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By Dennis Cox, Stephen P. Signer, Joanne Johnston

A method to assist in the evaluation and selection of roof bolts using in situ measurements of roof bolt loading has been developed by researchers of the Spokane Research Center, National Institute of Occupational Safety and Health. Both axial and bending forces are measured by strain gauges at many locations along the length of fully grouted bolts during various stages of mining. This information is then used to (1) predict bolt loading for variations in bolt spacing, grade, and diameter, (2) calculate the design changes necessary in zones where bending loads are high, and (3) determine if bolt length is adequate. Results from several case studies of full-column bolt loading in coal mine gate roads are used to illustrate the design method. This knowledge will give design engineers a tool for the selection of roof support systems that will improve underground safety by reducing roof bolt failures.

By H. K. Kutter

The pressure pulse generated by an underwater spark \vas investigated in relation to its potential use for rock fragmentation. The study established (1) the relation between the peak discharge current and the peak wave pressure; (2) the relationships among the peak wave pressure, the discharge voltage, and the spark gap width; (3) the type and pulse duration of the generated wave; (4) the percentage of energy transmitted in the spark as a function of spark gap width and discharge voltage; and (5) the percentage of energy converted into the pressure wave as a function of gap width and discharge voltage. Spark-generated fractures were studied in two-and three-dimensional rock and plastic specimens. The laboratory results indicated that the pressure pulse generated by an underwater spark is a potential practical tool for rock fragmentation. The paper contains an appendix describing the capacitive pressure gage specially developed for the laboratory tests.

Jan 1, 1969

By C. Melvin Lepper

To provide the U.S. mining and energy industries with information in the selection of seismic detectors for high-resolution applications, the Bureau of Mines evaluated 35 velocity detectors (geophones) and 9 accelerometers. It was found that velocity detectors with natural frequencies from 10 to 100 Hz were effective for seismic studies in the 5-to 600-Hz spectrum and that accelerometers were most effective in the 100-to 1,000-Hz range. Although the accelerometers described in this report performed about equally with the better velocity detectors tested, the accelerometers showed higher output voltage levels at higher frequencies, which is an advantage. It is important that a seismic detector and its intended purpose be matched properly to achieve the intended results in high-resolution applications. There are many factors that could affect proper matching, thus careful selection of the best detector for a particular application must be exercised.

Jan 1, 1981

By Peter F. Steidl

As part of the Bureau of Mines methane control program, the Upper Free-port coalbed was studied in Fayette County, Pa., where this coalbed lies about 650 feet below the Pittsburgh coalbed and contains the largest remaining reserves of any coalbed in the county. Its estimated recoverable reserves in Fayette County are between 670 and 800 million tons. Coal and overburden isopachs, structure and joint pattern maps, and a fence diagram were prepared using data from gas and oil exploration logs and coal outcrops. These maps will aid in determining the need and/or feasibility of degasifying the Upper Freeport coalbed in the study area. Much of the coalbed in this area is under 600 to 1,400 feet of overburden. By correlation with data from the Pittsburgh coalbed, the gas content at depths of this order is estimated to be between 140 to 300 cf/ton of coal.

Jan 1, 1977

By Ted C. Briggs

The Bureau of Mines is evaluating the thermodynamic properties of helium and helium-containing mixtures. Twenty-two compressibility runs were made with helium at 0° C and pressures to 800 atmospheres using a Burnett-type apparatus. Data from the 22 runs were treated simultaneously and as separate runs while different functional forms and weighting factors were used. A fourth-degree-polynomial equation in the pressure gives a statistically satisfactory representation of the compressibility factor when the data are treated simultaneously and a weighting factor of Pr-3/4 is used. The second virial coefficient of helium at 0° C from this investigation is 11.997±0.015 cm3 mole-1. The stated uncertainty is the random error standard deviation. Compressibility factors determined by this investigation are precise to better than 0.01 percent and are believed to be accurate to better than 0.02 percent.

