Search Documents

By Christopher J. Bise

The potential of the coal reserves in the western United States for meeting future energy needs has been recognized for quite some time. However, two of the major constraints which have tended to limit the development of these reserves which can only be deep-mined are the great thicknesses of the coal seams encountered and their high pitch. Although new mining methods may need to be developed to recover these reserves, at least in the short- term the industry has to incorporate presently available equipment which were not originally designed for thick-seam mining. The purpose of this paper is to present an analysis of the various equipment that are in use today and their possible application to thick-seam mining. The paper also addresses the various ground control and safety considerations that are unique to thick-seam extraction.

Jan 1, 1981

By H. C. Miller

Several agencies of the Federal Government are engaged in research and fact finding relative to petroleum and natural gas, and others are concerned with carrying out the provisions of specific laws that affect these natural resources in their broad aspects. The Bureau of Mines, however, is the only Federal agency designated by law to engage in research in oil and natures gas production, chemistry, refining, and

Jan 1, 1941

By E. P. Youngman

This paper is one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the mining laws of British Honduras has been prepared from the best available information in Washington and is released subject to amplification or correction, if necessary, by United States foreign-service officers. INTRODUCTION The mining law governing all mineral substances other than oil is ordinance No. 7 of 1927 (Minerals Ordinance, 1927), passed by the Legislative Council on March 25, 1927. The accompanying regulations, No. 3 of 1932 (General Minerals Regulations, 1932), made under the authority of section 66 of the minerals ordinance, were made by the Governor in Council on December 23, 1931.

Jan 1, 1934

By E. Robert Ruhlman

["Phosphate rock" is a broad term applied to natural deposits of minerals valued chiefly for their phosphorus content. More specifically, phosphate rock may be defined as a natural rock containing one or more phosphate minerals, usually calcium phosphate, of sufficient purity and in sufficient quantity to permit its use directly, or after beneficiation, in the manufacture of phosphorus-bearing products. The grade or quality of phosphate rock is expressed either in terms of its phosphorus oxide (P20S) content or the equivalent in tricalcium phosphate (Ca3(P04)2). The trade name for tricalcium phosphate is bone phosphate of lime (B. P. L.).]

Jan 1, 1958

By Robert L. Zook

Coal refuse slurry impoundments are dams constructed of coarse coal refuse to impound fine refuse (slurry) and water (25-30% solids). Both products are waste from coal preparation plants. A number of these structures in West Virginia, Pennsylvania and Kentucky were investigated to determine embankment stability. During the investigation a variety of embankment designs were encountered. The investigation determined the soil and geological characteristics of the embankments and the sites. This was accomplished by a test drilling and monitor installation (observation wells and piezometers) program, geologic study, and large scale mapping which allowed sub-surface profiles of the embankments to be constructed. The laboratory testing program concentrated on textural classification of the coal refuse, permeability and determining strength parameters to be utilized in the stability analyses. For the stability analyses, the Modified Fellinius Slip Circle, Simplified Bishop Slip Circle and Analysis for Translational Failure -were utilized. In all stability analyses hydrostatic pressure and earthquake were considered. This investigation indicated that 62% of the embankments analyzed are in a stable condition. The coal seam mined, the type of roof rock, and the gradation of the refuse influence the degree of compaction obtainable and the permeability of refuse. The shear strength of coal refuse appears to be controlled by its composition, moisture content, degree of compaction, amount and grain size of fines present. This investigation demonstrated these em¬bankments should not be treated as pure state-of-the-art dams; consideration must be given to the particular properties of coal refuse and the total refuse disposal system. Refuse dim slurry impoundments generally lack the site se- lection phase that is standard practice with siting most other types of dams.

