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By P. L. Swanson

Over a recent 20-month observation period, the U.S. Bureau of Mines obtained seismogram records from a single vertical-component, short-period seismometer installed at the surface of a metal mine in northern Idaho. The seismic events were analyzed for local (Richter) magnitude (M), time of occurrence, location, and relation to rock bursting and production blasting. Approximately 150 seismic events with -0.5 = M = 2.9 were located within the mine, yielding a b value (slope of the logarithm of the number of events with magnitude greater than M versus M) of 0.5. Event locations were constrained using a dense underground array of high-frequency accelerometers. Twenty of the surface-recorded events, with 0.5 = M = 2.9, were associated with rock bursts that produced damage requiring at least 1/2 day of cleanup and/or repair. Other possibly hazardous rock bursts, with magnitudes as small as -1.1, were numerous but were not associated with significant structural damage. Approximately 60 pct of the seismic events with M > -0.5 and 75 pct of damaging rock bursts occurred within 45 min of blasting. Estimates of characteristic rupture dimensions for rock bursts with -1.1 = M = 2.9, based on a conventional dislocation shear-slip model of failure, range from 3 to 300 m.

Jan 1, 2010

By Nar S. Dala1, Xianglin Shi, Val Vallyathan

"Electron spin resonance (ESRJ and cytotoxicity measurements were made on newly fractured silica to examine specifically the role of the fracture-induced, silicon-based radicals (Si· and SiO·) and silica-generated hydroxyl (·OH) radicals in the mechanism of the cell membrane damage by silica. The concentration of the Si· and SiO · radicals was controlled through decay processes, thermal annealing, and boiling, while that of the ·OH radicals was varied by using catalase, superoxide dismutase, KMnO, Na;iSeO:y ascorbic acid, and metal ions, and monitored via ESR spectroscopy. The dust's cytotoxicity potential was evaluated by measuring the silica-induced hemolysis and also by determining lipid peroxidation (using linoleic acid). From the comparison of hemolysis and ESR results it is deduced that the radicals play little or no role in the silica-induced hemolysis. However, the lipid peroxidation data indicate that the radicals might be involved in the initiation of an oxidative chain reaction leading to the macrophage membrane damage through lipid peroxidation. INTRODUCTIONThe biochemical mechanism of quartz-related pneumoconiosis is still not fully understood. It is believed, nevertheless, that one event of primary importance is the perturbation of cell membranes by the dust particles (Allison et al., 1966; Allison and Harrow, 1971; Bateman et al., 1982; Parazzi et al., 1968; Reiser and Last, 1979; Shi et al., 1989; Summerton et al., 1977). The ensuing cell: membrane damage unleashes certain lytic enzymes resulting in additional cell injury and eventual fibrosis (Nolan et al., 1981; Summerton et al., 1977). Thus considerable effort is currently being made toward the understanding of the processes by which quartz particles disrupt the membrane of a red blood cell (RBC) or a pulmonary alveolar macrophage (PAM). A simple but important method of evaluating the membrane damage potential of a dust is the hemolysis test (Harington et al., 1971). Even though this test is used routinely for screening dusts for their cytotoxicity potential, the biochemical mechanisms underlying the cell lysis by many dusts, including quartz, is still controversial (Kilroe-Smith, 1974; Singh and Rahman, 1987), and this provided us the impetus for the present undertaking."

Jan 1, 1990

By V. Vallyathan, Xianglin Shi, N. S. Dalai

While Cr(VI) is a known carcinogen, the underlying biochemical mechanism is still not fully understood (1). In a pioneering study Jennette (2) utilized electron spin resonance (ESR) spectroscopy to demonstrate that a long-lived Cr(V) species is generated during the reduction of Cr(VI) by microsomes in the presence of NADPH. Later Wetterhahn and co-workers (3, 4) showed that incubation of chromate with isolated rat liver mitochondria causes the reduction of Cr(VI), as well as the formation of a Cr(V) species. Analogous Cr(V) species have also been detected in the reduction of Cr(VI) by other cellular systems such as Hanserulla polymorphared (5) and blood cells (6, 7). All these as well as other studies (8-12) have suggested that this Cr(V) species plays a significant role in the mechanism of Cr(VI) toxicity. Thus far, however, the chemical structure of this dominant Cr(V) species formed in cellular systems has not been identified, and this observation provided an impetus for the present investigation. Another reason for undertaking this study was that some recent reports (10-16) suggest that hydroxyl ('OH) radicals may also play an important role in the mechanism of Cr(VI) toxicity. In particular, it has been shown that OH radicals are formed in reactions between Cr(V) species and H2O2 (13-16), and that the radical yield depends on the chemical structure of the Cr(V) species (15). For example, while Cr(V)-diol complexes efficiently generate OH radicals, another Cr(V) species, the tetraperoxochromate (CrO3/8) ion, does not (15). Thus in the present study, we focused our attention on the following: (a) structural identification of the Cr(V) species generated in the reduction of Cr(VI) by subcellular as well as cellular systems, using microsomes, mitochondria, and Escherichia coli; (b) possible detection of OH radical in the same systems since there is no earlier report of chromium-mediated generation of 'OH radicals in a cellular system; (c) possible involvement of molecular oxygen in chromium-related OH radical generation since a recent report (17) indicated that Cr(VI) mutagenesis is strongly oxygen dependent; and (d) elucidation of the mechanism of OH radical formation in these systems.

