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By Wilbur I. Duvall

Twelve millisecond delayed blasts in four limestone quarries in Iowa were instrumented with arrays of vertical velocity gages to determine if the direction of propagation through the rock or the method of initiation of the blast had any effect upon the level of vibration. Two gage arrays approximately 90° apart were used to test the effect of direction of propagation. The vibrations from blasts initiated by three methods were recorded. Vibration records from these tests were analyzed for peak particle velocity as a function of distance from the blast. The data are shown to fit a power Law equation. Direction of propagation is shown to affect the value of the exponent n. The effect of charge size per delay interval on the level of vibration is removed from the data by scaling the travel distance by the square root of the charge weight per delay period. The method of initiating the blasts is shown to have a strong effect upon the level of vibration and the spread in the data from one shot to another.

Jan 1, 1963

By Ralph Husack, J. W. Eckerd, G. A. Brady

The effect of gamma radiation on Pennsylvania anthracite and on reactions between anthracite and other materials was studied using a shielded , selfcontained 23,000 - curie cobalt 60 source . When anthracite was exposed to air at 65° C the reaction with oxygen was greater in the presence of radiation. than in its absence . Although drop- shatter tests indicated that exposure to radiation decreased the resistance to breakage of anthracite , this evidence of structural weakening was not supported by the results of grindability or particle- size studies . Irradiation caused definite changes in the gases evolved from evacuated samples of anthracite ; the percentages of hydrogen and carbon dioxide were increased, and the methane concentration remained unchanged . Carbon monoxide was evolved only from the unirradiated samples . Electron paramagnetic resonance (EPR ) measurements indicated large differences between evacuated samples and those exposed to air . There was little or no difference between irradiated and unirradiated samples , except that the free- radical content of unirradiated samples of anthracite increased progressively with higher temperatures of evacuation , but in the case of irradiated samples , no such behavior was found . Attempts to produce carbon disulfide and calcium carbide by reacting anthracite with sulfur up to 120 ° C , and with calcium oxide up to 400 ° C , were unsuccessful .

Jan 1, 1964

By M. R. Geer

Samples of coal from six beds in the Roslyn-Cle Elum field of Washington were subjected to float-and-sink tests to determine their amenability to the production of high-ash boiler fuel for on-site power generation. Grindability tests and analyses of ash were made. All of the coals would require some degree of cleaning to insure a product of 25 percent ash. With two of the coals the entire size range would have to be washed. With the other four, it would suffice to clean only the coarse coal and bypass the raw fines.

Jan 1, 1965

By Robert W. Smith

In a certain application2/ it was necessary to compute the beta function B(p, q) for a certain set of values p and q. Since t he set of p and q values was much mo re finely spaced than those in any published tables, the authors decided to make their results available in this report. In connection with this application the functionB(p, q) was needed at various points in the p, q plane at intervals of 0.05, 0.05<p = q< 10.00. Fletcher, Miller, and Rosenhead2/ state that the only tables available in the desired range are those of Rearson.4/ However, the interval used by Pearson was not small enough for the present application. For this reason it was decided to calculate B(p, q) for p = q =0.05 (0.05) 10. 00.2/ This table is published because of the fundamental importance in mathematical analysis of the complete beta function.

Jan 1, 1953

By Thomas Fraser, William L. Crentz

"INTRODUCTION Sulfur is a most damaging impurity in many of our American coals. From the older coal industry of Europe and Britain we can apparently learn but little about the problem of preparing and using high-sulfur coal. Although washing has long been established there for controlling ash content, sulfur is referred to rarely, as the important deposits are singularly low in sulfur.On the other hand, widely distributed coal deposits of America differ tremendously in sulfur content. Many of the more extensive beds contain too much sulfur for metallurgical use, and almost everywhere except in the Rocky Mountain and Pacific coast regions sulfur control is at least a potential problem. American coal-preparation engineers are confronted not only with great variations in the total quantity of sulfur in coal but with an intricately varying pattern of the physical and chemical forms in which the sulfur occurs. It must be conceded that the baffling problem of sulfur reduction in coal is as yet substantially unsolved, for there are but few isolated instances in which we have been able to prepare a satisfactory metallurgical fuel from coals containing as much as 2.0 percent sulfur in the raw state.It has been assumed generally that organic sulfur, being chemically combined with carbonaceous matter, is distributed throughout the coal matter and that it remains unchanged in the clean-coal part of the product during washing.Sulfur that may be washed out of the coal is that part that is combined with the iron in pyrite lenticles associated with the coal. In most of our coals it has been found that, besides the visible bands, lenses, and flakes of pyrite, extremely small and even microscopic particles of pyrite 4/ are distributed through the coal matter. Only the free, relatively coarse pyrite particles .are removed by conventional coal-washing devices, and usually most of the sulfur is still left in the product."

