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By Michael J. Brnich

Since 1991, Pittsburgh Research Center (PRC- formerly part of the Bureau of Mines) researchers have recorded extensive interviews with 30 individuals who are experts in the area of mine emergency response. These individuals, who have an average of 35 years of mining experience and 29 years of mine emergency response experience, related stories and observations from events that they experienced during their combined 850 plus years in mine emergency response. The purpose of this effort was to gather information that could be passed onto both today?s and tomorrow?s mine emergency responders to train and guide them in handling future events.

Jan 1, 1997

By S. H. Ash

"INTRODUCTION Mine fires have occurred since underground mining of minerals began, and they are still occurring. The technical literature is replete with papers relating to mine fires.Means and methods for controlling and extinguishing mine fires and preventing explosions and other accidents require the collection and analyses of samples of the atmospheres surrounding the fire. Such atmos¬pheres are complex mixtures of gases (1, 3, 4, 15, 21, 23).3/SUMMARYExperiences at mine fires (1, 3, 4, 15, 21, 23) have proved conclusively that mine-air analyses furnish the only means of judging what is going on in a mine fire area. Mine-air analyses give evidence of conditions that require immediate protection, govern the order and control the manner in which a fire is fought, show the necessity of bulkheads and establish the places to construct them, indicate whether or not a fire is being controlled or is being extinguished, and govern procedure in sealing and unsealing mine fires.It is commonly believed that danger to life and property from mine-fire atmospheres is greatest in coal mines; this is true only to the degree that the explosion hazard is greater in coal mines than in noncoal mines because of the presence of combustible gases. The problem of gas poisoning is greater in noncoal mines because of the more frequent occurrence of poisonous and innocuous gases, oftentimes the lack of controlled ventilation, and usually greater difficulties in sealing mine-fire areas. Sulfide minerals present a serious hazard in many metal-mine fires when sulfur dioxide is formed. The country rock or ore body itself may contain or be limestone, which may be calcined. Emanations of carbon dioxide are found."

Dec 1, 1950

By Steven J. Schatzel, Joseph Cervik, Gerald L. Finfinger

Gas drainage through surface bore¬holes has been the conventional means of methane control for U.S. longwall gobs. However, these vertical boreholes are becoming so costly, and the surface rights so difficult to obtain, that the Bureau of Mines is developing underground gob gas drainage as an alternate means of methane control for U.S. longwal..ls. Holes are drilled into the roof over the panel and on retreating longwalls, towards the working face from a location inby the face. As the longwall retreats, an increasing portion of the hole inter¬cepts the fracture system over the caved gob. A surface exhauster maintains a vacuum on a pipeline parelleling the panel and draws the methane mixture out of the mine. Auxiliary systems of gob gas drain¬age during longwall mining will be essen¬tial for an increasing number of coal mines. Deep and gassy mines often find ventilation insufficient for adequate dilution of methane in bleeder entries. Although this cross-measure method of degasification has been used successfully in Europe, some of the European tech¬niques cannot be directly applied to U.S. mines. This is the first study of its kind in this country.

Jan 1, 1982

By D. Cummins

This Information Circular presents a brief history of the lead-acid battery and describes ways to prevent serious injury from battery explosions when servicing and charging lead-acid batteries, particularly in the surface mining industry. The Mining Safety and Health Administration (MSHA), U.S. Consumer Product Safety Commission, battery manufacturers, and the mining industry have all contributed information as well as recommendations for injury-free handling for this report.

Jan 1, 1980

By C. G. Kirkland

An apparatus for determining trace impurities in Grade-A helium by mass spectrometer methods was designed and built by the Federal Bureau of Mines. Grade-A is the designation for helium commercially produced by the Bureau. Its nominal purity is 99.995 percent. The device, following a suggestion by Deaton, concentrates the impurities in the helium by freezing them out in a coil-and-trap assembly cooled by liquid helium. A known volume of helium is passed through the trap, the concentration ratio determined, and samples of the concentrated impurities are analyzed by mass spectrometer methods. The apparatus has been in service for approximately 20 months and has satisfactorily met all requirements. Over 200 analyses were made of helium contained in conventional cylinders, obtained from the Amarillo, Exell, Otis, and Navajo Helium Plants, during the 6-month period ending March I, 1959. Total impurity concentrations, in parts per million, were as follows: Amarillo, 19.1; Exell, 17.1; Otis, 11.3; and Navajo, 6.6. Neon and nitrogen were the major impurities. Complete data are shown in table 4 in the body of this report.