Jan 1, 1969

By B. Dimitriades

The Bureau of Mines measured the reactivities of 19 hydrocarbons known to be prominently present in automotive exhaust and ambient air in a smog chamber. Results agreed well with those obtained using two other smog chambers. Reactivity scales were developed for hydrocarbons and aldehydes using the results of this work and those of a previous study. Application of the reactivity scales to automotive exhaust samples gave fair agreement between predicted and observed rate-of-N02-formation values; however, predicted and observed ozone yields were neither in agreement nor did they correlate well. This lack of correlation for ozone yield was attributed to the inappropriateness of (1) the individual component reactivity data, (2) the reactivity classification scheme used, and (3) the linear summation method. In seeking to understand this problem and to develop more appropriate reactivity scales, the data were examined from a reaction mechanism standpoint, and further studies were suggested.

Jan 1, 1975

By F. N. Kissell, R. J. Bielicki

The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. Air samples were collected in glass syringes and analyzed by electron-capture gas chromatography. In these studies, the lower limit of detection was about 1 part per billion by volume (ppb) of SF6 per part of air. Experiments conducted in a Pennsylvania limestone mine showed this technique useful in evaluating the effectiveness of auxiliary fans, measuring low flow velocities, probing the air circulating near a working face region where ventilation appeared to be poor, and estimating volumetric flow rates in airways of large cross-sectional area and having low flow velocities. This technique was also used in a western vein-type metal mine to measure the amount of return air being recirculated into the intake air due to leakage through old stoped areas.

Jan 1, 1974

By J. Grumer

Nine dust and gaseous inhibitors of propagating coal dust-air flames (lean, stoichiometric, and rich) were evaluated in a newly developed 15-cm-id, 3.6-meter-long instrumented flame duct, under conditions such that wall quenching was virtually absent and the dust concentration was temporally and spacially uniform to within about t5 percent. Listed roughly in order of increasing efficiency, the inhibitors evaluated were rock dust (calcium carbonate), powdered oyster shells (calcium carbonate), Halon 1301 (trifluorobromomethane), Halon 1211 (difluorochlorobromomethane), sodium chloride, Super-K (potassium chloride), regular-grade fire extinguishant powder (sodium bicarbonate), Purple-K (potassium bicarbonate), and Monnex (potassium bicarbonate combined with urea). Experiments were extended to clouds containing 1 and 2 volume-percent of methane. The inhibition of lean, stoichiometric, and rich methane-air flames without coal dust was also examined in a few instances; results agreed with those obtained for coal dust-air flames.

Jan 1, 1971

By M. M. Jones

A procedure for the spectrophotometric determination of uranium has been developed in support of minerals research being conducted by the Bureau of Mines. Uranium is separated from the sample by tributylphosphate extraction from acid solution containing added aluminum nitrate and (ethylene dinitrilo)-tetraacetic acid solutions. The colored uranium-dibenzoy1methane complex is developed in the organic phase by adding an ethanol solution of dibenzoylmethane buffered with triethanolamine. Absorbance is measured at 410 nanometers, and the response is linear up to at least 100 micrograms U30S in the aqueous aliquot taken for analysis. Aliquots containing as little as 8 micrograms U30S may be analyzed with relative errors no greater than ±5 percent. For aliquots containing at least 35 micrograms U308, relative standard deviation at the 95-percent confidence level is about ±2.2 percent. Appropriate procedures are given for analyzing a wide variety of samples.

Jan 1, 1980

By Larry J. Nicks

The Bureau of Mines is investigating the catalytic activity of rare-earth compounds to develop a catalyst for the cathode reaction of a hydrogen-oxygen fuel cell. This report presents the results of studies of the catalytic activities of lanthanide oxides for the oxidation of hydrogen at 150° to 250° C. Preliminary activity tests were made with approximately stoichiometric mixtures of hydrogen and oxygen diluted with helium. A series of tests was also run under oxygen-rich conditions in which specific rate constants and activation energies were determined. Variations in rate constants up to 2,000 times were observed for the various lanthanide oxides. The three most active catalysts were oxides of Ce, Pr, and Eu, having specific activities of 6.93 X 10-7, 4.88 X 10-7, and 4.06 X 10-7 moles H2.sec-1.m-2, respectively, at 200° C.

