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By J. J. Forbes

The activities of the Bureau of Mines include the development and testing of self-contained oxygen breathing apparatus and other devices for respiratory protection, the development and tasting of devices for detecting dangerous or noxious mine atmospheres, and the training of men in the mineral industries in the use and care of this equipment to enable them to render effective service in mine rescue and recovery operations following mine fires and explosions, or under other conditions where irrespirable gases may be found in mines or mining plants. The first use of self-contained oxygen breathing apparatus for com- bating mine fires and explosions in the United States dates back about 30 years. Previous to that time, exploration for any distance ahead of fresh air was virtually impossible without great risk to life; moreover, the men called upon to render service at mine disasters were not well-versed in the properties and physiological effects of gases likely to be encountered. It was also impossible to work ahead of fresh air to restore ventilation, and if many stoppings were blown out by an explosion, air had to be introduced into whole areas or sections at once without knowledge of the conditions ahead; moving an explosive mixture of methane and air over live fire had to

Jan 1, 1938

By Roy H. Grau

Increased awareness of a healthy work environment is common to all industries and the stone industry is no exception. The presence of operating diesel equipment, welding, stone production blasting, and silica dust in a working environment all contribute to air quality issues in underground stone mines. Particularly recognized is the exposure of workers to diesel particulate matter (DPM). Recent regulations call for a DPM standard of 160TC ug/m3 (TC = Total Carbon). The National Institute for Occupational Safety and Health (NIOSH) has conducted research to improve the ventilation of these mines and consequently reduce the exposure of workers to harmful airborne contaminants. The results have shown that the ventilation of underground stone mines can be significantly enhanced using improved ventilation controls and techniques. Large-opening stone mines present specialized ventilation challenges because their entries are much larger than in other types of mines. Most stone mines have entries about 40 feet wide and up to 30 feet high, with bench areas that may extend even higher. These large entries present the positive opportunity to move large air quantities at relatively low mine fan pressures resulting in lower fan horsepower and reduced operating costs. However, the difficulty in ventilating large-opening mines is that even with large air volumes, the air velocity is often less than 100 feet/minute. Higher ventilation velocities more quickly dilute and remove contaminants from the face areas. Higher ventilation airflow velocities can be achieved by effective ventilation planning and proper choice of ventilation fans.

Jan 1, 2009

By Nirander M. Safaya

Revegetation success on surface mined lands is dependent upon the nature of the plant growth media. Soil physical and chemical properties dictate the needs for specific reclamation and subsequent management practices. Field experiments were conducted at six coal mine sites in Oliver and Mercer Counties, North Dakota to determine the subsequent effects of a single application of selected amendments on spoil and topsoils over the five year period, 1974-1978. Considerable variations in the physical and chemical properties were found in mine spoils from site to site. The texture of spoils ranged from sandy clay loamy at North Beulah I to loamy at Glenharold, and from sandy loamy at North Beulah 3 and South Beulah sites to loamy sands at the Center site. The pH of the sites ranged from 6.5 at South Beulah to 8.2 at North Beulah 3. In many cases, the pH values of mine spoils were not significantly different from the topsoils. The electrical conductivity (ECe) did not exceed 6 mmhos cm-1 at the test sites even though in other studies much higher values were recorded in the same vicinity. The spoils from Glenharold and North Beulah test sites can be classed as moderately saline, and those from Center and South Beulah as non-saline. The sodium adsorption ratios (SAR) varied from less than 1 to 32, with highest values in the spoils of North Beulah 3 followed by Glenharold; all other sites were nonsodic. Lowest SAR values (less than 1) were found in the topsoiled sites at South Beulah and Center. Spoils of North Beulah 3 test site were highly calcareous, followed by North Beulah 2 and Glenharold. Center mine spoils which were the least calcareous of the test sites, showed the calcium carbonate equivalent three times higher than that of the topsoil. The average calcium concentrations in the spoils of North Beulah 3 and South Beulah test sites were -13 and 14 me 100g -l while at North Beulah 2 and Glenharold test sites 25 and 22 me 100-1-1 were recorded, respectively. The overall magnesium concentrations ranged from an average of 4 to 16 me 100g 1. Sodium concentrations in all sites never exceeded 10 me 100g-1. Phosphorus concentrations on the average at North Beulah 1, North Beulah 2, and Center were 10.2, 4.6, and 22.2 µg g -1 spoil, respectively. Concentrations of potassium ranged from 200 ppm at South Beulah site to more than 375 pp in at the Glenharold site. High concentrations of sulfates (239-2778 µg g-1) seem to contribute to the salinity in these spoils. Chloride concentrations of spoils were low and never exceeded 40 µg g-1 spoil. Based on established critical levels of deficiency for micronutrients in agricultural soils, it seems that none of these were deficient. However, controlled environment experiments did reveal increased plant growth responses when some micronutrients were added to the mine spoils. Treatment effects were highly site specific depending on the nature of the soil/spoil characteristics and, of course, the properties of the various treatments. While slack coal amendment to the spoils at North Beulah 2 site affected significant increases in a large number of variables (both major and trace elements), amendment of the topsoils at the South Beulah test site with leonardite resulted in significant decreases in a number of variables, particularly trace elements. Spoils at Glenharold and North Beulah 3 demonstrated the fewest significant changes due to amendments. Calcium, magnesium, strontium, organic matter and nitrogen were consistently increased from site to site with the addition of lignitic materials. Other spoil/topsoil physical and chemical properties (30 variables) as affected by amendments and time are discussed.

