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By W. E. Anable

The Bureau of Mines studied the purification of commercially available yttrium by melting it in a 100-kw electron-beam furnace. Button-scale melts were made to determine the ultimate purification that could be attained by melting yttrium at 1,733° to 1,770° C at low pressure (0.05 to 0.1 micron) for 1 to 120 minutes. In addition, numerous melts were made to study the effect of doping yttrium with carbon, 17 selected metallic additions, and 3 compounds. Except for nickel and zirconium, the metallic impurities in yttrium were lowered significantly on extended treatment; silicon was lowered only slightly. The nonmetallic impurities} oxygen, nitrogen, and carbon, were not lowered except on short exposures. In isolated instances, the oxygen content was lowered from 5,860 ppm to about 5,000 ppm. In most instances the carbon con-tent was lowered from 545 to about 220 ppm in 20 minutes and then increased again. It was concluded that yttrium cannot be purified by direct heating or by the doping technique employed.

Jan 1, 1965

By T. J. McDonald

The methods used and the results obtained in the application of high-expansion foam on a recent fire in an operating mine in western Pennsylvania were reviewed. This is the first instance where foam has been applied extensively to a fire under actual mining conditions although considerable research has been conducted and experimental fires have been controlled. The Bureau of Mines began investigating the foam-plug technique in 1957 in its experimental coal mine, following reports of successful trials in Eng-land, where the basic methods, using the normal ventilating current, were developed. Early in the research it was apparent that the normal ventilating current in mines in the United States would not provide adequate air pressure to drive a foam plug the distance that might be required. Subsequently, the Bureau of Mines developed a portable high-expansion foam generating unit consisting of a fan having relatively high pressure potential, net, sprays, and metering equipment. To date, foam generators have been constructed by the Bureau, by at least one operating coal company, and by one manufacturer of safety equipment. A number of units from the latter supplier have been adopted by coal-mining companies as an integral part in their firefighting installations.

Jan 1, 1961

By Foster Fraas

In the separation of a component from a mixture , two fractions are obtained , one containing a high - percentage composition of the component and the other a low - percentage composition . The high - percentage fraction is frequently called the concentrate and the low - percentage fraction the tailing . In many separation processes the recovery is not complete , and the composition of the concentrate decreases as the recovery of the component, which is concentrated , increases . It is this particular class of separations to which this paper is confined .

Oct 1, 1942

By Michael J. Sapko, Samuel P. Harteis, Eric S. Weiss

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) recently conducted full-scale explosion experiments; these experiments evaluated the strength characteristics of various seal designs used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests were conducted within the multiple entry section of PRL’s Lake Lynn Experimental Mine (LLEM) employing the only currently accepted test method endorsed by the Mine Safety and Health Administration (MSHA) for seal design in American mines. These explosion tests are labor-intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. Therefore, the PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in-situ testing of seals in an operating mine. Two chambers within LLEM and one within the Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from tests in these chambers compare favorably with those from the large-scale explosion tests in the multiple entries. Preliminary size-scaling relationships for predicting the strength of standard seal designs as a function of entry size is also presented. In addition to testing seal designs at the required 20 psi static pressure level, the new facilities also allow for the determination of the seal’s ultimate failure pressure. This new approach shows promise as an alternative evaluation method for improving mine sealing technologies which, in turn, will enhance the safety of the underground personnel.

By Gerald J. Joy, Paul J. Middendorf

This study examines the patterns and trends in noise exposure documented in data collected by Mine Safety and Health Administration inspectors at U.S. coal mines from 1987 through 2004. During this period, MSHA issued a new regulation on occupational noise exposure that changed the regulatory requirements and enforcement policies. The data were examined to identify potential impacts from these changes. The overall annual median noise dose declined 67% for surface coal mining and 24% for underground coal mining, and the reduction in each group accelerated after promulgation of the new noise rule. However, not all mining occupations experienced a decrease. The exposure reduction was accompanied by an increase of shift length as represented by dosimeter sample duration. For coal miners exposed above the permissible exposure level, use of hearing protection devices increased from 61% to 89% during this period. Participation of miners exposed at or above the action level in hearing conservation programs rapidly reached 86% following the effective date of the noise rule. Based on inspection data, the occupational noise regulation appears to be having a strong positive impact on hearing conservation by reducing exposures and increasing the use of hearing protection devices and medical surveillance. However the increase in shift duration and resulting reduction in recovery time may mitigate the gains somewhat.