Mar 1, 1992

By James V. Luxner

The airflow and methane distribution patterns developed in an equipment-free entry 6.5 feet high and 12 feet wide, ventilated by line brattice operated blowing to or exhausting from the face, were determined by the Bureau of Mines for varying conditions. Results of these studies show that blowing line brattice systems of face ventilation are more effective than comparable exhaust systems. The face ventilating efficiency of any line brattice system is dependent upon the method of ventilation, the face distance, the tight rib distance, the volume of air delivered to the end of the line brattice, and the volume of methane released at the face. Experimental results indicate that maximum face ventilation efficiency is achieved when the inby terminus of the line brattice is installed 5 feet from the face and at a distance less than one-third the entry width from the nearest rib. Analyses of data are based upon the ability of a face ventilation system to dilute methane in the immediate face area.

Jan 1, 1969

By Maurice Deul

A special short-term research project was initiated to develop plant design parameters for treating mine waters to yield an effluent acceptable for discharge into streams and a sludge amenable to effective and economic disposal. Neutralization was investigated to provide simple and direct treatment of ferruginous acid waters using lime; coarse limestone, and limestone followed by lime. Limestone treatment was accomplished using a small cement mixer as a simple reactor to provide abrasive agitation of limestone and mine water. Results from tests with nine mine waters encompassing a wide range of iron and acid concentrations showed that coarse limestone, one of the cheapest neutralizing agents known, is potentially useful for treating mine water discharges. However, process variables must be defined more completely before the practical applications and limitations of the process can be fully established. In all the tests a pH of >7.2 was obtained ultimately with limestone. Reaction time to reduce the iron content below 7 ppm in the water was dependent on the original ferrous iron concentration. For waters with high ferrous iron content, treatment with limestone followed by lime rapidly produced an acceptable treated water, Sludges with good settling and handling characteristics resulted when limestone was used for neutralization either alone or with subsequent treatment. Reaction rates are expressed graphically as pH change and iron depletion curves; characteristic solids settling curves are shown. The temperature dependency of ferrous iron oxidation was verified.

Jan 1, 1967

By Elizabeth A. Johnson

Minor-element behavior and interaction in the copper matte-iron silicate slag system have been studied by the Bureau of Mines. In the present work, the possibility of interactions among the minor elements As, Sb, Bi, Se, and Te was investigated. Equilibrations of matte, slag, and one of each of the five minor elements were performed at 1,250° C under typical matte smelting atmospheres of CO, CO2, and S02 for mattes containing 40, 50, and 60 pct Cu. Results are compared with those of a previous Bureau of Mines study in which all five minor elements were present simultaneously.

