quantities in the fall, and railroads cannot be expected to deliver coal promptly on account of the need for transporting war materials. Some miners must join the armed forces, and those who are left may be unable to mine coal as rapidly as you will need it when winter comes. When the first cold days arrive, there may be a shortage of trucks to deliver coal. Deliveries may be planned in advance, and your turn might not come until it is too late.

Jan 1, 1942

By Agnes Y. Lee

The Bureau of Mines has developed an effective hydrometallurgical method to recover high-purity Pb metal and elemental S from concentrates. This low-temperature process eliminates S gases and Pb emissions, in contrast to the current high-temperature smelting technology. The method consists of (1) oxidative leaching with H202, Pb02, and waste fluosilicic acid at 95° C to produce a solution of PbSiF6 and a residue containing elemental S, (2) electrowinning the PbSiF6 solution at 35° C to produce 99.99 pct Pb metal and H2SiF6, and (3) solvent extraction to recover S, leaving a residue containing Cu, Ag, and other metal values. Spent electrolyte was recycled repeatedly, with impurity buildup controlled by controlling the leach parameters.

Jan 1, 1986

By Arden D. Fugate

This work was conducted to determine a feasible process for converting siliceous fluoride offgases to a commercially usable product. The offgases were generated by pyrohydrolytic defluorination of low-grade fluorspar in a gas-fired rotary kiln, and fluorine was collected as a hydrofluoric-fluosilicic acid. A silicon-free fluoride solution for further processing was then produced by neutralizing the acidic scrubber solution with anhydrous ammonia, silicon being separated as orthosilicic acid. Ninety to ninety-nine percent of the fluorine originally present remained in solution as ammonium fluoride. Silicon was also separated from synthetic fluosilicic acids, having F-to-Si weight ratios ranging from 3.50 to 14.3. The solutions below a ratio of 4.06, the F-to-Si ratio of H2SiF6, containing dissolved silicon were desiliconized as completely as those containing less than the stoichiometric quantity of silicon. An electrolytic-grade cryolite was recovered from the ammonium fluoride solution by reacting with either sodium aluminate or alumina trihydrate and sodium hydroxide. A product containing 97 to 100 percent of the fluorine, represented by Na3A1F6, was recovered, and 94 to 99 percent of the theoretical yield was realized.

Jan 1, 1963

By Charles W. Huggins

To determine the nahcolite and dawsonite content in oil shales, the Bureau of Mines compared X-ray diffraction, infrared spectroscopy, thermal methods, and a previously published method by Smith and Young based on the selective solubility of sodium compounds. The Smith and Young method and a new method based on the weight of carbon dioxide produced by thermal decomposition are recommended for determining nahcolite. X-ray diffraction and the Smith and Young method are recommended for determining dawsonite. X-ray diffraction, infrared spectroscopy, and differential thermal analysis were useful for identifying other minerals in the samples.

Jan 1, 1973

By J. S. Dunning

The objective of this research by the U.S. Bureau of Mines was to determine the effects of AI additions on the sulfidation resistance of Fe-Cr-Ni alloys. A series of Fe-Cr-Ni alloys with and without -additions of 4 pet AI were tested in a wet S vapor atmosphere at 677 C. A study of the morphology and composition of corrosion scales indicated a different corrosion mechanism for AI-free alloys compared with AI-containing alloys. Aluminum-containing alloys formed a compact, tightly adherent layer at the metal-scale interface that reduced corrosion rates by a factor of 3 to 10 compared with that of AI-free alloys. The thin, adherent AI-containing scale limited inward diffusion of 0 and S to the base metal and outward diffusion of Ni from the base metal. Aluminum-containing alloys formed a three-layer scale in oxidizing-S environments, while AI-free alloys formed a less protective two-layer scale.

Jan 1, 1989

By J. B. Zink, M. J. Peterson

A semiquantitative spectrochemical method was developed and applied to the analysis of ash of U.S. coals . A low- temperature ashing procedure was used to minimize the loss of volatile elements . The analytical procedure provides for the estimation of 68 elements including major , minor , and trace constituents . Standards for the trace elements were prepared in a synthetic base mixture that approximates the average composition of U.S. coal ashes . Excitation was achieved with a d- c arc , spectra were recorded photographically , and interpretation was made by visual comparison of spectra of unknowns with spectra of graded standards series . Thirty- six trace elements were found in the analysis of 900 samples . Details of the procedure are presented , including sample and standards preparation , excitation and exposure conditions , spectral lines used , and approximate limits of detectability .

Jan 1, 1964

By Alvin M. Cummings

During the period from June to September 1943, the Bureau of Mines undertook an investigation of the Vial mine, near the village of Linden I in Iowa County, Wis., as part of a general investigation of the zinc-producing area of southwestern Wisconsin. The work was done when every effort was being made to increase the production of metals important to the Nation's war program. The Bureau completed 29 churn-drill holes aggregating 3,348 feet of bore in areas immediately north and west of the old Vial mine, which had been worked intermittently between 1908 and 1939. The drilling supplemented a previous drilling program by the lessees and disclosed the presence of two significant zones of mineralization.

