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By James S. Browning

The Bureau of Mines conducted laboratory batch and small-scale continuous selective flotation tests of barite-fluorspar ores from two deposits near Marion, Ky., to determine the technical feasibility of recovering commercial grade fluorspar and barite concentrates. The lignin sulfonate-sodium fluoride method of floating the fluorspar successfully produced acid-grade fluorspar concentrates. Flotation of the barite from the fluorspar tailing using petroleum sulfonate collector yielded concentrates suitable for use in compounding oil-well drilling mud. The fluorspar and barite recoveries were about 82 and 85 percent, respectively.

Jan 1, 1963

By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations wi.thin a multiple-seam configuration. At two mine sites where such ground interactions were present, the Bureau performed a complete geological analysis and installed and monitored instrumentation to gather pertinent data on rock mechanics. Overburden depth varied dramatically in the vicinity of the study area and reached a maximum at the study site; innerburden thick-ness was less than a pillar width (40 to 4S ft); heaving was experienced in both mines where sandstone and/or shale floor units were observed; overlays of the mine layouts show pillars were not totally superpositioned; a maximum of S in of roof to floor convergence was measured; and pressure readings indicated pillar core loading only and increased to a maximum of 7,000 psig over instrument setting pressure.

Jan 1, 1987

By Irving Wender

This report describes Bureau of Mines experiments and reviews the work of others on the exposure of coal and coal-derived products to gamma rays and some other types of radiation. Results are presented on tests of three bituminous coals and a lignite that had been pulverized to minus 200-mesh particles and exposed to 1,000 megaroentgens of gamma irradiation from spent-fuel elements of a nuclear reactor. Of about 20 chemical and physical tests in Bureau work, only mass spectrometry of gases evolved during vacuum pyrolysis of the coals to 450° C gave results indicating differences in the irradiated and unirradiated samples. Mass-spectral distribution curves for CO and CO2 evolution showed fewer irregularities (reversals of curvature) for irradiated coals; thus, mass spectrometry appears to be the most sensitive method for determining radio-induced changes in coal. It is concluded that coal is not significantly altered by gamma irradiation owing to the resistivity of its highly condensed ring structure. High-level gamma irradiation, therefore, is unlikely to prove advantageous in coal processing and utilization. Specially treated coals, because of resistivity of coal to radiation damage, may be useful as an absorbent in processing radioactive wastes.

Jan 1, 1968

By Theresa Y. Schulz

It is interesting to study the noise standards that have been promulgated in the US over the last decade or so. These regulations are likely to have long-lasting impact. The Occupational Safety and Health Administration (OSHA) Hearing Conservation Amendment (March 1983) continues to have influence not only in the workplace but in the debate over new regulations. Both the Mine Safety and Health Administration (MSHA) and Federal Railroad Administration (FRA) regulatory preamble documents state the desire to be consistent with OSHA. An examination of Table 1, which compares the major components of the three regulations and the 1998 NIOSH “best practices” criteria, depicts the extent to which that intent is met. There has been some regulatory activity in the last decade which may give some hope for evolution and updating based on the wealth of science that has occurred during the last quarter of a century since the OSHA regulation was enacted. However there has also been some “back-sliding” toward more lenient standards. The MSHA noise standard made regulatory progress in September 2000 by emphasizing engineering and administrative controls, followed by personal protective equipment, in the hierarchy of noise intervention. MSHA’s requirement for technician certification (today only available from CAOHC) strengthened the training requirements for audiometric testing in hearing conservation programs and MSHA also added the requirement of dual hearing protection at 105 dB TWA. There were many subtle differences between OSHA and MSHA based on comments and a desire to clarify some of the vague aspects of the OSHA noise standard, and meet the needs of the regulated mining industry. One example pertains to the ceiling for exposures. OSHA says, “no exposures >115 dBA,” which is interpreted to mean no unprotected exposures above that level, giving credit for the assumed effectiveness of hearing conservation programs, hearing protection devices and administrative and engineering controls. MSHA specified that a “P” code1 violation be issued for any protected or unprotected exposures >115 dBA. The Federal Railroad Administration (FRA) noise standard for railroad operating employees, which went The Modern Evolution of Hearing Conservation Regulationsinto effect February 26, 2007, was expressly based on the OSHA standard but also uses MSHA for comparison. The preamble states that the FRA defers to OSHA as the “primary regulator of noise in the workplace,” but also acknowledges the need for some departure from the OSHA regulation (FRA Preamble II.B). As an example, FRA requires testing at 8000 Hz “because it will allow employers to identify hearing loss sooner.” The FRA rejected MSHA’s hierarchy of noise controls in favor of requiring specific engineering interventions and focusing on appropriate hearing protection which would still allow communication and audibility, and identification of excessive noise through employee-filed “excessive noise reports.”2 Where OSHA has no specific mandate requiring employees to take advantage of the employer-paid audiogram, it has been traditionally a condition of employment and is generally accepted that OSHA-covered workers require an annual audiogram. MSHA addressed this issue in its preamble; however, they made no significant change. MSHA employers are required to offer annual audiograms but MSHA stopped short of requiring employees to comply with annual audiometric testing. The MSHA preamble does allow that mine operators can also make audiometric monitoring a condition of employment. FRA requires employees to

