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By F. E. Block, Robert R. Brown, A. W. Henderson

The chlorination of Cr₂ 03 (chromic oxide ) in the presence of carbon with CC14 (carbon tetrachloride ) and COCl2 (phosgene ) chlorinating agents was investigated by employing the radioactive tracer carbon By tagging carbon mixed with Cr₂ 0з , the chlorination reaction was evaluated in terms of the competitive reaction of the elemental carbon and the carbon contained by the chlorinating agent . A unique gas - analysis train was used to separate the chlorination product gases ; CO , CO₂ , and COC12 . The C¹ activity of the gases was determined and used to calculate the reactivity of each source of carbon . Reactivities were determined for the temperature range from 600 ° to 900 ° C. The results of the investigation show that each source of carbon reacts significantly with the Cr2 03 and that the reactivity of each form of carbon depends on the reaction temperature , and each form is independent of the other . Radioisotope and gas - analysis techniques are discussed and a description of the experimental apparatus is given .

Jan 1, 1964

By James P. Ulery, Frank E. Chase

Clay veins found in coal mines have caused numerous injuries and fatalities. These structures plague all phases of mining, including entry development, pillar recovery, and panel extraction. Clay veins also increase production costs and may disrupt or halt mining. These detrimental aspects have prompted the Bureau of Mines to investigate the physical characteristics of and roof instability problems associated with clay veins. This was accomplished by observing and mapping clay veins in surface and underground mines. The occurrence and origins of clay veins were also investigated to determine predictive capabilities. The investigators found that clay veins normally occur in more stable, less rapidly subsiding coal basins. Clay veins result when tensile stresses develop fissures which are later infilled. These fissures can be propagated by compactional processes and/or tectonic stresses active during and subsequent to coalification. The Bureau also found that associated faults, fractures, and slicken-side planes commonly parallel clay veins and disrupt the lateral continuity of the immediate and, sometimes, main roof. When clay veins parallel or subparallel the direction of face advance, the roof is segmented into cantilever beams, causing unstable conditions. Consequently, the strata on either side of the clay veins should be bolted and strapped together to form a beam.

Jan 1, 1987

By A. B. Hooker

The flame safety lamp with metal-gauze enclosure was invented by Sir Humphrey Davy more than a century ago, primarily for its safe light; however, it soon became the standard device for detecting the presence of methane in mine atmospheres. It still is the most widely used device for this purpose and is also the most practicable means of detecting deficiency of oxygen in coal mines. A permissible flame safety lamp is similar in all respects to one that, after a series of tests, has been approved by the Bureau of Mines as safe for use in gassy mines. However, safety depends largely upon the way lamps are maintained and used.

Jan 1, 1944

By B. H. Eccleston

Experimental data were obtained from two medium-duty diesel engines derated to qualify for use in underground mines. Gaseous and particulate emissions from these engines were measured and results provide information on the effect of exhaust treatment devices on the emissions. The devices in the study were a catalyst, a particulate trap, and an exhaust gas cooler of the water scrubber type. Emission levels of carbon monoxide and hydrocarbons were observed to be very low in comparison with emission levels of comparable engines in full-rated operation. Oxides of nitrogen and benzo(a)pyrene content of the exhaust also were found to be somewhat low in comparison with previous findings. For particulate reduction, the combination of a particulate trap and a scrubber was observed to be the most effective combination tried; in some cases, over 60 pct particulate reduction was effected by the trap-scrubber combination.

Jan 1, 1981

The objective is to provide effective training on refuge chambers for underground coal miners. This training will increase knowledge about how to teach miners to operate, transport, and inspect a refuge chamber; what to expect psychologically and physiologically inside a refuge chamber; and how to decide when to use a refuge chamber. Background During 2006?2007, several disasters occurred at U.S. underground coal mines, resulting in 28 fatalities. These disasters led to new approaches to mine safety and health, as well as new federal regulations. One new technology mandated by federal legislation is the refuge chamber. Refuge chambers are movable shelters that are either made of steel or inflate from a steel skid as a tent. They can potentially save the lives of miners during an underground mine emergency by providing breathable air, food, water, and a safe environment for up to 96 hours. Because the refuge chamber is a new technology, recommendations, information, and training products are greatly needed.