Jan 1, 1960

Roof bolting is a slow, expensive, and absolutely necessary mining activity. Roof-bolting activities also account for the largest percentage of lost-time injuries in underground coal mines. Dull bits result in the application of excessive force, which bends drill steel; and changing starter and finisher steel was the most significant source of injuries associated with roof bolting. The tungsten carbide (WC) roof-bolt drill bits currently used in American, Canadian, and Australian coal mines are capable of drilling only one or two 4-ft holes and then they are resharpened once or twice to drill another one or two holes. Often, in medium-hard rock formations (sandstone), as many as 20 to 30 bits may be required to drill a single 4-ft hole. Objective To compare the performance, longevity, and cost of newly developed polycrystalline diamond compact (PDC) roof-bolt drill bits against WC bits. Research and Background Diamonds for industrial use have been scarce throughout history and continuous attempts have been made to produce synthetic diamonds. The first synthetic diamonds were manufactured in 1953. Economically produced synthetic diamonds are 1 to 10 µm in size, but in this size range, they are totally unsuitable for industrial applications. In 1972, General Electric Co. developed a process to sinter the artificially developed, minuscule diamond particles into usable products. In this process, several layers of diamond-particles-and cobalt mixture are overlaid on WC substrates and sintered at 2,350° F and 1,000,000 psi. The final product is known as PDC. Today, PDC's are available in many shapes, but their size is limited to 3/4 in, or less, in length or diameter, because pressures greater than 1,000,000 psi are required to manufacture larger PDC's. At present, diamond and PDC arc the hardest and strongest commercial materials available for wear surfaces. The PDC used in this study had a hardness 3.61 times greater than that of WC.

Jan 1, 1992

By John J. Mulligan

Ear Mountain is an isolated mountain mass that rises abruptly from the coastal plain on the northwest shore of the Seward Peninsula. Geologically it resembles the more accessible Brooks Mountain and Cape Mountain areas to the southwest, being composed of a granitic core surrounded and partly capped by metamorphosed sediments. The occurrence of lode- and placer-tin deposits in this area has been known since the early 1900's, when the Seward Peninsula region was prospected extensively for both gold and tin. The Federal Bureau of Mines investigated the tin deposits in the Ear Mountain area during the 1953 and 1954 field seasons. The objectives were to delimit the areas in which tin minerals occur, as a guide to future prospecting, and to determine the amount of tin in the known prospects. Work by the Bureau of Mines included both placer and lode sampling.

Jan 1, 1959

By Kenneth C. Stewart

This contract was directed toward a study of the attenuating properties of earmuffs as worn by miners. Two attenuation measurement procedures were utilized. Human subjects were tested in a diffuse sound field according to threshold shift procedures recommended by the American National Standards Institute and a physical measurement procedure was accomplished in the same diffuse field on the same human subjects with microphones placed simultaneously on the inside and outside of the muffs. All measurements were obtained in one third octave of random noise. The results of the study indicated that physical and psychophysical attenuation measurements are in essential agreement at frequencies from 125 Hz to 2 KHz. Above 2 KHz the psychophysical measurement demonstrates larger amounts of attenuation than the physical measurement. The difference in attenuation ranged from approximately 7.0 dB to 9.0 dB at frequencies of 4 KHz and above. A possible explanation for the observed differences in attenuation has been presented.

Jan 1, 1980

By M. D. Schlesinger

Mercury exists in coal in minute quantities, but the large tonnages of coal consumed could represent relatively large amounts of mercury entering the environment. Limits have now been placed on the emission of mercury, and it is important that reliable analytical methods be available to the chemist. The Bureau of Mines has evaluated analytical techniques used by a number of laboratories; most used vapor phase atomic absorption as the final detection method. Neutron activation was used by some of the laboratories. All of the methods described could be applied, but they require careful manipulation to prevent loss or mercury contamination. In the samples analyzed the mercury content ranged between 0.05±0.01 and 0.4l±0.06 part per million.

Jan 1, 1972

By Charles L. Kimbell

While the statistical summary focuses on 1991 data, this update and outlook section draws on information available to the author as of the date of final preparation in early 1993. For all the press notoriety associated with the shift in the Near East crisis from the defensive posture of Desert Shield to the restoration of Kuwaiti sovereignty through Desert Storm, this was not the dominant event governing global economic thinking in 1991 and the first half and more of 1992. From the global perspective, the momentous political changes in the area that was the U.S.S.R. and in the smaller emerging transitional economy states of Eastern Europe will have even greater current and long-lasting effects on world mineral industry activities than the crisis in the Near East.

