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By N. H. Darton

This report presents the results of an investigation begun by the Government in the summer of 1907, the investigation being started under the immediate supervision of Dr. J. A. Holmes and continued under him as director after it was transferred to the Bureau of Mines in 1910, the field studies being completed in the spring of 1912. The purpose of the investigation was to obtain information on the origin of the inflammable gases in coal and the conditions under which they occur. It was especially intended to ascertain whether there was any relation between the occurrence of gas and the structural or other geologic features of the coal beds. To this end many months were spent in mines and much time was devoted to the examination of mine maps, bore-hole records, and other data made available by the kindness of various coal companies. Two fields of work were selected-one in the northern anthracite basin of Pennsylvania, where the beds are considerably flexed, and the other in the southern part of the bituminous coal field of Illinois, where the beds lie nearly horizontal. In order to take advantage of results of previous investigations of the same general subject, an extended examination was made of reports of various investigators in Europe and America. A digest of the information obtained from these publications is included in the first part of this report, which constitutes an introduction to the discussion of the conditions governing the occurrence of inflammable gas in coal beds.

Jan 1, 1915

By G. S. Rice, H. O. Howarth, Greenwald. H. P.

"Electricity as a means of transmitting power was introduced in coal mines of the United States about 1891 for both haulage and coal cutting, only a few years after electrical haulage was first installed on street cars. At first, the hazards of electrical ignition ere not appreciated and the general use of open lights and black blasting powder made the possibility of electrical ignition of fire damp seem small by comparison.5 The possibility of igniting coal dust directly by electric sparks or arcs had not been considered.In the nine years prior to 1900, the progress of introducing electricity underground was slow, except that it was used for lighting shaft bottoms. Electricity had to contend with the more general use of compressed air for coal-cutting machines and, in mainline haulage, with the use of mule-teams and endless and tail-rope systems. During this period, great improvements were made in electrical apparatus, in surface installations as well as in mines. By 1900, therefore, the technique of applying electricity in mines had so far developed that it rapidly drove out the use of compressed air in coal mines because of the comparative ease of its installation and the marked economic advantages of its use over that of compressed air in practically all kinds of mining machines except percussion. rock drills.At this time, however, little thought was given to the hazard of indiscriminate use of electricity causing explosions and fires, and the possibility of electricity causing direct ignition of coal dust had not been considered. On December6, 1907, however, the Monongah, West Va. mine explosion occurred. This was the greatest mine disaster this country has over had, 361 men being killed. Although: there was much diversity of opinion, as to the origin of the explosion, many well-informed engineers concluded that the cause was ignition of coal dust do to wreckage of a runaway trip in a rope haulage entrance slope. This slope also served as a ventilating and it extended from the level of the coal bed to the surface. The runaway trip tore down electric cables and stirred up a cloud of dust when it was wrecked at the bottom of the slope. The dust was probably ignited by the electric arcing that occurred when the wires were knocked down. (Another but less probable source of ignition was the open flames of miners lamps.) From the foot of the slops the explosion appeared to have travelled into the mine, spreading as it went. If this ignition of coal dust was the origin of the explosion, it occurred on pure intake air entering directly from the surface."

Oct 1, 1930

By Will B. Jamison

An ignition detection and suppression system was developed under the scope of this contract. The objective of this machine mounted system was to detect flames caused by frictional sparking from the cutting bits of a continuous mining machine and to suppress it with sufficient speed to prevent the development of an explosion, and to keep the flame from harming the machine operator.

Jan 1, 1976

By Jeffrey Shawn Peterson

The testing procedures of the U.S. Mine Safety and Health Administration specify that intrinsic safety acceptance tests be conducted using a standard tungsten-cadmium electrode configuration in the break- flash apparatus. However, in realistic mining environments, other materials may be more likely sources of sparking. Information defining the probability of spark ignition between common materials such as aluminum, brass, copper, lead, tin, cold-rolled steel, and stainless steel is of more practical value in determining ignition hazards. The U.S. Bureau of Mines has completed an investigation of the influence of material on the ignition probability using the breakflash apparatus. By comparing ignition currents or ignition voltages corresponding to a probability of one ignition per thousand sparks to those found previously for cadmium, a margin of safety may be estimated for each material. This report presents the results of an investigation into the influence of disk electrode material on the probability of ignition.

Jan 1, 2002

By Kray Luxbacher, Mario Karfakis, Erik Westman, Peter Swanson

Three-dimensional velocity tomograms were generated to image the stress redistribution around an underground coal longwall panel to produce a better understanding of the mechanisms that lead to ground failure, especially rockbursts. Mining-induced microseismic events provided passive sources for the three-dimensional velocity tomography. Surface-mounted geophones monitored microseismic activity for 18 days. Eighteen tomograms were generated and high-velocity regions correlated with high abutment stresses predicted by numerical modeling. Additionally, the high-velocity regions were observed to redistribute as the longwall face retreated, indicating that velocity tomography may be an appropriate technology for monitoring stress redistribution in underground mines.

