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By J. K. Whyatt, B. G. White

A comprehensive survey of mine seismicity and rock bursting during development of two sublevels at the Lucky Friday Mine, Mullan, ID, USA, was conducted to better define rock failure mechanisms and sources of ground control hazards. Survey data included rock burst damage reports, seismic event locations and magnitudes and, for the most energetic events, first-motion information. Several subsets of this database, including large seismic events, rock bursts, and microseismic activity near the face, were analyzed. Elements of the large-event and rock burst data sets were nearly independent. That is, there was no relationship between the risk posed by a seismic event and its energy, although such a relationship is well established for the mine as a whole. All data sets showed that certain geologic features appear to control the spatial distribution of events and the spatial distribution of rock burst risk. The data also suggest that, within the scope of this study. the greatest risk of injury occurs when a pocket of heightened rock burst risk is first encountered and that this risk is controlled when miners adapt their practices to these conditions. Recognition of the role of particular geologic features in the spatial distribution of rock burst hazards provides an opportunity for anticipating, rather than only reacting to, a changing level of rock burst hazard- However, much work will he required to make good on this promise.

By Danny Riley, Brian Curry, Sandya Govindaraju, James Bain

Acute vibration causes vasoconstriction in naïve human subjects1. Vibration-induced decrease in skin perfusion has also been reported in the rat-tail vibration model 2. After vibration exposure, rat-tail arteries demonstrate vacuoles in smooth muscle cells, similar to that caused by pharmacological vasoconstrictors3. This study addressed the effects of different frequencies, durations and patterns of vibration on lumen size and vacuole formation using the rat-tail vibration model in male Sprague-Dawley rats (~300 g). Methods The different groups were: 4-hr continuous vibration at 30, 60, 120 and 800 Hz; continuous exposure durations of 5 min, 1 hr and 4 hr at 60 Hz; and 4-hr cumulative exposure of 60 Hz delivered intermittently in cycles of 10 min on and 5 min off. Acceleration was set at 49 m/s2 r.m.s. for all frequencies. Unanesthetized rats were restrained in cages on a nonvibrating platform with their tails placed on a vibrating stage driven by a B&K motor (4809). The sham control animals were also placed in the vibration apparatus but not vibrated. Room temperature was controlled at 25 ± 1°C. Ventral arteries from proximal tail segments 7 were immersion fixed in aldehydes, embedded in epon-araldite and sectioned (0.5 µm) for morphological analysis. Vascular lumen sizes were measured as the percent ratio of the lumen perimeter to internal elastic membrane length using Image J software (NIH). The number of vacuoles in the smooth muscle layer of each artery section was counted. Results Fig 1: Semithin sections of arteries. A. Sham control. B. 4-hr vibration 60 Hz. In vibrated arteries, the lumen decreases in size, and smooth muscle cells (SMC) exhibit vacuoles (arrow). Bar equals 40 µm for each panel. [ ]

Jan 6, 2006

By Fred Leonard

This report is principally concerned with the engineering and economic feasibility of area surface coal mining systems other than draglines. This analysis evaluates shovel/ trucks, shovel/crusher/conveyors, and shovel/rail excavation and haulage systems for an assortment of geologic environments and production rates in the Powder River Basin (PRB). Shovel/trucks, front-end loaders trucks, and shovel/crusher/conveyors were studied in a multi-seam, dipping geologic area of the Four Corners Region. The Texas lignite engineering and economic research involved bucket-wheel excavators (BWE), BWE/backhoes, and scraper/backhoe combinations for overburden and coal excavation. The PRB truck/shovel study utilized the most recent computer simulation available in both the design and cost analyses. Detailed engineering analysis, followed by in-depth operating costs (operating and depreciation), result in a complete evaluation of each mining system. Cost comparisons of the different mining systems under similar geologic and production constraints are presented in the report to illustrate the estimated capital investment and production costs per ton of coal and bank cubic yard of overburden.