Jan 1, 1973

By F. P. Haver

A procedure is described for recovering both lead and sulfur from galena flotation concentrate, comprising the following steps: (1) Aqueous oxidation of the concentrate, using ferric sulfate to convert lead sulfide to sulfate and to give elemental sulfur; (2) regeneration of the ferric sulfate by electrolysis in a diaphragm cell; (3) treatment of the leach residue with ammonium carbonate solution to change the lead to an acid-soluble form and to produce ammonium sulfate as a byproduct; (4) solution of the lead carbonate in hydro-fluosilicic acid followed by electrolysis to recover the lead as metal and regenerate the acid; and (5) extraction of the elemental sulfur from the final residue with an organic solvent. About 90 percent of the lead can be recovered by the above method as 99.9-percent-pure metal, together with two-thirds of the sulfur--half in the elemental form and half as ammonium sulfate.

Jan 1, 1970

By Laurance L. Oden

The Bureau of Mines studied three processes for preparing NaAl(OH)2C03) the intermediate compound which is calcined to produce alkalized alumina: (1) Mixing of Na2 C03 and of A12 (S04)3 solutions, (2) digestion of aluminum hydroxide in solutions of Na2C03 and NaHC03 at 90° C, and (3) addition of CO2 at 25° C to caustic solutions of aluminum to precipitate aluminum hydroxide followed by digestion at 90° C. The first process had the highest raw material consumption and washing requirements, and successful application of process 2 depended upon the availability of active aluminum hydroxide. Process 3 was the most effective, considering both process technology and raw material requirements. Procedures were also investigated for washing, filtering, drying, and calcining precipitates. Analytical methods included X-ray diffraction, atomic absorption spectroscopy, differential thermal analysis, and thermogravimetric analysis.

Jan 1, 1969

By J. C. Edwards

Fire experiments were conducted in the Safety Research Coal Mine (SRCM) at the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, with coal, diesel-fuel, electrical-cable, conveyor-belt, and metal-cutting fire sources to determine the response of fire sensors to products-of-combustion (POC). Metal oxide semiconductor (MOS) and smoke fire sensors demonstrated an earlier fire detection capability than a CO sensor. This capability was of particular significance for a conveyor-belt fire in which the optical visibility was reduced to 1.52 m with an increase in CO of less than 2 ppm at a distance of 148 m from the fire. Application of a neural-network program to the sensor responses from each type of fire source resulted in correct classifications of coal, diesel-fuel, cable, belt, and metal-cutting combustion with a mean of 96% of the test data correctly classified.

Jan 1, 2000

This chapter defines light as a type of energy, and tells how different features of light are measured. It 1s important to understand the units of light measurement because they are used throughout the rest of the book. But more Important, this will help you to understand the "regs" and how to get the best out of the lighting you have available! By the time you complete this chapter, you should know what candle-power, foot-candle, and foot-lambert refer to, and you will also be able to tell why the helmet that the new miner wears appears orange to human eyes. Light that you "see" is really radiant energy that hits the retina of the eye. Radiant energy moves out from a light source much like a series of bullets from a number of machine guns being fired at the same time in all directions.

Jan 1, 1976

By J. C. Edwards

Fire experiments were conducted in the Safety Research Coal Mine (SRCM) at the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, with coal, diesel-fuel, electrical-cable, conveyor-belt, and metal-cutting fire sources to determine the response of fire sensors to products-of-combustion (POC). Metal oxide semiconductor (MOS) and smoke fire sensors demonstrated an earlier fire detection capability than a CO sensor. This capability was of particular significance for a conveyor-belt fire in which the optical visibility was reduced to 1.52 m with an increase in CO of less than 2 ppm at a distance of 148 m from the fire. Application of a neural-network program to the sensor responses from each type of fire source resulted in correct classifications of coal, diesel-fuel, cable, belt, and metal-cutting combustion with a mean of 96% of the test data correctly classified.

