Search Documents

By R. K. Koch

The vapor pressures of liquid molybdenum and liquid zirconium were determined by the Langmuir free-evaporation method. An electron-beam furnace with a water-cooled copper crucible was used for melting. Temperature was measured with a two-color ratio pyrometer. The vapor-pressure data led to the following equations: [log p (atm) = 5.429 - 28,380 T for liquid molybdenum in the range 2,890° to 2,990° K, and log p (atm) = 6.521 - 30,940 T for liquid zirconium in the range 2,229° to 2,795° K.] Third-law evaluations of each data set gave mean heats of sublimation (298.15° K) of 157.6 ± 1.8 kcal/mole and 148.4 ± 2.4 kcal/mole for molybdenum and zirconium, respectively, where the uncertainties are two standard devia¬tions. Second-law standard heats of sublimation determined from sigma plots and tabulated enthalpies were 143.5 ± 2.7 kcal/mole and 149.2 ± 3.8 kcal/mole for molybdenum and zirconium, respectively. The better agreement in heats of sublimation for zirconium is attributed to the 566° K temperature range studied which permitted a more accurate definition of the vapor pressure curve than could be obtained from the 100° K span for molybdenum. This supposition was verified by making a sigma-prime plot which utilized solid vapor pressure data for molybdenum to extend the evaluation range by 800° K. This gave a standard heat of sublimation of 155.2 ± 1.6 kcal/mole which is in good agree¬ment with the third-law value. The plot also gave a standard entropy of sublimation (298.15° K) of 35.73 ± 0.48 eu.

Jan 1, 1968

By Maria I. De Rosa

Table 37 and figure 13 show the number of fires and fire injuries for surface stone mines by state during 1990-2001. Table 37 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 96 fires occurred in 31 states and 1 fire occurred in Puerto Rico. Sixty-eight of the fires caused 67 injuries and 1 fatality (including 6 fires and 5 injuries involving contractors). The yearly average was eight fires and 5.6 injuries. The Ewhr value was 689 x 106 hr (Irr = 0.02), and the LWD value was 7,399. Indiana had the most fires (eight fires and four injuries), followed by Georgia (seven fires and seven injuries) and Pennsylvania (seven fires and five injuries). Of these states, Georgia had the highest injury risk rate value (Irr = 0.058). Table 38, partly illustrated in figure 14, shows the number of fires, fire injuries, fire fatalities, risk rates, employees' working hours, and lost workdays by time period. The number of fires and fire injuries show an increase during the second period followed by a decrease during most of the remaining periods. Employees' working hours increased during most of the periods. The In values follow patterns similar to those shown by the injury values. Tables 39-44 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 15 shows the major variables related to fires for 1990-2001. Table 45 shows the number of fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

Apply state-of-the-art monitoring and computer systems technology to remotely monitor geostructural data and evaluate ground conditions in near real-time. Background Recently, the coal mining industry has progressed dramatically from a labor-intensive industry to highly mechanized and automated systems achieving significantly higher production rates. In underground longwall coal mines, production and face advance rates have increased by almost tenfold in the last 15 to 20 years. With increasingly high advance rates, geologic anomalies which affect rock mass quality are encountered more frequently, far exceeding the current rate at which ground control information can be processed and analyzed. As a result, mine operators find themselves with insufficient time or resources to cope with the rapidly changing ground conditions. To keep up with the technological advancement in mining and the associated ground control problems, the Bureau of Mines is conducting a multi-phase research pro¬gram to implement a computer-assisted Ground Control Management System (GCMS). Research is ongoing at present, but when completed the system will be designed to 1) monitor and evaluate data on rock properties, geologic conditions, and rock mechanics data from underground sensors in near real-time; 2) interpret the analyses to evaluate the interaction between various critical ground control parameters; 3) assess the structural integrity of the mine; and 4) determine failure modes and provide recommendations for control measures, design modifica¬tions, and alternative support procedures. The system will be expanded into its full capability during various phases of this research program.

