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By Donald W. Mitchell, John Nagy, Edwin M. Murphy

To increase safety and productivity in mining , the potential uses and hazards of rigid foam were investigated by the Bureau of Mines Experimental Coal Mine . This research resulted in the development of chemical formulations , spraying equipment , and application procedures that permit safe and effective use of urethane foams for improving mine ventilation , for reducing weathering of mine rock and steel , for constructing seals in fire areas , and for thermal insulation .

Jan 1, 1964

By N. S. Dalal, X. Shi

"Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(Vl) by glutathione redtuctase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(Vl). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals.C(Vl) compounds have been found to exert serious toxic and carcinogenic effects on humans and animals (1-3). In contrast, most Cr(III) compounds are relatively nontoxic, noncarcinogenic, and nonmutagenic (1,4). Cr(VI) and Cr(III) oxidation states are different in their metabolic pathways: Cr(VI) , ions are rapidly transported across cellular membrane (1,4,5), while Cr[III) moieties do not easily penetrate cells and are not oxidized by cellular constituents (!). Since it is known that the reduction of Cr(VI) ion is required for its reaction with DNA (1), the molecular mechanisms for the intracellular Cr(Vl) reduction has been the focus of current studies but the details are still not understood.Earlier studies on the mechanism of Cr(Vl) reduction include those on the reduction of Cr(VIJ by glutathione (GSH) .0,6-8), ascorbic acid (9), glucose (10), lactose (IO), galacturonic acid (11), microsome (12), and mitochondrial electron transport chain complexes (13). These studies have shown that the Cr(VI) reduction involves the formation of Cr(V)-containing species which are often considered to be the toxic form of chromium. Thus far, however, no information is· available on the subsequent fate of those biologically formed Cr(V) species, in particular employing well defined biochemical systems. In this context, we report here our investigations of the reduction of Cr(VI) by glutathione reductase (GSSG-R). This enzyme was selected because it is ubiquitously present in cellular systems and it has been postulated to be involved in the Cr(VI) reduction (14-17) but the underlying mechanism has not been clarified. We find that the reduction proces·s involves not only Cr(V) but also ·OH radicals. We further investigate the reactivity of Cr(V) and find that it catalyzes generation of OH radical from H2O 2 through a Fenton-like reaction. The role of ·OH in Cr(VI) carcinogenicity is suggested from this study."

Jan 1, 1989

By L. Y. Sadler

The Bureau of Mines conducted a study Lo determine the loss in weight of silica (Si02) volatilization from low-alumina (A1203) refractories used as hot face liner materials in such process equipment as coal gasifiers, synthesis gas transfer lines, and ammonia plant secondary re-formers. Small specimens of 80-and 40-pct-A1203 brick and 95-pct-SiO2 brick were exposed to steam in high-pressure furnaces at pressures of up to 1,000 psig and temperatures up to 1,400° C for periods ranging up to 120 h. Weight losses from the 40-pct-A1203 brick after 40 h of exposure were highest, 2.75 pet at 1,400° C and 1,000 psig. The rate of weight loss had dropped to near zero after 80 h of exposure at all temperatures. No relationship between total silica content of the specimen and weight loss could be established nor did scanning electron microscopic examination of the specimens before and after exposure identify specific regions (e.g., surface) suffering a disproportionate share of the silica loss. It was concluded that minor silica volatilization is likely to occur, if at all, at temperatures of less than 1,000° C and pressures below 1,000 psig, and that low-alumina refractories should be used as dry-ash coal gasifier hot face linings.

Jan 1, 1986

By L. J. E. Hofer

The Bureau of Mines determined rates of adsorption and desorption of methane as a function of particle size and temperature, using coals from the Pocahontas No.3 seam (lvb) from the Bishop mine of western Virginia, and the Pittsburgh seam (hvab) from the Pursglove No. 15 mine of northern West Virginia. For a given coal sample and temperature, the rate curves for adsorption and desorption are essentially the same when expressed on a fractional approach to equilibrium basis. The rates of adsorption and desorption increased eightfold as the particle size was decreased from 6-8 to 270-325 mesh per inch. The adsorption process appears to be diffusion controlled. Rate of sorption processes increased with increasing temperature; however, the amount adsorbed at equilibrium decreased.