Jan 1, 1948

By Jr. Kauffman

The data contained in this report were obtained incidental to the Bureau of Mine's investigation of the lime-soda sinter process as applied to the recovery of alumina from siliceous bauxite, kaolin, and other high aluminous materials. The Bureau of Mines was charged by Congress to investigate processes for the production of aluminum from domestic low-grade ores. The Eastern Experiment Station at College Park, Md., conducted laboratory and pilot-plant investigations of the recover-y of alumina by the lime-soda sinter process. Reports by the College Park staff covering the recovery of alumina from these sources have been published. The lime-soda sinter process involves the sintering of the finely ground siliceous bauxite or clay with limestone and soda ash in a rotary kiln. During the sintering the alumina supposedly reacts with the soda ash to form soluble sodium aluminate and the silica combines with the lime to form the insoluble orthosilicate. In the early stages of the investigation it was considered desirable to know the temperatures at which the phase changes occurred during the sintering operation. The total time involved in the passage of any given portion of the charge through the kiln was 28 minutes. The exposure time of the charge to temperatures above 600° C. (decomposition temperature of kaolinite) was, roughly, half the total. The exposure to the full temperature of the kiln, 1,100° C was only 3 minutes. (Subsequently, the maximum kiln temperature and retention time were increased.)

Jan 1, 1949

By V. A. Marple, K. L. Rubow

"4.1 IntroductionIn previous chapters impactors have been described as useful instruments for classifying particles by their aerodynamic diameters and for measuring particle size distributions. These impactors can be used most reliably if the user has some understanding as to how the impactor classifies particles and what parameters are important in this classification process. This understanding can best be obtained by a theoretical inspection of inertial principles.This chapter reviews the most recent theoretical impactor work and the latest theoretical efficiency curves. Procedures are then given for using these efficiency curves in the design and evaluation of cascade impactors. Finally, several examples are given comparing theoretical and experimental efficiency curves, pointing out when the theory can be used with great confidence and when the theory should be used only as a guideline.Due to the rather simple principle of operation of an inertial impactor (i.e., the impingement of a jet of particle-laden air on a flat plate) the impactor readily lends itself to theoretical analysis. Three notable works in the early 1950,s were those of Davies and Aylward (1951), Davies et al. (1951), and Ranz and Wong (1952).Davies and Aylward (1951) used a method of conformal mapping to obtain an analytical solution to Euler's equation for the flow of a frictionless fluid through a rectangular impactor. Numerical calculations were then carried out whereby the equations of motion of the particles were solved in a stepwise manner, leading to a determination of the efficiency curves. Since this theory assumed potential flow, the effect of Reynolds numbers on the characteristics of the impactor could not be determined.Ranz and Wong (1952) used an approximate flow field to calculate the efficiency of both round and rectangular nozzle impactors. In the vicinity of the stagnation point, the flow field was assumed to be that of frictionless stagnation flow. Here, the resulting equation of motion for the particles was found to be in a form similar to equations for free vibration with viscous damping. Therefore, the known solutions of the vibration equations were applied directly to the problem and the efficiency curves calculated. This solution technique, however, could not take into account the various geometric variations such as the jet-to-plate distance in the determination of the efficiency curves.The work of Ranz and Wong (1952) was later modified by Mercer and Chow (1968) and Mercer and Stafford (1969) so that the rather simple flow fields of Ranz and Wong (1952) could be used to account for various jet-to-plate distances. The same techniques, however, were used to determine the impactor collection efficiency curves."

Jan 1, 1986

By Robert J. Timkp, James D. Noll, Peter Hall, Robert Haney, Linda McWilliams

Diesel particulate matter (D PM) samples from underground metal/nonmetal mines are collected on quartz fiber filters and measured for carbon content using National Institute for Occupational Safety and Health Method 5040. If size-selective samplers are not used to collect D PM in the presence of car-bonaceous ore dust, both the ore dust and D PM will collect on the quartz filters, causing the carbon attributed to D PM to be artificially high. Because the D PM particle size is much smaller than that of mechanically generated mine dust aerosols, it can be separated from the larger mine dust aerosol by a single-stageimpacto1: The SKC D PM cassette is a single-stage impactor designed to collect only D PM aerosols in the presence of carbonaceous mine ore aerosols, which are commonly found in underground nonmetal mines. Howeve1: there is limited data on how efficiently the SKC D PM cassette can collect D PM in the presence of ore dust. In this study we investigated the ability of the SKC D PM cassette to collect D PM while segregating ore dust from the sample. We found that the SKC D PM cassette accurately collected D PM. In the presence of carbon-based ore aerosols having an average concentration of 8 mg/m3, no ore dust was detected on SKC D PM cassette filters. We did discover a problem: the surface areas of the D PM deposition SKC D PM cassettes, manufactured prior to August 2002were inconsistent. To correct this problem, SKC modified the cassette. The new cassette produced, with 99% confidence, a range of D PM deposit areas between 8.05 and 8.28 cm2, a difference of less than 3%.

