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By Efrem R. Reeves, David C. Byrne

This study was conducted as part of a project involving the evaluation of a new type of noise exposure monitoring paradigm. Laboratory tests were conducted to assess how “nonstandard” dosimeter microphones and microphone po­sitions measured noise levels under different acoustical condi­tions (i.e., diffuse ?eld and direct ?eld). The data presented in this article re?ect measurement differences due to microphone position and mounting/supporting structure only and are not an evaluation of any particular complete dosimeter system. To varying degrees, the results obtained with the dosimeter microphones used in this study differed from the reference results obtained in the unperturbed (subject absent) sound ?eld with a precision (suitable for use in an ANSI Type 1 sound level meter) 1/2 -inch (12.7 mm) measurement microphone. Effects of dosimeter microphone placement in a diffuse ?eld were found to be minor for most of the test microphones/locations, while direct ?eld microphone placement effects were found to be quite large depending on the microphone position and supporting structure, sound source location, and noise spectrum.

By William H. Lewis

Energy Research Corp., under contract to the Bureau of Mines, has developed a new miners' caplamp battery. The new battery is based on nickel-cadmium technology and offers significant improvements in performance with reduced size and weight when compared to the conventional lead-acid battery presently in use. This report describes the design and fabrication of the nickel-cadmium battery, which utilizes a roll-bonded electrode structure. The final battery design has a 15-A-h capacity in a 2-112-lb package, which is over 2 lb lighter than the present lead-acid caplamp battery.

Jan 1, 1983

Research personnel from the Bureau of Mines, a representative of the Mine Safety and Health Administration, and research contractors for the Bureau of Mines met with other Government and industry representatives at three seminar locations in December 1980 to discuss the findings and products of Bureau research on mine safety training. The research program is aimed at providing assistance to the mining community in its efforts to reduce industrial-type, human-error accidents through research establishing performance based methods and media for employee training. Research emphasis is directed toward development of baseline materials and instructional models; development of methods for structuring and evaluating health and safety, supervisory, and occupational training; and the continued investigation and application of current learning and simulation technology that could significantly enhance the effectiveness of training opportunities.

Jan 1, 1981

By Richard A. Dick

Underground blasting in permanently frozen gravel was studied in a 7-by 12-ft drift by running a nonreplicated 2 X 2 X 2 factorial experiment on the effects of type of cut, delay, and explosive on the fragmentation subsystem. Comparisons were made between a V-cut round and a burn-cut round, millisecond delays and half-second delays, and 40 percent special gelatin and 60 percent high-density ammonia dynamite. The number of large blocks in the muck pile) loading time, shuttle car operating time lost because of cleanup needs, length of advance per round, and length of muck pile were recorded and statistically analyzed. None of the blast parameters had a significant effect on the length of advance or length of muck pile, although the half-second delays tended to give a shorter muck pile than millisecond delays. The burn cut required less secondary breakage, less loading and cleanup time, and gave better overall fragmentation than the V-cut. The ammonia dynamite shots required less secondary breakage and less loading time than those using special gelatin. The half-second delays gave better overall fragmentation and required less cleanup time, but the millisecond delays gave a better loading rate. None of the differences between delays and explosives were notably significant.

Jan 1, 1970

By M. J. Ferrante

The preparation and subsequent reduction of vanadium trichloride was investigated as a process for the production of high-purity vanadium metal. Chlorine was reacted with vanadium oxide in the presence of carbon to vanadium tetrachloride. The contaminant vanadium oxytrichloride was also formed and later converted to tetrachloride by reaction with chlorine in the presence of activated charcoal. Vanadium tetrachloride was stirred continuously during thermal dissociation to vanadium trichloride powder from which volatile contaminants were removed by distillation. The vanadium trichloride powder was reduced to vanadium sponge by controlled feeding of the trichloride into molten magnesium. Excess reductant and byproduct salt were removed from the vanadium sponge by high-vacuum distillation. Batches as large as 6.5 kilograms of sponge metal were prepared at an average reaction efficiency of 98 percent. Vanadium sponge after consolidation by arc-melting contained 820 to 11330 ppm of interstitial impurities and had a hardness between Rockwell B 40 and 70, This metal exhibited excellent workability at room temperature. The purification of impure vanadium metal by electron-beam melting resulted in lowering interstitial impurities from 1,890 to 504 ppm and hardness from Rockwell B 87 to 28.