By Gary E. Sherman

This report presents a Bureau of Mines study on the cost of mine permitting and compliance with environmental regulations in Alaska. It discusses permitting requirements and procedures for placer and lode mines. Placer miners must comply with recently established (1988) water quality regulations and effluent treatment requirements. To estimate the impact differing treatment options (no recycle, 100% recycling, and flocculation) have on a placer mine's rate of return, three models (1,500, 1,000, and 500 yd3/d) were simulated. Rates of return for these models show a marked decrease as effluent treatment is increased. The incremental increase in operating cost from one treatment option to the next is relatively small; however the opportunity cost of lost production if' significant and accounts for the decreasing rate of return with increased effluent treatment. Lode mines face greater costs for permitting and compliance than similarly sized placer mines as a result of the impact of the operation. Direct permitting costs for lode mines range from 2 to 6% of total project cost, with 4% the most common figure cited by industry. Total costs for permitting and compliance are approximately double those for permitting. Indirect costs associated with compliance include mitigation, monitoring, and reclamation.

Jan 1, 1991

These proceedings consist of an introduction and four descriptive papers. The first paper is an update on fire protection for large haulage vehicles, the second paper is concerned with improved visibility systems for large haul- age vehicles, the third paper is on improved ladders for large haulage vehicles, and the fourth paper is concerned with large haul-age vehicle operator training systems.

Jan 1, 1980

By D. Harrington

"Coal—mine explosions are accidents that can and should be prevented. In former years hundreds of lives were lost each year in the United States as a result of such explosions, but after 1932 the numerous precautionary measures adopted had reduced their frequency and severity 75 percent or more until in 1940 several very disastrous explosions marred the good record. Unfortunately, both the number and severity of explosions seem to be tending to increase compared with the relatively good achievement from 1933 to 1940. The requisites for an explosion are ever present in all soft-coal and many hard-coal mines. A certain combination of circumstances, such as a flame or an arc in a cloud of dust or in a body of gas or both may start an explosion at any time. The fact that the frequency and severity of explosions were lowered for 6 or 7 years is no guarantee that such freedom from explosions will continue, as the bad record of 1940 has shown, and underground workers should feel honor bound to exercise the utmost care so that they will not help to bring about the circumstances that will cause an explosion.Although mine operators bear the main responsibility for preventing explosions, miners can do many things to help. As about 9 out of 10 explosions begin at a working face, it is largely within the power of workers to prevent them. All miners should do their part willingly and should not defend a fellow workman from punishment, even from discharge, for disobeying necessary rules, whose disregard may cause the death not only of the safety-rule breaker but also of many of his coworkers.When a miner is careless and is injured some other way than by an explosion he may be the only one to suffer, but if his carelessness causes an explosion he not only endangers his own life but also that of every other man in the mine and possibly the lives of persons outside the mine.Experiments have shown that ignition of as small a quantity as 150 cubic feet of an explosive mixture of methane and air under certain circumstances can start an explosion that will traverse an entire mine. Thus, ignition of an explosive mixture of gas 1 foot down from the roof and 13 feet back from the face of a 12-foot entry might cause a widespread explosion if the right quantity and kind of dust were present. Many persons have ignited much larger quantities of gas without being killed, but they survived only because dust, confinement, and other conditions were not exactly ""right."""

Nov 1, 1940

By James R. Cosby

This report describes work performed for the Bureau of Mines to evaluate available portable instruments for their effectiveness in detecting and locating damaged metallic shields in Types SHD and SHC cables. A second phase of the program is also covered wherein several instruments of a type which show promise are purchased for modification and testing to verify their performance.

Jan 1, 1980

By C. W. Morris

This study was performed for the U.S. Bureau of Mines. An existing computer simulation of a dragline was modified to simulate a dragline dumping into the hopper portion of a cross-pit conveyor system. This revised computer model was then used to study four proposed cross-pit conveyor systems. Parameters such as dragline position, hopper position, and digging procedure were varied to maximize the dragline production. This performance was compared with the conventional side-casting spoil method. I t was concluded that the cross-pit conveyor systems were competitive with the conventional side-casting technique.

