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By Forrest T. Moyer

All general measures of the safety record of the coal mining industry worsened appreciably in 1970. Injury experience for the year was 260 fatal and 11,552 nonfatal injuries at respective frequency rates of 1.00 and 44.40 per million man-hours of worktime. The fatality total was 57 higher and the rate of occurrence was 18 percent higher than the corresponding figures of 203 fatal injuries with a frequency rate of 0.85 in 1969. The worsened fatality record in 1970 resulted primarily from a major disaster (a single accident which results in the death of five men or more) on December 30, 1970, that killed 38 men. There were no major disasters in 1969. The total of 11,552 nonfatal injuries in 1970 was the highest annual total since 1960. It was 1,635 higher and the frequency rate was 6 percent higher than the corresponding totals for 1969 of 9,917 nonfatal injuries occurring at a rate of 41.76. The injury severity rate of 8,308 days lost or charged per million man-hours was 13 percent worse than that of 7,359 in 1969. Similarly, the average severity of 183 days lost or charged per injury in 1970 was 10 days or 6 percent higher than in 1969. Aggregate worktime of 260.2 million man-hours and production of 609.8 million tons in 1970 were, respectively, 10 and 7 percent higher than in 1969. An average of 144,480 men were at work on an average of 227 active days in 6,316 mines and 544 mechanical cleaning plants during 1970.

Jan 1, 1973

By Paul M. Tyler

The outstanding trend in the graphite market is the fast-growing demand for cheaper qualities of graphite and the declining consumption of the more expensive varieties. The manufacture of graphite, crucibles for melting metals was one of the earliest applications of the-mineral and for many years constituted by far the leading source of demand. In later, years, however; and more especially since the Great War, the increasing demand for high-grade steel ingots and castings instead of enlarging crucible sales has permanently curtailed the domestic demand for crucibles because it has hastened the introduction of electric, oil or gas fired furnaces to replace the older types requiring pots to hold the metal during melting. While there has been a substantial increase in the use of graphite for miscellaneous refractories the total consumption for such purposes is too small to offset the shrinkage in demand for crucible making, and though it consumes the better and hence more expensive grades of crystalline flake graphite, it does not call so insistently for the still costlier Ceylon grades.

Jan 1, 1929

By Joseph W. Horne

This report presents the results of an investigation by the U. S. Bureau of Mines in cooperation with the State of Colorado, on the yields and properties of oils produced from oil shale, lignite and subbituminous coal using the standard assay method developed by the Bureau for oil-shale testing,. The purpose of this work, which is part of the general study of oil shales being conducted by the Bureau of Mines and cooperating agencies, was to obtain information on the amount and character of the yield of crude oil or tar from different typical oil shales, the yield of light oil or naptha that might be suitable for use in motor fuels, and other products of shale oil. As the west has large resources both of oil shale and low-grade non-coking coals, it is of interest to know the relative yields of tars, light oils, and combustible gases that can be produced from these coals when retorted under conditions similar to those suited for oil-shale retorting. Source of Samples The coal samples were obtained from deposits on or adjacent to the public lands in the States of the Rocky Mountain region. Many of the mines sampled are operating under Government leases or permits. The number of coal samples secured from the various states are: Colorado, 6; Montana, 9; north Dakota, 6; New Mexico. 1; South Dakota, 1; Wyoming, 9. Of these samples, 14 were lignite coal, 16 subbituminous coal, and a bituminous coal. The standard channel method of the Bureau of Mines was used for sampling. Coal samples received at the Boulder Office weighed about twelve pounds each, and duplicate samples were sent to the Pittsburgh Station for proximate and ultimate analyses. The origin of the samples and description of the deposits are given in Table 1.

Jan 1, 1927

By J. H. Stears

Increasing use of Birmingham and other roof trusses prompted a Bureau of Mines study of support forces produced on a mine roof by these members. Equations, obtained from laboratory and field tests, are given for calculating the contact forces between the roof strata and a typical truss. Actual contact forces for a specific truss are difficult to estimate because of variable friction loss at the contact points. A finite-element analysis, using typical contact forces, indicated that trusses have a negligible effect on the stress field in massive, competent roof strata. The effectiveness of trusses in supporting broken rock strata was not analyzed. However, experience has shown that trusses are effective in supporting incompetent roof.