Dec 1, 1947

By Stephen C. Brown

THE expansion of the world economy which has been in process since 1958 continued in 1963 and both production and consumption of minerals rose. Gross national product (GNP) rose sharply in the United Kingdom and Japan, continued to expand in the United States and Canada, and maintained a high though slightly declining rate of growth in the European Economic Community (EEC) despite the appearance of excess capacity in certain lines and inflationary pressures in Italy and France. The steel and motor vehicle industries both increased output in North America, Western Europe, and Japan. The less developed areas benefited substantially from an improvement in their terms of trade, and their export earnings increased some 8 percent in 1963; although estimates of GNP for the majority of them are 110t yet available, it is probable that this increase was partly reflected in a substantial rise of GNP.2 In the United States the expansion was steady and extended through all sectors of the economy producing no distortions likely to disturb its continuing growth; at yearend with unemployment still at about 5.5 percent of the labor force and operating rates of industry estimated at about 87 percent of capacity, there was a substantial margin for further expansion. Though the balance of payments was still in heavy deficit for the year, in the last half it was moving rapidly toward equalibrium as net exports rose and capital outflows declined; prices were relatively stable, inventories increased only slightly and the activity of mineral-consuming industries remained high, steel output rising by 11 percent to highest level since 1957 and the auto industry output equalling the 1955 record.3

Jan 1, 1964

By Miles B. Royert

Crude Minnesota taconite was charged in the Bureau of Mines experimental blast furnace so that smelting characteristics of such highly siliceous raw materials could be studied and smelting costs compared with those of a standard Mesabi ore. The Bureau recognized that the highly siliceous nature of the crude ore and its relatively low metallic content would be serious economic deterrents to commercial use of the raw taconite, but compensating factors would be low capital investment in production facilities, large tonnage available on short notice, high recoveries of iron, and low delivered cost. Crude taconite smelted readily in the experimental blast furnace. Coke consumption per ton of metallic product was very high, compared with the average established requirements for smelting normal grades of metalliferous raw materials. Slag rates were also inordinately high. Metal quality was erratic as to silicon, and sulfur contents were objectionably high.

Jan 1, 1961

By B. W. Jong

As part of the Bureau of Mines program to develop substitute or improved performance refractory materials for metallurgical applications, the Tuscaloosa Research Center has evaluated the effect of additives on sintering and strength properties of aialon (silicon aluminum oxynitride) compositions fabricated by a conventional powder metallurgy technique. Additions of Y203, Gd203, CeO2, MgO, ZrO2, ZrSiO4, and MgA12O4 to a sialon composition containing 70 pct ß-Si3N4 + 30 pct a-A1203 increased sintered densities by as much as 50 pct over densities of undoped material. The studies also indicated that sintered densities reached a maximum between 20 and 30 mole-pct a-A1203 when a series of sialon compositions of a-Si3N4, having 6.7 to 57.9 pet a-Al203, were doped with Y203, Gd2O3, and MgO. In studies to establish the effect of the crystalline phase of the silicon nitride and alumina used, tests were made using a- and ß-Si3N4 and a- and ?-A12 03 as starting materials. The tests indicated that when using an addition of 5 wt-pct Y203, best results were obtained with a sialon composed of 74.4 mole-pct a-Si304 and 25.6 mole-pct ?-A1203. In other tests made with this sialon composition MOR values of 28,120 and 29,500 psi at 25° C, and 23,520 and 16,850 psi at 1,400° C, were obtained when doping with 5 wt-pct ZrSiO4 and ZrO2, respectively.

Jan 1, 1980

By Ernest W. Loya

A method for preparing gravimetric primary standards of helium in the parts per trillion range has been developed by the Bureau of Mines. The standards are used to calibrate a specially modified mass spectrometer used in determining the abundance of helium-3 and helium-4 in geochemical samples and of helium-3 in isotopically purified helium-4. The desired gas standards are prepared in 5-kg metal cylinders filled to 1,800 psia. Relative errors of less than 1 pct have been attained in the parts per trillion range using a successive dilution technique.

Jan 1, 1982

By B. B. Letson, D. F. Smith, T. E. Gardner, A. R. Taylor

Low- temperature heat capacities of strontium chloride (7° - 300° K) and strontium fluoride ( 11 ° - 300 ° K) were measured with an adiabatic calorimeter . Smooth values of heat capacity , entropy , enthalpy function , and free - energy function were calculated from the heat - capacity data . The smooth values are reported at 10 ° K intervals and at 273.15 ° and 298.15 ° K.