Jan 1, 1980

By Thomas Jenning, C. M. Keithly

"INTRODUCTION This report is one of a series. 4. 5. 6/ concerned with presenting historical development, and operating data on secondary-recovery projects in various States to stimulate interest in sound secondary-recovery programs. Preceding reports in this series have dealt exclusively with descriptions of and results obtained by water flooding in three states, but no recent publication of comparable purpose describes gas-injection 7/ practices. The authors intend to present material relevant to the development and operation of gas-injection projects in Illinois, with particular emphasis on those producing from oil-bearing horizons that had been depleted to a point near the economic limit of operation by past oil-recovery methods.Most operators realize that the energy expended on the movement of fluids through gas-expansion- or gas-cap-type oil reservoirs to producing wells must be supplemented to attain maximum recovery of the oil present. Under favorable conditions, many operators choose to maintain oil-propulsive forces at or near their original magnitude by injecting extraneous fluids into a reservoir or recycling produced fluids early in the life of a field. More common, and less desirable, is the practice of replenishing these forces after primary producing methods become unprofitable. The lattes practice has been adopted in many stripper fields in Illinois and most of the oil-producing States during the last 40 years, but other old oil fields, and oil properties within those fields which were partly exploited by secondary--recovery methods, also may offer favorable opportunity for further development. To encourage and, aid operators in the development of gas-injection projects in the old oil fields of the United States, four projects have been described in detail in this report."

Nov 1, 1944

By M. J. Ferrante

The Bureau of Mines investigated the applicability of the freeze-drying technique for preparing dispersion-strengthened tungsten powders suitable for conversion by powder metallurgy into materials which might have improved high-temperature strength. Extruded rods from compacts of tungsten-5 vol pct thoria had at 1,650° C a tensile strength of 30,300 psi and a 10-hour stress-rupture strength of 12,700 psi, These are slightly below those measured for swaged rods of commercial tungsten-3.7 vol pct thoria. Only those tungsten-thoria dispersions containing a stoichiometric deficiency of oxygen yielded a significant strengthening effect. A low-melting eutectic formed in extruded tungsten dispersions containing either zirconia or yttria, which caused a lowering of the tensile strengths. These tensile strengths were only slightly higher than strengths of elemental tungsten made from commercial powder having a particle size of 2.4 microns (Fisher subsieve). Sheet made from this commercial tungsten had a slightly higher tensile strength than tungsten made by freeze drying, but the freeze-dried tungsten sheet had a lower recrystallization temperature, a lower ductile-to-brittle transition temperature, and a higher purity.

Jan 1, 1971

By Russel Bohn

The purpose of this study was to evaluate the various techniques far mine roadway dust control. This evaluation included (a) the types of dust suppressants available, (b) the interaction of these products with the properties of the roadway surface, and (c) the costs and performance measures of the predominantly used dust suppressants. Over 30 products were identified having a wide range of effectiveness depending largely on the properties of the road base, subsurface, and wearing surface. The effectiveness of a dust suppressant was also found to depend on the application and maintenance procedures employed. As a result of this investigation five dust suppressants were identified s being predominant in the surface mining industry: Coherex, wetting agents, lignin sulfonate, water, and calcium chloride: An approximate cost-effectiveness analysis, limited by the lack of quantitative field performance data, showed that the five suppressants ranked in the order given above, with water being one of the least cost effective. This report also presents an analysis of applicable federal and state regulations.

Jan 1, 1981

By H. H. Schrenk

The Bureau of Mines midget impinger dust-sampling apparatus was described first in 1937.4/ Two supplementary reports5/6 were published in 1938. These reports are now out of print. The material published previously is combined in this paper to make information on this device available for distribution. The impinger was developed by the Bureau of Mines in cooperation with the United States Public Health Service in 1922. The underlying principle of this instruments is based on impingement land wetting, of the dust particles by drawing air through a nozzle at high velocity onto a smooth surface under a bubbling column of liquid. The dust particles are retained in the liquid. The apparatus has been used widely and permissible limits of dustiness have teen established in the United States on the basis of results obtained with this device in correlation with medical studies. However, it has been criticized for its bulk, weight, and power requirements.

