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By Audrey F. Glowacki, August J. Kwitowski, Richard L. Unger, Edward F. Fries

Well-prepared personnel and an effective emergency response plan are essential components of any emergency command center. Unfortunately, evaluating emergency preparedness is often difficult until a disaster actually occurs. For example, unexpected events may develop during an emergency that were not considered during the planning phase. Also, the command center may need to cooperate with organizations that it has not worked with previously. Preparation can be especially difficult for smaller or remotely located command centers, or those with limited resources to conduct mock drills. This paper explores the potential of using the Internet to teach and evaluate command center skills. The National Institute for Occupational Safety and Health (NIOSH) is developing an Internet-based, computer simulation training package for the mining industry. Trainees will play the role of command center leaders at a mine, while the actions of other individuals and organizations are simulated. Trainees will be able to test their emergency response plans and learn valuable lessons from past mine emergencies. Nationally recognized experts will be able to create new training scenarios and make them available to mines throughout the U.S. This product should better prepare command center personnel for large-scale disasters such as fires and explosions. Keywords: emergency preparedness, simulation, training, internet

By John D. Corrick

Three species of chemosynthetic iron- and sulfur-oxidizing autotrophic bacteria have been isolated from the leaching waters of copper mining areas. These species are: The sulfur-oxidizing Thiobacillus concretivorus, the iron-oxidizing Ferrobacillus ferrooxidans, and a sulfur- and iron-oxidizing bacterium closely resembling Thiobacillus ferrooxidans, INTRODUCTION Among several suggested new processes for treating marginal ores in the United States, none is more intriguing than the possibility of extracting metals from low-grade materials by the action of microorganisms One phase of a Federal Bureau of Mines investigation toward developing such a procedure was to isolate and identify specific chemosynthetic iron and sulfur. oxidizing autotrophic bacteria native to certain domestic copper deposits where leaching is practiced. The bacteria or microorganisms considered important to this investigation are those capable of producing solutions of ferric sulfate and sulfuric acid. Solutions of this type are excellent solvents for some copper minerals By establishing the presence of these bacteria at certain copper-leaching areas, strength would be given to a theory that microbial activity is partly responsible for the oxidation that takes place at these areas. Their presence also advances possibilities for controlled use of microbial action in metal extraction processes. Leathen4/ has demonstrated that one of the chemosynthetic iron-oxidizing bacteria, Ferrobacillus ferrooxidans, can oxidize 200 parts per million of ferrous iron to the ferric state in 3 days,

Jan 1, 1961

By J. M. Mutamansky

"Coal mine dust research throughout the world has been stimulated by the recognition of its importance in the development of coal miners' diseases, particularly coal workers' pneumoconiosis (CWP). A historical look at the problem and the present state of knowledge in this area of importance to the worldwide coal industry is presented. A summary of progress made in this area is provided and some research ideas for the future are discussed.1. INTRODUCTIONI thank Dr. Yong Won John, President of the Korean Institute of Mineral and Mining Engineers, for his invitation to address the International Symposium on Coal Mining and Safety. This presents me with an interesting opportunity to take a broad look at the research in coal mine dust and where we are going. From this broad perspective, we can all view the progress and problems that are apparent in the present state of knowledge of coal mine dust. One important element in the review of coal mine dust research and its role in miners' diseases is that of its history. The existence of diseases attributed to the mine atmosphere is often traced back to Pliny the younger in the first century A.D. His work on natural history mentioned observed human effects attributed to mine fumes and vapors. However, the subject of the effects of dust in the mine was not mentioned in published literature until 1556 when Agricola discussed the ailments of miners in his day (Seaton 1975).For many centuries, many medical ailments of the lungs were often categorized together and distinct diseases were often not recognized until more modern times. The ability to distinguish different lung diseases was limited until the discovery of X-rays in 1986. Nonetheless, Zenker in 1866 applied the term pneumonokoniosis to any disease where dust gathers in the lymphatic depots of the lungs. This term was changed to pneumoconiosis in 1932. While pneumoconiosis was defined in the 1800s, scant attention was paid to control of miners' diseases until recent decades. The first attempt to control disease through control of the mine atmosphere has been attributed to the South Africans who instituted a silica control in 1910 (Drinker and Hatch 1954)."