Jan 1, 1988

By Verne E. Hooker

Near-surface temperature measurements in two granite quarries show that diurnal temperature variations are significant to a depth of 1 or 2 feet, and annual temperature variations are significant to a depth of at least 25 feet. As a result, ground stress anomalies due to temperature exist near the surface, and their magnitude depends upon the time of day and the time of year. Rock stress and corresponding temperature measurements were made in one granite quarry over a rock temperature range of 33° to 81° F. Measured rock temperatures show good agreement with values predicted from one-dimensional heat flow theory. Calculated and measured stress-temperature coefficients for the two granites in this study are given. Thermally induced stress variations in near-surface rocks tested were as large as 1,690 psi from combined daily and seasonal temperature changes.

Jan 1, 1971

By G. W. Reimers

Conditions in the underground mine environment can cause self-heating of sulfide ores as a result of exothermic oxidation reactions, which may result in mine fires. This Bureau of Mines report describes thermal analyses of finely ground chalcopyrite, chalcocite, galena, pyrrhotite, marcasite, and arsenopyrite, to characterize their responses under oxidizing conditions. Thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) were used, in the temperature range 1000 to 5000 C. Chalcopyrite showed an initial weight gain, due to formation of sul-fates, a weight loss, caused by ignition of iron sulfide to iron oxide, and a final weight gain, indicating the conversion of copper sulfide to sulfate. Chalcocite did not ignite in the temperature range studied but exhibited a rapid weight gain, because of the rapid conversion of copper sulfide to sulfate. Likewise, galena failed to ignite but underwent a steady weight gain when oxidized in a moist atmosphere, showing conver-sion of lead sulfide to sulfate below the ignition point. Marcasite underwent a rapid weight loss, indicating ignition, at 2000 C. Moisture in the oxidizing atmosphere lowered the ignition point of marcasite and arsenopyrite but not that of pyrrhotite. All the sulfides exhibited exothermic behavior at temperatures below the ignition point.

Jan 1, 1987

By D. Harrington

Approximately 2,000 persons are killed annually in the coal mines of the United States. There is no question that this number is at least double and probably treble what it should be and by all means the least excusable of the fatalities are those caused by explosions and fires. Fatalities from explo- sions and fires in coal mines are almost invariably caused by carelessness or negligence. Table 1 indicates that the fiscal year ending June 30, 1931, ras by no means a satisfactory one as regaris either the number of explosions or the number of persons killed by them. This tabulation lists all ignitions to which the attention of the personnel of the safety division was called and in- cludes not only major disasters, but also explosions in which fewer than five were killed, as well as several explosions from which no fatalities resulted. It will be noticed that last year there were 26 explosions in mines in 10 States of the United States, resulting in 217 deaths. In the previous year there were 34 explosions with a death list of 199, and in the year before there were 38 explosions with a death list of 139. Hence, the past fiscal year had distinctly a poorer record of fatalities from mine explosions than either of the two previous years. Of the 26 explosions in the past fiscal year, Pennsylvania had 7, West Virginic 4, New Mexico and Ohio 3 each, Alabama, Oklahoma and Washington 2 each, and California, Illinois and Indiana 1 each; the one in California was in a tunnel being driven for water purposes but giving off explosive gas (methane). In fatalities Ohio had the worst record with 38, Oklahoma came next with 45, then Indiane with 38, and Pennsylvania with 23; although Alabama had 2 ignitions and Washington 1, they caused no fatalities. Utch, Colorado, and Kentucky had no explosions reported by the safety division of the Bureau of Mines during the past fiscal year, but were on the list for the previous year, though in the case of Colorado there were no fatalities. On the other hand, Indiana and New Mexico, neither of rhich was charged with an explosion in the two previous years, were on the list for the past fiscal year; New Mexico had the bad record of three explosions, though fortunately with but a total of eight fatalities. Ohio reported 3 explosions to the safety division of the Bureau of Mines in the past fiscal year, 2 in the pre- vious year, and 3 in the year before that, or 8 in the past three fiscal years with 92 fatalities; all of these eight explosions were in open-light mines.