Jan 1, 2000

By B. J. Scheiner

Carbonaceous gold-bearing ores of the type that occur in north-central and northeastern Nevada were investigated by the Bureau of Mines as part of its Heavy Metals Program. Specific objectives were to identify the carbon and organic compounds that prevent adequate gold recovery from the ore by cyanidation and to develop an economical process that would overcome the detrimental effect of the carbonaceous constituents. Activated carbon and long-chain organic compounds containing sulfur and nitrogen were found in the ore. Part of the material consisted of stable gold organic complexes. A mild oxidation technique that allowed gold extraction as high as 96 percent by subsequent cyanidation was developed. A variety of oxidants was shown to be effective in improving gold recovery, including chlorine and sodium hypochlorite (NaOC1). An electrolytic oxidation process was developed that was particularly advantageous from an economic and effectiveness standpoint.

Jan 1, 1971

By Margaret R. Egan

In an underground mine fire, a toxic mixture of combustion product gases and particulate matter is transported by the ventilating system endangering everyone downstream. To determine the magnitude of the problem that these toxic combustion products pose, the U.S. Bureau of Mines is investigating the combustion products of typical materials found in underground mines. The total toxicity of the combustion products depends upon the evolving gas species and particulate matter, the amount of material involved, and the ventilation rate. In a simulated mine environment, the products from smoldering poly- vinyl chloride (PVC) brattice and conveyor belting were analyzed for gas concentrations and smoke characteristics. The primary toxic gases are hydrogen chloride (HC1) and carbon monoxide (CO). Smoldering conveyor belts are more detectable than smoldering PVC brattice cloths. These results, combined with previous analyses, are used to estimate relative toxicities, product levels, and detect-ability of smoldering mine combustibles.

Jan 1, 1992

By Industrial Research Office

"The U.S. Bureau of Mines established on August 15, 1983, the Generic Mineral Technology Center for Respirable Dust within the Mining and Mineral Resources Research Institutes (MRIs) at The Pennsylvania State University and West Virginia University in association with participating MRIs at Massachusetts Institute of Technology and the University of Minnesota. The Center's research program has been developed with recognition of the stated objective of the Federal Mine Safety and Health laws which is to ""... permit each miner the opportunity to work underground during the period of his entire adult working life without incurring any disability from pneumoconiosis or any other occupation-related disease . . . ."" The Center's program is designed to permit an accelerated attack on the fundamental research problems for the control of respirable dust in mines.The primary goal of the Center is to reduce the incidence and severity of respirable dust disease through advancing the fundamental understanding of all aspects of respirable dust associated with mining and milling and the interaction of dust and lungs. The Generic Technology Center's research program explores these concerns with the objective of refining existing strategies and developing new respirable dust control techniques that are consistent with the fundamental dust-lung interaction processes that lead to mine worker disability. The work concentrates on: (1) control of dust generation; (2) dilution, dispersion and collection in mine airways; (3) characterization of dust particles; (4) interaction of dust and lungs; and (5) relationship of mine environment, geology, and seam characteristics to dust generation and mobility. The fundamental aspects of this work are applicable to the control of respirable dust problems in both hard rock mines and coal mines and to other dusts such as diesel-generated. The Center activities involve the training of engineers and scientists, graduate students and undergraduate students through their respective institutions, and the technology transfer to the industry. The Center also serves as the reference center for publications' in the respirable dust area.The Center is composed of faculty from the four universities/institutes listed above. The personnel, facilities and equipment that are available to the Center from these entities are diverse, complementary and comprehensive. More than fifty scientists, engineers; and medical personnel in the Center are engaged in respirable dust research. Additionally, the expertise and facilities of the NIOSH--Division of Respirable Disease Studies are available as a result of the existing relationship between NIOSH and West Virginia University.The breakdown of the dust research program into the five areas mentioned above recognizes the importance of an integrated fundamental research approach to the respirable dust problem compatible and complementary with the existing and ongoing U.S. Bureau of Mines activities. The specific projects in the research areas are a result of a careful evaluation of the past and ongoing research activities, the identification of areas where data and information are scarce, and awareness of the recommendation of the National Academy of Sciences Study on the Measurement and Control of Respirable Dust. Penn State is the administrative unit for the Center. Funding to date is nearly $6.5 million."