Jan 1, 1982

This publication contains 10 papers presented at a symposium on ATRS systems in Charleston, WV, on June 23, 1983. Included are papers by MSHA Technical Support (Roof Control), West Virginia Institute of Technology, the Bureau of Mines, and seven roof bolter manufacturers and/or designers of ATRS systems. These papers summarize the most recent developments in ATRS technology and can serve as a guide to potential designers, developers, and users of ATRS systems.

Jan 1, 1985

By James J. Snodgrass

A new technique was used to obtain detailed sonic logging data in drill holes above the water table at a coal mine site in northeastern New Mexico. The equipment was developed under contract to the Bureau of Mines and the U.S. Department of Energy to indirectly evaluate the in situ structural properties of coal and overburden. The system comprises a hydraulically operated, wall-clamping downhole probe compatible with standard four-conductor logging cable, and a surface control module. Resolution of layering is 0.6 meter (2.0 ft), and a redundancy of data from separate receivers provides accurate timing measurements. Preliminary results in the settled overburden of an excavated long-wall panel indicated a low average velocity zone, extending approximately 18 meters (60 ft) into the immediate roof of the coal seam. Subsequent measurements improved the field and recording procedures to produce high quality waveforms from which both P and S arrivals may be visually interpreted. Over a representative section of interbedded sandstone, siltstone, shale, and coal, Vp and Vs varied considerably even within lithologic units. Compressional wave velocity in the coal seam, Vp = 1,740 m/sec (5,700 ft/sec), was in the range of variability of published data.

Jan 1, 1982

By Michael J. Friedel

The permeability and flow capacity in unsaturated media are investigated by the U.S. Bureau of Mines for application to in situ copper leach mining. Moisture retention properties are derived and combined with scanning electron microprobe data to characterize the mineralogy, texture, pore size, distribution, and permeability of the host rock. Finite-element modeling is used to derive a saturated permeability, ambient degree of saturation, and assess various injection-recovery schemes. Recommended design modifications for optimization of solution distribution and maximum recovery from the rock matrix requires either (1) the injection pressures on the order of 1,500 psi and recovery wells operating in a suction mode, or (2) performing permeability enhancement, through in situ rubbling. Injection pressures can be reduced to 500 psi with improved recovery and containment of solutions.

Jan 1, 2010

By Scott Turner

To be successful , human exertion employed for the creation of value requires power and heat ; the ability to produce concentrated power in great quantities has resulted in the relatively recent industrial development that is so profoundly affecting the world . In our commercial history , we have advanced through several stages in the selection of the most suitable fuels , continuously striving to increase the flexibility and range of energy- transmission . The easy distribution of light , power and heat is the leading factor in the decentralization of industry which promises to correct some of the serious evils that have followed in the footsteps of our commercial development . The distribution of fuel in quantity in so convenient a form and with such an attractive reliability- factor as can be had with gas , meets the modern conception of efficient service . Natural gas has been used in this country for more than a century, but recently it has attained a prominence far in excess of anything known in its earlier history. We may consider that we are now getting into our real stride in the utilization of our natural- gas resources . : In a country like the United States , wherein we are accustomed to mammoth achievements , we may be inclined to accept casually the noteworthy technical and economic advances which have resulted in the expansion of natural- gas distribution . About three years ago , the transmission of natural gas a distance of more than 250 miles from its source was first accomplished , and this was really a noteworthy engineering feat . Today , this useful commodity is being transported twice that distance , and lines are being laid which will carry gas more than 900 miles from the points of occurrence . Let us not take such outstanding improvements too much as a matter of course ; the industry should be congratulated on its long steps forward .