Jan 1, 1974

By Sarkis G. Ampian

Crystalline silica (quartz, cristobalite, and tridyrnite) is regulated by the Mine Safety and Health Administration (MSHA) and Occupational Safety and Health Administration (OSHA) because of its potential for causing debilitating but nonmalignant lung diseases. In 1987, the International Agency for Research Against Cancer (IARC) conducted a review of the health literature and concluded that crystalline silica was a probable human carcinogen. As a result of this finding, OSHA was required to regulate crystalline silica under its Hazard Communication Standard (HCS). The standard requires that all materials handled by OSHA-regulated facilities be labeled according to the requirements of RCS and that workers receive proper training on the handling of the material if the crystalline silica content equals or exceeds 0.1 weight percent (0.1 %). MSHA currently is considering enacting its own RCS. This will be similar to OSHA's RCS. If the standard is enacted, most mineral producers will have to determine the respirable monitor filter and bulk crystalline silica contents of their ores and products so that workers and/or customers will know whether they are in compliance with the 0.1% HCS and/or the OSHA permissible exposure level (PEL) of 50 µg for an 8-hour workday for respirable crystalline silica as determined from monitor samples. Two major concerns with the RCS are the widespread occurrence of crystalline silica in nature and the suitability of current technology for routinely determining crystalline silica concentrations at the 0.1 % RCS level. Most ores are extracted from silica-bearing deposits and it is a common constituent of rocks and soils. OSHA's RCS will have the greatest impact on the producers of crushed stone, diatomite, dimension stone, gravel, industrial sand, perlite, pumice, pyrophyllite, sand, and talc because these materials frequently are shipped directly from the mill to the customer. MSHA's RCS would affect nearly all mineral producers. Those producers that have crystalline silica present in concentrations near the 0.1 % cutoff point will have the most difficulty with the analysis. Crystalline silica can be quantified at the 0.1 % level by X-ray diffractometry in simple systems containing one, two, and possibly three minerals if (1) none of the accessory minerals has X-ray diffraction reflections that coincide or overlap with those of crystalline silica and (2) the standard has a particle size distribution and crystallinity similar to those of the sample. In some instances, it may not be possible to determine the crystalline silica content of a sample with any degree of certainty using the recommended regulatory protocol. In all cases, it is recommended that a qualified mineralogist identify the minerals in a sample prior to any regulatory analysis. Additionally, the uncertainty as to whether some silica polymorphs should be classified as crystalline or noncrystalline and the suitability of metastable high-temperature standards, such as cristobalite and tridyrnite, for regulatory analysis at ambient temperatures should be addressed further. This overview is written both to highlight these problems and to serve as a guide for analysts, regulators, and industry personnel who are involved in the crystalline silica issue. It also covers some of the difficulties and/or shortcomings in quantifying crystalline silica, such as the ubiquitous mineral quartz, in the workplace.

Jan 1, 1992

By E. E. N. Smith

"Uranium exploration by Eldorado prospectors north of Lake Athabasca began in late 1944 and resulted in initial discoveries in 1946 in the Beaverlodge region with mill production starting in early 1953. The operation was closed in mid-1982 having produced 21,457,947 kilograms U30 8 from the Eldorado FayVerna mine, Eldorado satellite operations and from other district producers on a custom basis.The Fay- Verna mine consists of pitchblende-brannerite orebodies spatially associated with both sides of a regional eastwest structure, the St. Louis Fault. The orebodies in the footwall (Fay) are elongate deposits of two types raking steeply to the southwest along the 50 degree south dip of the fault.One type consists of networks of fractures and veins filled with pitchblende, calcite and quartz in chlorite, epidote-altered mylonitized mica schists and amphibolites of the Middle Aphebian Tazin Group. The other type is comprised of fragments of mylonitized metasomatic quartz-feldspar granite of Late Middle Aphebian age cemented with a matrix of pitchblende, brannerite, calcite and some quartz. The vein networks lie en echelon in the footwall of the breccia ore bodies which, in part, are capped by the mud gouge of the St. Louis Fault; in other places, the breccia orebodies are overlain by basal conglomerates, grits and arkoses of the late Aphebian Martin Formation which itself immediately underlies the plane of the fault.Orebodies in the hanging wall (Verna) are a series of irregular, tabular deposits lying within a tightly overturned syncline of Tazin mica schists, amphibolites and siliceous mylonites. They consist of pitchblende, calcite-filled fractures grouped into zones and deposits displaying stratabound habits within individual rock types.Also described are several Eldorado satellite properties which were significant producers of uranium and which display complementary geology to that in the Fay- Verna mine.In general, uranium deposits in the Eldorado Beaverlodge region are closely related to minor structures associated with major faults. Uranium appears to be best concentrated where the rocks are well mylonitized and brecciated. Pitchblende fills networks of veins and fractures in metasediments and metavolcanics as well as matrix material cementing brecciated, mylonitized granite. All deposits in the Beaverlodge region lie in close proximity to the unconformity between the Martin Formation and the underlying Tazin Group."