By Fred N. Kissell

A self-sealing brattice intended for use during coal mine rescue and recovery operations has been designed and tested by the Bureau of Mines. The major design difference between self-sealing and conventional brattice is that the fabric is cut and sewn BS a hemisphere instead of as a flat sheet. This new type of brattice offers reduced weight, leakage, and installation time. Preliminary testing indicates that the concept is worthwhile, but that further developmental research is required.

Jan 1, 1976

By Murray Jacobson

The Federal Coal Mine Health and Safety Act of 1969 established mandatory dust sampling of coal mines according to procedures prescribed in the Mandatory Health Standards, title 30, Code of Federal Regulations, part 70, published in the Federal Register on April 3, 1970. A laboratory was established in the Pittsburgh Field Health Group of the Bureau of Mines to process the coal mine dust samples collected by the mine operators. This paper describes the laboratory and presents the equipment and procedures used in processing these samples.

Jan 1, 1971

By T. J. Ballard

Corundum is a natural alumina (A120 ) and is next to the diamond in hardness . Except for the gem varieties , it is used principally as an abrasive , chiefly in grinding , dressing , and polishing metals and optical glass . Natural corundum is preferred to artificial abrasives for certain specialized jobs . Most of the corundum ( excluding emery ) mined in the United States came from the Corundum Hill mine in North Carolina and the Laurel Creek mine in Georgia . The Corundum Hill mine provided over half of the domestic production of corundum prior to 1900. Since 1900 , the importation of foreign corundum and the manufacture of artificial abrasives caused the decline of corundum mining in the United States .

Mar 1, 1947

By H. H. Fields, Joseph Cervik, G. N. Aul

Coal is a soft and brittle material. Drilling rates in the Pittsburgh coalbed using a drag bit exceed 3 ft/min at 2,500-pound thrust. However, maintaining the bit on a horizontal trajectory or parallel to bedding planes to attain lengths of 1,000 feet is difficult. This Bureau of Mines report presents a drill string configuration that can be guided through the coalbed. The angle of the borehole is measured periodically and by proper combinations of bit thrust and rotational speed (r/min), bit trajectory can be lifted or dropped to keep the bit in the coalbed. An example of a hole drilled to 2,126 feet is presented to show levels of thrust and rotational speed used to lift or drop the bit, the seemingly unexplainable events that occur, and the strategy used during drilling. Thrust levels during drilling range from 600 to 2,500 pounds. Hydraulic motors powered by a 30-hp, 440-volt motor provide ample power for drilling horizontal holes 2,000 feet long.

Jan 1, 1975

By H. B. Carroll

The Bureau of Mines has designed and built a controlled-environment test chamber specifically for instrument evaluation in simulated work atmospheres. The atmosphere inside the 300-liter stainless steel chamber can be controlled at any selected temperature and relative humidity in the range of 2° to 93° C and 20 to 95 percent, respectively. Instruments placed inside the test chamber are subjected to an atmosphere at a preset temperature and humidity containing various concentrations of toxic gases such as CO, C02, NO, NO2, S02, and H2S. Toxic gas losses resulting from wall reactions, monitoring instruments, and instruments under evaluation are compensated by the use of a dynamic gas blending system.

Jan 1, 1973

By Murray Jacobson

The respirable dust standard in the Federal Coal Mine Health and Safety Act of 1969 is designed to prevent disability and death from coal workers' pneumoconiosis. Beginning June 30, 1970, the operators of coal mines were required to maintain the average concentration of respirable dust in the active workings at or below 3.0 milligrams of dust per cubic meter of air. The standard is reduced to 2.0 milligrams per cubic meter after Dec. 30, 1972. This paper presents the equipment and procedures used by the coal mine operators in implementing the respirable dust sampling program established by the Secretary of the Interior and the Secretary of Health, Education, and Welfare and shows the effect of the law, during the first year, on the reduction of dust levels in selected mines. The system employed by the Bureau of Mines for analyzing and processing the dust samples is also presented.