Oct 1, 1930

By S. M. Dar

The U.S. Bureau of Mines constructed a full-scale model of a 15-ft-wide coal mine entry to use in combination with finite-element analyses to investigate roof support systems and various types of roof bolts. The objective was to enhance understanding of the fundamental mechanics of the interaction between rock and supports and the relative integrity of bolted mine roof as a function of roof bolt type, length, spacing, and tension, and the basic characteristics of the roof strata. The laboratory test results, when correlated with computer simulations using fmite-element analysis and underground verification tests, should provide a basis for desigillng safer, more cost-effective roof control systems and help to establish guidelines for employing fully grouted resin and mechanically anchored bolting systems. The background for this research, the research approach, the methods and equipment employed, and the results are described in this report.

Jan 1, 1989

By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature of ash, the free-swelling index, and the Hardgrove grindability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions~ issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor and, if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1956

By W. P. Huleatt, Jr. Traver, Jr. Hazen

"Vanadium and uranium occur widely distributed throughout western Colorado and eastern Utah, and a few deposits have been found in northeastern Arizona and northwestern. New Mexico. The area in which it occurs includes approximately 10,000 square miles and is generally referred to as the vanadium region of Colorado and Utah.The majority of the deposits consist of replacement bodies and impregnations of rare minerals in the lower Morrison formation of Jurassic age. The ore bodies are flat, with irregular margins, and most of them conform to the stratification.The ""rim rock"" topography of the region includes many steep-walled canyons and plateaus, which afford an abundance of outcrops that have been responsible for most of the discoveries of mineralized areas. Delimitation of ore bodies within the areas is accomplished most effectively by core drilling from the surface.The deposits were discovered in 1899 and from 1911 to 1923 wore worked extensively for radioactive uranium ores, principally carnotite.The discovery and marketing of the richer and more cheaply mined pitch-blende ores of the Belgian Congo left the Colorado-Utah deposits without economic importance as sources of radium and uranium, and the region became inactive in 1923. After a period of comparative inactivity, the rising demand of the alloy-steel industry for vanadium renewed interest in the deposits, which were known to contain that metal. By 1938, vanadium production in the area had achieved respectable proportions, and new impetus was given to it by the United States’ entry into World War II in December 1941. In 1942, new treatment plants for vanadium ores were completed in Monticello, Utah, and Durango, Colo. In order to meet the requirements of these and other plants in the region, it became necessary to open new vanadium mines and prepare old onus for production.In an effort to stimulate mining, the Metals Reserve Company initiated a stock-piling program and appointed the united states Vanadium Corporation, to act as its purchasing agent.The extra production was expected to come largely from small, independent operators whose limited funds did not permit them to maintain development and exploratory programs. Study of conditions made it apparent that extensive exploration would be necessary to sustain production, and accordingly the Bureau of Mines initiated an exploratory drilling project on a cooperative basis with the Geological Survey. The principal objects of the work were to enlarge the known ore reserves of the area and, if possible, discover new ones. The results have been gratifying in both respects."

Sep 1, 1946

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 SrF2-Y2O3 system for which liquidus and solidus temperatures and solid solubilities were determined. The information is presented as the phase diagram. The phase diagram was constructed from information obtained by ceramogra¬phy, X-ray diffraction, thermal analysis, and electron probe microanalysis of small specimens encapsulated in platinum-20 percent rhodium or molybdenum ampoules. The data indicate a simple eutectic system with limited terminal solid solubilities. The eutectic temperature is 1,457°±5° C, and the eutectic composition is 4±1 mole-pct Y203. Strontium fluoride containing up to 2 wt-pct 0 2 was studied to determine the effects of oxygen contamination. Oxygen levels in excess of 0.2 wt-pct resulted in eutectic formation between SrF2 and SrO. The eutectic composition is between 0.2 and 0.7 wt-pct 02, and the eutectic temperature is 1,447°±5° C. No intermediate oxyfluoride phases were detected.

Jan 1, 1974

By Andrew F. Conn

This report summarizes the results from the first year of an anticipated multiphase program to develop improved coal mining equipment which utilize the CAVIJET? cavitating water jet method. This laboratory parametric study demonstrated the advantages of cavitating jets over non­cavitating jets in cutting coal, by producing comparable slot depths at one-fifth of the operating pressure, at better than one-half of the spe­cific energy. These results suggest that CAVIJET-augmented mining devices can be developed with compact, low-pressure pumps. Thus, CAVIJET should be capable of operating with safer, lighter support equipment, while providing all of the advantages (reduction of dust and sparks, reduced damage to cutters) of conventional hydraulic mining methods.