By R. L. Balmer

This information circular, which describes the methods and costs of sinking a small underground shaft with steel supports at the Keystone mine of American Smelting and Refining Co., near Crested Butte, Colo., is one of a series being prepared by the Bureau of Mines on current shaft-sinking practices in various mining districts of the United States. Preparations for sinking a combined exploration, development, and production shaft from the lowest level of the Keystone mine began early in 1957. This vertical, three-compartment, 6-1/4-by 16-foot rectangular shaft was to be sunk in separate stages or lifts so as to correspond with the progress of an associated lateral exploration and development program. The first section of the shaft was collared and sunk to a depth of 209 feet between September 1957 and April 1958. Because of the depressed base-metal market, the mine was shut down as soon as the initial phase of the exploration and development program had been completed and before any deeper sinking could be attempted.

Jan 1, 1962

By G. L. Oldright

The Metallurgical Branch of the Bureau of Mines, as a part of its duties under the Organic Act, works to prevent wastes in industry and to disuse inmate information on the fundamentals of metallurgical processes. During the war, the necessity of large production was increasingly emphasized. Such duties necessitate from time to time the study of units of full commercial size, the operation of which is beyond the facilities of the Branch. When developments have reached this stage; work has been continued in cooperative agreements with operating companies that have been willing to contribute the use of their plants and staffs and to allow the publication of the results obtained for the common good of the industry.

Jan 1, 1948

By Hillary W. St. Clair

The reduction zone of the iron blast furnace is represented by a mathematical model of the chemical reactions and heat transfer that occurs between gas and solids during the deoxidation of iron oxide. The model consists of a set of equations and an algorithm whereby the equations may be solved to give the temperature and composition of gas and solids at any position in the reaction zone and at any time after a specified initial state. The model is applied to the special case in which ferric oxide is reduced by graphitic carbon and carbon monoxide produced by burning carbon in dry air. The rate of reduction, carbon consumption and maximum temperature are shown as functions of the temperature and rate of flow of the incoming reducing gas and external heat loss. The model of the reduction zone is the essential part of a general mathematical model for simulation of the iron blast furnace. The simulation model will serve as a research tool to be used in conjunction with an experimental or operating furnace. After the simulation model has been correlated with the real furnace, it is proposed that further experimentation be done mostly with the model. The real furnace will then be operated primarily to test and confirm the model.

Jan 1, 1967

By E. R. Cole

Laboratory heats of an 80 percent copper high-leaded tin-bronze alloy, similar to Brass and Bronze Ingot Institute (BBII) alloy 3A, were made with reduced tin content to determine whether an alloy comparable to BBII alloy 3A could be produced using less tin to aid in conserving this strategic metal. The tin content was lowered from 10 percent to 8 percent and 5 percent (nominal values), respectively, and the reduction in tin was offset by either increasing the lead content or adding zinc. Mechanical properties, machinability, and corrosion characteristics of the resultant alloys were investigated, and the mechanical properties were compared with BBII typical values and American Society for Testing Materials (ASTM) minimums for high-leaded tin-bronze alloy. Results indicate that the tin content of this alloy could be reduced approximately 1 percent (difference between the 8.4 percent actual tin composition obtained and the 9.3 percent BBII minimum) without seriously affecting the desired properties. Results also show the tin content could be reduced without significantly increasing the chances of rejects for mechanical property failures, which might result from normal variations in the casting process.