Jan 1, 1986

By Constance F. Acton

Based on laboratory structure analyses, a pilot plant investigation was undertaken to evaluate a Michigan conglomerate native copper ore. Comminution or sized feed was accomplished using wet, closed circuit autogenous grinding with and without crushing of the recirculating load. Coarse metallics were concentrated in two stages of jigging with fine metallic copper being recovered in a three-stage xanthate flotation circuit. With a feed averaging 2.09 % Cu, copper recovery ranged from 86-93 % Cu with an average grade of 55.5 % Ca. An evaluation of the processing flowsheet is made in terms of pertinent independent, dependent, and external variables and design factors. Rate equations are developed to describe the grinding and flotation circuits separately as well as the entire circuit as a whole. Performance equations for the overall operation and for the unit operation of autogenous grinding alone are developed in terms of suitable capacity, efficiency and energy consumption terms. Thus, the effects of feed rate, recirculating load and flowsheet design can be rationally evaluated. Energy consumption for various conditions in the pilot plant is compared to the laboratory value. Additionally, size and scale up factors are discussed. Recommendations are made for further studies to be undertaken to further quantify the ore characteristics and the nature of the autogenous grinding operation. However, the feasibilty of beneficiation of this type of native copper ore by means of an autogenous grinding/jigging/flotation circuit is clearly established.

Jan 1, 1977

By Zsuzsanna Zborovszky

Study of the energy transfer from an inductive circuit to the discharge under the conditions of the minimum discharge voltage being smaller than the source voltage. Analysis of the effect of the electrode separation speed on the duration and maximum power amplitude of the discharge. Recommendation for optimal electrode setting. Experimental data on the variation of maximum discharge power required for ignition as a function of volumetric gas content for methane-air and propane-air mixtures. Experimental determination of the ignition limit for discharges derived from a 24, 15, 10 and 6v inductive-resistive circuit in 8.3% methane-air mixture by using the PTB breakflash with Cd disc and W wires, and also with Cu disc and BeCu wires. Method for calculating ignition limits for other source voltages.

Jan 1, 1978

By T. E. Gray

This report describes the preparation characteristics of the significant coalbeds in Harrison County, W. Va. It is one in a series of Federal Bureau of Mines reports planned to determine coals suitable for the production of metallurgical coke, either as mined or after beneficiation. Over 6.5 million tons of coal was produced in Harrison County, W. Va., in 1958, of which over 3.7 million tons was cleaned mechanically in seven preparation plants. All of the coal cleaned was from the Pittsburgh bed. It has been estimated that more than 1,816 million tons of coal remains in the county in beds 12 inches or more thick. The Pittsburgh and Redstone beds were selected by the Bureau for a study based on current production rates and estimated minable reserves. Sample locations were selected following a study of the literature, conferences with mining engineers and mining company officials in the field, and examination of the available sites. Six samples were collected from the Pittsburgh bed, and three samples came from the Redstone bed, Float-and-sink tests of the samples collected from the Pittsburgh and Redstone beds showed that neither coal could be upgraded to a metallurgical fuel under the standards set up for this study, even after intensive preparation. Finer crushing of the samples moderately increased the yields and slightly reduced both the ash and the sulfur contents in the 1.30-specific-gravity float fractions. Finer crushing slightly decreased the yields in the 1.58-specific-gravity float fractions, whereas it reduced the sulfur content 0.11 percent for the Redstone sample and 0.46 for the Pittsburgh sample.

Jan 1, 1961

By Heinz W. Sternberg

A method for the electrochemical reduction of the benzene ring was developed and applied to the electrochemical reduction of coal. Successive electrochemical reductions of a vitrain from low-volatile bituminous coal in ethylenediamine saturated with lithium chloride resulted in the addition of 53 hydrogens per 100 carbon atoms. Ultimate analyses and pyridine solubility of the vitrain recovered after each reduction showed that hydrogen added at the beginning has a much greater effect on solubility than hydrogen added at a later stage. Surprisingly, the removal of sulfur from the vitrain takes place only after the more reactive aromatic rings are reduced. Nuclear magnetic resonance analysis and average molecular weight determination of the extracts of the reduced vitrain samples, representing about 18 percent of the vitrain, showed that these fractions had 95 percent of their hydrogen content on saturated carbon atoms and an average molecular weight of 800 to 900. A study of the effect of operating variables on current efficiency showed that current efficiency is highest with aluminum as cathode material and with lithium chloride as electrolyte. A substantial increase in current efficiency of difficulty reducible olefinic double bonds was achieved by adding a proton donor. This result is significant in connection with the electrochemical reduction of coal which proceeds from readily reducible aromatic double bonds to difficultly reducible isolated double bonds. It is proposed that reduction is achieved by electrolytically generated and subsequently solvated electrons and hence does not require prior adsorption of the substrate at the electrode surface. This offers a distinct advantage for electrolytic reduction of sparingly or insoluble substrates such as coal.