Jan 1, 1993

By J. P. Baur

The sensitivity of radiochemical techniques makes possible the study of the initial-stage sulfuric acid leaching kinetics of chalcopyrite and other copper sulfide minerals. This Bureau of Mines study of the initial leaching of chalcopyrite used techniques to evaluate the molecular and electrochemical processes. High-grade Transvaal chalcopyrite was neutron-irradiated in a TRIGA reactor4 to produce radioisotopes copper-64, iron-59, and sulfur-35. Dissolution rates were measured in the time interval zero to 60 minutes, during which time significant anomalies were observed. First was an initial period of rapid dissolution lasting a few minutes; second, an arrest or ?plateau? region usually lasting from 6 to 10 minutes; third, a second period of dissolution of lesser rate than the first. The effects of solution variables such as pH, oxygen partial pressure, and ferric ion concentration at different temperatures were measured.

Jan 1, 1974

By Douglas C. Peters, Valois R. Shea-Albin, Dennis R. Dolinar

An accurate assessment of the vertical stress on a coal seam at depth is important for mine design. Vertical stress calculation techniques presently available either are not sufficiently accurate or cannot handle complex surface topography. Therefore, the U.S. Bureau of Mines developed a computerized method to calculate vertical stress exerted on surfaces at depth that includes the effect of topography. Two input data sets are required: a digital elevation model containing topographic elevations and a coal seam file defining coal seam elevations at depth. Boussinesq's equation then quantifies the vertical stress resulting from topography. The computerized method was tested on a coal seam overlain by a complex topography where a vertical stress map encompassing several square miles was produced. Results show that depth mitigates the affects of surface topography, while the coal seam topography has a direct effect on the vertical stress. In comparison to the computerized method, the direct stress method overestimates stress under hills and underestimates stress under valleys. The largest difference between the two methods occurs under the steepest topographic relief. A limitation of the computerized method is that stresses cannot be accurately determined near an outcrop.

Jan 1, 1992

By Sidney Katell

This report is an economic evaluation of the production of hydrogen in a continuous system by the steam oxidation of partially reduced iron oxide in a fluidized bed at 7 atmospheres using producer gas to reduce the iron oxide. The oxidation-reduction step is based on experimental data obtained by the Bureau of Mines at the Pittsburgh Coal Research Center. The estimated capital requirement for a plant producing 30 million std. c.f.d.3 of 99.8 percent purity hydrogen at a discharge pressure of 450 p.s.i.g. is $13,100,000, using January 1961 equipment cost data. Based on a 330-day operating year, the operating cost before profit and taxes with coal price as a variable is estimated to be:

Jan 1, 1962

By Lisa Steiner, Robin Burgess-Limerick

In 2004, there were 646 underground coal mines in the USA employing 37,445 miners. These mines reported 3556 injuries to MSHA that year - 17% were associated with bolting machines (593 injuries), 8% with continuous miners (283 injuries), and 4% each with Scoop/LHD (1 51 injuries), shuttle cars (134 injuries), and personnel transport (145 injuries). The use of the frequency of reported injuries for the prioritization of risk control strategies has limitations because of the tendency to underestimate the importance of relatively rare but high-consequence events. Injury reports also underestimate the contribution of risk factors such as whole body vibration, which have a long-term cumulative contribution to an elevated risk of injury. However, taking these limitations into consideration, the results of the injury narrative analysis suggest the following hazards as the highest priority for elimination or control: • rock falling from supported roof • inadvertent or incorrect operation of bolting controls • handling continuous miner cable • collisions while driving LHD/Scoop, shuttle cars and personnel transport • rough road while driving or traveling in LHD/Scoop, SC & PT

By C. E. Jordan

The Bureau of Mines conducted tests on seven samples of Florida phosphate operations.slimes to develop a method to recover phosphate presently being discarded because of its small grain size. A system of hydrocyclones and hydroseparators was used to recover up to 96 pct of the plus 400-mesh material from the slimes. This plus 400-mesh material was subjected to fatty acid flotation, and concentrates containing up to 33.4 pct P205 were produced. As much as 88 pct of the phosphate (P205) was recovered from the plus 400-mesh material, and up to 29.6 pct was recovered from the total slimes.