Jan 1, 1966

By D. Harrington

Springing or chambering of deep drill holes is common practice in some quarries. It involves definite hazards from premature explosion during placing of the springing charges or the final charge due chiefly to heating of the bottom of the holes by the successive exploding of the springing charges or, in some instances, from burning of paper or other material following detonation of the explosives The danger is either unknown or disregarded in many instances by those who place the charges in the holes. Disregard of this hazard probably is, at least in part, responsible for the far too high fatality and injury rate due to charging explosives and premature slots in quarry work. Awareness of the danger' should result in elimination or at least of material decrease in injuries from this cause.

Jan 1, 1941

By Murray Jacobson

The Federal Coal Mine Health and Safety Act of 1969 established mandatory dust sampling of coal mines according to procedures prescribed in the Mandatory Health Standards, title 30, Code of Federal Regulations, part 70, published in the Federal Register on April 3, 1970. A laboratory was established in the Pittsburgh Field Health Group of the Bureau of Mines to process the coal mine dust samples collected by the mine operators. This paper describes the laboratory and presents the equipment and procedures used in processing these samples.

Jan 1, 1971

By James R. McVey

Tests during pillar robbing, longwall operations, and other mining activities indicate that roof-floor convergence rates can be used as an indicator of imminent roof failure. A large number of electrical-mechanical devices have been built to measure convergence as well as convergence rates, but most obstruct mine traffic and are costly and time consuming to install. The Bureau of Mines has designed and is evaluating three types of small ultrasonic units to make these measurements. The new instruments provide nonobstructing measurements up to 35 ft away. The ultrasonic transducers can be attached to a roof bolt, placed in an unsupported area (by means of a toss basket), or handheld. Total distance to the target and rate of closure are displayed digitally to 0.001 ft and 0.01 ft/min, respectively.

Jan 1, 1984

By Steven J. Page

Responding to the increasing concern for dust control in metal and nonmetal mining, the Bureau of Mines investigated typical dust reduction efficiencies of wet bar cutter machines as they are presently being used in salt mines. Wet bar techniques have previously been used in coal mines, achieving dust reduction efficiencies ranging from 11 to 60 pct. Two different wet bar techniques, namely, the front spray and the water trickle, have been studied as they are currently being used in two salt mines. Preliminary results show that the dust reduction efficiencies have a large variation (0 to 66 pct), as is the case for wet bars used in coal. However, whereas wet bars in coal required 3 to 4 gpm water consumption, wet bars in salt obtained similar efficiencies with only 0.1 to 0.4 gpm. The most reliable data obtained during this study show that the front spray system consistently performs at efficiencies between 41 and 66 pct, with an average of 54 pct. The results indicate that, although wet bar cutter techniques in salt mines are a relatively simple and inexpensive means of dust control with a minimum of water consumption, further investigation should be performed to fully evaluate and optimize wet bar cutter dust reduction efficiencies.

Jan 1, 1980

By Thomas J. Blalock

The volumetric determination of uranium according to the method of Sill and Peterson (6),3/ which uses cerate oxidimetry after the separation of interferences such as sulfides and cupferrates, has been used for some time by the Bureau of Mines and gives satisfactory results for many of the samples tested. However, in those instances where the uranium content did not exceed a few tenths of 1 percent and iron was present in the range of 10 to 40 percent (as Fe203),4/ the method was cumbersome and unreliable. The need for a more accurate procedure for the determination of small amounts of uranium in the presence of large amounts of iron, such as in shale or black sands, prompted this investigation. The Bureau desired that materials containing as little as 60 p.p.m. of uranium be assayed within reasonable limits of accuracy. One of the primary aims of this work has been to eliminate, as far as possible, the necessity for repeated cup ferron extractions.