Jan 1, 1968

This chapter presents an overview of fatal and nonfatal injuries reported to MSHA during 1986-1995. Reportable injuries follow the criteria for reporting specified in 30 CFR 50. These criteria are listed in appendix A. The data used for these analyses came from the MSHA accident, injury, and illness data closeout files for the years 1986-1995. The MSHA data are described in appendix A and methods used in data analysis in appendix B. There may be slight discrepancies between the figures presented here and other presentations of MSHA data for the following reasons: (1) injuries to nonemployees have been excluded from analysis; and (2) injuries identified by MSHA after the files were closed out are not included. Within the MSHA data, there are differences in reporting requirements for operators and contractors. Contractors are required to report only those injuries that occur during certain categories of work (described in appendix A). For this reason, data on injuries among employees of operators and contractors in the MSHA database should not be considered directly comparable. As discussed in the "Introduction," the MSHA data on fatal injuries differ from the CFOI data (chapter 1) because of varying definitions used for the mining industry. As compared to the CFOI data, MSHA data exclude injuries that occurred off of mine property and include injuries occurring at mills and processing plants on mine property. Tables 4-1 through 4-9 and figure 4-1 provide comparisons of injury frequencies and rates among the commodities. These comparisons are followed by sections 4A through 4E, which provide more detailed tables and figures for each commodity separately. The method used to calculate injury rates is described in appendix B. Since denominator data for occupations (lob titles) were available for 1986 only, estimates of rates by occupation for the entire 10 year period are based on extrapolation from 1986 data. For this reason, estimates of injury by occupation should be interpreted with caution. Fatal Injuries A total of 1,078 fatal on-the-job injuries were reported to MSHA during the 10-year period 1986- 1995. The average annual fatal injury rate for all commodities combined during this period was 30.9 per 100,000 full-time equivalent workers. Mine operators accounted for 908 (84%) of the fatalities and had an average annual fatal injury rate of 28.2 per 100,000. While mine contractors comprised only 16% (n = 170) of the total number of fatalities, their average annual fatal injury rate was 2.3 times higher than that of mine operators (65.0 per 100,000). Table 4-1 presents the number and rates of fatal injuries by commodity for operators and contractors. Contractors in metal, nonmetal, stone, and sand and gravel are grouped together, since MSHA data on employment were not available for rate calculations for these commodities separately. The highest average annual fatality rate for the period, 66.5 per 100,000, occurred among metal and nonmetallic mineral mining contractors, followed closely by coal contractors (63.1 per 100,000). Among mine operators, the highest average annual fatal injury rate was in coal (38.9 per 100,000); the lowest was in nonmetal (14.3 per 100,000). Table 4-2 shows the average annual fatal injury rate by type of operation for each commodity for mine operators only. Of commodities with underground mines, all except stone had higher fatality rates at underground than at surface operations of these mines. The highest fatality rate for any operation occurred in surface operations at underground stone mines (124.5 fatal injuries per 100,000 workers). Stone had the second highest fatality rate for underground operations at underground mines (77.9 per 100,000). The highest rate for underground operations at underground mines occurred in metal (87.6 per 100,000). Table 4-3 shows the number and rate of fatal injuries by U.S. Bureau of the Census occupational groups (described in appendix D) for the 10 occupation-commodity groups with the highest fatal injury rates. These data should be interpreted with caution because the denominator used in calculating the rates was based on an extrapolation from data for the year 1986 only, as described in appendix B. Extractive occupations are represented in this group for three commodities: coal, metal, and sand and gravel. Construction trades are included for coal, sand and gravel, and nonmetal. The distribution of fatal injuries by commodity and work activity for mine operators is presented in table 4-4. A description of the work activity categories is in appendix C. Overall, the leading work activity at the time of injury was using or operating tools and machinery (26.4%) followed by constructing, repairing, and cleaning (24.0%), vehicular operations (18.8%), and materials handling (12.6%). The distribution varied by commodity. The largest percentage of fatal injuries occurred while operating tools and machinery in both coal and stone; during vehicular operations in metal; and during constructing, repairing, and cleaning activities in nonmetal and sand and gravel. Table 4-5 shows the distribution of fatal injuries by commodity and MSHA accident classification for mine operators. A description of the MSHA accident classifications appears in appendix E. The largest proportion of injuries overall occurred during powered haulage (28.5%). The

