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By Charles W. Huggins

A study of the high magnification of some inorganic fibers which are found in nature or produced in the laboratory, has been conducted with the electron microscope. This series of electron microqraphs shows the important morphological differences exhibited by potassium-lead silicate, lead-aluminum silicate, chrysotile, wollastonite, silicon nitride, potassium titanate, cobalt chrysotile, magnesio-fluor-richterite, fluor-richterite, refractory oxide fiber, silicon carbide, massive serpentine, and palygorskite. A ribbon or a thin lath 250-2500 A. wide is the structural form of potassium-lead silicate and lead-aluminum silicate. Chrysotile, cobalt chrysotile, and massive serpentine all have a tubular structure and a fairly uniform (150-300 A.) diameter. Wollastonite, potassium titanate, fluor-richterite, and magnesio-richterite crystals have a lath shape, and potassium titanate laths are laminated ribbons. Single fibers of silicon nitride and palygorskite are ribbons, and the silicon nitride sample contains many twins (branching fibers). Palyqorskite fibers are highly flexible and have cross-sectional measurements of 150-300 A. Silicon carbide fibers differ from other fibers because their structure consists of several different forms. The sample used in this study had, predominately, a margarite-type structure. The refractory oxide fiber lost, all its apparent fibrosity after being prepared for electron microscopic examination, and only irregular fragments are visible in the electron micrographs.

Jan 1, 1962

Quickly and cheaply consolidate underground slimes to facilitate their use as backfill and permit their easy handling for other reasons. Approach: The slurry containing slimes is pumped into active stopes and electrokinetically dewatered to provide consolidated back fill. How It Works: To densify slimes electro-kinetically two electrodes are placed in the material to be dewatered and densified. Typically, the electrodes are pieces of wire mesh fencing. One is placed on the bottom, and the other is suspended in the slurry near the surface. Figure 1 is a simplified section of a test. A d-c voltage of 100 to 400 volts is applied across the slurry. This causes the solid particles which are in suspension in the water (usually these are negatively charged) to migrate toward the anode; simultaneously, the water moves toward the cathode. Water immediately adjacent to the negatively charged solid particle surfaces contains an excess of dissolved positive ions. When these ions are attracted to the electrode and move towards it, they also exert

Jan 1, 1976

By Eldon C. Pattee

THE BUREAU OF MINES began an investigation of tungsten resources of Montana in September 1953. This report presents information obtained from July 1955 to September 1957 on tungsten deposits in and near the Mount Torrey batholith. The batholith comprises part of the Pioneer Mountains of Beaverhead County in the southwest corner of Montana. Included in the report are assays and preliminary-examination data on 22 properties. Tungsten minerals are known to occur in 19 of the properties. The major producer is the Brown's Lake mine which has produced more than 625,000 tons of ore. Nearly all of the deposits are in the Lost Creek, Utopia, and Bald Mountain mining districts along the east and south margins of the Pioneer Mountains. The districts are less than 27 miles from Dillon, Mont.

Jan 1, 1960

In 2006, 14,885 mining operations reported employment data to the Mine Safety and Health Administration (MSHA).1 Almost half (48.2%) were sand and gravel mines, followed by stone mines (30.7%), coal mines (14.2%), nonmetal mines (5.0%), and metal mines (1.9%).

Jan 1, 2008

By R. Barany

In this paper, closed expressions have been obtained for the frequency spectrum of a Born-Karman square lattice in terms of elliptic and hyperelliptic integrals. This work is part of continuing research by the Bureau of Mines with the thermodynamic properties of metals and minerals. Although other workers have obtained various types of approximations for the general case of the frequency spectrum of a square lattice, no one previously has obtained closed analytic expressions for this spectrum. To understand the optical and thermodynamic properties of crystals, several investigators have studied the distribution of frequencies of normal modes of vibration of the crystal lattice. Born and Karman3 laid the foundation for the theory of lattice dynamics and obtained detailed results for the case of a one-dimensional lattice. Blackman4 used numerical techniques to estimate the frequency distribution of a two-dimensional square lattice. Mbntroll5 analytically determined the frequency distribution of a square lattice for a particular value of the force constants. He also studied the more general problem and obtained some analytic approximations, using the method of moments. However, the calculations by this method were so difficult that it was not always practicable to carry them out. Van Hove6 and Montroll7 studied the nature of the singularities in the frequency spectrum of both a two and