Jan 1, 1960

By M. S. Seehra, R. S. Pandurangi

"INTRODUCTION Silica and kaolin (a layer aluminosilicate) are among the major constituents of most coal mine dusts.' Whereas kaolin is cytotoxic in vitro but nonfibrogenic in vivo in humans and experimental animals,2-4 the cytotoxic and fibrogenic potential of silica is rather well established.5 Wallace and co-workers 6-8 have studied the cytotoxic potentials of both native and surface-modified silica and kaolin and inferred that retoxification is slow in the case of occluded silica vis-à-vis native silica. Recent epide¬miological studies indicate that silica concentration alone in a mine dust, as determined by transmission IR spec¬troscopy (TIRS), does not correlate well with the pro¬gression of coal workers' pneumoconiosis. 9 This obser¬vation has led to the suggestions that silica particles occluded by clays such as kaolin may not be fibrogenic. This proposal requires accurate estimations of kaolin, silica, and occluded silica. The current method of silica analysis in a mine dust sample employs TIRS of the 797- cm -1 band of silica, although its accuracy, as well as that of x-ray diffraction studies, is no better than 25 % , even in a laboratory-generated dust.° In this paper we have employed the techniques of diffuse reflectance spectros¬copy (DRS) and photoacoustic spectroscopy (PAS), in conjunction with an FT-IR spectrometer, for the quan¬titative determination of silica in laboratory-generated silica-kaolin mixtures.One of the main advantages of DRS and PAS is that, in these techniques, problems arising from sample prep¬aration of the KBr-based disks used in TIRS are avoided. There are, however, several other considerations (e.g., particle size effects and saturation phenomenon) which complicate the use of DRS and PAS for quantitative work. 10-25 In this paper, we have carried out a systematic comparison of the quantitative abilities of the two tech¬niques, as applied to the silica-kaolin mixtures, with par¬ticular attention to the saturation behavior of several bands with different absorption coefficients. In particular, we show that a weaker band for silica at 1875 cm-1 is suitable for quantitative purposes, and that quantitative accuracy is higher in DRS than in PAS. Details of this work are given below."

Mar 1, 1992

By John Dasher

The impetus given to mineral dressing arid chemical engineering by the war has placed many persons without previous experience in positions where they are concerned with the size of solid materials they are testing. Many good textbooks cover this field in considerable detail but are more concerned with the "why" than with the "how" For beginners and those to whom size is not of primary concern, this brief circular has been prepared. Refer-

Jan 1, 1942

By Albert E. Long

Since December 10, 1945, the Mount Weather Branch, Mining Division, Bureau of Mines, has been maintaining detailed performance and cost records on the diamond coring bits used throughout the United States by the Bureau of Mince. Figure 1 is a copy of a typical master record sheet showing the scope and type of information recorded for each bit. It is the intention of the Bureau of Mines to issue analytical reports covering the effects of diamond size and quality on the cost of core drilling in different rocks as the information on a significant number of bits used in any one type of rock is accumulated. This report is the first of such a proposed series and is based on the diamond loss and bit costs incurred in the use of 539 AX bits in coring operations on 10 different projects involving 6,097 feet of drilling in gneiss. The 10 projects were located in New York, Pennsylvania, and New Jersey (fig. 2). As a result of the information accumulated on the use of diamond-coring bits in drilling in gneiss, it has been found that the type of bit, the matrix, the percent of core recovered, and the size and quality of diamonds used have a definite effect on the cost of bits per foot drilled.

Jan 1, 1950

By F. N. Kissell, R. J. Bielicki, J. H. Perkins

A sorption apparatus for measuring the equilibrium sorption isotherm and the rate of diffusion of methane from fine-sized coal was designed and constructed. Preliminary work that used Pittsburgh and Pocahontas No. 3 coal shows that the diffusion coefficient varies with pressure and that the fracture spacing in these two coals is substantially different.

Jan 1, 1972

By G. W. Reimers

Exothermic oxidation reactions of sulfide minerals can produce self-heating situations in underground mines. If the self-heating is unchecked and the resulting heat is not sufficiently dissipated, the result can be spontaneous combustion fires. This U.S. Bureau of Mines report describes laboratory tests conducted to measure the reactivity of pyrite following treatment with additives to counter its self-heating tendencies. Thermal gravimetric analysis (TGA) and isothermal oxidation procedures were used to obtain information on pyrite ignition and the behavior of pyrite during low-temperature oxidation to ferrous sulfate. The determination of treatment effectiveness was evaluated by adding 5 wt pct of the compound to the pyrite before milling. The resulting samples were then heated in moistened air and after 24 h, the amount of pyrite oxidation determined. Results of these tests indicated that several phosphate compounds reduced the oxidation of pyrite to sulfate to about 50 pct or less compared with the oxidation of untreated sample at 200° C. Cupric sulfate reduced oxidation to about 20 pet untreated sample at 200° C. Sodium, calcium, and potassium chloride reduced pyrite oxidation to levels of approximately 15 pct or less of the untreated sample. Using only 1 pct of sodium or calcium chloride was effective in slowing pyrite oxidation to less than 20 pct of the untreated sample.