Jan 5, 2000

By M. Clair Smith

This report is one of a series being prepared by the Bureau of Mines on exploration, development, mining methods, and costs at various open-pit mines in the United States. These reports have been prepared in cooperation with various mining companies. A similar program, conducted from 1928 to 1939, was generally conceded to have contributed to improving the efficiency of mining operations. The purpose of these reports is to promote development and conservation of our mineral resources by disseminating technological information on mining methods and practices. This report describes exploration, development, equipment, and mining by open-pit methods of the remainder of an ore body that had been previously worked by underground methods. The Tripp pit of the Consolidated Coppermines Corp. is located at Kimberly, Nev., a small mining company town having an elevation of 7,250 feet, 9 miles by road west of Ely, Nev. (fig. 1). The pit extends over the area formerly mined by underground methods from the Morris and Brooks shafts.

Jan 1, 1962

By Laurance L. Oden

The Bureau of Mines is developing melting data for binary combinations of the alkaline earth fluorides and yttria to facilitate the formulation of slag compositions. The present report deals with the CaF2-Y203 system for which solidus and liquidus temperatures and solid solubilities were determined. The information is presented as the phase diagram. All specimen compositions were blended from high-purity materials and encapsulated in Mo or Pt20Rh prior toheat treatment. Liquidus temperatures were determined by ceramographic examination of heat-treated and quenched specimens. Solidus temperatures were determined by differential thermal analysis and by electron microprobe analysis of quenched specimens. Terminal solid solubilities were derived by parametric methods. The peritectic system was found to be pseudobinary due to the formation of yttrium oxyfluoride at temperatures near the liquidus. The peritectic point occurs at 7 mole pct Y203 and 1,438° ± 5°C. The terminal solid solubility of Y203 in CaF2 decreases from 7 mole pct at 1,438° C to 1 mole pct at 1,100° C, and the solubility of CaF2 in Y203 decreases from 9.5 to 7 mole pct over the same temperature interval.

Jan 1, 1970

By Donald W. Mitchell

Research shows that water neutralizes the explosion hazard of coal dust when present in sufficient quantity and when intimately mixed with the dust. The quantity of water required to neutralize coal dust and coal-rock dust mixtures is about equal to the limiting moisture adsorptive capacity of the dust; the adsorptive capacity increases with increase in the fineness and volatile content of the coal. Pools of water or high atmospheric humidity do not reduce the explosion hazard. Although wetted dust is less dispersible than dry dust, poor dispersibility cannot be relied on as the sole safeguard against explosion. Dust mixtures that contain water in excess of their limiting adsorptive capacity are dispersed and ignited by severe initiation sources. Pure coal dust adsorbs water with difficulty and retains water poorly; adsorption and retention is increased by the addition of rock dust the coal; the rock dust agglutinates wetted coal and assures that incombustible is present should drying occur. Therefore, it is advantageous to rock-dust wet areas in bituminous coal and lignite mines. When coal-rock dust mixtures are wetted and subsequently dried, the explosion hazard is about the same as for dust which was not wetted.

Jan 1, 1962

By Choon Kooi Quan

Water availability is essential for mining and minerals processing. To provide government and industry with recent data for water use planning and management, the Bureau of Mines canvassed a number of U.S. producers of nonfuel minerals to determine their water use in 1984. Data were analyzed and compared with previously published data in order to examine historical trends in water utilization in the nonfuel minerals industry and to estimate water requirements in the year 2000. Total water use in the domestic nonfuel minerals industry during 1984 was estimated at 2,267 billion gal, of which 571 billion gal was new water and 1,696 billion gal recirculated water. The largest users of water were the phosphate rock, iron ore, copper, sand and gravel, and crushed stone industries, together accounting for almost 90% of total used. More than one-half of all water was used in Florida, Michigan, and Minnesota. In the year 2000, total water use will amount to an estimated 2,679 billion gal, of which 810 billion gal will be new water and 1,869 billion gal recirculated water. Most of this water would be used in producing the foregoing suite of minerals,