Jan 1, 1939

By Roger A. Dworak

This report describes in detail the work done on the development of the Time Domain Reflectometry Microcomputer (TDRM). Modifications to the FMC-Model 302A Cable Fault Locator is described in Appendix D. The TDRM unit uses an 8080 microcomputer to accurately locate major faults in low capacitance cables to within ± 1 foot when properly calibrated. Major faults in high capacitance cables are usually located within ± 5 feet. The upper limits of fault detection are <1 kilohm shunt fault and >7 ohm series fault. In practice fault detection limits are reduced to <300 ohms shunt fault and >30 ohms series fault because of discontinuities caused by cable repair.

Jan 1, 1977

By Manuel Gomez

This report presents prediction equations for 12 variables that are indicative of metallurgical coal quality. The variables include six for coke strength and six for carbonization product yields. All variables were predicted for coking coals having volatile matter contents from 16.3 to 42.1 percent, dry basis. The prediction equations, developed by mathematical-statistical techniques, were based on information from the proximate and ultimate analyses, the size consist, and the petrographic composition of bituminous coals carbonized in BM-AGA retorts at 800°, 900°, and 1,000° C. The equations were evaluated for validity with independent data derived from the 900° C carbonization of 33 binary blends of various coals and 22 binary blends of Pocahontas No. 3 low-volatile bituminous coal with 11 high-volatile bituminous coals. Results show that metallurgical coal quality can be predicted ahead of mining because data used to derive the prediction equations can be obtained at the time of exploration. Capability to forecast coal quality is useful in mine planning and should provide basic information for optimization of blending and crushing techniques and thus lead to the production of uniform coke.

Jan 1, 1970

By Oliver Bowles

The use of fire as a source of heat was the first step from primitive existence toward modern civilization, and heat has performed functions of inestimable importance throughout the ensuing ages. The first commercial steam engine invented in 1698 demonstrated that heat was an important source of power, and heat has since become the motivating force for railroad trains and steamboats as well as for machines in multitudes of factories. Aside from its function of supplying power, heat is an agent of vast importance in chemical reactions and engineering processes. Because of the high temperature of steam under pressure, losses by radiation from boilers and pipes become excessive unless the radiating surfaces are covered with insulating materials. Insulation is important also for hot-water pipes and many other types of equipment from which heat may radiate. Radiation losses from heated surfaces increase rapidly

Jan 1, 1943

By L. E. Cardwell

This publication contains routine analyses and related source data for 475 natural gas samples from 17 States and two foreign countries. Of this total, 454 samples were collected during calendar year 1971. The remaining 21 samples were collected during previous years, but releases granting permission to publish the analyses were not received until 1971. All samples were collected as part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863 and 576.4 Thirteen previous publications have presented the results of 9,427 gas analyses prior to 1971. The first three, Bulletins 486,5 576,6 and 617,7 contain analyses and related source data on 5,218 gas samples collected from

Jan 1, 1972

By T. H. Jeffers

The U.S. Bureau of Mines has developed porous beads containing immobilized biological materials such as sphagnum peat moss for extracting metal contaminants from waste waters. The beads, designated as BIO-FIX beads, have removed toxic metals from over 100 waters in laboratory tests. These waters include acid mine drainage (AMD) water from mining sites, metallurgical and chemical industry waste water, and contaminated ground water. Following the laboratory studies, cooperative field tests were conducted to evaluate the metal adsorption properties of the beads in column and low-maintenance circuits, determine bead stability in varied climatic situations, and demonstrate the beads&apos; potential as a viable waste water treatment technique. Field results indicated that BIO-FIX beads readily adsorbed cadmium, lead, and other toxic metals from dilute waters; effluents frequently met drinking water standards and other discharge criteria. The beads exhibited excellent handling characteristics in both column and low-maintenance circuits, and continued to extract metal ions after repeated loading-elution cycles. Based on laboratory and field data, cost evaluations for using BIO-FIX technology to treat two AMD waters were prepared. Operating costs for BIO-FIX treatment, which ranged from $1.40 to $2.30 per 1,000 gal of water treated, were comparable with chemical precipitation costs.