Jan 1, 1972

By Louis H. Berkelhamer

"INTRODUCTION ""Free silica"" includes all free forms of silicon dioxide, such as quartz, chalcedony, tridymite, cristbbalite, opal, diatomaceous earth, and lechatelierite. The term, has been used rather loosely however, as synonymous with quartz, as quartz is the most abundant form of free silica. ""Combined silica,"" on the other hand, has been reserved to denote silica combined with other elements as silicates.Improvements in methods for the determination of free silica, and quartz in particular, have been the subject of considerable interest during the past decade, owing mainly to the accented and increased knowledge concerning quartz as a causative factor in silicosis. Analysis for quartz, however, is of importance in many other fields, including the determination of quartz in ceramic raw materials, such as feldspar and clay; the evaluation of a beneficiation procedure by the ore dresser, such as in the concentration of iron ore; control studies of a manufactured product, such as silica brick; and routine analysis of rock, mineral, and ore samples by chemists and petrographers."

Jul 1, 1944

By A. B. Pederson, G. E. Bartlett

As a part of our study of how coal mine dusts injure the lung we have studied the effects of dusts and dust-exposed pulmonary alveolar macrophages (PAMs) on the growth of lung fibroblasts (LF). Fibroblasts were cultured near confluence in low-serum medium, either alone or in the presence of dusts, dusts plus PAMs, dust leachates or superriatants of dust-exposed PAM cultures. We report here provisional conclusions, based on initial observations. Rat LF were relatively unresponsive to direct effects of dusts, showing weak stimulation in only a few cultures, and there was no evidence that dust-exposed rat PAMs had released any growth-regulatory products. In contrast, guinea pig cells were more responsive to the dusts. The pattern of responses was quite complex. Three of the dusts stimulated LF directly (with no mediation by PAMs). Two dusts were essentially inert when added directly to fibroblast cultures, either with or without PAMs, but their leachates were active: 867 leachate was inhibitory and RF leachate was stimulatory. Dust 1361, either directly in the cultures or as an aqueous leachate, was stimulatory, and it activated cocultured PAMs to stimulate LF growth; however, supernatant products of 1361-stimulated PAMs were inhibitory. Direct exposure to 1192 stimulated LF, but its leachate was inert; cocultured PAMs exposed to 1192 had weak stimulatory effects, but supernatants of 1192-exposed PAMs were mildly inhibitory. MP3-3 had effects similar to 1192, except that the cocultured, dust-exposed PAMs had no effect on growth. We conclude 1) that guinea pig lung cells are more responsive to dusts than are rat lung cells, 2) that dusts can influence growth of LF by four kinds of interaction (by direct dust-cell interaction, by release of soluble dust components into the culture medium, by activating P AMs to exert direct cell-cell interactions, and by activating P AMs to release growth regulatory products into the culture medium), 3) that each kind of interaction may be neutral, inhibitory or stimulatory, depending on the dust tested, 4) that four of the dusts tested were neutral, inhibitory or stimulatory, depending on the assay (the fifth <lust was either neutral or stimulatory), and 5) that the effects of soluble mediators (leachates or products of activated PAMs) frequently did not correspond with the direct dust-cell or PAM-fibroblast effects. These results suggest that the nature of the dust-lung interaction at the level of cells and molecules is exceedingly complex. These observations need to be confirmed and extended to determine what characteristics of the dusts determine the nature of the cellular responses, and to determine which patterns of responses are detrimental and which are beneficial in the overall health of the dust-exposed lung.

Mar 1, 1989

By Terry McMahon

This Bureau of Mines report describes the rock burst problem and measures being taken for its alleviation in the deep underground mines of the Coeur d?Alene Mining District in northern Idaho. The geologic features that contribute to rock bursting in that area are discussed and briefly compared with similar features in other burst-prone mining districts throughout the world. Early investigations to understand and control rock bursting are reviewed, and the mechanics of bursting are discussed in terms of the seismic events that produce them. Sources of strain energy, rock failure mechanisms, and the conditions necessary for the release of seismic energy are covered in detail. Rock burst research in the Coeur d&apos;Alene District is described. Included are discussions of the microseismic method as both a research tool and as a rock burst monitoring system, rock destress blasting and preconditioning methods for rock burst control, and stoping methods currently being developed to reduce rock burst hazards.

Jan 1, 1988

By J. A. Eisele

The Bureau of Mines conducted bench-scale cyclic tests to determine the composition of recycled leach liquor in the Bureau?s proposed clay/HCl leach/ HCl sparge process for producing Al203 from clay. The data developed from these tests make it possible to synthesize leach liquors for predetermined steady-state operating conditions when conducting large-scale crystallization tests. The results of two sparge tests were compared. One was a 20-cycle test with a 36-pct-HCl concentration in the mother liquor; the other was a 10-cycle test with a 26-pct-HCl concentration in the mother liquor. The effect of impurity concentrations in the leach liquor on the purity of aluminum chloride (AlCl30?6H20) crystals was determined, but there was poor correlation between this data and results that have been obtained from miniplant-scale work.