Jan 1, 1988

By S. Peterson, E. C. Westman, P. L. Swanson

Coal bumps are brittle, violent failures associated with high stresses and competent host strata. To study bump mechanisms, conditions in the vicinity of a deep longwall mining face in bump-prone strata were monitored using three discrete systems. First, a microseismic monitoring network recorded mining-induced seismic events throughout the mine and surrounding strata. Second, pressure variations and distributions on the longwall shield legs across the face were recorded. Last, tomography surveys imaged seismic transmission properties ahead of the face. Results from the three systems were correlated in an effort to increase understanding of mining-induced stress redistribution and bump potential. An initial, one-week study showed that the correlation between averaged tomogram values and seismically active areas had a coefficient of correlation (R) of 0.89. Further results of these studies demonstrate that the tomography system is capable of imaging heavy shield-leg loading and bump-prone conditions prior to them disrupting the face operations.

By Hazel B. Comstock

[This material survey on magnesium and magnesium compounds is one of a series of Bureau of Mines publications designed to serve the needs of Government and industry for comprehensive, up-to-date information on mineral commodities and activities Magnesium, the world's lightest structural metal has become a most useful material in airborne and space vehicles, automotive equipment, machine tools, and consumer products. Use of magnesium on in basic refractories for iron and steel furnaces has expanded as the production of iron and steel has increased. Progress in converting steel furnaces to the use of oxygen has further increased the use of magnesium and magnesite brick.]

Jan 1, 1963

By Hazel B. Comstock

This materials survey on magnesium and magnesium compounds is one of a series of Bureau of Mines publications designed to serve the needs of Government and industry for comprehensive, up-to-data information on mineral commodities and activities. Magnesium, the world's lightest structural metal, has become a most useful material in airborne and spare vehicles, automotive equipment, machine tools, and consumer products. Use of magnesium ores in basic refractories for iron and steel furnaces has expanded as the production of iron and steel has increased, Progress in converting steel fun cares to the use of oxygen has further increased the use of magnesia and magnesite brick.

Jan 1, 1963

By George A. Morgan

There was little change in the mineral industry of Benin in 1986, as the economy remained in the grip of a regional recession exacerbated by failing oil prices, which nullified much of the income from Benin's oil production. Benin's industrial sector accounted for less than 10% of the gross domestic product (GDP), with the mineral industry providing about one-half of that total. Several major projects initiated over the last several years continued to perform and/or progress below Government expectations. These included the Save sugar refinery, the Dassa-Parakou section of the Dassa-Cotonou highway, the Benin-Togo Nangbeto hydroelectric plant, the Onigbolo cement plant, and the Semé Oilfield. Funding for these projects is the major source of the Beninese external debt, which was estimated to be over $800 million.2

Jan 1, 1988

By C. Thomas Hillman

The practical concern of economic minability of large, high-grade manganese nodule deposits in the northeast Pacific Ocean is addressed in this Bureau of Mines report. Principal objectives are to (1) estimate tonnage and grade of deposits with significant potential and (2) describe and estimate profitability of operations designed to mine and process deposits with greatest apparent potential. Analysis of data from over 800 ship stations identified three areas for detailed study. Average metal contents of these areas range from 1.30 to 1.45 wt pet nickel, 1.00 to 1.24 wt pct copper, 0.21 to 0.26 wt pct cobalt, and 26.8 to 27.8 wt pct manganese. Estimated recoverable nodule resources are 67.0, 66.9, and 148.8 million dry metric tons (t). A system to mine, transport, and process nodules from the three sites is described and costed. Although hypothetical, the system utilizes hydraulic mining and Cuprion (Kennecott) processing, which have been successfully tested at pilot scale. Nickel, copper, and cobalt are the three primary products, but ferromanganese is a considered option. Estimated capital requirements are approximately $1.5 to $1.7 billion for three-metal production. If ferromanganese were recovered, an additional investment of about $130 million would be required. Operating costs range from $71 to $83 per dry metric ton of nodules without manganese, and from $103 to $123 per dry metric ton with ferromanganese. Discounted cash flow analyses predict low returns, ranging from 2.7 to 5.2 pct with ferromanganese and from 4.1 to 6.0 pct without.