Nov 1, 2009

By Leland H. Johnson, D. O. Kennedy, John Hyvarenen

"SUMMARYA chronological list of accidents at metal and nonmetal mines and quarries (excluding coal mines) in the United States in which five or more lives were lost has been compiled. Many accidents were described in more detail because of their unusual features. Tables have been included to indicate the number of major disasters and fatalities by the principal product mined, by State, and by 10-year intervals prior to 1945. The number of men employed to indicate man-hours exposed is unavailable; therefore, a true picture of disaster data by principal product mined, by State, and by 10-year intervals is not possible. However, the data are presented to indicate the causes of major accidents and bring to the attention of those affiliated with metal and nonmetal mines and quarries the hazards involved and lessons that can be practiced to keep such accidents at a minimum.INTRODUCTIONThe Bureau of Mines was requested to compile a chronological list of accidents at metal and nonmetal mines and quarries (excluding coal mines) in the United States in which five or more lives were lost. Data have been assembled on accidents from all causes in these mines and quarries from the earliest available information (describ¬ing an underground mine fire in Nevada in 1869) to the last reported major accident (a fire at a company-owned bunkhouse in Arizona in 1945).The accounts of the accidents were taken from articles in the technical press and from published and unpublished reports of the Bureau of Mines. Many of the accidents have been selected for more detailed descriptions because of the unique circumstances and to show the variety of dangers involved.Tables are included to indicate the number of major accidents, with resultant fatalities, by the principal metal and nonmetal producing groups, by State, and by 10-year intervals previous to 1945. The interval 1869-1875 does not cover a 10-year span because of incomplete records previous to 1869.ACKNOWLEDGMENTSThe information contained in this report was obtained from the Engineering and Mining Journal from 1874 to 1947, the Mining and Scientific Press from 1908 through 1922, from various published and unpublished reports of the Bureau of Mines and from reports by State departments of mines. Daniel Harrington, retired chief of the Health and Safety Division; E. H. Denny, supervising engineer, District H; R. M. Loucks, mining engineer; and other engineers of the Division contributed much valuable information and assisted materially in the study."

Apr 1, 1949

By James Westfield

Uranium activity has introduced a comparatively new hazard to United States mining. In addition to the hazards common to all mines, uranium mines have a complex health problem of radiation damage. Like many new processes, radiation and nuclear energy can be made to serve man in many useful ways when properly understood and handled; but, like fire, gases, and electricity, their potential dangers must be known and respected, and appropriate precautions must be taken or death may result. Since 1950 the Public Health Service has been conducting basic investigations on exposure to radon and its daughter products and the effect of exposure upon the health of miners in uranium mines of the Western States. The Bureau of Mines assisted in several of these investigations, especially in mines on Indian lands. The studies have shown that a serious health hazard exists from radioactive exposure that might cause lung cancer if continued over a number of years. The Public Health Service report, Control of Radon and Daughters in Uranium Mines and Calculations on Biologic Effects,6/ shows that 55 percent of the uranium mines employing 64 percent of the miners had atmospheric concentrations more than five times the working level now accepted as reasonably safe for industrial exposures. Extensive control measures are necessary to reduce these concentrations to the suggested working level of less than 300 micromicrocuries of total radon daughter products per liter of air.

Jan 1, 1958

By Jos. R. Guiteras

This paper is one of a series published by the Bureau of Mines on mining and milling methods and costs. It describes operations in the Alma district of Colorado in September 1937, supplemented by some additional data collected in July 1938. ACKNOWLEDGMENTS The author wishes to express his appreciation of the friendly cooperation extended him by the mine operators in the district. The greater part of the information was obtained from mine and mill superintendents to whom individual acknowledgment is made in the text.

