Search Documents

Miners, like everyone else, must be able to see well in order to work well. But simply hauling bigger and brighter lights into the mines does not necessarily produce better mine illumination. This chapter tells why. Increasing the power of the light source can create problems of portability, glare, adaptation and contrast. This chapter also discusses some ways to increase illumination by Improving the reflectability of walls, roofs and other exposed surfaces. In Chapter IV you learned that the "brightness" of a room or work area was really a matter of how much light was reflected from the walls, roof, and other surfaces. Therefore, if you want to Improve visibility you should increase the amount of reflected illumination. O HOW DOES ONE DO THAT? One way of Increasing reflected illumination would be to increase the power of the light source.

Jan 1, 1976

By James R. Wait

It is the purpose of this paper to review theoretical model concepts in through- the -earth transmission of electromagnetic waves. While the subject is very broad in its defined scope, we will be conscious of the specific applications to mine rescue and emergency telecommunications in coal mine environments. The plan of the paper is to outline previous theoretical efforts without attempting to attach names or organizations to the specific developments. However, we include a guide to the literature as an appendix. Without pretending to be entirely impartial we include a critique of the limitations of the available analytical models. As I see it the central problem is to calculate the steady state mutual impedance of a four-terminal network that is the black box characterizing the through-the-earth path. Problems of secondary importance include the determination of the input impedances of the two pairs of terminals and the associated transient responses. [ ]

Jan 1, 1973

By H. C. Ko

As part of the Federal Bureau of Mines effort to provide thermodynamic data for the advancement of minerals technology, energy conservation, and environmental preservation, the standard enthalpies of formation of a-magnesium sulfate, a-magnesium sulfate, and magnesium sulfate monohydrate were determined by hydrochloric acid solution calorimetry. The values of the standard enthalpies of formation in kcal per mole at 298.15 K are -307.95 ± 0.13 for a-MgS04, -307.03 ± 0.13 for ß-MgS04, and -384.72 ± 0.13 for MgS04 .H2O.

Jan 1, 1979

By Thomas L. McVay

The Bureau of Mines made laboratory batch and small-scale continuous flotation tests of a sample of pegmatite rock from a deposit of the Lithium Corporation of America, Inc., near Kings Mountain, N.C., to determine the feasibility of producing commercial-grade spodumene concentrates. Various reagents and flotation procedures were tested to determine the optimum conditions for floating the spodumene and retarding the gangue minerals. The best results were obtained when sodium fluoride and lignin sulfonate were used as the pulp conditioner and oleic acid was used as the spodumene collector. The continuous flotation tests indicated that commercial-grade. spodumene concentrates analyzing 6.4 pct. Li2O could be produced with recovery of 77 pct. of the lithia in the ore.

Jan 1, 1962

GLOSSARY TERM DEFINITION ACCOMODATION The process by-which the eye changes focus from one distance to another. ADAPTATION The process by which the retina adjusts-to more or less light then it was exposed to during an immediately preceding period. Also involved, to a lesser degress, is the change in the size of the pupil which regulates the amount of light entering the eye. Adaptation results in a change in the sensitivity of the eye to light. CENTRAL VISION (FOVEAL) The seeing of objects in the central or foveal part of the visual field. It is approximately two degrees in diameter and permits seeing much finer detail than does peripheral vision. DIRECT GLARE The effect of brightness or brightness differences within the visual field sufficiently high to cause annoyance, discomfort, or loss in visual performance. FOOT CANDLE A measure of the amount of light falling onto a surface. FOOT LAMBERT A measure of the amount of light that is being reflected by a surface. GLARE The effect of brightness or differences in brightness within the visual field sufficiently high to cause annoyance, discomfort, or loss in visual performance. LAMP A generic term for a man-made source of light. By extension, the term is also used to denote sources that radiate in regions of spectrom adjacent to the visible.

Jan 1, 1976

By Donald P. Tuchman

The U.S. Bureau of Mimes is investigating Fourier transform infrared (FTIR) spectroscopy for on- filter quartz analysis of respirable dust. A custom accessory is described for full-face examination of filters utilizing a large-diameter infrared (IR) beam. The accessory positions samples to match diameters with that of the diverging analytical beam. Sample absorbance is then measured. With nonuniform deposition of dust on collection filters being a major issue for such analyses, this approach is the most direct way to accomplish sample area averaging. The approach is unconventional since it utilizes large-beam geometries instead of the usually desired minimized beam dimensions. The issues and problems involved in the analysis of quartz on a filter matrix are discussed. Absorption bands chosen, light-scattering effects, curved baselines, random noise, interference fringes, and possible solutions to technical difficulties are the topics covered. The more significant findings include a 20-pg detection limit for quartz when the custom accessory is used and minimal occurrence of light-scattering effects at low wavenumbers. The custom accessory performance was satisfactory and merits further work. With continued research, an on-filter method for quartz analysis of respirable dusts seems achievable.

