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By Richard H. Singleton

Native asphalt was produced in 1978-79 by six companies in four States. Leading States were Texas and Utah. Output in-creased 37% in 1978 to 1.7 million tons and decreased 5% in 1979 to 1.6 million tons while value increased 39% in 1978 to $19.3 million and 33% in 1979 to $25.6 million. Bituminous limestone was produced by Whites Uvalde Mines and by Uvalde Rock Asphalt Co. in Uvalde County, Tex.; by Southern Stone Co. in Colbert. Ala.; and by Barton County Rock Asphalt Co. in Barton County, Mo. The product was used mainly in street and road repair. Gilsonite was produced by American Gilsonite Co. in Uinta County, Utah, and by Ziegler Chemical and Mineral Corp. in Weber County, Utah. This material was used for purposes other than road repair.

Jan 1, 1980

By Robert K. Koch

Laboratory-scale studies on defluorination of natural and synthetic fluorspars by pyrohydrolysis at 1,500° C. were made to determine the feasibility of developing a process for producing hydrogen fluoride from siliceous fluorspars. It was found that the reaction (at 1,500° C.) is not promising for process development, even though a silica-free offgas can be generated. The primary difficulty is the low hydrogen fluoride content of the offgases; an HF content of 6 percent was the best achieved. Previous research by the Bureau of Mines has demonstrated that offgases averaging 27 percent hydrogen fluoride can be produced under carefully controlled conditions at 1,280° C. The lower temperature process is a better method for production of HF. However, charges in which the CaF to Si02 mole ratio varied from 0.4 to 2 could be processed with similar results. Also, combined alumina and ferric oxide contents up to 25 mole-percent did not noticeably alter the rate of defluorination. Therefore, virtually any natural siliceous fluorspar would respond in essentially the same manner when exposed to water vapor at 1,500° C.

Jan 1, 1962

By Harry Dobroski, Larry G. Stolarczyk

Theoretical and experimental research sponsored by the U.S. Bureau of Mines shows that medium frequency (MF) electromagnetic (EM) signals propagate great distances in an underground environment such as a tunnel or mine. This propagation is enhanced by different mechanisms associated with the geology, and with the existence of metallic conductors in the entryways. In stratified geologies, a transverse electromagnetic (TEM) mode of signal propagation is possible if a low conducting layer is bounded above and below by higher conducting layers. In general, the difference in conductivities must be at least several orders of magnitude. Such geological waveguide conditions often exist in underground mines. Propagation via the waveguide effect is known as the "seam mode" of propagation. Another mode of propagation, the "tunnel mode," exists in underground entries with electrical conductors such as power cables, metal pipes, and phone lines. A monofilar mode of propagation exists when signals are impressed upon conductors and return via the surrounding rock. A bifilar mode of propagation exists when all signals exist only on local conductors. In a given location there is a combination of monofilar and bifilar modes that make possible an interaction between the conductors and a transmitting device in a tunnel or entryway. Signals can be impressed on or received from local conductors via magnetic dipole antennas (loops) or line couplers.

By R. J. Matetic, D. Elsworth

The objective of this U.S. Bureau of Mines hydrologic-subsidence investigation was to evaluate the effects of longwall mining on the local ground water regime through field monitoring and numerical modeling. Field data were obtained from multiple-position borehole extensometers (MPBX's) that were used to measure subsurface displacements. Survey monuments were installed to measure mining-induced surface deformations. Numerous drawdown and recovery tests were performed to characterize hydrologic properties of the overburden strata. Coreholes were drilled above the study area to determine lithologic and strength characteristics of the overburden strata using the rock samples collected. Electronic recorders were installed on all monitoring wells to continuously monitor ground water levels in coordination with mining of the longwall panels. A combined finite element model of the deformation of overlying strata, and it's influence on ground water flow was used to define the change in local and regional water budgets. The predicted effects of the postmining ground water system determined by the model correlated well with field data collected from the field site. Without an infiltration rate added to the model, a static decrease of 3.0 m (10 ft) in water level would occur due to mining of both longwall panels and if an infiltration rate was inputted in the model, no predicted long-term effects would occur to the ground water system.