Jan 1, 1967

By I. Iwasaki

The effects of percent solids, mill loading and grinding time on product size distribution and ball wear were studied in a laboratory ball mill for a taconite ore. Mild steel balls and HCLA steel balls were used to examine the role that ball hardness play in grinding. Net production of minus 325 mesh - material reached maximum at 70% solids, whereas the ball wear decreased as pulp density increased. HCLA steel balls ground the taconite ore finer than mild steel balls under otherwise identical conditions. Examination of ball surfaces with a scanning electron microscope suggested that grinding with mild steel balls involved nipping rather than attrition, whereas grinding with harder HCLA balls involved both nipping and attrition.

Jan 1, 1984

By W. J. Campbell

This report by the Federal Bureau of Mines Particulate Mineralogy Unit recommends mineralogical definitions and identification-characterization concepts for selected silicate minerals and their asbestiform varieties. Precise definitions acceptable to mineral analysts, regulatory personnel, and medical scientists are essential because of the present lack of conformity in terminology concerned with measuring and controlling asbestiform particulates and their related health effects. Because of the complexity and variability of crystal morphology in different mineral groups, the descriptive terms are generally explained by illustration rather than by numerical values. Applications and limitations of several analytical techniques for particulate identification and characterization are discussed.

Jan 1, 1977

By Paul E. Melancon, Vincent C. Kelley, Dale F. Kittel

Uranium of the Grants region occurs predominantly in continental sandstones of the upper part of the Jurassic Morrison Formation, but significant lesser deposits are found in limestone of the Jurassic Todilto Formation and in black shale of the Cretaceous Dakota Formation. The deposits are disseminations that form runs ranging from a few hundred tons to several million tons. The ore consists mainly of uraninite, uraniferous carbonaceous material, coffinite, and such secondary oxidized minerals at tyuyamunite, carnotite, and uranophane. In sandstone, the ore runs were locallized by mudstone, interstitial carbonaceous material, and primary sand channel trends. In limestone, ore deposition was related to folds and fracture zones. The great bulk of production has come from the Ambrosia Lake mines in the Grants district and the Jackpile and Paguate mines in the Laguna district. The ores, which generally have been 0.20 to 0.30 per cent U3O8, are treated at mills operated by Kerr-McGee Corporation, Homestake-Sapin Partners, and The Anaconda Company, all in the Grants district. In 14·years after discovery in 1950, the deposits had yielded concentrates valued in excess of $800,000,000. Since deposition of the Jurassic host rocks, a geologic history involving tilting, faulting, erosion, changing ground-water environments, and oxidation has considerably influenced the existence and character of the deposits. It is evident that their ongm is not simple. However, a degree of agreement appears probable for a pre-Dakota age for the original ore runs, and, at Ambrosia Lake, two principal stages of ore formation, separated by Laramide faulting, are recognized. All earlier ores have been modified by Quaternary oxidation, solution, and enrichment during which time much secondary tyuyamunite, metatyuyamunite, carnotite were formed.

Jan 1, 1968

By M. A. A. de Klaver

Due to the current cost and availability of crude oil in Brazil, Samarco Mineracao S. A., as part of its program of quality and productivity optimization and reduction of operating costs, has undertaken tests to utilize alternate energy sources for fuel oil used in its pelletizing plant at Point Ubu, Espirito Santo, Brazil. The energy program undertaken by Samarco consists of two basic steps. The first step was to reduce energy consumption, that is, to improve the thermal efficiency of the process. Secondly, a program was started to substitute the fuel oil with coal.

Jan 1, 1984

By Elger. G. W.