Jan 1, 1962

By August J. Kwitowski

This Bureau of Mines report summarizes the development of a protective operator compartment for a new generation thin-seam mobile bridge carrier. The developed compartment is commercially available and is currently employed on approximately 15 bridge carriers used in the mining industry. The design of the compartment, which employed human factors engineering and small- and full-scale mockup models, is fully described. Details of the compartment's fabrication, evaluation, and demonstration in a commercial low-seam coal mine are also provided.

Jan 1, 1986

By Grant R. Brown

The report provides guidance for determining those environmental impacts associated with the surface mining of steeply pitching coal seams. In addition to the environmental impacts, four additional issues are addressed, namely (1) Time and motion studies of those coal mining systems employed in mining seams which pitch in excess of 250, (2) Assessment of those mining techniques, (3) Development of rationale for the mining methods employed, (4) Identification of the reclamation practices and determine whether these practices were in compliance with appropriate Federal and State regulations. Five surface mines located in three geologically distinct basins of the United States were analyzed during the period of August through November 1979. The three basins include the Hanna Basin of Wyoming, the North Park Basin of Colorado and the Southern Anthracite Field of Pennsylvania.

Jan 1, 1980

The development of an onboard contaminant diagnostic monitor to continuously measure contaminant level in a mining machine was advanced to a prototype stage in this contract. Several concepts were investigated and it was found that a static spool type sensor was the most reliable and accurate. Laboratory and field tests showed that an instrument based on this concept is capable of measuring contaminant levels and/or size distribution, depending on the configuration of the sensor. Moreover, this instrument can function on emulsions or homogeneous fluids. Current laboratory equipment can operate on homogeneous fluids only.

Jan 1, 1983

By G. W. Josephson

WHILE methods of utilizing blast-furnace slag have been developing, a great deal of literature on the subject has accumulated, but no comprehensive summary of information that would be helpful to engineers, contractors, architects, chemists, and others in under-standing and more successfully using this byproduct of the iron and steel industry has been published in the English language. The National Slag Association recognized the need for such a publication, and the Problems Committee of the Association under-took in 1943 to accumulate the necessary material. Over a period of several years this committee compiled pertinent information in manuscript form, and in 1948 the Bureau of Mines and the National Slag Association made an agreement whereby the Bureau was to prepare the data for publication as a cooperative bulletin of the Bureau of Mines and the National Slag Association.

Jan 1, 1949

By Edward W. Parsons

The transverse force developed by expansion-shell rock-bolt anchors on the wall of a drill hole as the bolt is tensioned was measured by the Bureau of Mines using a device specially designed and fabricated for attachment to a universal testing machine. Load cells equipped with electrical-resistance strain gages provided the data from which the transverse force, in pounds, was calculated. Seven different expansion-shell anchors were tested, and the ratio of transverse force to bolt-tension load was found to range between 0.98 and 1.94 to 1.0. The drag load appeared to be the major cause of the transverse-force variation, but the relative effects of individual factors that affected the ratio between the transverse force and the bolt tension were not determined.