Jan 1, 1991

By James H. Aase

Selected glacial lake clay deposits in Minnesota were sampled, tested, and evaluated to determine their suitability for use as a bonding agent in iron ore pellet manufacturing. Preliminary tests conducted on clay samples obtained from five ancient glacial lake basins identified the clays in the Lake Agassiz glacial lake basin near Cook, Minn., as having the greatest bonding potential. An auger drilling program was conducted to obtain substantial quantities of representative material for detailed testing. The drilling indicated the presence of large clay reserves in excess of 500 million tons within the 12-square-mile area investigated. Bench scale tests indicated that the bonding properties of Cook area clays, when activated with relatively small quantities of sodium carbonate monohydrate (Na2C03?H2O), imparted excellent strength characteristics to iron ore pellets. Larger scale continuous pelletizing tests were made to confirm the bench scale results. These tests indicated that use of 1 percent activated clay alone as binder gave the iron ore pellets an overall strength slightly lower than with 0.75 percent bentonite, considered the industry standard. Use of 0.5 percent activated clay plus 0.5 percent bentonite produced better pellet strength qualities than use of 0.75 percent bentonite alone, without increasing the silica plus alumina content. The data from both bench scale and larger scale continuous tests suggest that the Cook, Minn., clays can be utilized after activation either alone or in combination with bentonite at an economic advantage over present pelletizing practice with bentonite.

Jan 1, 1968

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health conducted a study of the explosibility of various metals and other elemental dusts dispersed in air, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating the explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafhium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties - from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" (very low volatility) elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechc ignitors. The experimental data obtained included the minimum explosible concentrations, maximum explosion pressures, and maximum explosion temperatures. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from -1 550 K for tin and tungsten powders to -2800 K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures. In general, the dusts whose experimental temperatures were closer to the adiabatic values were those with the finer particle sizes, those that were more easily vaporized, and/or those that were intrinsically more reactive.

By J. W. Montoya

The chemical, mineralogical, and physical properties of berylliferous tuff from Spor Mountain, Utah, were determined in laboratory research conducted by the Bureau of Mines. Two beryllium-bearing minerals--a hydrated form of bertrandite and a berylliferous saponite--were found to be present in the tuff. Each of the beryllium mineral forms predominated in samples from certain areas of the district. The possibility of practicably separating the beryllium minerals from the tuff by physical methods appears remote because of the complexity and nature of the mineral associations. Beryllium mineralization in the region occurs in a rhyolitic tuff usually overlaid by unaltered rhyolite. The beryllium is distributed erratically throughout the tuff in individual mineralized bodies. Many samples of mineralized tuff were examined and found to contain from 0.2 to 1.8 percent BeO. All samples contained a hydrated form of bertrandite that was nearly cryptocrystalline, whereas samples from one area also contained a berylliferous saponite of variable beryllium content. Neither mineral has been previously reported, although related bertrandite-like minerals have been found in the U.S.S.R. and berylliferous minerals of the montmorillonite group have been synthesized. Most of the minerals of the tuff are finely crystalline, intergrown, and have similar densities. The complexity and intimacy of the mineral associations, the difficulty of achieving effective mineral liberation, and the highly friable nature are characteristics that lead to the conviction that tuff of the type examined cannot be effectively concentrated by gravity, magnetic, electrostatic, attrition, washing, sizing, or flotation methods.

Jan 1, 1962

By Gerrit V. R. Goodman, Charles D. Taylor, Edward D. Thimons

Future coal mining systems will be able to cut from crosscut to crosscut where advances could exceed 100 ft. However, limitations arise when ventilating such mining systems. In deep advance mining, there would be no workers at the face to advance ventilation tubing or curtain manually. Traditional methods also provide no means for maintaining face ventilation after the miner backs away from the face. U.S. Bureau of Mines research is studying means to provide effective ventilation at cut depths beyond the current limit of 40 ft. Several innovative ventilation schemes are currently being considered. One such method is the use of a jet fan to ventilate a deep cut. A jet fan is simply a freestanding fan using little or no ducting to direct the ventilation flow. Jet fan testing in a 90-ft entry revealed that higher exit velocities and greater penetration depth occurred when various configurations were used to confine and direct the air flow. Additional testing also indicated that 2,200 cfm of fresh air was delivered to the face 90 ft distant when a check curtain was used to limit entrainment around the fan. Without this curtain, this quantity dropped to only 1,000 cfm This testing indicated that a jet fan was capable of providing ventilation to a distant face area. It also highlighted potential problems, such as recirculation at the fan and reentrainment in the jet flow. Despite these potential problems, jet fans may be adequate for ventilating cuts exceeding 40 ft.