Jan 1, 1971

By Lewis C. Karrick

This paper is based on data obtained in the course of the oil - shale investigations of the U. S. Bureau of Mines , conducted in cooperation with the State of Utah . The amount and quality of oil that can be produced from any shale may be made to vary to an important degree by changing the temperature relations existing in the shale charge during destructive distillation . The rate at which the oil is formed from the shale is affected by the rate of heat supply , and therefore by the temperature of the shale during its thermal de composition . The quality of the oil formed may be controlled by altering the temperature of the shale , and therefore , the rate of formation of the oil . Variations in the yield and quality of shale oils may be caused by inherent properties of the retort used , but in any event the properties of the crude oil and yield are very largely the result of the extent to which the thermal de composition has progressed . Recognition of these principles will aid in explaining to a large degree the reasons for the wide variations in oils produced from the same shales by different " processes " . These principles also may be applied in the operation of different types of retorts in order that crude oils of a type most profitable to the operator may be produced . The Bureau of Mines has conducted an extended series of tests in the dee structive distillation of oil shales , in order to determine the wide variations that may be effected in the quality and yield of shale oil by changing the rate and temperature at which the oil is formed . These tests furnished interesting information on the four related points : yield of oil , quality of oil , temperatures required to distill shales , and time required for distillation .

Mar 1, 1923

By R. Hogg, T. F. Dumm

"Procedures for particle size analysis on respirable dust from coal mines have been evaluated. Using respirable dusts dispersed in a laboratory dust chamber, size distributions measured using cascade impactors have been compared with the results of a variety of laboratory sizing methods performed on samples collected on filters placed side-by-side with the impactors. The laboratory techniques included centrifugal sedimentation, laser diffraction/scattering and automatic particle counting. The general agreement among the various methods was very good, with systematic differences which can be attributed to the different definitions of size used. Simple conversion factors have been obtained which can be used to transform the laboratory data to equivalent aerodynamic sizes.Similar comparisons have been made on samples collected in underground coal mines. Again, the results are in quite good agreement although small discrepancies were observed in· some cases. These have been attributed to some degree of agglomeration in the airborne dust, leading to slightly coarser apparent distributions in the impactor samples INTRODUCTIONA primary goal of mine ventilation is the control of airborne dust, especially in the ""respirable"" size range, typically defined as finer than about 5 to 10 µm. It follows that determination of the amount and characteristics of the respirable dust is an important factor in evaluating the performance of ventilation systems. Particle size information on airborne dust in mines is commonly obtained by in- situ measurements using cascade impactors. However, these tend to be inconvenient for routine data collection and the alternative approach of collecting samples in the mine, on filters for example, and returning them to the laboratory for detailed analysis is very attractive. Questions have often been raised, on the other hand, as to the appropriateness of this approach. How well · do such laboratory methods describe the distribution of aerodynamic diameter of the airborne dust particles in the mine environment? The purpose of the work described in this paper was to evaluate some laboratory sizing methods and to compare the results of such measurements with the size data obtained by the direct, in-situ method."