Jan 1, 1980

By Gary A. Kingston

Rolled steel, steel forgings, and steel castings in the Pacific Northwest (Washington and Oregon) are produced principally in the Seattle, Wash., and Portland, Oreg., metropolitan areas. Steel-mill products are rolled from carbon and some alloy &eels by three companies into shapes such as reinforcing bar, rods, rounds, squares, flats, and hot-rolled strips; structural shapes, - such as angles, channels, and I-beams, also are rolled. Carbon and alloy steel ingots are poured and forged at a Seattle plant into ship shafting, drive shafts, billets, slabs, bars, rings, hooks, and other items. Static, shell, investment, and centrifugal castings are produced at 19 steel foundries in a wide range of steel specifications. All Pacific Northwest steel output is based on remelting steel scrap. Local iron ore might be used in the future to supplement steel scrap as a metal source. Ore reduction would probably be achieved by methods other than the blast furnace. Current melt-shop practice and problems are basically the same in Pacific Northwest steel plants as in cold-melt shops in other parts of the country. Quality steel production is receiving more emphasis in this region with the installation of modern analytical equipment and vacuum pouring and melting facilities.

Jan 1, 1962

By Rethel L. Hubbard

Fourteen straight-run asphalts were prepared in the laboratory from bitumens obtained from three sources: (1) native bitumen from Rozel Point, Utah, (2). bitumen extracted from Athabaska bituminous sandstone at Canada, and (3) bitumen extracted from Edna bituminous sandstone outcropping in San Luis Obispo County, to seven asphalts with penetrations ranging from 19 to 287 at 77 F. were prepared from each of the bitumens. The yields of the prepared asphalts ranged from 74.5 percent for a 27-penetration asphalt from the Athabaska bitumen to 99.5 percent for a 271-penetration asphalt from the Rozel Point bitumen.

Jan 1, 1949

By John H. Johnson

This report covers the third and final year of work conducted under U. S. Bureau of Mines Grant G0166027, "Monitoring of Mine Air Pollutants". The report discusses work performed in three areas. These are the White Pine Mine (WPM) Experimental Unit, diesel mine-vehicle tailpipe emissions monitoring, and mine ambient air concentration data analysis. The WPM experimental unit was used to study diesel exhaust stratification in an 80 foot long dead-end heading while loading ore with a Wagner ST-5D scoop train LHD. The MTU Mine Air Monitoring Laboratory (MAML) was used to gather temperature and CO2 concentration data at 10 locations. Three different ventilation conditions were compared. The data substantiate the presence of strong buoyant forces of the hot exhaust gases which result in temperature stratification in dead-end headings. The diesel mine-vehicle tailpipe emissions monitoring study involved laboratory measurements of diesel undiluted exhaust pollutant concentrations by the portable tailpipe emissions measurement apparatus (EMA) assembled for in-mine use. The results were compared with simultaneous measurements by standard laboratory exhaust monitoring instruments. These results indicate that accurate field source quality control measurements can be obtained for CO2, CO and NO but NO2 results were low for all engine conditions. The mine ambient air concentration data analysis study included analysis of diesel pollutant concentration data in the Orchard Valley Mine air and comparison of the results with data collected earlier in the White Pine and Brushy Creek mines. The analysis included preparation of lognormal frequency distributions and calculations of C02-based concentration ratios and correlations. In the three mines compared, pollutant concentrations are distributed quite similarly, and the concentrations appear to be controlled to present standards.

Jan 1, 1979

By August J. Kwitowski

This report presents the results of a joint Bureau of Mines-U.S. Department of Energy project that evaluated a newly developed low-coal mining system: the 4M miniminer system. The evaluation took place from April through October 1981 and determined potential health, safety, and productivity factors for the mining system using the surface test facilities at Bruceton, PA. The planning, testing, results of testing, and a summary evaluation of the 4M miniminer system are included in the report. The miniminer system was found to be a very good concept with future potential for safe, healthful, and economic production in thin-seam mining. The mining system was also judged to have considerable potential for use in some coal seams that are presently considered unminable by other existing mining equipment. The preproduction, prototype version of the miniminer system that was tested suffered from several safety and production problems. These problems are also described, along with suggested remedies.