Jan 1, 1977

By Wilbur I. Duvall

In a review of so 40 papers on damage to residential structures resulting from blasting, only 3 were found that present data on the observed amplitude and frequency of the vibration levels produced by blasting together with an observed degree of damage to a residential structure. The data from these three reports have been analyzed statistically to determine if one of the quantities, displacement, velocity, or acceleration, is more reliable than the others for estimating the degree of damage to a residential structure. From this analysis the conclusion is drawn that a given degree of damage to a structure is most closely related to the magnitude of the particle velocity of the wave motion passing thru the earth at the structure location. On the average, only minor damage it observed for peak particle velocities of 5.4 inches per second, and major damage is observed for peak particle velocities of 7.6 inches per second. When the spread of the data is taken into consideration, the following statement can be made: Wave motions that have a peak particle velocity in excess of 2 inches per second have a fair probability of producing some damage to structures, whereas wave motions that have a peak velocity less than 2 inches per second have a very low probability of causing any damage. Therefore, the recommendation is made that vibration levels in the vicinity of residential structures should be maintained below a peat particle velocity of 2 inches per second. The above criterion for safe blasting is considered to hold over a wide variety of soil and rock conditions because the original data were obtained for a wide range of soil and rock conditions and on various types of residential structures. INTRODUCTION Ever since explosives were discovered and developed for mining purposes, there has existed the problem of what effects the air and ground vibrations resulting from blasting have on structures of various types. This problem is

Jan 1, 1962

By J. B. Zadra

Tungsten metal, chemically equivalent to commercial grade, is produced by electrolysis of impure tungsten compounds or scheelite in an alkali, phosphate or borate electrolyte. A preliminary investigation of fused-bath electrolysis shows the effect of electrolyte composition, temperature, and current density on current efficiency, yield, crystal structure, and purity of product. Experiments show that tungsten can be electrowon from scheelite in a fused alkali, phosphate, or borate bath with similar results. Studies on electrolyte composition show that the addition of sodium chloride is essential to both electrolytes in treating scheelite. Although its main function is to react with or flux the CaO, it also increases the bath fluidity. Temperature studies revealed optimum ranges between 900° and 1,100° C.; 900° C. proved satisfactory for tungsten trioxide, and 950° to 1,050° C. for scheelite. Current efficiencies were satisfactory for all current densities ranging from 10 to 57 a./dm.2. Yields were 400 to 650 g./kw.-hr. over the same current-density range. Crystal size and purity of the product are functions of temperature, current density, and amount of impurities in the electrolyte. Deposited crystals vary in shape from spherical grains to clusters of dendritic hexagonal needles, and in size from smaller than 35 to 570 microns. The purity of the tungsten metal produced ranges from 99.7 to 99.94 percent.

Jan 1, 1959

Papers presented at a U.S. Bureau of Mines (USBM) technology transfer seminar describe the causes of violent material failure in U.S. mines, measurement techniques for monitoring events that result in violent failure, and mitigation techniques for controlling failure. Specific factors contributing to violent failure are identified on the basis of geotechnical monitoring in 16 U.S. hard-rock and coal mines and on statistical analyses of 172 coal bump events. New monitoring and analysis techniques developed as tools for assessing violent failure; geotomographic methods that provide new capabilities for the study of material failure and stress changes over large areas; and seismic methods for determining source locations, calculating energy release, and determining source mechanisms are described. Fair correlations have been established among seismic parameters, elastic stresses, face support load, and violent events. USBM studies have identified the advantages using both yielding and stable pillars for coal bump control. A computer program has been developed as an aid for selecting room-and-pillar layouts. The practical aspects of implementing a destressing program is outlined for coal mines, while the importance of mine orientation and timely support installation in controlling buckling-type failure is identified for hard-rock mines.

Jan 1, 1995

By Wilton Johnson

Native asphalt was produced by three companies in two States, Texas and Utah. Bituminous limestone, used primarily as a paving material for street and road repair, was produced by one firm, R. L. White Co., Uvalde County, TX. Gilsonite, a solidified hydrocarbon found only in Colorado and Utah, was mined by two firms, American Gilsonite Co., a division of Chevron Resources Co. (a subsidiary of Standard Oil Co. of California), and Ziegler Chemical and Mineral Corp. Hydrocarbon Mining Co. (a subsidiary of Oberon Oil Inc., a Utah corporation) closed its mining operation during the year.

Jan 1, 1988

By Michael Schmitz, John A. Organiscak

ABSTRACT: A method (patent pending) has been developed to determine the quality of environmental cab filtration systems. This method utilizes specially configured filter cartridges to remove carbon dioxide from the ambient air with the environmental cab’s air filtration system. A real-time gas monitor is placed inside an unoccupied cab with the filtration system running to time decay the carbon dioxide to its lowest concentration or equilibrium level. The outside carbon dioxide concentration level can be measured concurrently with another gas monitor or with the same inside cab gas monitor during a representative period before and after the inside sampling is conducted. Cab filtration system leakage is comparatively deduced from the difference between the special cartridge filter efficiency and overall cab efficiency. Laboratory trials have illustrated that desirable high efficiency test filter configurations (greater than 99 % efficiency) can be devised, but have air quantity and test time limitations. These trials also demonstrated that CO2 penetration was reflective of controlled air leaks around a high efficiency filter under equilibrium conditions. This report examines the elements of this patent pending method.