Jan 1, 1989

By H. B. Freaman, C. L. Colburn, C. M. Bouton

"The mine telephone has been perfected to such an extent that it is giving satisfaction in most mines were the wiring is well insulated. Very often the telephone cannot be depended upon on account of falls of rock, grounding due to worn insulation or extreme dampness. In the event of a disaster it frequently happens that the mine telephone system is put out of commission by the agency that causes the disaster, at the time when it is most urgently needed. On this account the mining industry is interested in any kind of telephone system that can be counted upon in an emergency. Many requests have been received by the Bureau of Mines to devise means of utilizing wireless methods for this purpose.The results of some preliminary experiments conducted by the writers at the Bureau of Mines experimental mine at Bruceton, Pennsylvania, in the ordinary sending and receiving of radio waves through earth strata are described below. The experiments were made in cooperation with the Westinghouse Electric end Manufacturing Co., which assigned to this work three of its radio engineers, C. A, Boddie, E. C. Douglas, and F. D. Fessler,The preliminary experiments consisted first in receiving signals from without the mine by means of a receiver located inside the mina, and second, both sending and receiving messages underground through the strata. It was found that with a receiving instrument set at a point 100 feet underground, signals from KDKA station, of the Westinghouse Electric and Manufacturing Co. East Pittsburgh, Pa., could be heard distinctly. Station KDKA is at a distance of about 18 miles from the experimental mine. About 50 feet from the receiving station used in this test was a 6-inch bore-hole from the surface, lined with iron pipe and containing electric light wires which extended therefrom through-out the mine. The presence of these wires evidently assisted greatly in the reception, for when the receiving set was carried to another point in the mine removed from wires and tracks the signals were barely audible through 50 feet of cover. The fact that signals were detected, however, even though faintly, is sufficient evidence of transmission through the ground to encourage further experimenting.In sending waves underground the Westinghouse 20-watt B.T. model T.F. transmitter was used in such a manner as to send out continuous waves of 200 to 300 meters length."

Oct 1, 1922

By A. Wahab Khair, Richard D. Begley

"This paper presents results of destructive tests performed on rectangular coal specimen under the influence of two vertical and simultaneous wedge indentation forces. Several wedge designs and spacings were utilized in compression tests. The objective of these experiments was to qualitatively monitor the effect of different wedge designs and spacings on the stress distribution within the coal specimen.Coal samples from the Waynesburg coal seam were cut and trimmed to cubical dimensions of approximately 5 X 10 X 20 cm. These specimen were subjected to parallel compressive forces through two vertically applied wedge indentors. Loading was achieved with a hydraulic hand pump in order to facilitate interferogram construction. The load increments were limited due to the sensitivity of the holographic interferometric technique (holometry) in measuring small displacements; therefore, interferograms were taken only during similar increments in order to allow for a qualitative comparison between different wedge design and spacings. In some cases, interferograms were taken immediately before and after failure of the specimen.Introduction Failure Modes Three distinct modes of failure occur when geologic materials are subjected to wedge indentation forces. As shown in Figure 1, a crushed zone is located immediately adjacent to the indentor while chipping can occur if the fractures initiated in the crushed zone extend upwards to the free surface.. The third failure mode is a zone of intricate frac¬tures located between the crushed zone and the chipping zone. Several experiments have been conducted over the years to better understand crater formation and stress distribution within geologic materials under the influence of an indentor. Generally speaking, crack initiation and propogation observed in these experi¬ments correlate fairly well with wedge indentation theory; however, the nature of the .fractures is greatly influenced by different material properties such as grain size and cleavage planes. In other words, a wide range of behavior has been found in different rocks subjected to wedge penetration. For example, it has been observed that some rocks are merely crushed and indented while others are more prone to cracking and chip formation. Therefore, the development or nondevelopment of chips depends mostly on wedge geometry, rock type and depth of penetration. This work is part of the study associated with opti¬mization of cutting parameters, which is best modeled by using brittle materials and subjecting them to rigid wedge penetration tests."

Jun 1, 1988

By Leonard Greenburg

The analytical procedure necessary when using this new impinger•bubbler eil)paratus is almost identical with that em:r;,loyed with the Palm0r a:pp8.ratua. As sugar is not employei, the new apparatus por.;sesses the advantage over the eug.r tube method in having vsry low control errors, being, therefore, much simple in laboratory manipulation during analysis.