Jan 1, 1989

By Pramod C. Thakur

In This Chapter [Origins of coalbed methane Reservoir properties of coal seams Thresholds for coal seam degasification Methane emissions in mines Methane drainage techniques How to transport gas safely in mine pipelines and Economics of coal seam degasification Recommended publications on coal seam degasification are Gas Control in Underground Coal Mining [Creedy et al. 1997], Coalbed Methane Extraction [Davidson et al. 1995], and Methane Control for Underground Coal Mines [Diamond 1994].] ORIGINS OF COALBED METHANE AND RESERVOIR PROPERTIES OF COAL SEAMS Origins of coalbed methane. Coal seams form over millions of years by the biochemical decay and metamorphic transformation of plant materials. This coalification process produces large quantities of byproduct gases, such as methane and carbon dioxide. The amount of these byproducts increases with the rank of coal. It is the highest for anthracite, where for every ton of coal nearly 1,900 lb of water, 2,420 lb (20,000 ft3) of carbon dioxide, and 1,186 lb (27,000 ft3) of methane are produced [Hargraves 1973]. Most of these gases escape to the atmosphere during the coalification process, but a small fraction is retained in the coal. The amount of gas retained in the coal depends on a number of factors, such as the rank of coal, the depth of burial, the type of rock in the immediate roof and floor, local geologic anomalies, and the tectonic pressures and temperatures prevalent at that time. The gases are contained under pressure and mainly adsorbed on the surface of the coal matrix, but a small fraction of gases is also present in the fracture net-work of the coal. Methane is the major component of gases in coal, comprising 80%–90% or more of the total gas volume. The balance is made up of ethane, propane, butane, carbon dioxide, hydrogen, oxygen, and argon.

Jan 6, 2006

By Jerry B. F. Champlin

NIOSHAn accelerated testing procedure developed by the Bureau of Mines for evaluating commercially available corrosion inhibitors is described. Ultra-sonic agitation of the corrodent solutions and the hot-finished mild steel test coupons was used to evaluate the effects of several variables on the effectiveness of two corrosion inhibitors. Small changes in the weight of the test coupons in both controlled and inhibited corrodents, before and after exposure, affected the precision and accuracy of the results. Minute amounts of oxygen in the systems were found to be causing the relatively large deviations in the corrosion developed in the controlled tests. Microscopic examination of the test coupons revealed that both surface preparation and internal strains resulting from fabrication methods materially affect corrosion behavior.

Jan 1, 1965

By Charlie Wyche

The British Solomon Islands Protectorate continued developmental work on bauxite deposits on the Islands of Rennell and Vaghena. A feasibility study was completed by Mitsui Mining & Smelting Co., Ltd., and Pacific Aluminum Ltd. (a subsidiary of Conzinc Riotinto of Australia Ltd,), and negotiations with the Government were in progress. The Government will receive a 25% share if the project is realized. It was estimated that the Islands contain 60 million tons of bauxite with an alumina content of 45% to 50%.

Jan 1, 1980

By W. J. Fene, G. W. Grove

An important activity of the Safety Division of the Bureau of Mines , in its efforts to reduce accidents , is the safety inspection of mines . Inspections are made at the request of the operators and are not connected with the inspections by the various State departments of mines . The operating management is furnished with a confidential report of the results of the Bureau's inspections , with recommendations for elimination of the hazards found . These mine - safety inspections include a study of mining practices , conditions , and equipment and in some cases the sampling and analysis of mine air and coal dust . The Bureau of Mines has no regulatory powers , therefore the recommendations made in these reports are merely suggestions , and operators are not required to adopt them . Mine inspections are a check on safety standards , methods , and practices and are essential to any accident -prevention program . A foreman or superintendent may be sincere in his efforts to operate a mine safely and believe that he has done everything possible to attain this end . However , experience has shown that because of his familiarity with the mine and the consequent " nearness " of its various features many unsafe conditions may be , and in most cases are , overlooked ; an inspector , particularly an outsider who is trained to look for hazards , can point out the unsafe conditions overlooked by the foreman or superintendent . Some companies employ safety engineers who make regular inspections of their mines , report substandard conditions and hazards found , and make recommendations for correcting them . Unless these recommendations are carried out the inspections have little value . In making recommendations , due consideration should be given to the feasibility of carrying them out ; the management may and very often does consider a recommendation impracticable because of the

Mar 1, 1935