By G. R. Peterson

To determine the availability of lead and zinc from demonstrated resources, the Bureau of Mines evaluated 235 mines and deposits in 31 market economy countries. Of the 235 mines and deposits evaluated for this study, 186 were evaluated as zinc operations, 30 as lead operations, and 19 as copper operations. Demonstrated lead-zinc resources of market economy countries in 1981 were approximately 4.3 billion metric tons (t) of ore containing 221 million t of zinc and 97 million t of lead. Of these amounts, approximately 154 million t of zinc and 70 million t of lead are estimated to be recoverable. The analyses indicate that demonstrated resources in market economy countries should be sufficient to satisfy projected demand for primary lead and zinc through the balance of the century. The U.S. lead industry will continue to have a comparative advantage over the rest of the world industry, barring any drastic increase in the cost of compliance with pollution control regulations. It appears that the comparative disadvantage faced by the U.S. zinc industry will probably intensify owing to the relative quantity of lower cost zinc resources in other countries, especially Canada, Australia, Mexico, and Peru.

Jan 1, 1985

By Donald O. Capstick

The U.S. Bureau of Mines conducted an inventory of the prospects and mineral resources in the Scodies RARE II area (No. 5212) in 1982. No mineral production is recorded from the area, and no mines are being developed. The Scodies RARE II area is comprised primarily of light colored granodiorite with minor inclusions of mafic granitic rocks. Late stage differentiates of magmas resulted in quartz veins and pods. Metasedimentary rocks which have been mineralized in some parts of the Sierra Nevada were not observed within the study area during this investigation but small inclusions have been reported.

Jan 1, 1983

By George T. Faust

The petrographer engaged in examining the products resulting from the beneficiation of ores and rock minerals is constantly required to develop new means and methods of assaying microscopically the results of such operations. From time to time investigators have published descriptions of apparatus that have aided in solving problems in processes f physical separation. Thus, in 191.9, Coghill and Bonardi 31 published a paper covering the application of the binocular microscope and camera lucida to the microscopic analysis of pulverized ores. Similar work has been published by Schneiderhohn 4/, Schwartz 5/, and Head and his associates6/, 7/, 8/. The present paper goes further and considers application of the polarizing comparison-microscope to problems directly concerned with mineral dressing where it is desirable to compare analogous products, and in addition it suggests new uses in various related fields. This work was conducted under the cooperative agreements of the Southern Experiment Station of the Federal Bureau of Mines and. the University of Alabama.

Jan 1, 1940

By Craig C. Johnson

The purpose of this effort was to investigate the feasibility of employing a piezoelectric transducer for seismic communications applications in mine environments. The transducer, a government furnished device incorporated a high Q, spring-mass resonator to load the air side of the piezoelectric crystal. The resonant frequency was seismic load dependent and fell in the range of 300 to 340 Hz. The effort included a mathematical analysis of the transducer, with corroborative laboratory tests, together with actual communications experiments performed first in an open-formation limestone quarry and finally in an operating iron mine. This work showed that the transducer could be coupled efficiently to hard, competent rock media with power conversion efficiencies of 70 to 80 percent (electrical to mechanical) in typical installations. In the iron mine, when radiating peak power was about 30 W (acoustical) in a gated pulse mode, signals were received at a distance of 760 ft through a massive rhyolite porphyry formation. This represents a 15% radiation efficiency with an input of 200 watts. Despite the high ambient noise level due to operating mine machinery, a signal-to-noise ratio of about 20 dB was achieved using a very narrow band filter to process the received signal, and a data rate of about two pulses/sec was demonstrated.

Jan 1, 1972

By James J. Snodgrass

The Bureau of Mines has investigated vibration levels produced by blasting at four underground sites to establish how such factors as type of explosive, delay blasting, charge weight, and geology affect amplitudes of ground motion. A summary of the work is presented and the results of further analysis of the data are discussed. Square root scaling was found applicable to two of the underground sites and could be applied with minor error to all the sites. Comparison of empirical propagation equations in the different rock types indicates that although the site effect is apparent, the combined data may be used as a basis for engineering estimates of vibration amplitudes from subsurface blasting in many different rock types. Recommendations for predicting and minimizing vibration amplitudes from underground blasts are given.

Jan 1, 1974