Aug 1, 1922

By C. J. Johnson, C. J. Bise

"IntroductionCoal extraction by continuous miners (CM) is currently the most common underground method in the US industry and accounts for slightly more than two-thirds of the nation· s deep mining production (National Coal Association, 1987). Even if longwall mining should become more commonplace, it can proceed only af1er ventilation and access entries have been driven by CMs. Since an area of concern continues to be the effects of the dust generated on the health of mineworkers, this paper discusses the relationship between the elemental composition of mining-generated airborne dust sampled from the immediate ventilation return of a CM and laboratory-generated dust derived from channel samples taken from the mines.There are several potential contributions of this type of study to the coal mining industry. First after more fundamental knowledge of the causes of Coal Worker's Pneumoconiosis (CWP) is learned, the laboratory-generated respirable dust could be used to identify a potentially hazardous coal seam. Also, this study could possibly aid in understanding the fundamental causes of CWP by producing mining-simulated samples of coal dust that could be used in epidemiological studies.Further, assuming that there is no difference in the elemental composition of a drill-core sample and a channel sample from the same location a mining company could predict anew mine's respirable dust elemental composition In the immediate ventilation return by using exploratory drill core samples of the roof ,coal, and floor rock to prepare the laboratory dust. Ventilation engineers could then use engineering design and control measures during premine planning to reduce the incidence and severity of CWP by better ventilating the potentially hazardous coal seam. If this proper planning prevented any future changes to the ventilation equipment and mine design, much time and money could be saved.Scope of workTo investigate the variability of the chemical characteristics of respirable dust, airborne dust samples from eight underground coal mines located in the eastern and mid western United States were collected with eight-stage Sierra Model 298 Marple cascade impactors, as well as 25 channel samples of mined material. Each channel sample was removed from the middle of the coal face before mining occurred. Sampling of the mining-generated dust was conducted by Lee ( 1986) by sampling the entire working sections, primarily for characterization purposes, to obtain information on the locational variability of dust characteristics. Research performed for this study used the elemental analyses of the mining-generated dusts he sampled in the immediate ventilation returns of CMs."

Jan 1, 1989

By E. L. Garton

An active list of permissible explosives was published in July, 1931, as part of United States Bureau of Mines Report of Investigations 3134, under the title of "Active List of Permissible Explosives and Blasting Devices Approved Prior to June 30, 1931." Changes in that list were authorized in August, September, October, November, and December, 1931, and January and March, 1932, as published in Reports of Investigations 3140, 3147, 3150, 3155, 3158, 3161, and 3163, respectively. By these changes the following explosives were added to the active Permissible list: Austin Red Diamond No. 1, L. F. Gel-Coalite W, L. F;" Austin Red Diamond No: 5. Gen-Gel No. 2. Black Diamond Nu-Gel No. 1 Genite C-1 Burton 1, L. F. Liberty No 4 Burton 2, L. F. Liberty No. 5 Burton 10, L. F. Peerless D Burton 12, L. F. Permigel 1, L. F. Burton F, L. F.

Jan 1, 1932

By F. W. Hoertel

The Bureau of Mines investigated the use of depleted uranium as a sacrificial anode for the cathodic protection of submerged and underground structures of iron , steel , and copper . Uranium-metal couples were tested in simulated marine environments of varying oxygen contents at pH values between 5.5 and 8.5 and under simulated boiler service condition in Rolla , Mo. , city water . Similar couples were tested in samples of Missouri soils to simulate underground service . Uranium remained anodic to iron , steel , and copper in the simulated marine environments and under simulated boiler service if the electrolyte was oxygen- free city water . Uranium appeared to offer limited protection to iron , low- carbon steel , stainless steel , copper , and zinc in the simulated underground tests . Uranium anodes offer a space advantage because 1 cubic inch of uranium gives approximately the same protection as 2 cubic inches of magnesium or 1-1 /2 cubic inches of zinc .

Jan 1, 1963

By Edward L. McHugh, Jami M. Girard

While less than 1% of reported accidents are associated with slope stability problems, slope failures were responsible for about 15% of all U.S. surface mine fatalities between 1995 and 2001. Small rockfalls, which may involve hand-sized rocks weighing only a few kilograms, can cause fatal injuries to workers away from the protection of large machinery. Massive highwall failures containing a million cubic meters of material or more can be fatal even for heavy equipment operators. As part of an ongoing study at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health, several remote-sensing technologies are being evaluated as tools to monitor slopes for hazards and to assess slope stability. Field tests of a hyper spectral imager were conducted to assess its value for improving geologic maps of potentially unstable alteration zones on mine slopes. An interferometric radar device capable of detecting very small displacements on slopes awaits final assembly and field testing. Computerized monitoring methods using images from digital and video cameras are being assessed for application to mine slope surveillance. These and other techniques will eventually provide new tools to augment current methods for monitoring ground control hazards in mines.