Jan 1, 1963

By R. V. Higgins

As part of a study of application of the Buckley-Leverett method to an analysis of oil-reservoir performance covering a wide range of relative permeabilities and oil saturations, a method has been devised for quickly deter-mining average water saturation at breakthrough from relative permeability data. The base for the relative permeability used in the report is either the permeability to air or the effective permeability to oil at the irreducible water saturation. The permeability to air also was used because of the large backlog of air permeabilities available to reservoir engineers. The basic data were calculated by an electronic computer and are presented in a single graph from which the point of breakthrough may be obtained. In this study the water saturation at the beginning of the depletion is the connate or interstitial or irreducible water saturation. These water saturations are considered to be synonymous and to have a practical value.

Jan 1, 1960

By T. M. Ruff

A prototype mucking machine designed to operate in narrow-vein stopes was developed by Foster-Miller, Inc., Waltham, MA, under contract with the U.S. Bureau of Mines. The machine, called a compact loader-trammer, or minimucker, was designed to replace slusher muckers in narrow-vein underground mines. The minimucker is a six-wheel-drive, skid-steered, load-haul-dump (LHD) machine that loads muck at the front with a novel slide-bucket system and ejects it out the rear so that the machine does not have to be turned around. To correct deficiencies of the tether-remote-control system, a computer-based, radio-remote-control system was retrofitted to the minimucker. Initial tests indicated a need to assist the operator in guiding the machine in narrow stopes. An automatic guidance system that used ultrasonic ranging sensors and a wall-following algorithm was installed. Additional tests in a simulated test stope showed that these changes improved the operation of the minimucker. The design and functions of the minimucker and its computer-based, remote-control system are reviewed, and an ultrasonic-sensor-based guidance system is described.

Jan 1, 2010

By John R. Reeves

The data presented in this paper form the chief part of a general survey of the oil-shale resources of Indiana. Other papers* have already been published which contain data an various aspects of this resource. In combination, these papers present data with reference to the following points; (1) distribution of the New Albany shale; (2) amount of shale available; (3) homogeneity and thickness of the formation; (4) amount and quality of the oil obtained from the shale; (5) nitrogen content of the shale; (6) extractibility of the shale and its amenity to breaking; (7) some economic factors bearing upon the utilization of the shale; and (3) other miscellaneous factors and data. In the future, technical work on other phases of the general problem is expected to be done with the object of making a complete survey of this resource which is of much potential importance to the state and nation.

Jan 1, 1923

By A. B. Clayton

The Bumpus Cove area is in Unicoi County, Tenn., about 9 miles south of Jonesboro and 5 miles northwest of Erwin. Iron and lead ores were mined in the Bumpus Cove area before the American Revolution. The production of those metals continued intermittently until 1916. In 1850 this area was the most important producer of iron in the South. In 1911 several carloads of zinc ore was recovered from old dumps and shipped to Missouri smelters. In 1913 systematic mining of zinc ores was begun and continued until 1916. After that year, mining again became sporadic and continued so until discontinued in 1943.

Jan 1, 1949

By Frank J. Wiebelt

The Veta Chica and Cerro Colorado chromite deposits of the McGuffy Creek area, Siskiyou County, Calif. were selected as worthy of investigation by the Bureau of Mines in accordance with the Strategic Minerals Act of 1939. These were two of many chromite deposits examined by engineers of the Bureau of Mines during their extensive wartime mineral examination and exploration campaign. Exploration by the Bureau of Mines consisted of 2,234 feet of diamond drilling, surface trenching, and sampling during the months of May and June 1942.

Jan 1, 1949

By J. P. Capp

The Federal Bureau of Mines and the Alabama Power Company conducted an experiment in underground gasification of coal at Gorgas, Ala. involving the use of hydraulic fracturing to increase the air acceptance of a coalbed for the introduction of combustion air and removal of product gases. Air acceptance is defined as the flow rate of air which can be injected into the coalbed at 65 p.s.i.g. This was the second time the hydraulic-fracturing technique was used at Gorgas. Sand suspended in a heavy oil served as the fracturing fluid in the first experiment; in the second the sand was two to six times larger and was suspended in a water-starch gel. In addition to providing further tests of the underground-gasification process, the purpose of the second experiment was to determine the effects of the larger sand and greater volumes of a water-base fluid on (1) the extent of the fractured area, (2) the air acceptance of the coal, and (3) the rate at which a gasification path could be carbonized (linked) through the coal, and to compare these results with those of the first experiment. The coal was fractured by injecting 11,000 lb. of sand and 33,580 gal. of water and water-gel at 200 to 600 g.p.m. and 900 to 1,000 p.s.i. The fluid fractured the coal and the sand served as a propping agent to hold the cracks and crevices open. Pressures during the fracturing operation at test boreholes indicated that the fracturing fluid extended only about 150 ft. from borehole H, the point of application of the fracture. Injection of air revealed that the air acceptance of the coalbed within this e t was materially increased. On the other hand, increased air acceptance also was noted at boreholes up to 280 ft. from borehole H and at the electrolinking area 300 to 400 ft. away, indicating that the fracture effects extended considerably farther than was evident from observation. Similar effects were noted at approximately the same distances after the first hydraulic fracture.