Jan 1, 2010

By A. E. Isaacson

Bureau of Mines researchers developed and tested equipment to measure corrosion rates on a commercial scale mill. Bench-scale experiments were designed for duplicating ore grinding conditions closely enough so that realistic rate determinations could be made in laboratory tests. Rates measured in a laboratory system compared favorably with those measured in the field. Cast steel was found to have corrosion rates in a copper mill and laboratory test cell of 22 and 21 mpy, respectively. Corrosion was found to account for less than 5 pct of the total grinding media wear in the operations studied.

Jan 1, 1988

By William Cochran

The mineral waste disposal system at the Grace Mine, Morgantown, Pa., was designed to minimize environmental effects while allowing much of the waste from the iron mine, mill, and concentrator to be utilized. Standard cost estimating procedures were used by the Bureau of Mines to determine waste disposal costs. Mill tailings and rock waste disposal costs were estimated at $0.151 and $0.276 per ton, respectively, for the 1965-67 production period. Total waste disposal cost was reduced about $0.015 per ton by utilizing part of the waste as aggregate. The net average cost for disposal of all mineral waste was $0.189 per ton.

Jan 1, 1969

By James P. Bennett

The Bureau of Mines investigated the effect of refractory oxide additions, introduced in soluble form, on the high-temperature properties of 90- and 98-pct-MgO brick. Brick samples were soaked in solutions containing Al, Ca, Cr, Co, Fe, Mg, Mn, Mo, Ni, Si, Sr, Sn, Ti, or Zr ions. Additions to 98-pct-MgO brick did not generally result in statistically significant property improvements. Statistically significant improvements were noted in hot modulus of rupture (MOR), slag resistance, and spalling resistance of the 90-pct-MgO brick for additions of Al, Mg, or Sn. High-temperature performance of treated 90-pct-MgO refractories was equal to or approached that of 98-pct-MgO brick. The marked improvements due to tin were obtained with additions of only 1.14 wt pct Sn02.

Jan 1, 1985

By E. O. Binyon

The Blue Metal corundum-andalusite deposit, in the Buckskin Mining district, Douglas County, Nev., was explored by the Bureau of Mines in 1945. The results of that work were presented in Report of Investigations 3895, exploration of the Blue Metal Corundum Property, Douglas County, Nev. published in August 1946. That report also describes the property in detail, giving location, ownership, history, geology, and data on beneficiation tests. Further exploration was carried on in April and Way 1947, the results of which are presented in this report. The work consisted of 175 feet of drift and crosscut, bringing the total to 398 feet of underground working, as shown in figures 1 and 2. The 23-foot drift, which was the last work of the initial project, was extended 99 feet northward along the shear zone, and three crosscuts, spaced at approximately equal intervals along the drift, were driven to country rock on the hanging and foot walls of the zone.

Jan 1, 1948

By Robert C. Bates

This Bureau of Mines report converts published data on the cost of ventilating uranium mines to a common price base and analyzes these data to determine the cost per ton of uranium ore at various levels of radiation exposure control. There appears to be an exponential increase of cost as the radiation level is lowered. The 1967 base costs are extrapolated to present dollars, and some cost comparisons are given for other radiation control measures.

Jan 1, 1981

By Robert F. Droullard

The Bureau of Mines has investigated techniques of using gross alpha or beta detectors to continuously measure working levels. Both methods measure radioactive particulates collected on a filter paper using a constant airflow. Inherent-error studies indicate a value of about ±3 percent for the gross alpha method and about ±8 percent for the beta method in typical mine atmospheres. However, the beta method avoids problems associated with alpha detectors and is therefore more useful. Applications of these continuous working-level detectors include work area monitoring of exposure levels in underground openings, such as mines and caves, and calibrating personal dosimeters exposed over extended time intervals.

Jan 1, 1977