Jan 1, 1984

By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

"K. A. DIGREGORIO, E. v. CILENTO, AND R. c. LANTZ. Measurement of superoxide release from single pulmonary alueolar macrophages. Am. J . Physiol. 252 (Cell Physiol. 21 ): C677-C683, 1987.-An electrooptical method was developed to quantify superoxide (02) release from single rat pulmonary alveolar macrophages (PAM) during adherence to the bottom of a culture dish. This was done by measuring the reduction of nitro blue tetrazolium (NBT) to a diformazan precipitate at 550 nm from videorecorded images of individual cells. Temporal changes in cell optical density, which are proportional to the mass of diformazan produced, were calculated from videophotometric measurements of the change in light intensity over individual cells. Total diformazan produced increased 78 and 1263 with an increase in NBT from 0.5 to 1.0 and 2.0 mg/ml, respectively. Total diformazan produced and maximum rate of production among individual PAM varied two- to threefold providing strong evidence for heterogeneity in 02 production. Specific inhibition of 02 production by superoxide dismutase, iodoacetate, and chlorpromazine significantly reduced the total diformazan produced and maximum rate of diformazan production. Hydrogen peroxide was not involved in NBT reduction, since catalase alone did not significantly change diformazan production. This novel method to quantify 02 release from single PAM should be valuable in analyzing heterogeneity and single cell kinetics of O; production, in assessing the effects of exposure of cells to particulates on O; release, and in relating release to electrophysiological measurements.rat; nitro blue tetrazolium; macrophage heterogeneity; single cell kinetic PULMONARY ALVEOLAR MACROPHAGES (PAM) protect the lungs by phagocytizing foreign debris and bacteria (24). This process involves ingestion as well as destruction of foreign matter. Phagocytosis is usually accompanied by a respiratory burst that increases cellular oxygen consumption and glucose metabolism in the hexose monophosphate shunt (7), which leads to the release of highly reactive oxygen metabolites at the surface of the · plasma membrane (6, 27). These agents have been implicated in the killing of bacteria by phagocytes (22), but have also been shown to be toxic and have been linked to cancer, emphysema, arthritis, diabetes, and other diseases (17, 22, 30). Toxic effects may be a result of either an abnormally low production of metabolites, resulting in damage to lung tissue by respirable bacteria and dusts, or an abnormally high production, resulting in direct damage to lung tissue by metabolites themselves."

Jan 1, 1989

By L. G. Marshall

The geology, mining, beneficiating, types of products, and costs in terms of percent of total costs and of labor, power, and supplies of two crushed-limestone operations in Madison County, Iowa, are described in this paper. The operations are basically similar, differing in refinements in mining, product types, and markets. The operations are comparable as to personnel and as to weighted costs in terms of percent of total costs and in terms of man-hours, power, and sup-plies. The waste-to-stone stripping ratio is 1 to 0.8 at both operations, the powder factor is 0.29 pound of explosives per ton of stone, and daily production is 95 tons per man-shift. Both companies use crawler-mounted diesel shovels for loading, truck transportation, wagon drills, and dry screening.

Jan 1, 1963

By A. G. Galaitsis

The two volumes of this report summarize the noise control work performed by BBN on a rail personnel carrier operated in coal mines. Volume I of the report - submitted November 1977 - describes the aboveground work performed to identify the noise sources, design, fabricate, and install the treatments, and evaluate the treatments through noise and vibration tests. The current volume (II)-describes the underground work conducted by BBN to determine the deterioration, if any, of the treatments when the vehicle is operated normally in a mine. There were no significant changes in the acoustical performance or mechanical integrity of the treatments at the end of a three-month period.

Jan 1, 1980

By J. B. Zadra, S. M. Shelton, M. M. Fine

"Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced; although it is well known that there are large deposits of low-grade ore in the United States, the production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stockpiled ore is depleted through inability to procure adequate supplies from foreign sources. Consequently, a program of laboratory and pilot-plant investigation designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines.This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program. The scope of the program and the organization that woo set up to direct and supervise the work were discussed in the foreword of the first paper of this series, Report of Investigations 3606, Manganese Investigations. 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent, and C. R. Schack. Other reports will be published as the work progresses."

Mar 1, 1942

By T. J. Ballard

Corundum is a natural alumina (A120 ) and is next to the diamond in hardness . Except for the gem varieties , it is used principally as an abrasive , chiefly in grinding , dressing , and polishing metals and optical glass . Natural corundum is preferred to artificial abrasives for certain specialized jobs . Most of the corundum ( excluding emery ) mined in the United States came from the Corundum Hill mine in North Carolina and the Laurel Creek mine in Georgia . The Corundum Hill mine provided over half of the domestic production of corundum prior to 1900. Since 1900 , the importation of foreign corundum and the manufacture of artificial abrasives caused the decline of corundum mining in the United States .

Mar 1, 1947

By Victor E. Kral

The Valery fluorspar deposit , also known as the Hamilton deposit , is northeast of Lovelock and 4 miles by poor dirt road east of U. S. Highway 40 . It is in the Humboldt Mining District , on the west side of the Humboldt Range , at an altitude of 6,000 to 6,500 feet . The property was examined by the Bureau of Mines on February 83/ and April 8 , 1944.4/ The last examination was made with an engineer of the Geological Survey.5/ Exploring by means of trenches , cuts , shaft sinking , coyote holes off the shaft , and a small amount of prospecting with short drill holes , was begun in January 1945 and was completed June 30 , 1945. An engineer6/ of the Geological Survey visited the property in April and again in June 1945 to complete a topographic map of the area and to note the results of exploration by the Bureau of Mines . Only minor surface exploring had been done on fluorspar occurrences previous to the Bureau's work . No mining equipment or living facilities are on the property .