Jan 1, 1968

By Robert E. Manning

At present, a need exists for more effective noise control in the coal-mining industry. In particular, new muffler designs with the required acoustic performance are needed for percussive pneumatic drills. Accordingly, the U. S. Bureau of Mines issued a contract to USS Engineers and Consultants to design a muffler capable of attenuating the noise from the air exhaust of a pneumatic drill. The specific objective of the contract was to design and deliver a prototype muffler that would attenuate the air-exhaust noise to 90 decibels on the A scale (90 dbA). The test drill used in this investigation was one used for roof-bolting purposes in coal mines. Using the combined approach of analysis by digital-computer program and experiment by simulated-noise tests, three prototype mufflers were designed and constructed at U. S. Steel Research. The mufflers consisted of a variety of resonator chambers and expansion-contraction chambers, and were of the following sizes: A muffler with a 3- by 5-inch elliptical cross section and about 8 inches in length. A muffler 5 inches in diameter and about 5-1/2 inches in length. A muffler 5 inches in diameter and about 10-1/2 inches in length. These mufflers were subjected to laboratory tests to determine their effectiveness in attenuating exhaust noise, mechanical noise, total drill noise, and simulated noise. All mufflers reduced the exhaust-noise level by about 25 dbA - from about 115 dbA without a muffler to below 90 dbA with a muffler - and thus were successful in meeting the contract objective. Field tests were conducted with the three prototype mufflers at U. S. Steel's Robena No. 4 Mine, and no icing problem was encountered. A fourth prototype muffler was designed to fit around the leg of the pneumatic drill. Tests showed that this kidney-shaped muffler also reduced the air-exhaust noise to below 90 dbA.

Jan 1, 1973

By Paul S. Goodman

This report examines absenteeism and accidents. The first section provides some background information on absenteeism. The second section examines trends in absenteeism in underground coal mines over time. The third section examines causes of absenteeism. Models were examined. The first model looks at self-report reasons for absenteeism. The second examines demographic correlates of absenteeism. The third model includes demographic and attitudinal predictors of absenteeism. The next section of the report examines the effect of absenteeism on accidents. The last section contains strategies for reducing absenteeism.

Jan 1, 1985

By Walter D. Holland

This study was undertaken to determine miners' breathing zone concentrations of diesel exhaust components, to investigate any relationships between these concentrations and vehicle type, the presence of emission controls, vehicle usage, and ventilation conditions, and to make recommendations for monitoring and ventilation requirements. Twenty-four mines including two con l mines were surveyed. Sampling was done for CON, NON, SOx, PNA, aldehydes, and particulates. hi most mines, concentrations of at least one contaminant exceeded one half the standard or TLV. The concentrations of gases arc probably sufficiently reduced by a minimum air velocity of 50 fpm. A sufficient reduction of particulate concentrations may require as high as 400 fpm air velocity. Vehicle age, type, or usage appear to have little or no effect on contaminant concentrations. PNA levels were below detection limits in all but a very few samples. Minimum requirements for routine monitoring should include formaldehyde, COx, NO2. It is further recommended that better definition of the minimum ventilation requirement be obtained.

Jan 1, 1978

By Phillip N. Yasnowsky

This Bureau of Mines publication tabulates State taxes levied on nonfuel minerals that have the characteristics of a severance tax.

Jan 1, 1978

By Grant R. Brown

The report provides guidance for determining those environmental impacts associated with the surface mining of steeply pitching coal seams. In addition to the environmental impacts, four additional issues are addressed, namely (1) Time and motion studies of those coal mining systems employed in mining seams which pitch in excess of 25°, (2) Assessment of those mining techniques, (3) Development of rationale for the mining methods employed, (4) Identification of the reclamation practices and determine whether these practices were in compliance with appropriate Federal and State regulations. Five surface mines located in three geologically distinct basins of the United States were analyzed during the period of August through November 1979. The three basins include the Hanna Basin of Wyoming, the North Park Basin of Colorado and the Southern Anthracite Field of Pennsylvania.

Jan 1, 1980

By Millard M. Gilkey

This Bureau of Mines report presents results of a detailed study of water usage in the Wyoming mineral industry along with projections for the future In 1964, the mineral industries of Wyoming used 20 billion gallons of new water, nearly all self-supplied, and reused 72 billion gallons, a total usage of 92 billion gallons. Consumption amounted to 2.8 billion gallons. About one-half of the 20 billion gallons of new water was obtained from [srface] sources and the rest from ground water. Reported costs, covering power and maintenance, for the self-supplied new water at mineral industry operations ranged from less than 1 cent to 20 cents per thousand gallons and aver-aged 8 cents. At one mineral-related operation, water was hauled by truck to supplement a well supply. The cost was $2.00 per thousand gallons delivered. However, the supplemental requirement was only 10 gpm. Cost figures for the recirculation of water, covering power and maintenance, averaged 2 cents. In terms of water usage, the value of product for the entire industry was $25 per thousand gallons of new water intake and about $180 per thousand gallons consumed. The study revealed that Wyoming has a water deficiency but that the shortage is less severe than in the arid Southwest. Projection of the water needs of the Wyoming mineral industries indicates that the demand for new water will increase from the 20 billion gallons used in 1964 to 25 billion gallons in 1980, a 25-percent increase. The projected new-water requirement for the year 2000 is 40 billion gallons, a 100-percent increase compared with the 1964 figure.