Jan 1, 2010

By Fun-Den Wang

This report presents theoretical studies and experimental work dealing with the detection of dangerous roof and pillar conditions in underground mines through measure¬ment of temperature differences on the surface of the mine opening. The theoretical work is directed at modeling the circumstances where a loose slab of rock might be detected. The experimental work provides input data for the theoretical models. At the beginning of the project, little was known by the authors of the conditions that would permit detection of a loose slab of rock or coal by measuring the surface temperature differences. The U.S. Bureau of Mines had found that there were detectable surface temperature differences on the roofs and pillars of mines. The Bureau contracted with Colorado School of Mines to measure temperature profiles around mine openings in an effort to learn if the temperature differences they had detected were directly related to loose pieces of roof and pillar rock. The Bureau was principally interested in learning if loose rock could be found in coal mines by measurement of surface temperature differences with an infrared thermometer.

Jan 1, 1972

By Charles L. Kimbell

For the world mineral industry as a whole, the year 1981 was a period of continuation and, in some instances, an acceleration of negative trends extending back into 1980. Most available statistical data reflected stagnation or downturns in activity. Levels of production, trade, and consumption declined for a substantial number of leading mineral commodities, including, most notably, steel and petroleum. Investment, if not lower than in 1980, was evidently increasing at a more modest rate. Prices for major mineral commodities were generally lower, at least in terms of constant dollars, and in some cases even in terms of current dollars. Prospects of a major reversal of these patterns seemed dim. The mineral industry, however, was far from alone in this general downturn; most other elements of the national economies of the world&apos;s nations fared little better. General conditions of inflation, recession, and reduced industrial product consumption were reflected in most other sectors of the total economy. International political events continued to influence mineral output and flow but had less influence on overall levels of activities than on the geographic distribution of these activities. The Iran-Iraq war certainly played a role in reducing mineral industry activities in those nations, but the commodity most affected, petroleum, was available from other sources in sufficient quantity that, in the face of reduced demand, a substantial surplus developed.

Jan 1, 1983

By John R. Bartels

This report discusses an improved method for rerailing underground railcars devised in a joint effort by the Bureau of Mines and Hoesch MFD. This improved method utilizes a lightweight hydraulic ram with hand-pump activation to move a bridge-mounted roller carriage in conjunction with steel-reinforced air-lift bags. This method provides a lightweight portable system in which only two workers are required to perform the mine car rerailing operation. Because of the very narrow confines in underground mines, use of overhead cranes and other surface rail techniques is not possible. This new system is designed for very low profile work, and provides the necessary lifting force from light- weight compressed-air bottles.

Jan 1, 1985

By W. A. Young

Vermiculite deposits on the. Platt ranch, 12 miles southeast of Encampment Carbon County, Wyo., were investigated by the Bureau of Mines early in 1949. Major activity was centered on property held under lease by the Mikolite Mining & Development Co. (figs. 1 and 2). Vermiculite occurs in masses and lenses of varying size and as disseminations in altered hornblende diorite. Alteration of the host rock probably resulted from the proximity of dikes and irregular masses of pegmatite. Investigation of the Mikolite property consisted of surface trenching, diamond drilling, and sampling. Four trenches totaling 5,401 linear feet were excavated with a bulldozer and Diesel power shovel. Three diamond-drill holes totaling 600 feet were drilled from the surface to determine the character of mineralization at depth. Eighty-one bulk samples were obtained from the trenches, and 130 sludge samples were collected from the drill holes. Samples were analyzed, and ore-dressing tests were made in the Bureau of Mines laboratories at Salt Lake City.

Jan 1, 1952

By J. E. Tiffany, Gaigler. Z. C.

