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Pillar design is the first line of defense against rock falls—the greatest single safety hazard faced by underground coal miners in the United States and abroad. To help advance the state of the art in this fundamental mining science, the National Institute for Occupational Safety and Health organized the Second International Workshop on Coal Pillar Mechanics and Design. The workshop was held in Vail, CO, on June 6,1999, in association with the 37th U.S. Rock Mechanics Symposium. The proceedings include 15 papers from leading ground control specialists in the United States, Canada, Australia, the United Kingdom, and the Republic of South Africa. The papers address the entire range of issues associated with coal pillars and have a decidedly practical flavor. Topics include numerical modeling, empirical design formulas based on case histories, field measurements, and post failure mechanics.

Jan 5, 1999

By D. W. Richardson

This Bureau of Mines publication provides the enthalpy of formation of malachite [Cua(COs)(OH)2] as determined by hydrochloric acid solution calorimetry. At 298.15 K the enthalpy of formation from the component oxides is -15.l0±0.30 kcal/mole and from the elements, -251.9±0.5 kcal/mole.

Jan 1, 1974

[In selecting deposits of exploration projects, tabular deposits or large mineralized masses are favored because they may be explored systematically and because they afford the best opportunity for blocking out reserves in advance of mining, whereas irregular, small pipes and scattered]

Jan 1, 1941

[In selecting deposits for exploration projects, tabular deposits or large mineralized masses are favored because they may be explored systematically and because they afford the best opportunity for blocking out reserves in advance of mining whereas irregular, small pipes and scattered]

Jan 1, 1941

By James C. Barker

Yttrium and rare-earth element. pegmatite dikes are associated with a peralkaline granitic and nephelene syenite complex near Dora Bay on southern Prince of Wales Island. Mineralized dikes were mapped and sampled during USBM investigations in 1987 and 1988. Coarse-grained pegmatite dikes, which emanated as late-stage magmatic fluids from the intrusion, further evolved into vein-dikes and ultimately silica-rich veins. The dikes can be traced up to two miles along a north-south zone. Lithophile elements exhibit a pronounced zonation in vein-dikes and veins that are distal to the Dora Bay complex with increasing values correlating with increasing distance from the complex. The pattern of mineralization suggests very late stage magmatic fluids containing the incompatable lithophile elements were injected into a preexisting north-south fracture zone. REE mineralogy exhibit fine-grained intergrowths of principally thalenite and bastnaesite with lessor monazite and eudialyte. Euxenite contains most of the columbium values and zircon is commonly associated with the dikes. Estimates of inferred and hypothetical resource tonnage range from 1.7 X 1C6 to 8.5 X 106 st for two deposits. Contained RED (including yttrium) averages 0.5 pct and ranges up to 2.0 pct. Deposits are of polymineralic composition and about half of this resource comprises the heavy yttrium subgroup.

Jan 1, 2011

By J. R. Allsup

The Bureau of Mines studied the characteristics of simulated coal gas as an automotive fuel in two multicylinder vehicles in a standard and high-compression-ratio engine configuration. While using simulated coal gas fuel, increasing the engine compression ratio improved the fuel economy and vehicle performance but increased hydrocarbon emissions by 40 pct. photochemical reactivity of exhaust hydrocarbons was found to be extremely low using the coal gas fuel. An oxidizing catalyst used with the simulated coal gas fuel eliminated all but trace amounts of carbon monoxide and reactive hydrocarbons in the exhaust. Spark gap geometry and firing voltage were varied and, within the range tested, had little effect on vehicle performance and emissions using simulated coal gas fuel.

Jan 1, 1975

By Michael J. Brnich

On November 20, 1968, a massive explosion rocked the underground workings of Mountaineer Coal Co.?s Farmington No. 9 Mine in West Virginia. Of the 99 miners who were working in the mine at the time of the explosion, only 21 survived and escaped the mine. This group included eight who were rescued from the Mahan?s Run air shaft. Nearly 40 years after the event, researchers from the NIOSH Pittsburgh Research Laboratory conducted oral history interviews with two of the eight survivors rescued from the shaft. The Farmington No. 9 Mine disaster ultimately led to passage of the Federal Coal Mine Health and Safety Act of 1969 (amended in 1977).