Jan 1, 1967

To provide a means for accurately and reliably warning of impending roof falls or rock bursts and for evaluating support systems. The Approach: Development of a device for measuring rockbolt loads which is not affected by harsh environments nor by eccentric loading conditions and is easily adapted to various size rock bolts. How It Works: The Rock-Bolt Tension Load Cell, developed by the Bureau's Spokane (Wash.) Mining Research Center, is installed on a bolt and sandwiched between a conventional doughnut washer bearing plate and a torqueing nut (Fig. 1). As the bolt takes load, the bearing plate transmits the load axially to the cell through a ball and socket arrangement, compensating for uneven bearing surfaces. The cell body strains in proportion to the applied load: the strain is sensed by welded strain gages as change in electrical resistance. The resistance change is read through a Wheatstone Bridge and, through calibration, the applied load is determined.

Jan 1, 1974

By Francis E. Federspiel

Based on the investigation by the Bureau of Mines, tungsten is the principal metal found in the study area; gold and silver were the primary metals found at one property. Tungsten occurs in tactite zones formed near contacts of calcareous metasedimentary with granitic intrusive rock. Gold and silver were found primarily along quartz veins in granitic rocks; small amounts of those petals also occur in the tactite zones. Since 1856 approximately 200 lode claims or relocations have been recorded, mainly in the southwest corner of the study area. Tungsten production in this part of the area has been inure than 7,800 short ton units (70,800 kg) of tungsten concentrates; about 4,800 short ton units (43,500 kg) were from the Mud Lakes Mine; and 3,100 short ton units (27,200 kg) were from the Rainbow Mine 1/.

Jan 1, 1981

By William J. Campbell

Expansion measurements of platinum, added as an internal standard, are used for thermal calibration of X-ray cameras and diffractometers. Accuracy of the temperatures derived by this technique depends on the precision of expansion measurements and the reliability of reference expansion data. Temperature measurements to ± 1° C. require ?d or ?a to be determined within ± 0.001 percent. Selected expansion data are concluded to be reliable to 2° C., 5° C., and 25° C., over the temperature ranges 0° C. to 700° C., 700° C. to 1,000° C., and 1,000° C. to 1,700° C., respectively. Tabular expansion values from 25° C. to 1,700° C. in 2° C. intervals were calculated from the following equation; Expansion, percent = [8.91 + 1.28 x 10-3(t-25) + 0.04 x 10-6(t-25) ] [t-25.104 ] These tabular values facilitate future corrections of published temperatures as more reliable expansion-temperature data become available.

Jan 1, 1962

By Alex C. Smith, Michael J. Sapko

A series of explosive detonation experiments was conducted in NIOSH’s Bruceton and Lake Lynn Experimental Mines to evaluate low level (<6 psig) detonation wave propagation behavior in single and multiple entry configurations. Entry cross-sectional area varied from 5 to140 m2 and explosive weights of Pentolite ranged from 0.24 to 2.4 kg. Behavior of the detonation wave was evaluated through recording of the pressure as a function of time and distance from the explosive detonation in single and multiple entry interconnecting tunnels. Peak pressure from detonation of an explosive in an underground mine maintains magnitude for a greater distance than is the case on the surface and is shown to follow the simple scaling rela-tionship P = 702.8(W/Vt)0.514(0.65)n, where P is the peak detonation pressure in kPa, W is the weight of the explosive charge in kg, Vt is the total volume in m3, and n is the number of splits, n = 0, 1, 2, …n. The total energy, or impulse, I, generated by these detonations can be expressed as I = 1.34(W/A)0.64n, where W is the weight of the explosive charge in kg, A is the area of the main tunnel in m2, and n is the number of side en-tries, n = 0, 1, 2, …n.