Jan 1, 1989

By R. L. Grayson, W. E. Wallace, M. D. Attfield, A. Q. Wearden, P. Bolsaitis, R. D. Kennedy, M. J. Keane, J. C. Harrison

"Respirable high-silica particles from four coal mines. a clay mine and a tunnelling site were analysed for silicon vs aluminum composition by performing scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS) at electron accelerating voltages of 20 kiloelectron volts (keV). The same particles were analysed at 5 keV to determine possible differences in surface vs bulk composition. In some cases high-silica particles exhibited a decrease in the ratio of silicon to aluminium K-alpha line intensities with decreasing electron beam accelerating voltage. This behaviour is consistent with aluminosilicate surface contamination or occlusion of a silica particle. Some 20 high-silica particles were analysed from each of 10 samples. Powdered aluminosilicate glass was used as a control for the behaviour of silica with a homogeneous distribution of aluminium in the particle. Significant differences were found between the control and sample means for an Illinois bituminous coal mine dust, two western and one central Pennsylvania bituminous coal mine dust low-temperature ashes. and a clay mine and mill dust sample, but not for an anthracite coal mine dust and two central Pennsylvania bituminous coal mine dust low-temperature ashes. INTRODUCTIONRESPIRABLE dust quartz content commonly is measured on bulk samples by using i.r. spectroscopy or X-ray diffraction. For research purposes, individual particle-by particle SEM-EDS analysis at 20-30 keV electron beam accelerating potential may be used also. Such measurements have not provided an unambiguous association of quartz content with occupational pulmonary disease prevalence in exposed workers (WALTON et al., 1977). Rather, there is evidence that coal rank modifies the relationship between dust exposure and pneumoconiosis development (WAL TON et al., 1977; ROBOCK and BAUER, 1990; ATTFIELD and MORRING, in press). SEM-EDS analysis was performed to measure the silicon fraction, Si/(Si +Ai), at 20 and at 5 keV on high-silica particles to determine if some respirable quartz particles generated by mining exhibit heterogenous composition with depth (WALLACE et al., 1990), which might affect the bioavailability of the quartz surface."

Dec 1, 1995

By Dana Reinke, William Wiehagen, Launa Mallett, Charles Vaught, Kathleen M. Kowalski, Michael J. Brnich, Lynn Rethi, Lisa Steiner

Safety and health professionals from all sectors of industry recognize that training is a critical element of an effective safety and health program. A major concern in the mining industry today is how to train the present aging workforce plus the expected influx of new and less experienced miners and mine operators as the cohort of older workers retire. This paper defines the problem, offers a model to structure the inquiry, and presents the key issues a multi-disciplinary team of NIOSH researchers identified, based on an extensive review of the current literature in relevant areas. Issues include differences between cohorts, such as the newer workers (Generation M), and present workers (Boomers) with respect to their physical, social, psychological, and cultural characteristics, their learning styles and work expectations. Specific issues for an aging workforce are discussed. Some preliminary recommendations are offered on the type of training needed.

By R. Karl Zipf

MULSIM/NL (multiple seams, nonlinear) is a new U.S. Bureau of Mines boundary-element-method (BEM) program for calculating stresses and displacements (is., convergence) in coal mines or thin, tabular rnetalliferous veins. This manual gives detailed operating instructions for MULSIM/NL and illustrates its use with several practical examples. While this manual concentrates on the practical aspects of actually running and using MULSIM/NL, another companion report titled "MULSIM/NL- Theoretical and Programmer's Manual" provides mathematical and programming details to those engineers and programmers who need to fully understand the FORTRAN program or desire to alter and enhance it. MULSIMINL analyzes one to four parallel seams that have any orientation with respect to the Earth's surface. Three main features distinguish MULSIM/NL from its predecessors: (1) nonlinear material models, (2) multiple mining steps, and (3) comprehensive energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material including (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. The multiple mining step capability enables the user to simulate a changing mine geometry. Finally, MULSIM/NL performs comprehensive energy release rate calculations.

Jan 1, 1992

By W. P. Stroud

In this U.S. Bureau of Mines report, the conditions required for the direct reconstruction of a tomogram from observed line integrals are examined. Because of the limited access to the working faces in coal mines, the special case of access to only two opposite faces is emphasized. Classical matrix methods were used for small dimensional (2 by 2, 3 by 3, and 4 by 4) applications to determine the limitations and the requirements for a solution. The results for large (n by n) grids were then inferred and generalized from those of the smaller grids and matrices. Limited access tomography is found to be appropriate for in-seam hazard detection from seismic and microwave data, but it is shown that additional data must be added to obtain a direct solution.