By William L. Porter

From the first day of new miner training until the day they retire, mine workers will experience changes due to the normal aging process. It is an unfortunate fact of life that many age-related changes result in diminished physical, sensory, or cognitive capabilities. Of course, workers also gain a tremendous wealth of experience, knowledge, and insight as they age, making them a vitally important resource for their company. Effective leveraging of this precious resource requires both an appreciation of the changes that occur with age and an understanding of methods that can be used to reduce the injury risk that may result. The purpose of this training is to provide the information necessary to accomplish these objectives. Aging workers may not necessarily have a higher injury risk overall; however, the effects of a musculoskeletal injury (MSI) on older workers may be more extreme. MSHA data show that not only does the percentage of MSIs increase when workers are over age 30, so does the number of days lost per injury, as shown in the graph below [MSHA 2005]. [ ] Protecting the safety and health of aging workers requires matching the demands of the job to worker capabilities. This means reducing or eliminating risk factors for injuries, such as heavy lifting, awkward postures, static postures, repetitive movements, and/or vibration exposures. In other cases, it may mean improving visibility or streamlining processes. Designing jobs to accommodate the changing capabilities of older workers will not only reduce injury risk for older workers, it will have the added benefit of protecting younger employees as well.

Jan 1, 2008

By John A. Breslin

This publication provides an historical overview of research undertaken by the U.S. federal government over the last 100 years to improve the health and safety of our nation?s miners. Federal research efforts began with the establishment of the U.S. Bureau of Mines (USBM, or the Bureau) in 1910. They have continued over the past century, even after the Bureau?s closure in 1996. It is hoped that this publication will give the reader an appreciation for the work of mining health and safety researchers over the past century, and of the miners served by this research. Although not a comprehensive history, this report highlights the key organizational changes made within the Bureau and the federal government that affected mining safety and health research. Some mention is also made of Bureau research not directly related to mining health and safety. Note that the work classified as safety and health research has varied over the last century. For example, before 1970 the Bureau separated mining research and safety and health research. At that time, mining research included ground control and methane drainage because they had direct implications for mine safety. Explosives research was also reported separately from health and safety, even though permissible explosives research was obviously related to safety. Therefore, where budget figures from the Bureau are mentioned in this report, it is often not possible to separate safety and health research from other types of research. This history is generally chronological, with a few exceptions. Because of their prominence and direct links to Bureau research, most of the Public Health Service mining studies completed before 1970, when NIOSH was established, will be discussed in a single section, even though the work spanned many decades. Likewise, for convenience, the brief histories of the Bureau?s mining research centers are located in one section.

Feb 1, 2010

By C. E. Reistle

The generation of steam for drilling operations has visually been accomplished in the past by the use of portable locomotive-type boilers without the aid of auxiliary equipment or advanced for economizing fuel or water consumption. This has been due primarily to the fact that the steam-generating plant of a drilling well must necessarily be of temporary and portable design, and the amount of steam generated has not been considered sufficient to justify the additional expense necessary to obtain more economical operation. However, with the constantly increasing depth to which oil wells are being drilled and the use of larger and heavier equipment, the steam requirements have reached a point where equipment and methods that were previously considered as applicable only to permanent plant installation can be and are being used to a decided advantage by the more progressive operators. As an example of the present-day requirements and the rapidly increasing steam consumption in rotary drilling, a comparison between the requirements during the intensive drilling period in the Seminole end Oklahoma City fields of Oklahoma is of interest. In the Seminole field. There the approximate depth of rotary drilling was 3,500 feet, the general practice was to use three 85 to 90 or 100 horsepower A. P. I. code boilers operating at a working pressure of 175 to 200 pounds per square inch. The fuel end water consumption was approximately 450 to 500 thousand cubic feet of gas and 700 to 750 barrels of water per day. In the Oklahoma City field, where the average drilling depth is approximately 6,500 feet, the general practice is to use either four 100 or 116 horsepower or three 123 horsepower A.P.I. code boilers, operating at a pressure of 250 pounds per square inch. The fuel and water consumption varies from 550 to 750 thousand cubic feet of gas and from 1,000 to 1,500 barrels of water per day.

Jan 1, 1930

By L. B. Pankratz

Thermodynamic data on the sulfides were reviewed, evaluated, and compiled at the Bureau of Mines Albany Research Center. Values for Cp°, S°, H°298 -(G° - H°298)/T, ?Hf°, ?Gf°, and log Kf are given in tabular form. Cp°, H° - H°298, ?Hf°, and ?Gf° are also expressed algebraically.

Jan 1, 1987

By Wilbur L. Webb

This publication reports on the design, fabrication and test of an Improved methane monitor system for compliance to 30CFR75.313. The system will Initiate automatic shutdown of mining machinery when excessive concentrations of methane are encountered. The prime consideration: In the design were small size, Improved accuracy and reliability, fast response and a transient resistant power supply capable of reliable operation from any mine power source. The power supply contains an internal battery that provides operating power to the detection system prior to mining machine start-up or after machine shutdown. This report documents the development program from conception through in-mine testing.

Jan 1, 1978