Jan 1, 1992

By W. H. Ode, F. H. Gibson, W. A. Selvig

The great expansion of production of aluminum for war purposes has aroused some concern regarding the available supply of carbon suitable for making carbon electrodes required in the electrolytic aluminum process. Approximately three-quarters of a pound of carbon electrode is consumed for each pound of aluminum produced. 5 Because of its small amount of impurities and its suitable physical characteristics, calcined petroleum coke is the standard material used by the aluminum industry for making electrodes As it may be necessary to use some substitute materials, the possibility of using coke made from coal has been considered. Besides this possible use, information concerning the source of low-ash coals is of general interest. Specifications of the aluminum industry for calcined petroleum coke suitable for the manufacture of electrodes are very stringent in regard to allowable impurities. In one such specification the maximum allowable ash is 1.0 percent; the maximum allowable content of iron (as Fe) is 0.06 percent and that of silicon (as Si) is 0.08 percent; the maximum for cal- cium (as Ca) and for sodium (as Na) is 0.12 percent for each, but the two combined may not exceed 0.12 percent; maximum allowable sulfur is 2.0 per- cent. The presence of barium, nickel, chromium, manganese, cobalt, or vanadium is objectionable, and only extremely small amounts are allowed. In regard to physical properties, the coke is required to be so thoroughly calcined that it has a real density of at least 2.02.

Nov 1, 1943

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

RECOMMENDATIONS FOR FURTHER WORK Based on the development effort and full-scale tests conducted during this program, a number of technical areas for future research and development have been identified. Further work in these areas would help to improve the reliability, speed of operation and efficiency of the remote sealing system. Recommendations for future work are summarized as follows 1. Development of an Inert Gas Generator For the sake of expediency in conducting the field test program, fresh air was used as the fluidizing medium for the fly ash. However, in an actual mine fire application the use of fresh air is likely to be prohibited. An inert gas, such as nitrogen, carbon dioxide or air containing less than 8 percent oxygen would be required. Using combustion as a means of reducing the oxygen content of air appears to be an attractive solution to the generation of the high flow rates of gas required (2500 to 5000 scfm). Such an inert gas generator would serve a dual purpose for the overall fire extinguishing operation. First, it would provide the inert gas for fluidizing the fly ash. Second, it could be used for inerting the fire area after the seals had been placed, thereby reducing the time required to extinguish the fire. It is recommended that the Bureau undertake a program to develop a field-operable, inert gas generator to satisfy these two requirements. 2. Development of a Field-Operable Sonar Initial Probing System A first stage prototype of a sonar initial probing system was developed during this present program. The results obtained with

Jan 1, 1973

Reduce rockfall fatalities and injuries by using innovative blasting practices to reduce damage to the rock at the excavation limits with little or no increase in cost. The Problem Falls of highwall have been a leading cause of fatalities, injuries, and equipment damage in the surface mining industry. Although the number of highwall falls is not great, when such an incident does occur it is about 14 times more likely to be fatal or result in severe injury and damage to equipment than other types of surface mine accidents. Overbreak or damage to the rock from poor or improper blasting practices is a major factor contributing to rock falls. Presplitting or cushion blasting is the technique most often recommended for improved wall control. This type of blasting however, adds to drilling and blasting costs and is not universally accepted by the industry. Air gap presplitting techniques, also called air decks, are currently being used in some mines as a less costly alternative to conventional presplitting. Approach Blasting can cause highwall damage, but proper blasting techniques have been shown to reduce the magnitude of rockfall problems. In preventing rock falls, it is important to maintain the natural strength of the rock structure to the greatest extent possible. Improved blasting practices have three main advantages: 1) they are preventive rather than corrective in nature; 2) they are cost effective; and 3) they have a very low impact on the mining operation when properly implemented. New ways of evaluating highwall integrity, such as seismic refraction tomography, were investigated.

Jan 1, 1991

By Richard H. Oitto

The Bureau of Mines and Kaiser Steel Corp. are cooperatively demonstrating the shield-type roof support in the longwall mining of a 10-1/2-foot-thick coalbed at the York Canyon mine near Raton, N. Mex. As part of the demonstration, the shield supports have been successfully and safely moved from a completed longwall face to a new longwall face. When these shield supports were moved in 1976 they were the largest and heaviest longwall support system in use in U.S. coal mines. The shield supports, preparations for moving them, the actual move, and installation at the new face are discussed.