Aug 31, 1989

Objective To develop a passive, inexpensive technique for monitoring explosion overpressures within sealed areas in underground coalmines. Background From 1994 to 2000, seven explosions of methane and/or coal dust occurred within the worked-out, sealed areas (gobs) of underground U.S. coal mines. These explosions, believed to have been started by lightning, destroyed many seals and caused much damage external to the sealed area. One gob explosion went undetected until the mine operator reopened the sealed area and discovered the damage. Fortunately, these gob explosions did not cause any fatalities or injuries. Because lightning occurs in just about all mining areas, several questions arise. Could gob gas explosions be occurring in other sealed areas and going undetected? If so, what is the magnitude of the resulting explosion overpressures? The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) undertook a study to identify and evaluate passive measuring devices to monitor and quantify the overpressures associated with such explosions. This work was done in parallel with full-scale explosion experiments for evaluating the strength characteristics of seals used for isolating areas in underground coal mines. Approach Evaluation studies were done in PRL's 20-liter explosion test chamber and in the full-scale Experimental Mine at Lake Lynn Laboratory to evaluate the response and accuracy of various commercially available automobile tire pressure gauges to overpressures generated from gas and dust explosions. The first series of tests was done in the 20-liter chamber, which is used to study the explosibility and inerting of fuel dusts and gases. Data from the tire pressure gauge tests were compared to the pressure-time data obtained from the 20-liter chamber 's traditional electronic strain gauge pressure transducer recorded on a high-speed data acquisition system. To evaluate the tire pressure gauges, the valved inlet (tip) of the candidate pressure gauge was removed and the body of the gauge was cemented with epoxy into a 0.25-in pipe elbow and attached to the outside of the test chamber. A second series of tire gauge evaluation tests was done at Lake Lynn during explosion-resistance testing of seals used in underground coal mines. Full-scale seals (20 ft wide by 8 ft high)were constructed as one wall of a 2,000-ft3 chamber and exposed to a series of methane explosions. Average overpressures ranged from20 to 80 psi. The seals were built with various strength materials ranging from 7 to 48 in thick. The modified tire gauges are attached on the outside of the chamber to a 0.25-in NPT pipe that extends into the chamber (figure 1). The axis of the gauge is mounted at a right angle to the plane of the seal to minimize the coupling of any seal movement to the stem of the gauge that may cause inaccurate readings. The internal explosion pressure history is recorded with a strain gauge pressure transducer mounted inside the chamber. Methane is injected into the chamber, mixed with air, and ignited with an electric spark located at the geometric center of the chamber. Maximum explosion overpressures are recorded and compared with the tire gauge pressure.

Jun 1, 2001

By Glenn C. Reed

"Preliminary examination of the Glass Buttes mercury deposits, Lake County, Oregon, was made in August 1945 at the request of W. S. Lazier, present lessee of the deposit.Most of the prospect openings in the area were inspected. The more significant workings were sampled and napped in detail. This report presents the data obtained from the investigation to date.In its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. noon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. P. S. Dean, assistant director.Special acknowledgment is due to S. H. Lorain, chief, Albany Division, Mining Branch and to S. R. Zimmerley, chief, Salt Lake City, Utah, Metallurgical Division, for analyses of the ores.The presence of quicksilver in the Glass Buttes district has been known since about 1930. The area immediately north of Middle Butte has been superficially prospected by numerous test pits, trenches, shafts, and short adits, which revealed a number of opalized zones. Many of these opalized zones contain weak to strong concentrations of cinnabar. The area has not boon explored thoroughly; no mercury has been produced from any of its deposits.A block of 48 full-size claims has been located to cover a large part of the area in sections 34 and 3, Tps. 23 and 24 S.,R. 23 E.,W.M. These claims, held by, location are owned by H. S. Miller, lumberman of Bend, Ore. W. S. Lazier, 10N. W. 20th Avenue, Portland, Ore., currently controls the property under,a nominal leasing agreement. J. W. McDaniel, 44 Lake Place, Bend, Ore., has done much of the underground and surface exploration on the property.The Glass Buttes district is an area of low relief in the Deschutes River drainage system near the northeast corner of Lake County, Ore. (See fig. 1.) The arid climate is marked by extremes of winter and summer temperature. Water for cane use is not available in the immediate area. Well water, however, can be obtained in limited supply on ranch property 5 miles to the south."

Aug 1, 1946