May 1, 2009

By J. Mitchell Linne

In 1985, at the request of Bureau of Land Management, the U.S. Bureau of Mines studied a 54,480-acre portion of the 93,205-acre Dry Valley Rim Wilderness Study Area (CA-020-615), in order to evaluate its identified resources. The area studied is in Washoe County, NV, and Lassen County, CA, about 35 miles east of Susanville, CA. No metallic resources were identified. The Red Rock and Willow Springs areas contain 85 million tons of altered basalt with zeolite amygdules. This material, averaging more than 50 percent chabazite, constitutes a subeconomic zeolite resource. This zeolite-bearing material would require beneficiation to upgrade it for higher value uses. Natural zeolites have a small market in the United States, which is presently supplied by other higher grade material. There is low probability that these resources will be mined in the foreseeable future. The Capricorn claims, adjacent to the study area, are on alluvial sediments containing more than 30 percent montmorillonoid clays. The material is not usable as pozzolan and was not tested for other uses such as absorbency, oil clarification, or insecticide carrier. The term pozzolan refers to a number of siliceous materials which are combined with portland cement to enhance the physical properties of the resultant concrete. The area is remote from market and contains low value material. It is improbable that this occurrence will be mined in the foreseeable future.

Jan 1, 1987

By Joseph D. Davis

Selection of a suitable coal or coals for the manufacture of coke of desired quality with due consideration of the purpose for which the coke is intended requires careful thought, and often it will pay to go to considerable expense in testing such coals as may be available. In general it will

Jan 1, 1942

By W. H. Kerns

The Critchfield manganese deposit, Huntingdon County, Pa., was investigated by the Bureau of Mines in October 1942. Iron ore was mined from an open cut just southeast of the manganese deposit about 80 years ago. The Critchfield Sand & Feldspar Co. was operating (1942) a clay-mining and beneficiation plant northeast of the manganese deposit. The Bureau completed six rotary bucket-drill holes and three hand-auger holes, aggregating 370 feet on the deposit. This report describes the work performed and presents the results obtained.

Jan 1, 1948

By C. W. Huggins

The objective of this Bureau of Mines research was to compare the size distribution of respirable quartz collected at coal mines with that of several reference standards used to quantify quartz in coal mine dust samples. Particle size measurements were made on 23 samples and 4 ref-erence standards using a scanning electron microscope in the backscatter electron mode of operation, interfaced with an image analysis system. The Mine Safety and Health Administration provided the 23 respirable coal mine dust samples, which were collected at surface and underground coal mines in 7 States. The accumulated particle size measurements in-dicate three of the reference standards, minus 5-um Min-U-Sil, minus 5-um Supersil, and NBS 1878, would be preferred over the fourth, Silver Bond B, for quantitative quartz determinations in coal mine dusts by X-ray diffraction and infrared spectrometry.

Jan 1, 1985

By Alla D. Mah

The need for more and better basic thermodynamic data for the oxides of many of the rare metals is evident to anyone who attempts thermodynamic calculations involving these substances. In continuation of a Bureau of Mines program to meet this need, this paper reports new experimental values of the heats of formation at 298.15° K. of the hexagonal crystalline variety of germanium dioxide and germanium dioxide glass. The values were obtained by means of combustion calorimetry and sodium hydroxide-solution calorimetry. The calorimetric results also made possible the derivation of values for the heat and entropy of fusion of hexagonal germanium dioxide at its melting point. The newly measured data were combined with previously known entropy and high-temperature heat content values to obtain heats and free energies of formation of germanium dioxide (in the hexagonal crystalline, glassy, and liquid states) over the temperature range from 298.15° to 2,000° K.