Jan 1, 1977

By Motohisa Kanda

The time and amplitude statistics necessary to adequately describe electromagnetic (EM) noise in mines are illustrated through computer software techniques. They are 1) Allan Variance Analyses (AVA), 2) Interpulse Spacing Distributions (ISD), 3) Pulse Duration Distributions (PDD), 4) Average Crossing Rates (ACR) , and 5) Amplitude Probability Distributions (APD) . These statistics are illustrated using data taken from a rather large store of raw analog data recorded in operational mines. The curves generated for the illustrations characterize the noise environment in the mines from which the corresponding data were taken, and should aid in the design of reliable communication systems for such mines.

By P. D. Bergman

The high price of pollucite ore, its limited availability, and the need to provide stack removal of S02 present formidable obstacles to the use of pure cesium as a seeding material in MHD power generation. Cost estimates indicate that mixed potassium-cesium seeding is preferable to the use of either pure cesium or pure potassium. Cheaper electricity and higher open-cycle MHD operating efficiencies result from the use of mixed seed. Savings of $3,000,000 per year in power costs for a 1,000-MWE open-cycle MHD power-plant are envisioned if the mixed seeding technique is adopted.

Jan 1, 1972

Native asphalt was produced in 1977 by six companies in four States. Leading States were Texas and Utah. Output declined 39% to 1,237,000 tons valued at $18,874,000. Bituminous limestone was produced by Whites Uvalde Mines and by Uvalde Rock Asphalt Co. in Uvalde County, Tex.; by Southern Stone Co. in Colbert. Ala.; and by Barton County Rock Asphalt Co. in Barton County, Mo. Gilsonite was produced by American Gilsanite Co. in Uinta County. Utah, and by Ziegler Chemical and Mineral Corp. in Weber County. Utah. The asphalt was used for streets and roads, and for other purposes.

Jan 1, 1980

By L. A. Johnson

This Bureau of Mines report presents the analysis of three cores from the Asphalt Wash area of the P.R. Spring tar sand deposit of northeastern Utah. Two tar sand zones are indicated in the Asphalt Wash Area. Total net thickness of the tar sand ranges from 23 to 39 ft, with occurrences between 56 and 263 ft in depth. The sand has average porosity of 24.7 pct of bulk volume, average permeability before and after extraction of 87.5 and 596 md, respectively, and average oil saturation of 58.1 pct of pore volume. Oil gravity averages 10.9° API.

Jan 1, 1975

By James J. Olson

Previous Bureau of Mines studies of vibrations from quarry blasts have shown that the square root of the charge-weight may be used to group particle velocity data from various charge sizes, and that empirical propagation equations may be used to estimate vibration amplitudes. Particle accelerations of the sandstone roof of the White Pine Copper mine, Michigan, were measured to determine whether similar propagation equations may be developed for underground mine blasts. Vibration data from White Pine blasts were best grouped by scaling with the square root of the charge weight. Cube root scaling did not effectively group the data. The empirical propagation equation AW1/2 = 50,000 (R/W1/2)-2.21 where A is peak-to-peak acceleration in g's, W is the zero-delay charge-weight in pounds, and R is the distance from the blast in feet, may be used to estimate maximum vibration amplitudes from production sized blasts. Vibration differences among headings and types of explosive charge (AN-FO and dynamite), while statistically significant, were not a major factor in the estimation of maximum vibration amplitudes with an empirical propagation equation. Vibration differences between types of explosive charge were larger than the differences among headings, indicating that some reduction of vibration amplitude might be gained by using AN-FO rather than dynamite. Acceleration records from both White Pine's AN-FO and dynamite production blasts show that high intensity vibrations from the delayed portions of the blast (each delay interval = 25 milliseconds) were separate events, and that the zero-delay portion of the blast produced the maximum vibration amplitudes. If the pull of the underground blast round can be maintained, a reduction of the zero-delay charge-weight may effectively reduce the maximum vibration amplitude of the blast.