Jan 1, 1940

By Mark S. Sanders

Based on laboratory tests and preliminary field tests of off-the-shelf steel toed rubber boots, a molded sole design was developed to provide increased traction over conventional calendared sole miners' boots. The pattern provided sharp edges perpendicular to both lateral and fore-aft slip vectors. The sole was designed to reduce mud caking. An instep lace-up capability was added to better secure the foot inside the boot. A five month field evaluation compared the prototype boots to the boots the participants usually wear. Although objective slip and fall data showed no significant advantage for the prototype, subjective evaluations made by the participants indicated increased traction for the prototype boots. Approximately 75 percent preferred the prototype to their own boot. Approximately one-third used the lace-up capability. It was concluded that molded soles provide better traction than calendared soles for the underground mining environment.

Jan 1, 1982

By Andrew Allan

[This report describe the first experiment of the Anthracite Research Laboratory, Bureau of Miners, in attempting to reduce underground-mining costs and conserve anthracite as a natural r-source by introducing now minim methods. The work war, dons in cooperation with one of the large anthracite-producing companies. It applies to productive mining, characterized by comparatively low cost, per ton and high production per man, as differentiated from development mining, which is always necessary before the, productive or retreat phase can begin. The system d scribed in this report is believed to be generally applicable to beds pitching 70° to 90° and, under certain conditions, to beds pitching loss than 70°. After development hate been completed, an openings is made, extending the full width of the 9- to 10-foot coal bad and reaching from the haulageway to the vertical limits of the solid coal. Long drill holes (20 to 50 feet) charged with about one stick of permissible explosive riper foot of length are fused to break the coal. Once broken, the coal is loaded onto a shaker conveyor by gravity and thence into mine: cars. The coal is mined retreating in 15- to 20-foot sections that are broken and loaded onto the conveyor through a specially constructed chute. In the Bureau?s experimental work, the height of sections arse ranged from 35 to 60 fact, depending on the geologic extent of the coal bed.]

Jan 1, 1952

Construction workers may be exposed to hazardous dust containing silica when working in enclosed cabs during construction activities. The National Institute for Occupational Safety and Health (NIOSH) found that equipment operator exposure could be reduced by retrofitting air pressurization and filtration systems on existing cabs, using sweeping compounds on soiled floors, and implementing a dust control program.

Jan 1, 2009

By Jack G. Croeni

The Bureau of Mines developed a method to extrude low-density tungsten powder billets into rods and sheet bar with high-energy-rate forming equipment. Billets were compacted and sintered in an atmosphere of hydrogen to obtain a density of approximately 60 percent. Extrusion was conducted at reduction ratios of 6.25 to 1 and 9 to 1 at 1,800° C to prod e high-density, sound material. Yield strengths obtained were higher than those of material produced by conventional powder-metallurgy techniques, but ductility was lower at high temperatures.

Jan 1, 1966

By Todd M. Ruff

Researchers at the National Institute for Occupational Safety and Health (NIOSH), Spokane Research Laboratory, are investigating technology and methods to monitor the blind areas around large haulage equipment used in surface mines. On average, six fatalities a year can be attributed to equipment colliding with other vehicles or pedestrian workers, or backing over the edge of a dump point. Several off-the-shelf technologies exist for monitoring areas that an equipment operator cannot see from the cab, including radar, video cameras, and radio signal detection systems. NIOSH researchers have tested many of these systems on large dump trucks both at their test facility and at surface mines. This article discusses the technologies available for this application and their effectiveness in detecting objects near an off-highway dump truck. Also, guidance is presented for mine safety personnel who are planning to evaluate collision warning systems or cameras on their haulage equipment. Available Technology Over the past few years, the number and types of systems available for monitoring the blind areas around heavy equipment have increased. Systems marketed for the automotive and recreational vehicle industries have been around for a while. Small video cameras can be found