Jan 1, 1995

By John Durkin

Field studies have been conducted in a large number of coal mines throughout the U.S. to determine the effectiveness of electromagnetic techniques in locating men trapped underground following a mine disaster. Data from these tests have been used to generate models of expected signal and noise distributions as found above mines throughout the coal fields. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results indicate an expected 45% probability of detecting a miner's signal from a depth of 1,000 ft, a depth which exceeds 903 of the coal mines within the U.S. and a 90% probability at a depth of 500 ft, a depth which exceeds 50% of the mines.

Roof screening for ground control originated with metal miners in the western United States. At first chain-link fence was used, but because it was so difficult to handle, the miners started installing a more rigid welded wire screen used in the concrete industry. Eventually coal mines in the west began to use screen, and now more and more coal operations, especially longwall mines, are installing roof screen on a regular basis. Screen use has recently increased in the Illinois basin and is now making its way to underground coal mines in the eastern U.S.

By d&apos, Kathleen J. Amico

This summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operations at or near mines.

Jan 1, 1967

By l.J Prosser

from 1990 to 1996, 16 states reported 92 injuries from falls of roof, rib or face in the more than 90 underground stone mines in the United States (Fig. 1). Missouri, Pennsylvania and Kentucky accounted for 48% of the total number of injuries (Fig.2). Of this total, 11 miners were killed. Of the 11 fatalities, 10, or 91 %, were associated with unrecognized loose or failed rock within the roof beam. Additionally, unrecognized roof beam failures resulted in a majority of the falls of ground injuries occurring in underground US stone mines from 1990 to 1996.

By Yael Miron

Coal mines that undergo self-heatings, and specifically mines that sustain both floor heave and self-heatings, would benefit from the use of sealants to minimize air ingress to susceptible areas. The U.S. Bureau of Mines(USBM) evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gel. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the USBM Safety Research Coal Mine. Two formulations resulted in stable gels that lasted for at least 12 months in the mine. Semi continuous preparation of gel using an eductor was evaluated and appears feasible. Although guar gum gel is expensive, selective use to prevent heatings in specific areas would be cost-effective, both interms of productivity and enhanced mine safety.

Jan 1, 1995

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which 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 laws of Colombia has been prepared from the best available information in Washington, but is released subject to correction and amplification; if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State. SYNOPSIS OF LAW Minerals in Colombia belong to the owner of the soil unless otherwise provided in the law. The following lands and deposits, however, are described as fiscal property of the State: Class 1. The public lands, mines, and salines which belong to the individual States (now Departments) prier to the adoption of the present constitution (1886).

Jan 1, 1929

By Homer J. Ballinger

A multiple drill carriage or "jumbo," which is believed to be unique in both design and performance, was constructed and has been in use for the past year at the Bureau of Mines experimental oil-shale mine near Rifle, Colo. This jumbo mounts four long feed percussion drills and is so designed that two men can operate all four drills. Before the jumbo was placed in operation, a minimum of eight man-shifts was required to drill 72 fifteen-foot holes in headings 60 feet wide and 27 feet high. The sane round is now drilled by two men in about 6 hours. Over 500 feet of drilling per man shift is easily and consistently accomplished. Use of the jumbo has resulted in a 75 percent reduction in drilling labor and a substantially lower drilling cost.

Jan 1, 1950

By D. R. Babich, E. R. Bauer

The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of equipment sound levels and worker noise exposures in the stone/aggregate mining industry. Six stone/aggregate mines (three surface and three underground) were recently surveyed, and the findings (ire presented here. The surveys consisted of sound-level measurements conducted around various equipment and machinery (including stone processing and crushing equipment) and full-shift dose measurements to determine worker noise exposures. The findings identify the equipment and machinery that are likely to cause worker overexposures and identify the workers found to he experiencing overexposures. In addition, the benefit of cabs in reducing mobile equipment operator noise exposure is discussed.