Jan 1, 1992

Coal-bearing beds underlie 23,000 square miles, about one third of Missouri's total area. Twelve out of more than twenty named coal seams have been or are being commercially mined. The remainder are too thin for commercial production. The coal is high volatile bituminous, with reserves estimated to be six billion tons, 1.24percent of U.S. coal reserves. Coal-bearing strata are generally thin seams which can be up to five feet thick. Typically, mined seams are about 28 inches thick. Coal deposits were first mined in Missouri in the 1840s, with the coal used primarily for domestic heating and blacksmithing. Production increased with the introduction of steamboats on the Mississippi. Coal production in 19 17 was six million tons. Production has steadily declined from a high of nearly seven million tons in 1984 to 2.3 million tons in 1991. Declining production is the result of several factors, including competition from other energy sources and the high sulfur content of Missouri coal. Today, coal-fired electric generating plants are the biggest consumers of Missouri coal. The Missouri regulatory program was conditionally approved November 21,1980, and fully approved January 17,1983. Its Abandoned Mine Land program was approved January 29, 1982.

Jan 1, 1992

By Pablo Velasco

The Ecuadorean mineral sector and overall economy have retained their traditional dependence upon the production and export of hydrocarbon products. Exports of crude oil and its products accounted for 62% of the country's export earnings in 1985. Ecuador's major mineral commodities produced and exported were cement, gold, limestone, liquefied natural gas, liquefied petroleum gas, natural gas, natural gasoline, crude petroleum and condensate, raw steel, semimanufactured steel products, and sulfur.

Jan 1, 1987

The twelve latexes listed in Table XI penetrated A horizon soil as shown by elution through a laboratory soil column and gave good sealing efficiency. See details in Table XII. High elution through laboratory soil columns of 4 to 6 inches depth is desirable because it predicts penetration of latex to a greater depth in the field. No definite correlation was evident between penetrating ability and particle size, surface tension, or pH. Most of the materials, however, were characterized by low surface tensions in the 36 to 53 dynes/cm range while particle sizes were usually in the intermediate range of about 1500 to 2500 Å. Naugatex J-3471 (a highly crosslinked styrene-butadiene copolymer) was the most promising of this group for stability, penetrating ability; and sealant efficiency. It also showed utility with [B] profile soil. Many of the other latexes tested in this investigation showed good sealing efficiency but were judged unsatisfactory because they gave low penetration or formed surface films with & horizon top soil. In general, latexes containing cationic surfactants were not satisfactory because they formed a heavy surface film. This is due to neutralization of the positive latex charge by the negatively charged soil particles.

Jan 1, 1972

By Thomas O. Glover

Cameroon's mineral industry continued to be dominated by crude petroleum, The economic development of the country depended on the production and export of crude on. Output was estimated to be 49 million barrels in 1985 compared with 56 million barrels in 1984 and 47 million barrels in 1988. The country's only refinery consumed approximately 12% of the daily production of crude oil while operating at slightly over 50% capacity. The refinery output, however, supplied the domestic need for motor fuel and heating oils. Cameroon's economic prospects were heavily dependent on the oil sector, which bad been responsible for the recent strong growth in the economy. The country consistently sought to avoid the problems associated with an overdependence on oil and followed a relatively broad-based development strategy, using oil revenues to sustain and encourage growth in other sectors. Approximately 75% of the gross domestic product (GDP) was attributed to the mineral industry in some form. GDP growth was approximately 6.5% during 1985.

Jan 1, 1987

By Gordon L. Kinney

Following a year of great uncertainty, the political situation in Bangladesh improved during 1976. The major problem for Bangladesh remained the high birth rate and crowded conditions. Bangladesh had the highest population density of any agrarian country--over 80 million people in a land area of 144,000 square kilometers, 65% of which is considered arable. The Government, with considerable foreign assistance, was actively encouraging voluntary family planning, and set a growth rate target of 2% per year or less. However, even if the growth rate was reduced to the target level immediately, the population of Bangladesh would nevertheless nearly double within 20 years.

Jan 1, 1980

By R. Karl Zipf

MULSIM/NL (multiple scams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines and thin metalliferous veins. It can analyze one to four parallel seams that can have any orientation with respect to the Earth's surface. Three main new features distinguish MULSIM/NL from its predecessors: (1) nonlinear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. Detailed checks show that numerical stress and displacement calculations compare well to known analytic solutions for simple problems. The total energy release calculated by MULSIM/NL is comprised of three basic terms: (1) strain energy release from the mined-out material, (2) linear kinetic energy release due to change in gravitational potential over the mined-out area, and (3) nonlinear kinetic energy release due to nonlinear materials in the total backfill and gob area. The strain energy release term is modified to account for nonlinear stress-strain behavior in the unmined materials. Comparisons of these numerical energy release rate calculations with known analytic solutions show excellent agreement.