Dec 1, 1931

By Stephen A. Swan

This Bureau of Mines report discusses research to analyze and evaluate extended bumper systems in order to determine the degree of protection provided to equipment operators in the event of rear-end collisions be-tween off-road rear-dump haulage trucks. The basic characteristics of rear-end collisions were determined, and a detailed analysis of the col-lision dynamics was performed to identify the magnitude and direction of impact loads, the amount of energy that must be absorbed during impact, and the major factors that affect the outcome of a collision. Separate bumper designs were developed to facilitate attachment to four 170-st-capacity haulage truck frame types.

Jan 1, 1987

By Alvin M. Cummings

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

Jan 1, 1948

By J. Ronald Lawter

The purpose of the work described in this report was to measure the effects of diesel engine emissions on the air quality of work areas in a coal mine. Concentration measurements of a number of diesel related air contaminants were made at the Martin County Coal Corporation Mine in Inez, Kentucky. Compounds measured included carbon dioxide, carbon monoxide, formaldehyde, nitric oxide, and nitrogen dioxide. In addition, concentrations of the two classes of odorous compound;, aromatic hydrocarbons, and oxygenates were obtained along, with aldehyde concentrations. Surveys were made of the mine by odor analysts to determine the perceived intensity of diesel-produced odors. It was found that the concentrations of the measured species were well below their Threshold Limit Values. Odor intensity levels in the moderate to strong range were observed in the mine.

Jan 1, 1977

By R. Blickensderfer

The sparking and gas-igniting tendency of steels and alloys were evaluated my measuring the radiance of spark showers produced by grinding a sample on an abrasive wheel in air, the time required for a spark shower generated on an abrasive wheel to produce an ignition in an explosive gas mixture, and the energy and speed required for impacts between various materials to ignite an explosive gas mixture. Mixtures of air-methane were found quite resistant to ignition by showers of sparks. A mixture of air-9.S pct hydrogen was used to increase the sensitivity of the tests and to thereby extend the range of materials that could be evaluated. The results of the spark-shower tests indicate that carbon steels and the alloy steels found in coal-cutter tools are among the most sparking and most incendive of any materials tested. Stainless steels, nickel alloys, and tungsten carbide are among the least sparking and least incendive. The brightness of the spark showers depended upon the degree of oxidation of the abraded particles. Impact tests against hard rocks such as solid quartz and sandstone, showed that high-carbon steel was more inc endive in the hydrogen mixture than were the softer steels or the alloy steels found in coal cutters. Ignitions were found much less likely to occur at speeds somewhat lower than the speeds currently in use in continuous mining machines.