"Fire fighting in metal mines under the best of conditions is a dangerous, a slow, and a difficult task. Certain gases generated from combustible material burning in restricted areas are poisonous, even in small quantities, and can not be breathed without serious and often fatal results. In addition to poisonous gases, smoke is given off which obscures the vision of the fire fighter and frequently prevents him from gaining access to the fire area. Many fire-fighting crews have had to turn back because their vision was so impaired by the dense smoke that the fire area could not be located and there was danger of them becoming lost in the mine.In mines having mechanically controlled ventilation - that is, mines not dependent entirely upon natural air currents - the gas and smoke can be forced ahead of the fire-fighting crews, thereby facilitating exploration of the mine and saving the time, energy and oxygen of the mine rescue apparatus crews.Where currents of fresh air can be circulated up to points near the fire without danger of seriously spreading the fire, fresh air bases can be established in the immediate vicinity, and a more intelligent campaign for fighting or controlling the fire can be mapped out.Positive air currents through forced ventilation may also result in saving the lives of miners who otherwise might have been trapped in smoke and poisonous gases.It is generally known that comparatively few metal mines have attempted to regulate or control air currents, with the result that when a fire occurs underground, the normal ventilation may be reversed, short circuited, or the air current may be in one direction one minute and in the opposite direction the next; or, generally speaking, the ventilation can not be depended upon, and smoke and poisonous gases may accumulate in any part of the mine or ""drift"" on the fire-fighters or on the miners endeavoring to escape."

Apr 1, 1921

By T. R. Taubert, D. H. Carlson, J. H. Johnson

"ObjectiveDevelop a portable emissions measurement apparatus to sample and measure tailpipe concentrations of diesel particulate matter (DPM), carbon monoxide (CO), carbon dioxide (COJ, nitric oxide (NO), and nitrogen dioxide (NOJ under steady-state engine load and speed conditions during a 1-minute test.BackgroundThe U.S. Bureau of Mines (USBM) has a comprehensive research program to develop ways to reduce exposure of miners to diesel exhaust pollutants. Engine maintenance has been shown to have important effects on such exposure.Accurate measurements of tailpipe emissions are becoming an essential part of a good maintenance program for underground mines that use diesel-powered vehicles. Past studies of particulates in U.S. underground coal mines have shown that DPM alone may be present at concentrations greater than 1 milligram per cubic meter (mg/m3), half the 2-mg/m3 limit for respirable coal mine dust. A poorly tuned (smoking) diesel engine may be the sole cause for respirable dust concentrations exceeding the limit. Although there is currently no standard specifically for DPM in U.S. mines, regulatory steps are underway, and significant reductions of DPM levels in both coal and metal mines will most likely be required.Tailpipe emission measurements can provide diagnostic information to identify engine malfunctions such as clogged air cleaners, faulty injectors, or incorrect injection timing. In some cases, mine vehicle tailpipe DPM concentrations have been reduced up to 50 percent by engine maintenance and adjustments.An accurate measuring instrument would also be useful for determining the effects of exhaust control devices on tailpipe emissions. Little information is currently available about the overall effectiveness of exhaust controls after long-term use. Raw exhaust concentrations with and without the control device can be measured in underground mines, and from these data a control efficiency can be calculated. Knowledge of the effectiveness of exhaust control devices over time is needed to make intelligent decisions on bow to use and maintain these devices, and when to replace them."

Dec 1, 1995

By Charlie Wyche

The principal minerals produced in the Dominion of Fiji in 1982 were unrefined gold, silver, and tellurium. The combined value of these commodities was about $16 million,2 representing over 85% of the total value of mineral output. Cement, sand and gravel, and quarry products were the other minerals produced in Fiji. Despite the small part played by minerals in Fiji's economy, exploration on land and in the coastal areas was carried out by several international mining companies representing Australian, British, Canadian, West German, and U.S. interests. At the end of 1982, 30 prospecting licenses covering 2,300 square kilometers were issued. Most licenses were for copper, zinc, gold, and silver. Total expenditure on mineral exploration was $3.5 million.