Feb 1, 1947

By Stewart W. Towle

In 1989, the u.s. Bureau of Mines initiated a contract to gather engineering, operating, and environmental cost data for 1988 for 30 major foreign primary copper smelters in market economy countries. Data were collected for 29 of the designated smelters together with information on applicable environmental regulations. Materials balance data obtained were used with available data for the eight U.S. smelters to determine the approximate extent of copper smelter sulfur emission control in 1988. A broad characterization of the status of sulfur emission control regulation was made. The 37 U.S. and foreign smelters represented roughly 73.2% of world and 89.3% of market economy primary copper production in 1988. The 29 non-U.S. smelters attained 55.3% control of their input sulfur in 1988. Combined with the 90.4% control of U.S. smelters, an aggregate 63.4% sulfur control existed. Roughly 1,951,100 mt of sulfur was emitted from the 37 market economy smelters in 1988. Identifiable SO2 control regulations covered 72.4% of the 29 foreign smelters, representing 66.5% of smelting capacity. Including U.S. smelters, 78.4% of the major market economy smelters were regulated, representing 73.1 % of smelting capacity. Significant changes since 1988 that may increase sulfur emission control are noted.

Jan 1, 1993

By Matthew N. Plis

This U.S. Bureau of Mines report presents the documentation for COALVAL, a coal property evaluation software package developed on Lotus 1-2-3,4 version 2.2, spreadsheets. The software is compatible with version 3.1 as well, and may provisionally be run on the earlier 2.01 version. COALVAL is a menu-driven program that produces a prefeasibility-level cost analysis of mine-planned coal resources. The package contains cost models for each of five coal mining methods commonly employed in Appalachia: auger, contour strip, mountain top removal, continuous miner, and longwall. Other models, such as a dragline cost model, will be incorporated as the Bureau's Coal Recoverability Program matures. COALVAL allows mine operators, evaluators, consultants, and Government entities to input resource data and the various production, operating, and cost variables that pertain to their property. The program can evaluate up to 25 seams, each to be mined with up to five different mining methods, within a given area. Summary spreadsheets listing the cost per clean ton to mine the resources, f.o.b. the tipple, are produced for each property, seam, and mining method/seam combination.

Jan 1, 1993

By J. R. Thoenen, B. H. Clemmons, A. H. Reed

"INTRODUCTION AND SUMMARYOverall red-ore reserves in the Birmingham, Ala., area were estimated in 1910 by E. F. Burchard 4/. Since then mining has progressed into areas classed by Burchard as ""unavailable for exploitation"" under conditions existing at that time. This is understandable when it is considered that red iron ore was valued at $1.19 a gross ton at the mine in Birmingham in 19102/ and by 1948 had risen 300 percent; 6/ that skips had replaced cars in slope haulage; that mechanical loading and rubber-tired haulage had replaced hand loading and mule or locomotive haulage; and that other more efficient mining methods had been introduced. Intensive study during the intervening 40 years has been given to ways and means for upgrading the low-grade ores in the area and combining or blending them with raw red and brown ores for improved blast-furnace feed.It is reasonable to expect that future progress in mining efficiency and increased knowledge of the beneficiation characteristics of marginal ores will permit extraction of red-iron minerals now considered uneconomic.The Bureau of Mines has undertaken to restudy iron-ore reserves of the Birmingham area to determine what tonnage and grades of mineral are present; what is necessary to make them amenable to mining; what further advancement is possible in beneficia¬tion methods; and where increased production may be obtained in the area if and when required. This study has been underway for the past 2 years, but research into the beneficiation of marginal ores has been in progress at the Southern Experiment Station for the past 30 years. Many results of that research have been adopted in commercial practice in the area. Other results have not been published but are pre¬sented here in condensed form as an important factor in assessing marginal deposits with respect to their importance as ore reserves.An interim discussion of the salient features of past history and progress, as well as the data developed during the years of research in beneficiation at this station and the present field investigation, will make for a better understanding of the present position as well as be useful in evaluating future potentialities. Discussion in this paper is confined to the main Birmingham Basin area, which contains the largest concentration of hematite ores in the district."