Jan 1, 1976

By W. F. Faragher, W. A. HORNE

Previous interrogation of German scientific personnel by numerous in- vestigators and the examination of evacuated documents indicated that fur- ther information was desirable on a miscellany of products and processes of interest to the Petroleum Industry. Accordingly, Dr. Pier and a large number of other men of the I.G. Farbenindustrie, A.G. plant at Ludwigshafen/ Oppau were further interrogated in July-1945. The information contained in this report supplements that previously reported in the CIOS report of 16 August, 1945: "Report on Investigations by Fuels and Lubricants Teams at the I. G. Farbenindustrie A.G. works at Ludwigshafen and Oppau", edited by Lt. Col. R. Holroyd, (FP).

Aug 1, 1943

By Mohan K. Wali

Soil and vegetation development were studied on abandoned mine sites near Velva in Ward County, North Dakota. The sites studied were 1, 7, 17, 30 and 45 years old since abandonment; unmined sites were also studied to provide measures of comparison. Species diversity was the highest at unmined sites (114) and lowest at the I year old site (26); sites 7, 17,30 and 45 years old had 37, 52, 43 and 68 species, respectively. Stand ordination revealed that site ages were the most important in influencing species diversity and composition. Stand-environ-mental complex ordinations encompassing 53 variables showed topographic variables to be the most important followed by site ages. Rates of nutrient accumulations were as follows: organic carbon 13.1 g m-2 yr-1; nitrogen 2.5 g m-2 yr-1; phosphorus 0.01 g m-2 yr-1; potassium 0.49 g m-2 yr-1. Carbon-nitrogen ratios showed the widest range for 1 year old sites (5-40) but 70 percent of the 45 year old sites showed values below 15 which were com-parable to the unmined mixed grass prairie sites. Species distributional diagrams are provided to show their habitat preferences which may be helpful in formulating species prescriptions for revegetation.

Jan 1, 1982

By Martin H. Stanczyk

The direct dissolution of a typical zinc sulfide flotation concentrate by elevated temperature and pressure leaching was investigated. The concentrate assayed about 55 percent Zn, 32 percent S, 6 percent Fe, and 1 percent Pb and contained minor quantities of copper and precious metals. The influence of various factors on the dissolution of the zinc in acidic and ammoniacal pulps when using oxygen as the oxidant was determined. The tests revealed that the sphalerite was difficult to oxidize. Complete dissolution of the mineral required vigorous and intimate nixing of the gaseous, liquid, and sold phases. The addition of pyrite or sulfuric acid to water slurries of the concentrate was required to obtain a high zinc extraction when leaching under acidic conditions. The quantity of pyrite and acid used was about 0.125 and 0.25 pound, respectively, per pound of zinc sulfide contained in the leach charge. In tests with acid, about 96 percent of the zinc was extracted from the concentrate in 1 hour at 200° C. when the oxygen partial pressure was 75 pounds per square inch gage or higher. Leaching with a continuous flow of air as the oxidant gave results that were almost as good as those obtained when oxygen was used, In tests with air fed through the autoclave at 320 liters per hour, 95 percent of the zinc was dissolved in 1 hour, Acid leach solutions assaying approximately 58 grams Zn per liter and containing Fe, Ni, Cr, and Cu impurities were produced in the better tests. The leached residue consisted essentially of red iron oxide together with substantially all of the lead and precious metals.

Jan 1, 1961

Provide a more efficient method of cooling hot working environments in deep mines than is possible with single stage spray coolers or cooling coil heat exchangers. Approach Pass warm mine air through several stages of horizontally oriented water sprays fed by the chilled water supply of the mine. How It Works This concept extends the capabilities and potential applications of the coolers described in Technology News nos. 71 and 93. In this multi-stage design, hot ventilation air is cooled while passing through horizontal water sprays. Air enters the cooler through a diffuser section which slows the airflow and distributes it evenly across the cooler with a minimum of pressure drop. This ensures uniform exposure of the warm air to the cool water and consequent high thermal efficiencies. In the three-stage cooler shown, cold mine service water is sprayed from the first water stage manifold on the downwind end of the cooler. Slightly warmed water from this spray stage is collected in a sump, pumped and then resprayed through the second stage manifold. The process is repeated again for the third-stage. An overall counterflow heat exchange effect is thus achieved by exposing the hottest incoming air to the warmer, third-stage water spray first and to the coldest, first-stage water spray last. Wave plate eliminators can be employed between stages of water sprays to increase thermal efficiency or at the outlet to minimize the water discharged into the mine ventilation air. Cooled air can then be ducted to hot work spaces or simply released