Jan 1, 1970

By Maria I. De Rosa

The U.S. Department of Energy Pittsburgh Research Center2 conducted experiments with mine conveyor belt samples in a 20-L furnace and in a laboratory fire tunnel to measure and compare the major toxic gas concentrations evolved during the combustion of the materials. The toxic gas concentrations, measured simultaneously through a multiport sampling device and treated as yield values, included hydrogen chloride (HO), hydrogen cyanide (HeN), oxides of nitrogen (NO, treated as NO), and carbon monoxide (CO). The data obtained from the two experimental systems were in good agreement. Correlations were developed for the toxic gas yields as a function of the percentage of chlorine (for HO gas), nitrogen (for HCN and NO, gases), and carbon (for CO gas) contained in the original materials. The toxic gas yields were also used to calculate a toxicity index (TI) parameter to assess the potential gas toxicity of belt materials during a fire. Furthermore, the TI and the mass loss burning rate values were used to calculate a toxicity hazard (TH) parameter to estimate the toxic gas hazard produced by a burning belt in a ventilated system. Results show that polyvinyl chloride (PVC) belts released higher HC1 concentrations because of the higher chlorine content; styrene-butadiene rubber (SBR) belts released higher CO, HCN, and NOz concentrations because of the higher carbon and nitrogen contents. The TI's, however, were greater for the PVC belts due primarily to the higher levels of HC1 produced. The fire tunnel data indicate that the SBR belts can bum with higher mass loss rates than the PVC belts, resulting in a potentially higher toxic hazard (higher TH values) even though their TI values were lower than those of the PVC belts.

By E. D. Regad, W. E. Wallace, V. Vallythan, V. Castranova, P. Hathaway, F. H. Y. Green, M. J. Keane

"Abstract—Inhaled particle contact with pulmonary surfactant in the hypophase lining pulmonary alveoli was modelled in vitro by exposing two respirable sized dusts, kaolin and silica quartz, to lecithin, a major component of pulmonary surfactant, emulsified in physiological saline. Lecithin adsorbs to the dusts upon incubation at 3TC and suppresses their cytotoxicity as measured by pulmonary macrophage and erythrocyte assays, suggesting that pulmonary surfactant provides a defence system against prompt cell membrane lysis by inhaled dusts. Subsequent pulmonary macrophage phagocytosis and lysosomal enzyme digestion of the coated dusts was modelled in vitro by incubation with phospholipase A2 for one hour. With increasing lipase activity, silica haemolytic potential was restored to native silica levels. Kaolin was retoxified to levels far in excess of native kaolin haemolytic potential. Elution, thin layer chromatography and phosphate assay of treated dusts indicate that most lecithin on silica is digested to lysolecithin and desorbed, silica retoxification being due to surface and adherent lysolecithin effects. Most lecithin on kaolin is not digested in the same time; that which is. results in adherent lysolecithin which is responsible for the kaolin retoxification. Digestion with phospholipases A2 and C together produces only weakly retoxified kaolin. Results suggest that surface adsorption properties which control the adherence of prophylactic surfactant distinguish the pathogenic potentials of quartz, kaolin and mixed dust.INTRODUCTIONERYTHROCYTE HAEMOLYSIS and pulmonary macrophage enzyme release assays show quantitatively comparable high cytotoxicities for both silica quartz and kaolin respirable sized dusts (BROWN, et al., 1980; DANIEL and LE BOUFFANT, 1980.) This contrasts with the strong potential for respirable quartz dust to induce pulmonary fibrosis and the much more limited potential of kaolin dust to do the same (MORGAN and SEATON, 1975).In an attempt to understand this anomalous situation, assays were performed on quartz and kaolin dusts incubated with dipalmitoyl lecithin emulsified in physiological saline, to simulate the initial contact of a respired dust with the pulmonary alveolar hypophase. The ability of kaolin dust to adsorb dipalmitoyl lecithin from physiological saline has been quantified (WALLACE, et al., 1975). Such lecithin treatment suppresses the cytotoxicity of both silica and kaolin to background levels (WALLACE, et a1.,1984).Surfactant coated detoxified dusts should then be phagocytised by pulmonary macrophages, incorporated into a macrophage secondary lysosome and exposed to hydrolytic lysosomal enzymes. Among these is phospholipase A2, which hydrolyses diacyl lecithin to lysolecithin. This was modelled by incubating lecithin treated dusts with phospholipase A2 in vitro to determine if the enzyme can digest the dust-adsorbed lecithin, and if the retoxification differs between the two dusts in a manner which might distinguish their pathogenicity."