By David L. Veith

Caustic scrubbing followed by silica flotation with cationic ether primary amine proved effective in upgrading commercial magnetic concentrates to supergrade products containing 2 percent SiO2, or less. Samples representing 41 million long tons per year of commercial magnetic concentrates from the Lake Superior region were tested by the Bureau of Mines. Bench-scale and pilot plant research indicated an estimated potential of 32 million long tons per year of superconcentrates to be available. Two pilot plant investigations yielded superconcentrates containing 1.1 and 1.9 percent SiO2 that were derived from commercial concentrates containing 7.0 and 4.2 percent SiO2, respectively. Corresponding iron recoveries were 90 and 93 percent at reagent costs of just over 33 cents per long ton of superconcentrates produced. Additional sources evaluated on a bench scale resulted in iron recoveries of 72 to 95 percent in products containing 1.7 to 2.0 percent Si02. Although reagent cost ranged up to 60 cents per long ton of superconcentrate, it is probable that these costs would be reduced in plant applications where benefits are derived from material and reagent recycle.

Jan 1, 1974

By J. H. Holden, G. R. Strimbeck, L. F. Willmott, W. R. Huff

A pilot - scale fluidized feeder was developed for continuously feeding up to 1 ton of pulverized coal per hour to a pressure gasifier . Fluidization in the 3 - foot - diameter by 34-1 / 2 - foot - high feeder is effected by two streams of inert gas , a technique called zone fluidization . A stream of inert gas through a drilled plate in the base of a central column near the bottom of the feeder fluidizes the coal . Another stream through a drilled plate in the annulus between the central column and feeder wall provides a source of semifluidized coal for the central column . Fluidized coal from the central column discharges through an extraction funnel and discharge line . Zone fluidization provided good fluidization with moderate requirement for fluidizing gas . Instruments were developed for metering and recording the flow rate of fluidized coal . A system was developed for storing , and weighing pulverized coal , and then delivering it in fluidized form at about 1 to 8 tons per hour .

Jan 1, 1964

By Doris M. Hyde

The petroleum sector continued to dominate Ecuador's economic activity in 1978, accounting for nearly 10% of the gross domestic product (GDP) and 42% of total export earnings. In 1978, a more flexible petroleum export price was adopted which permitted an expansion of foreign market opportunities. During 1979, Ecuador took advantage of disruptions in the world petroleum supply and renegotiated existing export contracts to accomodate the rapidly escalating world market price. Petroleum sales on the spot market were maximized, and prices reached unprecedented levels. By taking royalty payments in-kind, Ecuador increased its volume of petroleum available for term and spot sales. Although the volume remained about the same as in 1978, the total value of 1979 petroleum exports increased to about $920 million, reflecting a 76% increase over the $523 million received for 1978 crude oil exports. Concerned about its steadily decreasing petroleum reserves (recently estimated at about 1.1 billion barrels), rapidly increasing and heavily subsidized domestic consumption, and the prospect of having to import substantial amounts of petroleum by 1983, Ecuador announced plane which it anticipates will double reserves within the next 5 years. The Government plans to spend $1 billion over the 5-year period. Plans include drilling 325 exploration and development wells and establishment of a secondary recovery program for the Sachs and shushufindi fields. Some exploration wells are expected to reach a depth of 17,000 feet. It is thought that substantial reserves exist in the southeast Amazon region. Late in 1979, it was announced that some 10 million hectares will be available for exploration tenders-probably in blocks of about 200,000 hectares each-in the Amazon jungle of the Orients and in the coastal and offshore regions. The Government planned to commission a private, independent analysis of Ecuador's petroleum reserves that would also include recommendations on efficient production levels.