Jan 1, 1962

By C. B. Manula, R. L. Sanford, R. A. Rivell

A - Contains the coordinate pair information for deriving the co¬efficients of the 3rd degree polynomial which approximates the loading station equation. C(N) - Coefficients for third degree approximating polynomial. I - General DO LOOP variable. K - Position in BRANCH of next character. L - Format specification in DEFINE FILE statement. X - Uniform displacement for random uniform number. Y - Load increment At. AO-A3 - Coefficients of approximating polynomial for loading station equation. GR - Grade direction, or grade resistance. IQ - Counts quadruples of distance grade speed and end of route for determining total distance. IT - Intersection counter in XXXDEF. Il - Station number trip is leaving. Jl - Station number for trip destination. J2-J8 - Motor assignments and functions for given trip. KK - Location of starting grade and distance in DISTGR KK - Position of decimal point in real number. KZ - DO LOOP variable for motor assignment check. LL - Location of ending grade and distance in DISTGR. Ll - Position in IECB of station satisfied. L3 - Next available position for IECB sort. MM - Flag for printing the failure of sanding to overcome slippage. NN - Trip destination in MOTSER RR - Rolling Resistance. XK - Station level or type.

Jan 1, 1974

By J. Vance Batty

The Permian Red Bed copper deposits of the South Central States are a potentially important resource. Only the higher grade, near-surface ores are now exploited because conventional froth flotation does not recover oxidized copper minerals which comprise 10 to 15 percent or more of the copper content of typical ore. Laboratory-scale beneficiation studies were initiated to devise a method capable of recovering both sulfide and oxidized copper mineral. Testing established that the high clay and gypsum content of typical ore prevented effective flotation of the oxide mineral using sulfidizing, fatty-acid, or oil emulsion techniques. A modified leach-precipitation-flotation (L-P-F) procedure recovered over 90 percent of the copper, compared to a recovery of 77 percent obtained by conventional sulfide flotation. The higher costs of the L-P-F method would reduce the increased revenue from higher copper recovery. An increase in copper price and/or an increase in oxide copper content of the ore would make the L-P-F process comparatively more attractive.

Jan 1, 1970

By E. C. Lane

During the past 15 years the Bureau of Mines has made and published several hundred analyses of typical petroleums and has developed a system of interpreting the analyses and of classifying crude oils. In describing crude petroleum frequent reference is made to the "base" of the oil, a usage the petroleum industry has found convenient. As part of its general study of the characteristics of crude oils, therefore, the Bureau of Mines has developed a system of classifying them according to "base." This system as first published in 19274 was limited to four classes and in its original form is no longer considered adequate. Since the system was first published the Bureau has analyzed a large number of crude oil-, including representative samples from nearly every important producing field in the world, and has found that the system of classification could be revised and amplified to advantage. The revised system is presented herein. Bulletin 2916 states that many oil producers and refiners use the word "base" much as it is used in pharmaceutical work. For example, the "base" or "basis" of an ointment or salve is the fatty material (lard, petroleum, or lanolin) used as a vehicle or carrier for the active medicinal principles. Apparently many of the pioneers in the petroleum industry considered crude oil similar in nature to these medicinal products in that it consists of a semisolid, nonvolatile base and 1 volatile portion can be distilled off to make gasoline, kerosene, and other products. Many crude oils when chilled slowly deposit a waxy material (paraffin); this fact may have been one reason for the use of the term "paraffin base" in referring to such oils. Almost all of the petroleum first discovered in the United States was of this nature; not until the oil industry was extended to California and along the Gulf coast was petroleum found that contained no wax but apparently did contain asphaltic material Accordingly, these oils were known as "asphalt-base" oils. The use of this term, however, seems unfortunate, as better-grade oils of this type contain little if any asphalt; the descriptive term "naphthene base" now seems to be a more desirable term than "asphalt base." The term "intermediate base" is also used commonly in referring to oils intermediate in oharacteristios between those of paraffin and naphthene base.