Jan 1, 1982

By Albert E. Long

Diamond-bit performance and cost data accumulated in core-drilling sandstones reveal significant trends of economic interest. Large-size, AA-Grade drill bort suffered less diamond loss per foot drilled than any other size or grade of diamonds assessed. Detailed analyses of the factors that affect diamond-bit performances -diamond size, diamond quality, bit size, bit type, percentage of core recovered, and physical characteristics of bit matrices -are assessed in the tables, graphs, and discussion. INTRODUCTION Since 1945 the Bureau of Mines has been compiling detailed performance records on diamond bits used in core drilling throughout the United States and Alaska. Analytical reports covering bit performance in various rocks are issued as in-formation on a significant number of bits used in anyone type of rock is accumulated. The first three such reports analyzed bit performance in gneiss,2/ schist,3/ and lime-stone and dolomite.4/ This report evaluates diamond-bit performance in sandstone. Data obtained from 627 bits, which drilled 42,665 feet on 45 different projects, are presented. The geographical distribution of the projects is shown in figure 1.

Jan 1, 1958

By J. H. Perry

The Bureau of Mines is conducting research to determine the effectiveness of long holes in degasifying an area of the Upper Split of the Lower Sunnyside coalbed at Kaiser Steel Co.'s Sunnyside No.1 mine. These holes were drilled from the two outside entries of a section that was closed to mining because of excessive methane emissions. Two holes drilled to 430 and 450 feet produced initial gas flows of 160,000 and 127,000 cfd, respectively. Sixteen days after the completion of the second hole, the total gas production declined to just over 144,000 cfd. In 9 months of degasification, over 35 MMcf of commercial-quality gas has been removed from the coalbed. The combined gas flows declined to 106,000 cfd in the 9-month period. The two holes have reduced face emissions by about 40 pet.

Jan 1, 1978

By J. J. Geraghty

U.S. Bureau of Mines researchers investigated the development of an innovative transport system for underground coal mining. A one-half commercial-scale bench model was constructed. Novel magnetic levitation (mag-lev) technology was developed. Frictionless and contact-free transport of a prototype materials container and payload has been demonstrated.

Jan 1, 2010

By D. J. Parker

Since the introduction of electricity into the mines of the United States , the hazards incident to the industry have increased materially in both coal and metal mines . For economic reasons the tendency at present , particularly in coal mining , is decidedly toward the adoption of electrical mine machinery , including alternating current machinery , on a more extensive scale than ever before . Obviously, the growing use of such equipment will result in an ever -increasing number of underground transformer stations . The principal electrical hazards in mines are threefold ; fire , explosion, and contact . Of these , fire is the greatest hazard involved in the use of electricity underground , and several fires have originated in underground transformer and motor generator set stations . The fire hazard due to improperly installed and poorly maintained underground transformer stations is an ever-present one , and failure to take the necessariman remedial action is likely to result , sooner or later, in the destruction of life and property . Upon suggesting the necessary corrective measures with respect to such installations , one is often confronted with the statement to the effect that even though this particular hazard has existed over a period of years , there have been no unfavorable results therefrom thus far . Frequently , the desirability for action is not apparent to the mine management until it is too late . Because a mine has a record free from fires , explosions , etc. , over a number of years of operation during which these hazards existed , such good fortune should not be taken as a guarantee that this or any other mine is immune from these common dangers . When the elements of an existing hazard are properly balanced or in the right proportion, the unfortunate combination must of necessity culminate in misfortune of one kind or another. The fire hazard due to underground transformer installations can be very definitely minimized by proper installation and maintenance . In coal mines the transformer banks , connected to 2,300 and occasionally to 4,400 volt circuits , are often found located in open- ended crosscuts , mounted on concrete or timber foundations , and in nonfireproof surroundings .

Jul 1, 1930

By Isaac A. Zlochower, Michael J. Sapko, Ronald S. Conti

This paper describes a U.S. Bureau of Mines investigation of large-scale coal dust explosions in an experimental mine using a high speed electro pneumatic mechanism for the rapid grab-sampling of gases and dusts. This technique enables the monitoring of pyrolysis and charring in fuel dust particles, and the collection of gaseous combustion products, in both large and small-scale explosions. Data obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Test facility show the following: Rapid sampling appears to "freeze" the burned gas compositions at the flame temperature values. Gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen. The particles collected in the flame zone show signs of extensive pyrolysis and charring. Measurements of gas concentrations and particle flame temperatures suggest that char burning may have occurred in the flame zone.