Jan 1, 1981

By L. M. Demers, R. E. Edelson, M. P. Rose, D. T. Superdock

The pulmonary alveolar macrophage is a major defensive cell which counteracts the invasive properties of bacteria and particles when these substances invade the pulmonary environment. Pulmonary exposure to coal dust particles is believed to activate these macrophages to release a host of d1emical mediators which can neutralize or contribute to the harmful effects of these dust particles. Our efforts have been concerned with assessing a specific family of mediator substances produced by the alveolar macrophage from arachidonic acid when these cells are in contact with activating substances such as coal dust. Metabolites of arachidonic acid produce a vast array of effects which can impact significantly on pulmonary function both with normal pulmonary events and with pathologic processes of the lung. Our studies demonstrate that isolated alveolar macrophages obtained from rats or guinea pigs cultured in vitro release appreciable amounts of the cyclooxygenase products prostaglandin E2 and thromboxane A2 and release significant amounts of the lipoxygenase products .5-HETE and LTB4. In the presence of l x 104 -1x10·7 g/ml of a coal dust suspension, alveolar macrophages from the rats and guinea pigs alters their pattern of arachidonic acid metabolite release. In the rat, exposure of alveolar macrophages in vitro to the higher concentrations of coal dust causes a significant reduction in PGE2, TXB2 and LTB4 in a 4 hour time course study. In contrast, macrophages from the guinea pig in response to coal dust had little change in TXB2 release, only a slight inhibition in PGE2 production and an initial stimulation in LTB.t release over the 4 hour time course. Cells from guinea pigs released considerably more TXB2 than the rat under these conditions while rat cells formed considerably more LTB4 than guinea pig alveolar macrophages. These findings support the following conclusions.

Mar 1, 1989

By J. A. Eisele

The Bureau of Mines has reviewed the literature related to the recovery of A1203 (alumina) from coal ash. A small amount of unpublished data is also reported. Of the processes studied, the alkaline-sinter process is the most promising from a technical standpoint. However, owing to the high cost of processing coal ash, the dispersed location of powerplants, and the domestic availability of higher grade alternate materials, coal ash does not rank as a primary source material for replacing imported bauxite.

Jan 1, 1979

By P. T. Brooks

A process for extracting 69 percent of the vanadium from weathered Nevada dolomitic shale containing about 1 percent V205 was developed on a laboratory scale by the Bureau of Mines. The process essentially is comprised of salt roasting, leaching with dilute sulfuric acid, solvent extraction, and precipitation of vanadium as ammonium metavanadate. Carbonaceous unweathered shale was less amenable to treatment. A preliminary cost estimate for mining and processing 1,500 tons per day of weathered shale indicated a production cost of about 1 dollar per lb of V205. Considering recent sales at nearly $1. 75 per lb of contained V205, larger scale testing to obtain more definitive process design and evaluation data may be warranted.

Jan 1, 1974

By Gerald W. Elger

This report describes development of the fusion-leach crystallization precipitation process for producing a hafnium content feed material for hafnium-zirconium separation plants. Mixtures of zircon, potassium silicofluoride, and potassium carbonate (or potassium chloride) were fused to prepare soluble potassium zirconium hexafluoride-potassium hafnium hexafluoride salts. High extraction of these salts was obtained by countercurrent leaching the fused material in dilute hydrofluoric acid. About one-half of the hafnium was recovered in hafnium-enriched mother liquor by cooling clarified lead: liquor to crystallize most of the zirconium salt. Additional hafnium was recovered from the primary crystals in a multiple dissolution-recrystallization step. Hafnium-enriched oxides having a hafnium-zirconium ratio of more than three times that of zircon were precipitated from the combined mother liquors. The hafnium and zirconium recoveries in the precipitate were 83 and 24 percent, respectively. About 71 percent of the zirconium and the remainder of the hafnium were recovered in potassium zirconium hexafluoride crystals of low-hafnium content.

Jan 1, 1966