Jan 1, 1972

By Bruce K. Cantrell, Jon C. Volkwein

Exposure to mineral aerosol is an occupational health hazard in mining and mineral processing industries because of the risk of developing pneumoconiosis. Agricola (1556) described this hazard for metal mining in Carpathia. He described shortness of breath and consumption, conditions that are now associated with asthma and emphysema. By the end of the nineteenth century, several respiratory diseases were known to affect miners, including silicosis and coal workers' pneumoconiosis (Fletcher, 1948; Seaton et al., 1981). For example, silicosis, not tuberculosis, was clearly recognized as the hazard in the Vermont granite quarries and stone-cutting sheds (McFarland, 1927). The Gauly Bridge Tunnel disaster in the mid-1930s caused the deaths of an estimated 700 workers by acute silicosis and focused the nation's attention on this disease (Cherniack, 1986). By the mid-twentieth century, it was clear that risk of simple pneumoconiosis is associated with a miner's cumulative exposure to mine aerosol in the respirable size range and that prevention lies in reducing that exposure through regulation (Seaton, 1986). In the United States, regulation of mine worker exposure to airborne mine dust is the responsibility of the Mine Safety and Health Administration (MSHA) in the U.S. Department of Labor. The key legislation relating to improved mine worker health was the Federal Coal Mine Health and Safety Act, enacted in 1969 (U.S. Congress, 1969) and subsequently amended as the Federal Mine Safety and Health Act of 1977 (U.S. Congress, 1977). MSHA receives technical assistance from the National Institute for Occupational Safety and Health (NIOSH). NIOSH also provides recommended exposure limits (RELs) for contaminants to MSHA. MSHA's regulation of mines includes the establishment of a dust standard administratively based on the these RELs. Some mine operators must submit a dust control plan designed to meet the dust standard. Periodic mine inspections determine if mines are com- plying with both the dust standard and the dust control plans (MSHA, 1991). The most common dust measurements are those for respirable dust (according to the definition given in Fig. 26-7), that is, the fraction of aerosol particles able to reach the gas exchange region of the lungs. The other health-related size fractions (inhalable and thoracic-see Fig. 25-1, and "total" dust) are also occasionally measured. A "total" dust measurement is defined by the common practice of the last 30 years or so, using 25 mm or 37mm plastic cassettes (e.g., from PAL, MIL, SKC ). The types of mines have been categorized

By T. R. Jolley

This publication describes the control of fires in inactive coal deposits in the Western United States, including Alaska by the Bureau of Mines. Material presented should contribute to a better understanding of the purpose, process, and benefits of the program. Forty fires were extinguished or controlled in the Western United States and Alaska from 1948 to 1958 under a national program directed by the Bureau's Health and Safety activity. Thirty-five fires were controlled by smothering; three were controlled by the isolation method; and two were extinguished by removing the burning coal, smothering it with incombustible material, and backfilling the fire zone. The fire-control projects were distributed as follows: Alaska 2, Arizona 1, Colorado 9, Montana 9, New Mexico 4, Utah 2, and Wyoming 13. The total cost of the 40 fires extinguished or controlled was $1,203,957. Of this cost, 12.8 percent was engineering and administrative and 87.2 percent was contractual services.

Jan 1, 1959

By D. J. Bauer

The Bureau of Mines demonstrated the feasibility of fractionating lanthanide nitrates with a tertiary amine on lanthanum-cerium and thulium-ytterbium pairs. Optimum values were determined for pH, phase concentration, and percent chelation of metal ions in the aqueous phase. Percent extraction is markedly dependent on the concentration of lithium nitrate in the aqueous phase. Selective masking of the heavier element in each extraction system with DTPA or EDTA aqueous-phase chelating agents resulted in lanthanum-cerium separation factors of 8.5 and thulium-ytterbium separation factors of 3.4.

Jan 1, 1966

By R. G. Lett

Gaseous products resulting from rapid pyrolysis of coal and coal/inhibitor mixture's by a ruby laser and a flash-tube were monitored on-line by time-of-flight mass spectrometry. The distribution of stable gases from the coal is not Greatly influenced by the addition of small quantities of powdered flame inhibitors. Preliminary studies of the reaction of elementary radicals with coal and coal/inhibitor mixtures are described. The different types of experiments are discussed with regard to possible modification and application to studies of flame inhibitor action.

Jan 1, 1973

By S. B. Levin

The Bureau of Mines has been investigating deposits of critical and essential minerals in the United States and Alaska since 1939. During the fall of 1942, the Bureau of Mines put down nine diamond-drill holes at the Cape Rosier zinc-copper-lead mine in Hancock County, Maine, that aggregated 2,883 feet of bore. These holes supplemented 13 holes, aggregating. 5,501 feet, put down on the property about 2 years earlier by the St. Joseph Lead Co. Veins of mixed sulfides were intersected in 15 of the holes drilled. Beneficiation tests were made on samples of ore obtained from old dumps. Zinc-copper-lead sulfides occur at the Cape Rosier mine as lenses in a zone of altered agglomerate beneath and between a series of diorite sills. The mineralized zone strikes F. 17° E. and dips southeast. Between July 1881 and September 1883 the mine produced about 10,000 tons of ore reported to have contained 20 percent zinc, 2.8 percent copper, and some lead. The crude ore was hand-sorted, and some. 3,000 tons were reported shipped.