Jan 1, 1935

Provide reasonably priced, reliable fire protection for loading shovels. Approach An automatic fire, sensing and suppression system using both dry chemical and Halon 1301 was developed. It is more rugged than similar industrial-type fire protection systems. How It Works Temperature sensors detect heat from a fire, and trigger the system. These sensors are located inside the machinery house and under the house and shovel frame where it rotates around the crawler chassis ring gear. An alarm is sounded, and extinguishing agents are released either in the machinery house or in the ring gear area. The system can also be triggered by a manual control. If the fire Is detected in the machinery house, all power is shut down to the motor-generator sets, ventilation fan, and all electrical controls. Doors are automatically closed. After a delay to allow time for the ventilation fan to stop, Halon 1301, a gaseous fire extinguishing agent, is released inside the machinery house until it reaches a concentration of about 7 percent. This concentration is sufficient to extinguish a fire, but isn't toxic to personnel

Jan 1, 1980

The Minerals Data Source Directory is a compilation of descriptive information on the availability, content, and location of minerals data in the Federal Government. It is intended to assist Government personnel and the general public in locating and acquiring minerals information. Included in the Directory are descriptions of data bases, publications, information systems, and information offices containing data pertaining to all aspects of mineral production, consumption, trade, and related information. These mineral data sources include the Federal agencies such as the Department of the Interior's Bureau of Mines and Geological Survey whose major mission is the collection and dissemination of mineral information. Also included are agencies such as the Departments of Agriculture, Commerce, Labor, State, and Treasury, and the Central Intelligence Agency, whose primary mission is the collection of data in non mineral subject areas, but in which the mineral industry is a component.

Jan 1, 1982

By John E. Shelton

The growing interest in beryllium as a structural material, and its in-creased use in recent years for atomic energy application, have led both government and industry to express concern over the inadequacy of the beryllium resources in the United States and the free world. Contemplated and proposed uses for this unique material will surpass the capacity of the domestic beryllium mining industry to supply raw material, which is presently extracted from relatively small deposits by hand sorting. The need for a simple beneficiation process for beryl ores has long been recognized by the Bureau of Mines, but to date no single process has proved satisfactory for treating deposits containing a sufficient tonnage of beryl ore to warrant commercial exploitation. As a part of the Bureau's continuing effort to develop an economical recovery process, this report describes flotation research on samples of beryl-bearing pegmatites from the George Roebling mine in Connecticut, and the Colony mine in New Hampshire. The study resulted in two methods of treatment to which the ores responded reasonably well.

Jan 1, 1961

By T. E. Marshall, D. R. Dolinar, C. S. Cornpton, L. J. Prosser, A. T. Iannacchione, D. C. Oyler

The U.S., Australian, and United Kingdom coal and the Canadian hard rock mining industries have long recognized the significance of high horizontal stresses as a factor affecting the stability of roof and rib conditions in underground mines. Recently, a growing segment of the U.S. underground stone mining industry has also begun to recognize that horizontal stresses occur in some of its more than 90 mines. Considering the typically high strength and massive nature of limestone, this fact is a revelation in itself. High horizontal stresses produce extensive and sudden rock failures and, in some cases, resulted in injuries to mine workers. Through the years diverse control strategies have been proposed and experimented with. Reorientation of mine entries to reduce stress concentrations have proven successful and are widely accepted in practice. Other solutions, like rock reinforcement, are poorly understood and less accepted in practice. It is the purpose of this National Institute for Occupational Safety and Health (NIOSH) study to develop a better fundamental understanding of these ground control strategies under high horizontal stress conditions through a series of field and laboratory studies. To this end a design technique is presented which provides stone miners with a method for making stability assessments. The consequences of widening rooms, changing geology and horizontal stresses, and different rock bolts on roof beam failures are discussed.

By Jesse L. Hoyer

A Bureau of Mines turbomill was evaluated for use in the production of high-purity, ultrafine x-Sic powders suitable for advanced ceramics that could substitute for high-temperature alloys containing critical materials such as chromium, cobalt, and nickel. The effect of milling param-eters, such as type of dispersant, temperature, pH, and gas environment, on the milling of x-SiC was studied. The addition of dispersants improved the grindability of x-SiC. Of the six dispersants studied, the best results were obtained with Mara-sperse N-22. Grinding efficiency was also increased when the x-SiC was milled in a basic slurry and at elevated temperature. Gas environments did not appear to affect grinding of x-SiC. Optimum grinding efficiency was obtained at 50° C in a slurry at pH 9.5 with Marasperse N-22 as the dispersant. Under these conditions, minus 100-plus 200-mesh x-SiC was ground to 80 pct less than 1 um in 4 h.

Jan 1, 1987