Jan 1, 1961

By R. Hogg, T. F. Dumm

"There is a considerable need for standardized respirable dusts with consistent, reproducible characteristics which simulate those of actual mine dust. The availability of such materials should be a significant factor in promoting coordinated research into dust characterization and mine monitoring, dust control, and the biomedical aspects of dust toxicology. The use of an opposed-jet, fluid-energy grinding system in closed circuit with a cross-flow, centrifugal air classifier for preparing bulk quantities of respirable-size dust has been investigated, and appropriate, standardized procedures have been established. By stage-crushing, screening, and fine-grinding with a Donaldson Acucut classifier/mini-grinder system, it is possible to produce bulk quantities of respirable dust at relatively high rates. Using minor modifications to the system, broader or narrower size distributions can be prepared within the respirable range. The system has been shown to reach steady-state with respect to product size distribution very rapidly. However, preferential grinding/classification effects appear to lead to a slow build-up of mineral matter in the circulating load with a corresponding slow change in product composition with time. In those applications where the dust composition is required to match that of the feed coal, it may be necessary to allow considerable time for a true steady-state to be established.Standard respirable dust samples have been prepared from coals representing the western (high volitile A bituminous), central (medium volatile bituminous) and eastern (anthracite) mining areas of Pennsylvania. Quartz and kaolin clay samples, representing important mineral constituents of coal dust have also been prepared. Extensive characterization studies have been performed on the samples to evaluate chemical and mineralogical composition and the distributions of particle size and specific gravity. Detailed information on the original coals is available from the Penn State Coal Data Base. The standard coal dust samples appear to simulate actual mine dust very well with respect to particle size and shape, but generally have somewhat lower ash content. Samples of these standard dusts have been made available to research groups concerned with respirable dust in mines."

Mar 1, 1989

1. In 2003, a total of 734 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include, but are not limited to, the mining of clay, shale, barite, potash, trona, phosphate rock, rock salt, gypsum, talc, gemstones, mica, perlite, and pumice. • Nonmetal mines comprised 5.1% of all mining operations. • Nonmetal mining operations are located in all states and territories except Alaska, Delaware, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands. • Mines producing common clay comprised 28.6% (n = 210) of all nonmetal mining operations.

Feb 1, 2005

By Robert P. Vinson, Kissell. Fred N., Edward D. Thimons

"The Bureau of Mines investigated the presence and extent of methane accumulations in mine roof cavities using a full-scale mine model. Methane was released at a constant rate into the roof of a cavity built onto a 700-ft wind tunnel. Two box-shaped roof cavities were used in the study: one had a volume of 114.7 cu ft; and the other had a volume of 57.3 cu ft. Methane concentration was measured at 28 sampling points in the cavities using 21 different combinations of gas emission rates and air velocities. Brattice hung in the cavity helped reduce methane concentrations without auxiliary ventilation. It was also found that the effective ventilation rate increased by a factor of 40 in the large cavity and by a factor of 20 in the small cavity when air velocity was increased from 100 to 600 fpm.INTRODUCTIONAny location in a coal mine where 5 pct or more of methane is present constitutes a potential site for an explosion and roof cavities are likely locations. Unfortunately, little is known about the buildup of methane in roof cavities. Some research has been done using scale models where no air flows past the cavity so that methane disperses only by diffusion (5) 4 a rare situation in mines.No known cavity-model investigations have been made that simulate air and methane flow conditions normally encountered underground. These Bureau of Mines studies were undertaken to determine the extent and manner of methane buildups in coal mine roof cavities with air velocities in the range normally found in coal mines and with various methane emission rates."

Jan 1, 1978

By G. S. Scott, G. W. Jones

"INTRODUCTION An important phase of the accident-preventing program of the Bureau Mines is the determination of the explosion hazards of various combustible gases, vapors, and liquids encountered in mining and allied industries and the development of methods of eliminating or mitigating them.Recently, isobutane has become a commercially important raw material in the production of aviation gasoline by the alkylation process. 4/ in which isoparaffins are combined with olefins to give higher molecular weight compounds of branched-chain structure.Because of the anticipated commercial importance of isobutane in industry, it has been deemed necessary to study and determine its general explosion haz¬ards. This report gives its limits of inflammability, minimum ignition temper¬atures, and the amounts of nitrogen and carbon dioxide required to render isobutane-air mixtures noninflammable."

Jun 1, 1947