Jan 1, 1992

By R. D. Leitch

In the course of another investigation4 during 1926 and 1927, samples of water collected from a few abandoned coal mines indicated that their drainage was usually lower in acidity than water from active mines in the same locality. In order to determine whether this condition might have a bearing on the advisability of sealing abandoned mines, a number of such mines were visited, samples of drainage were collected, and as much information as possible was obtained from officials of the mining companies and older residents of the district. The results of this work are the basis of the present report. ACKNOWLEDGMENTS The authors are indebted to E. W. Robertson, F. F. Spowart, J. H. Nagle, and W. D. Adams of the Northwest Mining & Exchange Co.; E. M. Fasset, Fred Lane, Wm. Humphreys, and Dr. T. A. Hutchison of Brockway, Pa.; C. W. Faulk of the Shawmut Mining Co.; James Hau of Kersey, Pa., and do others for information received; and to Dr, R. R. Sayers of the Bureau of Mines, under whose direction the work was conducted.

Jan 1, 1928

Objective Develop field measurement and computer modeling methods to predict the potential for hang-ups and structural failures in underground mine ore paws. Background Analysis of Mine Safety and Health Administration (MSHA) accident statistics has identified ore pass hazards as a significant safety problem in underground metal mines in the United Stales. Recent ore pass failures have underlined the lack or ore pass design methods ant1 standards available to both MSHA and mine engineers. Injury and fatality data for the 20-ycar period between 1975 and 1095 show that nearly 75% of the injuries were directly or indirectly related to pulling or freeing ore pass chutes, the use of hand tools, falls or broken rock, and structural failures or chutes or gates and ore pass walls.

Feb 1, 1998

Native asphalt was produced by five companies in two States, Texas and Utah. Bituminous limestone, used primarily as a paving material for street and road repair, was produced by White Uvalde Mines and by Azrock Industries Inc., Uvalde County, TX. Gilsonite, a solidified hydrocarbon, found only in Utah and Colorado, was mined by American Gilsonite Co., a division of Chevron Resources Co. (a subsidiary of Standard Oil Co. of California), by Ziegler Chemical and Mineral Corp., and by Hydrocarbon Mining Co. (a subsidiary of Oberon Oil Inc., a Utah corporation) from properties in Uintah County, UT.

Jan 1, 1984

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

MINE VENTILATION NETWORK ANALYSIS

Jan 1, 1977

By Thomas O. Llewellyn

Laboratory semicontinuous and continuous heavy liquid cyclone separation pilot plant tests were made to determine the feasibility of producing a high-grade kyanite concentrate from a kyanite-quartz rock sample from Graves Mountain, Ga. Use of a three-stage heavy liquid cyclone circuit demonstrated that a 96.4-to 99.0-percent kyanite concentrate could be obtained with recoveries of 95.5 to 96.7 percent. The test work showed that by steam stripping with 6.9 tons of steam per ton of ore and two stages of detergent scrubbing the residual TBE content of kyanite cyclone products was 0.22 pound per ton of ore.

Jan 1, 1971

By T. O. Llewellyn

Laboratory batch and semicontinuous studies showed the feasibility of using methylene bromide and trichloroethylene in heavy liquid cyclone concentration of a Nevada brucite ore. Cyclone tests of minus 20- plus 200-mesh material at specific gravities of 2.42 and 2.44 recovered 71.6 to 74.9 percent of the MgO at grades of 95.5 and 95.4, respectively. Neither increasing the feed pulp density from 5 to 25 percent solids, nor varying feed pressures from 25 to 60 psig had any apparent effect on the heavy liquid separation.

Jan 1, 1971

By John C. Machisak

THIS CHAPTER of the Minerals Yearbook (Volume III) contains overall employment and injury experience for coal mines-bituminous, lignite, and anthracite; coke, petroleum and natural gas; and peat and slag plants; metal and nonmetal mines; sand and gravel operations; stone quarries; metallurgical plants, including metal mills and smelters; and nonmetal mills for 1959. Volume I of the yearbook contains injury experience and employment data in the metal, non-metal, sand and gravel, slag, and quarrying industries, and the milling operations and related plants. Volume II contains the injury experience and employment data in the fuel industries--coal, coke, petroleum and natural gas, and peat. Surveys conducted by the Bureau of Mines were the source of injury and employment data used to compile the tables and furnish information for the accompanying text. Response to the surveys was voluntary except that for coal mines. The Coal Mine Safety Act requires operators of coal mines to furnish the information requested.

Jan 1, 1960

This report was limited to a search of available literature on under- ground methods to combat acid water pollution. From this review it is evident that very little work has been done in this specific area. It is also evident that there are specific areas of mining engineering and mining related hydrology and geology that need further research efforts to solve the many water problems. They are: (A) Composition, variation and availability for oxidation of sulfur in strata. (B) Rate of oxidation of sulfuritic materials. (C) In situ limestone and its influence on underground acid drainage. (D) Structural, stratigraphic and hydrologic character of old mining areas as a basis to make decisions about adjacent new mining areas. (E) Operational changes in mining methods to prevent pollution. (F) Sealants for underground coating to exclude water from contact with pyrite to inhibit formation of the contaminants. Such a program has been initiated on refuse piles. The prime purpose of this report is to investigate those practices which have been used to regulate or control water accumulation and prevent harmful mine drainage. A supplemental purpose is to indicate those areas which need further research to prevent underground mine water pollution.

Jan 1, 1970