Jan 1, 1948

By William S. Roberts

The Bureau of Mines has initiated a program to determine the availability of land for mineral exploration and development in Alaska. Researchers involved in this pro-gram are comparing land availability, based on ownership and government policies and regulations, to the distribution of known mineral deposits and terranes. This report on southeastern Alaska presents the findings of the first of six regional studies that will cover the State. The study consisted largely of data compilation and analysis using various mapping techniques. Summary land availability data are presented on copies of U.S. Geological Survey (USGS) quadrangles at a scale of 1:500,000. Five categories of land availability were identified: open to mineral exploration and development (approximately 9.4 million acres, or 38% of the 24.8-million-acre study area), open but with possible use restrictions (4.2 million acres, or 17%), selected (0.5 million acres, or 2%), patented (0.74 million acres, or 3%), and formally closed to mineral exploration and development (10 million acres, or 40%). Of the 1,187 known mineral deposits in the study area, approximately 38% are on land in the open category. Mineral terranes comprise approximately 6.7 million acres, or 27% of southeastern Alaska. Approximately 34% of these terranes are on open land.

Jan 1, 1985

By H. M. Thorne

Oil shale, a potential source of products presently obtained from petroleum, is found in many countries. The most extensive known deposits from the standpoint of potential shale oil in place are those in Brazil and the United States of America. Mining methods used for oil shale range from open-pit operations for shallow deposits to room-and-pillar and longwall techniques for deposits with thick overburdens. Oil shales from different sources vary greatly in the amounts and types of organic and inorganic constituents. By retorting, the organic material is converted to oil, gas, and coke. The largest percentages of oil are obtained from materials having the highest hydrogen content. Over 2,000 retorting systems have been patented, but only a few have been used industrially, and no single process seems best for all types of shales or economic conditions. Shale oils have different characteristics, depending on the source rock and method of retorting. They contain large quantities of olefinic hydrocarbons and more oxygen, nitrogen, and sulfur derivatives of hydrocarbons than most petroleums. Consequently, petroleum refining methods usually must be modified for shale oil. This is particularly true in catalytic processing. Hydrogenation, even under mild conditions, improves shale-oil refinability. Several byproducts may be obtained from both the retorting and refining steps.

Jan 1, 1964

By C. E. Rork

This paper discusses various mechanical improvements that have been gradually incorporated in the copper-willing plants of the Southwest daring the past 14 years, power plants for concentrators, use of large-size units of equipment, and the effect of plant capacities on costs. The improvements in mechanical equipment and plant design have contributed in the reduction of operating costs; in some instances a saving in the capital cost per ton of daily capacity milled has resulted.

Jan 1, 1935

By T. A. Henrie, J. D. Marchant, E. S. Shedd

Cerium metal was electrowon in a fluoride bath from cerous oxide and tapped from the cell during prolonged operation . Electrolyte constituents were CeF , BaF₂ , and LiF. Twenty- seven pounds of metal of 99.8 percent purity were produced at a rate of 3 pounds per hour and tapped from the cell . Principal impurities were molybdenum , aluminum , oxygen , and carbon . The operating parameters , such as electrode geometry , bath compositions , and oxide feed rate , were investigated . Anode reactions were found to be important factors in cell operation . Stable cerous oxide reacted more uniformly at the anode surface than ceric oxide . Electrowinning was conducted in crucible hearths consisting of both frozen electrolyte and molybdenum metal . Both materials proved satisfactory and did not react with the molten cerium . Stable cerous oxide was prepared by carbothermic reduction and used as a feed material . Cell design proved to be an important factor in continuous cell operation . Complementary to the investigations of electrowinning of cerium , the metal was purified by electrorefining in a chloride electrolyte .

Jan 1, 1964