Jan 1, 1983

By E. S. Shedd

Amenability studies were conducted by the Federal Bureau of Mines on an electrooxidation technique for the extraction of mercury from cinnabar ores, particularly those that are too low in grade to be furnaced or retorted economically. Oxidation was accomplished by electrolysis of the ore while slurried with brine. Mercury was dissolved through the formation of the soluble tetrachloro mercury complex, HgC142-. Mercury extractions ranged from 90 to 98 percent in 4 to 6 hours of processing time when tests were made on eight different types of cinnabar ores containing from 0.7 to 18 pounds mercury per ton ore. Salt concentration was varied from 4 to 10 weight-percent depending on whether Pb02 anodes and iron cathodes were used or whether graphite was used for both electrodes. Power consumption ranged from 17 to 64 kilowatt-hours per ton of ore treated. Ninety-nine percent of the mercury was recovered from pregnant solutions by precipitation on an active metal such as zinc, followed by distillation of the resulting amalgam at 600° C.

Jan 1, 1975

By Michael Kaplan

An investigation was conducted of the use of a mechanical rock splitter as the primary means for rock fragmentation in underground hard rock mining systems. Analyses and scale model tests showed that reasonably sized splitters that could be mounted on the booms of conventional drill jumbos were capable of fragmenting over a ton of rock per cycle. Detailed drill-split mining systems were developed for entry development, room and pillar, bench mining, and cut and fill mining. Economic analyses of these systems showed them to be generally competitive with conventional drill-blast methods. Except for bench mining, drill-split offered substantial cost savings over drill-blast. The investigation also included a technical evaluation of the mechanical splitter, an analysis of health and safety, and a determination of the potential applicability of drilling and splitting.

Jan 1, 1979

By Eldon C. Pattee

Reconnaisance samples of reported beryllium occurrences in Idaho, Washington, Montana, and Oregon were chemically and spectroscopically tested in a mobile laboratory. The two predominant types of occurrences were green beryl associated with Cretaceous intrusions and disseminated aquamarine associated with Tertiary intrusions. Although the beryllium content of known deposits in the Northwest is too low for economic development at present, total submarginal-grade beryllium resources in pegmatites are estimated to be 570,000 to 1,870,000 tons containing 0.024 to 0.167 BeO. A potential source of 500,000 to 700,000 tons of beryllium-bearing tactite in Idaho and Montana averages 0.033 to 0.080 percent BeO.

Jan 1, 1968

By A. A. Cochran

The purpose of this Bureau of Mines research was to investigate the theoretical and practical aspects of using ionizing radiation to promote chemical reactions that are of interest to metallurgists, and to carry out a radiation study of a suitable reaction. The effect of 44,000 roentgens per hour of 120,000-volt X-rays on the chlorination of highly pure mixtures of rutile, carbon, and various catalysts at temperatures up to 540° C. is described. At these low temperatures, recoveries were very low; however, in the eight different systems studied, an increase in yield due to X-rays was statistically significant in two instances and was of borderline significance in a third instance. In the other five systems, the differences in yield were not significant. Impurities and added catalysts caused relatively large variations in the yield of TiC14 from the reaction. Although the catalysts employed were reported in the literature as positive catalysts for the reaction, most of them were negative catalysts for the highly pure system studied. With only one exception, each increase in the purity of the charge resulted in a decreased yield of TiCl4. The experimental results indicate that many substances catalyze the reaction studied and suggest that the differences in reactivity of the charge stocks may be due to their various contents of positive and negative catalysts.

Jan 1, 1962

By C. Ogasawara

This document describes the direction and progress of the Bureau of Mines Oil Shale Mining Environmental Research Program as of January 31, 1979. It is aimed at focusing the Bureau's role in environmental research supporting oil shale development with respect to the activities of other involved government agencies and private industry. Environmental considerations in oil shale extraction, such as ecological disturbances, health and safety hazards, waste management, and socioeconomic impacts, are discussed along with the type of research known to be planned by organizations to ameliorate these problems.

Jan 1, 1979