"PREFACEIn presenting this list of permissible explosives and blasting devices, the Bureau of Mines desires to call attention to pages 16 and 21 outlining the conditions in use under which, and only under which, the explosive or blasting device is permissible.In view of a recent publication recounting trade practice favoring the use of a blasting device without stemming, particular emphasis is placed upon condition 4 on page 16 and condition 2 on page 21. An explosive or a blasting device enumerated in the permissible lists of this Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming.PERMISSIBLE EXPLOSIVES TESTED UNDER SCHEDULE 17CAn active list of permissible explosives was published in December 1937 as part of Bureau of Mines Report of Investigations 3361, under the title ""Active List of Permissible Explosives and Blasting Devices Approved Prior to June 30, 1937.n This list included 196 brand names.Changes in the list that have been authorized to June 30, 1938, placed 7 additional brands of permissible explosives on the active permissible list as a result of tests, changes in brand names, or transfer from the inactive list. Twelve permissible explosives were transferred from the active to the inactive list. The present list contains 191 brand names. The brand names of the permissible explosives placed on the active list are as follows:"

Oct 1, 1938

By J. M. Singer

This study was undertaken to obtain some fundamental information about hazardous mixtures of coal dust and methane (firedamp) likely to occur in mines. Fuel concentration limits for ignition of mixtures of coal dust, methane, and air have been determined by a hot-gas ignition method. The limiting concentration of each of the two fuels was usually less than that corresponding to its lean flammability limit in air. The lean limits of flammability of coal dust vary with the type and size of the dust; in this study coal dust concentrations were less than 80 mg/liter. Ignition jets were turbulent pulses (emerging from a channel of 0.5 cm diam) resulting from explosions of stoichiometric mixtures of methane, oxygen, and nitrogen, Temperatures of the ignition jets were varied by changing the oxygen index (OI) = O2/(02 + Nj2) of the primary methane-oxygen-nitrogen mixture (adiabatic flame temperatures from 2,000° to 3,000° K). The objectives of the study were to establish quantitative relations between concentrations of each fuel at ignition limits of hybrid mixtures and to study the mechanism of ignition of these hybrid mixtures by hot turbulent gases, Empirical equations were fitted to concentrations for four coals, namely) Pittsburgh Seam (sizes A, B, and C), Sewell No.2 Seam, pocahontas No.3 Seam, and anthracite. Equivalences of coal dust to methane were computed from these equations; equivalence being defined as -Ac/Am, where c is the coal dust concentration and m is the methane concentration, each in milligrams per liter of air. It was found that the equivalence increases as the temperature of the hot-gas jet decreases. In general, the equivalence is also an inverse function of volatile content of the coal and a direct function of the particle size, However, volatile con-tent in itself is not a sufficient correlating variable, nor is the specific surface area of the coal dust.

Jan 1, 1967

By Merle L. Bowser

An alinement (steering) sensor for continuous mining machines has been developed under a Bureau of Mines contract. A laser source in the entry projects a beam parallel to the centerline of the entry. The beam is optically shaped to a narrow, vertical fan and illuminates an array of optical sensors bunted on the mini machine. These sensors interpret the location of the beam into meter readings of heading (angle) error and lateral displacement errors. The system, which was tested for 5 months in an operating mine, appears to be fundamentally sound, and with some modification, should be applicable to remote or automatic guidance of continuous miners and other machines.

Jan 1, 1976

By J. J. Wallace

This report describes the initial phase of Bureau of Mines research in the hydraulic mining of bituminous coal. The mining site and equipment are described, and the test procedures and results obtained with a bar-mounted monitor are given. Tests showed that hard Pittsburgh-bed coal can be mined hydraulically from a solid face at water pressures of 4,000 pounds per square inch.4 Coal was penetrated to a depth of 4 feet in 20 seconds with 225 gallons of water per minute coming from a 3/8-inch nozzle at 4,000 pounds per square inch pressure. Some difficulty was encountered in cutting the binders occurring in the coal; it was not possible Lu penetrate directly the overlying draw slate.

Jan 1, 1961