Jan 1, 1985

By Charles W. Huggins

To determine the nahcolite and dawsonite content in oil shales, the Bureau of Mines compared X-ray diffraction, infrared spectroscopy, thermal methods, and a previously published method by Smith and Young based on the selective solubility of sodium compounds. The Smith and Young method and a new method based on the weight of carbon dioxide produced by thermal decomposition are recommended for determining nahcolite. X-ray diffraction and the Smith and Young method are recommended for determining dawsonite. X-ray diffraction, infrared spectroscopy, and differential thermal analysis were useful for identifying other minerals in the samples.

Jan 1, 1973

By Maria I. De Rosa

The U. S. Bureau of Mines performed experiments to determine if the primary gas toxicities evolved during the early (~300° C) and later (~400° C) combustion stages of chlorinated polyester-reinforced mine ventilation ducts could be predicted by a smoke particle characteristic, for the development of a test parameter. The experiments were conducted in an approximately 20-L furnace, at 14-min durations at set furnace temperatures of 2500 and 1,000° C, with an airflow through the furnace of 10 L/min. The variables studied, as a function of time, were the hydrogen chloride (HCI), carbon monoxide (CO), carbon dioxide (C02), and oxygen (02) concentrations, furnace temperatures, the sample mass weight loss, the average smoke particle diameter (dg and average number and concentration (no), and the product of the average smoke particle diameter and concentration (dgno). Results show that the inverse of the smoke particle diameter-concentration product [(l/dgn0)], correlates directly and significantly with the primary gas toxicities evolved during both early (HCI) and later (CO) stages of combustion.

Jan 1, 1989

By Lester J. Crow

A preliminary survey was performed to investigate the impregnation of relatively weak, porous volcanic tuff and a relatively strong, dense sandstone with five different monomers. Increases in compressive strengths by factors of 2 to 5, and elastic moduli by factors of 2 to 3.5, are reported for natural rocks (tuff., sandstone, dacite), which were impregnated with five monomers (methyl methacrylate; chlorostyrene; 40 percent TMPTMA-60 percent styrene; 40 percent TMPTMA-60 percent chlorostyrene; 60 percent polyester-40 percent styrene); polymerization took place after monomers were forced into the rock. Impregnation was performed (1) by pressurizing rock specimens from one end, or (2) by a vacuum-soak operation. Polymerization was accomplished by either radiation or chemical initiation techniques. Strength improvement is dependent on (1) the type of monomer used, (2) the amount of polymer incorporated into the rock, and (3) the degree of water saturation of the rock. Water saturation strongly reduced the effectiveness of the method for the polymer systems tested. The more viscous monomers (for example, 60 percent polyester-40 percent styrene) were more effective in displacing the water from the rock, and compressive strengths of wet rock were doubled with these systems. Water saturations ranging from 25 to 100 percent of maximum saturation gave essentially identical results. Further tests on other types of mine rock; including shale and coal, are planned. Water-compatible polymer systems should be developed, or present systems should be suitably modified. For application to tunnel stabilization, design studies evaluating the improvement in rock strength and its influence on the support system are also recommended.

Jan 1, 1971

By H. A. Doerner

"Statistics show3 that in 1927 the United States consumed 60 per cent of the world's production of chromite and produced none. The uses of chromium are rapidly expanding, and a dependable supply is essential to our industries. Since the political and commercial control of our supply of chromite is now in foreign hands it is prudent to determine how this nation can best prepare to supply its need for chromium if the imports were cut off or restricted and whether it is now possible and desirable to stimulate production of chromium from domestic deposits. We have only small amounts of chrome ore of high enough grade to meet present trade requirements. Therefore the Bureau of Mines is making a study of methods for beneficiating our low-grade ores.Chromite (Cr203.Fe0), is the only commercial source of chromium. For refractories, a minimum of 40 per cent Cr203 and a low silica content (5 to 8 per cent) is usually specified. In most instances bricks or lumps having a physical structure that will not crack when heated are required. The only way an inferior ore could be adapted to this use world be to concentrate it and develop a satisfactory binder to make bricks out of the concentrates.For making ferrochrome the requirements are a minimum of 45 per cent Cr203 and an iron content not exceeding one-third of the chromic oxide. On some low-grade ores gravity concentration will give a product meeting these requirements; other ores yield concentrates containing too much iron or other impurities to be saleable."

Jun 1, 1930