Jan 1, 2010

By John S. Berber

Tar produced as a byproduct from low-temperature carbonization of coal contains only small amounts of valuable lower boiling tar acids but relatively high percentages of high-boiling tar acids. These high-boiling tar acids are characterized by a high degree of alkylation and can be converted into the lower boiling homologs by catalytic treatment to remove the alkyl groups or decrease their chain lengths.

Jan 1, 1965

By W. T. Millar

Magnetite mines in the Sterling tract, Orange County, N. Y., were operated almost continuously from pre-Revolutionary days until 1923. The Red-Back mine, one of several in this tract, was discovered in 1780; operated briefly in 1880; and abandoned, presumably because the iron ore contained considerable sulfur. The mine is in rough, mountainous country, with altitudes ranging from 500 to 1,100 feet. The magnetite deposit occurs in complex metamorphosed pre-Cambrian formation and is thought to be a replacement of limestone by magnetite. A dip-needle survey, completed in 1916, traced magnetic anomalies for a mile along the outcrop. A preliminary examination of the Red-Back mine was made by W. T. Millar, Bureau of Mines engineer, in December 1942. The Bureau of Mines bored seven diamond-drill holes aggregating 2,727.6 feet during the winter of 1943-44. A zone of magnetite mineralization was intersected in each of the holes.

Jan 1, 1949

By E. J. Gleim

In April 1932, the Bureau of Mines published Information Circular 6595, entitled "Data in Reference to Installation of Cables in Shafts and Boreholes", in which were described methods followed in various sections of the United States when electrical circuits are taken into mines by means of cables suspended in shafts and boreholes. In view of the present tendency to extend high-tension cables along entries and passageways from the bottom of the shaft, borehole, or other point of entrance to coal mines rather than over the surface, it is deemed that the various methods of installing such cables deserve careful consideration, particularly in mines in which gas and coal dust contribute to explosion hazards. This is especially true of localities where there is an inclination to restrict the extension of 2,300- and 4,000-volt circuits into the mines. Probably it is feared that accidental contact with the cables of such circuits may result in more serious shock than with lower voltages; also, it is possible that new circuits are regarded merely as explosion hazards additional to those already existing, regardless of the manner in which the new circuits may be installed. It is the firm belief of some engineers that the circuits can be installed so that they will not be damaged by wrecks or roof falls, thereby eliminating the hazard of explosion from this source while at the same time making the chance of accidental contact remote if not impossible. Moreover, some believe that fire hazards from direct-current systems can be reduced by keeping motor-generator sets close to load centers. Thus, although the alternating-current circuits would be lengthened, the size and extent of direct-current circuits would be kept to a minimum.

Jan 1, 1939

By M. G. Downey

The stone resources in certain localities and the kinds of stone available often influence manufacturing companies in their choice of plant location and in possible expansion of their activities. Limestone in particular is an important raw material for many processing industries. In planning highways and public works and placing contracts therefor, the availability of aggregates and road stone is significant. On the other hand, persons who contemplate entering the stone business or opening now quarries need information as to possible competition. To meet the growing need for regional data of this type, the Bureau of Mines has compiled from its records and presents herein the location of stone quarries by States and counties and by kinds of stone. The list covers all stationary and portable commercial quarry operations whose production statistics for 1940 were reported to the Bureau of Mines but does not include undeveloped deposits and noncommercial or Government-operated quarries.