Jan 1, 1984

By F. W. Benn

The Bureau of Mines investigated flotation methods for recovering fluorite and byproducts from two samples of the Fish Creek deposit in Eureka County, NV. The preferred method for tre.ating a fluorite-beryllium sample included (1) fluorite rougher and cleaner flotation, (2) desliming at 20 um, (3) muscovite flotation, (4) silicate flotation, (5) sodium hypochlorite wash of silicate concentrate, and (6) beryllium rougher and cleaner flotation from the silicate concen-trate. Laboratory results showed that over 94 pct of the fluorite was recovered in a recleaner concentrate containing 98 pct CaF2, Beryllium flotation produced concentrates containing in excess of 5 pct BeO with recoveries over 70 pet. The preferred method used for a fluorite-mica sample consisted of (1) fluorite rougher and cleaner flotation, (2) desliming at 20 um, and (3) mica flotation using an anionic-cationic collector system. Laboratory results showed that 84 pct of the fluorite was recovered in a recleaner concentrate containing 96 pct CaF2, Mica flotation produced a concentrate containing 95 pct mica at 85-pct recovery.

Jan 1, 1986

By Frank G. Schwartz

The Bureau of Mines developed a rapid test method for predicting the stability of motor gasoline during long-term storage. The amounts of gum and inorganic residue formed in 13 gasolines during a l6-hour oven test at 200° F were compared with the amounts formed in the same gasolines stored at 110° F, and analyzed following 8-, 16-, 32-, 44-, and 52-week storage periods. Satisfactory methods were developed for predicting gum and inorganic residue formation during fuel storage periods as long as 32 weeks at 110° F, the approximate equivalent of 5.7 years at 80° F. The only data required to apply the methods are the amount of gum and inorganic residue formed, and the amount of oxygen that reacted, during a l6-hour oven test. A direct relationship existed between inorganic residue formed during the oven test and during 110° F storage. Statistical treatment of the data showed predicted values were as reliable as determined values. By use of a modified Arrhenius equation, the 110° F storage time can be extrapolated to equivalent time at any temperature below 110° F. Thus by combining the stability prediction method with the mathematical extrapolation, the storage performance of motor gasoline for extended periods can be estimated at any temperature up to 110° F.

Jan 1, 1968

By G. M. Kintz, E. H. Denny

Although some engineering colleges recognize the importance of instructing young engineers in industrial safety , the different institutions handle this instruction in various ways . It is believed that a recent industrial safety course , conducted at the Colorado School of Mines through the cooperation of this school and the Bureau of Mines , U. S. Department of Commerce , presents some unusual features that are of interest to other schools and to the mining public .

Sep 1, 1930

By B. W. Madsen

A nearly dormant copper sulfide pilot-scale experimental leach containing 8.7 tons of are was injected with oxygen to determine its effect on the copper-leaching rate. Prior treatment of the uncrushed 0.25-percent-copper, mine-run stripping material consisted of 461 days of acid ferric sulfate leaching, which extracted 47 percent of the total copper. The permeability of the bed had decreased, and the percolation rate had decreased from an initial 20 gallons to 0.8 gallon per square foot per day. Copper extraction had nearly stopped. After injecting oxygen into the ore column and leaching for 30 days, the percolation rate was increased to 6 gallons per square foot per day. In an additional 298 days of leaching, an additional 40.7 percent of the copper was extracted. The improved leaching after the use of oxygen is attributed to stimulated bacterial action, better oxidation, and increased permeability.

Jan 1, 1975

By W. E. Miller, W. P. Yant, G. W. Jones, R. E. Kennedy

"The determinations of the limits of inflamability of diethyl ether and ethylene in air described in this report were made primarily for comparison with similar determination of other compounds in the same apparatus and by the same laboratory technic. The experimental procedure and the results obtained differ somewhat from those of other investigations. The work also included determinations of the limits of inflamability of these combustibles in oxygen The investigation,was conducted at the Pittsburgh Experiment Station of the United States Bureau of Mines in cooperation with Merck & Co., Inc. LIMITS OF IMFLAMIABILITY OF DIETHYL ETHER-AIR MIXTURESThe limits of inflamability if diethyl ether in air were determined for upward propagation of flame in an upright, closed 8-liter, cylindrical iron bomb 10.2 cm in inside diameter and 96.5 cm in length. This bomb been described in a previous publication. 6Two brands of diethyl ether were used, one a C. P. sulphuric ether manufactured by Baker & Adamson, and,the other Merck & Co. product manufactured for anaesthesia and containing about 3.5 percent of ether alcohol."

Jul 1, 1935