The Bureau of Mines investigated preheating of continuously fed, fragmented ferrous scrap charges by furnace offgases and utilizing substitutes for imported fluorspar to condition electric steelmaking slags. Three types of continuous scrap charging procedures were investigated to determine electrical energy consumption in a I-st (short ton) electric arc furnace. Cold and preheated scrap charges were continuously fed at rates averaging 37.5 and 43.7lb/min, respectively. The feed rate varied appreciably from test to test owing to hangup of the scrap in the charge bin. Approximately 7 pct less electrical energy was consumed in melting scrap preheated to 8400 to 1,1100 F by furnace off-gases than in melting cold scrap. Overall energy consumptions were 888 kW'h/st for cold scrap, 829 kW'h/st for preheated scrap" and 637 kW'h/st for conventional backcharged scrap. Stack gases from scrap preheating averaged 1200 F and a flow rate of 1,615 scfm compared with 2200 F and 1,302 sefm for cold-charged scrap. Slag conditioners tested included synthetic fluorspar, boric acid, hydroboracite, used aluminum potlining wastes and aluminum anode tailing wastes, and Sorelflux B. The boron-containing conditioners fluidized the slags the best, followed in order by the conditioners containing fluorine and titanium.

Jan 1, 1987

By Albert L. Toenges

The State Division of Geology Arkansas Resources and Development Commission, and the Arkansas-Oklahoma Coal, Operators Association requested assistance from the Bureau of Mines in a study of coal-mining methods and practices in .Arkansas coal mines with the objective of reducing production costs. On October 7, 1946, a joint meeting was held by representatives of the Arkansas Resources and Development Commission, approximately 30 coal-mine Operators of the Arkansas -Oklahoma Coal Operaters Association, and representatives of the Bureau of Mines. The many problems confronting the coal industry in Arkansas, including mechanical mining in thin beds, costs, labor, and working time were discussed. Following this Meeting, a joint letter from Harold B. Foxhall, State geologist, and -P. R. Stewart, commissioner, Arkansas-Oklahoma Coal Operators Association, was addressed to Dr. R. R. Sayers; former ,Director of the Bureau of Mines, requesting that mining conditions in Arkansas be studied.

Jan 1, 1949

By William E. Lamont

The Mineral Resources Institute (MRI) of the School of Mines and Energy Development (SOMED), University of Alabama conducted studies to determine the potential for upgrading the Eastern Devonian shales by flotation. Results of those studies indicate that flotation concentrates containing 150 liters of oil/t (36 gal/t) can be produced from shale containing 50 liters of oil/t (12 gal/t) as determined by Fischer Assay with good recovery of the kerogen. Organic carbon and trace elements such as molybdenum, vanadium and uranium also are concentrated with the kerogen. Kerogen concentration was found to be a function of the size of grind.

Jan 1, 1983

By Lester M. Adams

In 1980, the Bureau of Mines surveyed a group of mine seals in Randolph County, WV, to evaluate their effectiveness for reducing toxic pollutants in mine water discharges. The survey focused on 11 block wet mine seals, but mine seals of several other types were also examined. The seals were installed in 1966 and 1967 in abandoned drift portals by the Federal Water Quality Administration (FWQA), a predecessor of the Environmental Protection Agency (EPA), in cooperation with the Bureau of Mines and other Federal and State agencies, in a project known as Elkins Mine Drainage Pollution Control Demonstration Project. The seals were designed to prevent air from entering the mine portals while allowing mine water to flow out. It was believed that by preventing air from entering inactive or abandoned mines, the formation of toxic pollutants and acid mine drainage (AMD) could be reduced. Evaluation of the seals was based on water flow measurements, water analyses, and visual observations. The Bureau's 1980 data were compared with past data collected by the EPA. Several leaks and failures were observed in the clay seals, as evidenced by apparent blowouts and the absence of vegetation where the mine water surfaced. Analyses of the 1980 data indicated some improvement in the quality of water discharged from many of the wet air seals.

Jan 1, 1984

By William L. Rose

Production scheduling is an integral part of intermediate- and long-range open-pit mine planning, affecting equipment selection, manpower requirements and project economics. The development of mining phases, or pushbacks, is discussed in conjunction with generating the best spatial extraction sequence. An approach to scheduling production from these mining phases is then described. Using computers and a production scheduling algorithm, the impact of cutoff grade and advanced stripping policies can be evaluated through sensitivity studies to maximize the return on project investments.

Jan 1, 1985