Jan 1, 1988

By Michael J. Sapko, Eric S. Weiss, Kenneth L. Cashdollar

A fundamental safety research area for the National Institute for Occupational Safety and Health (NIOSH) is to eliminate the occurrence of coal mine explosions or to mitigate their effects. One approach is to develop and evaluate new and innovative seal designs that provide increased explosion protection for mining personnel. The NIOSH Pittsburgh Research Laboratory (PRL) cooperated with HeiTech Corp. of Virginia, Barclay Mowlem Construction Ltd. of Queensland, Australia, and the Mine Safety and Health Administration (MSHA) in three separate research programs to evaluate the strength characteristics and air leakage resistance of numerous innovative seal designs and ventilation control structures for use in underground coal mines. For each phase of the program, various full-scale seals, stoppings, and an overcast design were constructed in PRL's Lake Lynn Experimental Mine near Fairchance, Fayette County, PA. The seals and stoppings were built in crosscuts and were subjected to explosions to evaluate their strengths. Four pumpable cementitious seal designs ranging in thickness from 610 to 915 mm (24 to 36 in) were evaluated in the first cost-reimbursable research program with HeiTech Corp. A simple wooden framework with brattice liner was used as a form to contain the cementitious slurry during the curing period. As the seal designs decreased in thickness, higher compressive strength cementitious grout was used. All four seals withstood an explosion pressure pulse of at least 138 kPa (20 psi) while maintaining acceptable air leakage resistance. In the second cost-reimbursable research program with Barclay Mowlem Construction Ltd. of Australia, several innovative seal and stopping designs and an overcast design were evaluated. Each of the seal designs and the overcast side and wing walls used one or more air-inflated vinyl bladder assemblies anchored to the mine roof and hitched into the ribs and floor. The air within these bladders was displaced with a high-strength cementitious grout. The overcast deck consisted of a 200-mm ('7.8-in) thick reinforced cementitious slab. This was the first time that an overcast structure had been explosion tested under full-scale conditions. All of the seals, stoppings, and overcast design passed the air leakage tests before being subjected to a series of explosions with static pressure pulses ranging from 14 to 475 kPa (2 tab 69 psi). Instrumentation measured seal and overcast wall displacement as a function of time. The 450-mm (1 7.7-in) thick seal in the 2.8-m(9-ft) high third crosscut withstood an explosion pressure of 170 kPa (25 psi), but failed during a later test, which generated a peak static pressure of 475 kPa (69 psi) at the seal location. A similar 450-mm-thick seal in the 2.1-m (7-ft) high second crosscut withstood three explosion tests, which generated peak static pressures of 195, 205, and 370 kPa (28, 30, and 54 psi) at the seal location. Next, the overcast design withstood four explosions, which generated static overpressures ranging from 16 to 47 kPa (2.3 to 6.8 psi). A third program at the request of MSHA evaluated the effectiveness of using pressurized grout bags (Packsetter bags) along the mine roof and ribs in lieu of floor and rib hitching for a standard-type solid- concrete-block seal. This program was initiated to address an urlusual geological mining condition encountered when building seals in entries where required rib hitching is not a viable option due to soft friable coal. Results showed that the use of these quick-setting grout-filled Packsetter bags pressurized internally to 300 kPa (44 psi) not only provides a seal that can withstand a 138-kPa static pressure explosion, but also provides a sealing option where rib hitching is not possible.

Jan 1, 2003

By L. B. Berger

In this investigation, the ampoule type of carbon-monoxide (CO) detector which is manufactured under license of U. S. Patent 1,644,014 (October 4, 1927) was tested for sensitivity and reliability. This detector was devised primarily for examining the air of manholes and sewers for possible dangerous contamination with CO before workman enter those places, but dine to the simplicity of the device it may have a more general usage for examination of atmospheres which are known or suspected to be contaminated with CO. Some of the suggested uses are the examination of the air in garages, tunnels, mines, around blast furnaces, gas plants, and in the home.

Jan 1, 1930