Jul 1, 1953

By Gilbert L. Forst

The objective of this program is to identify and evaluate superior, lightweight substitutes for selected coal mine roof support concepts such as crossbars, posts, and crib blocks. Engineering analysis and concept design identified, through tradeoff studies, that some materials are promising, from a technical standpoint, as support substitutes: E-glass reinforced polyester resin, high strength low alloy steel, aluminum, and very high early strength (VHE) cement. An economic analysis indicates that none of the lightweight substitutes are economically competitive with wood on an initial cost basis; however, in terms of life cycle costs based on current dollars, the high strength low alloy steel appears competitive for crossbars, and the VHE cement and E-glass/resin appear competitive for posts.

Jan 1, 1978

By J. R. Thoenen

Occurrences of titanium, zircon, and other heavy minerals are widespread in Florida. Deposits concentrated as "heavy sands" by wave and wind action have been mined an or near Atlantic coastal beaches since 1916. An important inland concentration at Trail Ridge; .believed, to have formed along an ancient share line, was disclosed by preliminary investigations (1947) by the Bureau of Mines. This report describes investigations to determine the extent and grade of "heavy-sand" concentrations in other inland stabilized dune areas in the central and northeastern parts of the peninsular region of the State (fig. 1). Portions of the central highlands south of Trail Ridge and terraces and dunes in the coastal lowlands region, east and northeast of the ridge were investigated. Holes were drilled in 10 areas (see table 1 and fig. 2) along State and County roads and on private property. They were spaced 250 to 2,000 feet. apart to obtain a cross-sectional picture of "heavy-sand" content in the dune areas. These sections were generally placed in east-west directions normal to the general trend Of the peninsula to intercept one or more of the ancient shore lines in the various areas (figs. 3 to 13, incl.). A total of 433 drive piped and 333 jet holes were drilled, and 7,293 bulk and core samples were taken. Intermediate holes were placed at closer intervals when field analysis indicated 1 percent or more of heavy minerals present. All of the holes drilled and the analysis of samples that contain 1 percent or more of heavy minerals are listed in table 2. Profiles (figs. 14 to 20, inclusive) show the more favorable concentrations, which are irregular in outline and erratic in mineral content. The highest concentrations averaged 1.0 to more than 2.0 percent heavy-mineral content, but a few individual hole samples exceeded 3.0 percent in grade.

Jan 1, 1949

By M. D. Aldridge

The results of a four-year research effort aimed at developing a practical and effective electronic system for monitoring safety conditions throughout a coal mine by displaying, at a central location, remotely measured parameters are described. This document reports on the design details of the sensor packages and the data processing program used in an experimental monitoring system. The results of special ventilation monitoring experiments and several sub-system considerations are also described.

Jan 1, 1974

By S. K. R. Iyengar

This report presents the results of a study to develop optimal designs for light-weight mine roof supports for use in underground coal mines. A load capacity of 196 kN (22 tons) and a height adjustable between 1.829 m (72 inches) and 2.438 m (96 inches) were taken as the design parameters and the design goal was a unit weighing less than 22.3 kg (50 lbs). Three alternative design concepts were explored, viz. mechanical, hydraulic, and hydro-mechanical and a total of 13 designs analyzed in detail. Steel, aluminum alloy and composites were the main potential construction materials investigated for suitability from structural, life, and safety and other considerations. The designs considered most promising for development were: (i) the mechanical screw-pin type using telescopic tubes and a fine adjustment screw thread section (ii) the all-hydraulic type, of steel, aluminum alloy or aramid graphite construction (iii) the hydro-mechanical design using telescopic tubes and a short stroke hydraulic cylinder for fine adjustment It is shown that by using realistic mathematical models for stress and deflection calculations, it is possible to reduce prop weight to the design goal. The analysis presented for all-hydraulic props is applicable to hydraulic cylinders on all mining equipment and similar machinery. This report includes the computer program and user's guide for analyzing hydraulic cylinders as well as a cross-indexed bibliography on structural composites.

Jan 1, 1978

These proceedings consist of an introduction, nine descriptive papers, and a summary. The first paper is an overview of the respirable dust research program, the second paper describes the Mining Enforcement and Safety Administration's proposed changes in the respirable dust enforcement program, and the third paper describes respirable dust measurement. The remaining papers, by Bureau and contractor personnel, describes methods of reducing the amount of respirable dust to which coal miners are exposed. Of the six methods of reducing exposure to respirable dust described, two are methods of preventing or reducing the amount of respirable dust raised during mining operations, two are methods of collecting or removing dust after it has been released into the mine atmosphere, 2nd two describe methods that are combinations of prevention and collecting .

Jan 1, 1977