Jan 1, 1941

By M. S. Seehra, R. S. Pandurangi

"A comparative study of the intensities of the IR modes in the pjlotoacoustic and. FrIR spectroscopy of amorphous and crystalline SiO2 particles is presented. It is observed that in photoacoustic spectroscopy of amorphous SiO2, IR modes of surface species are enhanced by over an order of magnitude compared to the bulk IR modes of SiO2. This effect, though not yet understood, may find applications in surface science.Since the publication of the Rosencwaig-Gersho theory of the photoacoustic effect in solids in 1976 [1], a great deal of attention has been paid to the development .of photoacoustic spectroscopy (PAS) into an analytical technique for condensed matter studies, especially when combined with the modern Fourier transform infrared (FTIR) spectrometer [2-8]. PAS has now been applied to a variety of experimental situations [2, 3] and it is particularly suitable for opaque powders and for cases where ~ample preparation (e.g. mixing with KBr as is usually done in FTIR spectroscopy) is not desirable. Another area of interest is the depth profiling feature of PAS, which is studied by varying the modulation frequency of the incident radiation [2-8]. The one-dimensional Rosencwaig-Gersho theory for non-porous samples has been extended to other cases [9-12]. Recently it has become known [11, 12] that for porous samples with porosity the IR modes are enhanced by a factor proportional toe. This enhancement is due to the pressure wave set up in the interstitial gas in the porous sample and this enhancement has been reported by a number of groups [12-14].In this Letter we report the observation of anomalously large enhancement of the PAS signal for certain surface IR modes on the surface of amorphous silica particles. This observation differs from the previous reports in that certain surface modes are enhanced by over an order of magnitude compared to the bulk IR modes. Although the reasons for this enhancement of the surface IR modes in PAS are not understood at present, this observation may open up new approaches to the study of surfaces. Results of these initial observations are given in this Letter. ·Experimental studies reported here were carried out on an FTIR spectrometer (Mattson Instruments, Model Cygnus 100) equipped with an MCT detector. The same instrument was used for PAS studies in conjunction with an MTEC (Model 100) PA cell. The sample cell and the spectrometer are continuously flushed with dry, CO2 free air obtained by the use of Balston Instruments Air Dryer Filter System (Model 75-60). Usually data were collected for 32 scans at 4 cm-I resolution, although both scan and resolution can be varied. For FTIR studies, samples were mixed with IR-grade KBr and pelletised. For PAS, no sample preparation is necessary and data are ratioed against dry carbon black [4, 5]."

Jan 1, 1989

By Thomas P. Meloy

"The presence of respirable quartz-bearing mineral par-ticles has been well documented in many coal mines, and the Mine Safety and Health Administration regulations address the quartz content of mine dusts. Unfortunately, the correlation between the quantity of respirable quartz-bearing mineral particles and the pathogenicity of the dust is not strong. Work is currently underway by the National Institute for Occupational Safety and Health/U.S. Bureau of Mines and work is being included in the Respirable Dust Center Program by Dr. Seehra to determine the surface availability of quartz in mixed composition mine dusts. However, this paper propose a possible source of surface quartz or a spe¬cial region in the coal that may contribute to the pathogenicity of selected particles in the respirable dust.Assumed in this model is the hypothesis that either the cleat surface is coated with quartz or some cytotoxic sub-stance that in the body is capable of destroying macrophage and thus inducing a fibrotic response (1) that during the frag¬mentation a reasonable proportion of the respirable size coal particles contain some of the original cleat surface and that these particles have the same order of in vivo cytotoxicity as do the quartz particles. It may be that these cleat surfaced respirable size particles are only contributory to the overall pathogenicity of the coal dust, nevertheless, there are enough of these particles to to considered as a potential source of the cytotoxic dust particles.This paper demonstrates that if the cleat surfaces are mineralized with quartz or have a pathogenic coating, then in many mines there will be enough respirable coal dust particles containing some cleat surface to cause a fibrotic reaction. To understand why some of the dust particles contain as part of their surface some of the cleat surface, consider what happens when a beer bottle is broken. While there are a large number of beer bottle fragments, many of the fragments, particularly the larger fragment sizes, will have as a fraction of their surface part of the original beer bottle surface. The model and mathematics of this problem have been worked out by Meloy.(2-4)In the homogeneous IAC model, (2-5) a fragment or par-ticle resulting from comminution is equally likely to occur anywhere in the material being broken. Therefore the probability of a particle of size x having part of the cleat surface in it, p(x), is proportional to x. Thus:"

Mar 1, 1989

By 1928-05-01

"The carnotite ores of Colorado and Utah were the chief source of radium for many years. In the fall of 1922; news of the very rich deposits of radium ore discovered in the Belgian Congo caused almost complete cessation of domestic production. The Congo ore contains pitchblend and a number of alteration products, including the new minerals bequerelite, curite, kasolite, stasite, and dewindite. Reports indicate that a considerable amount of ore containing over 50 per cent U308 has been produced. It seemed certain that radium could be extracted from the Congo ore at a much lower cost than from the relatively low-grade carnotite; and in order to preserve their elaborate marketing organizations, the larger American producers made agreements with the Belgium syndicate to market the foreign product in this country. The price of radium has been held at $70 per milligram. Extraction of radium from carnotite by the usual methods does not appear to be profitable at that price. With one exception, all American firms ceased production after their accumulated stocks of ore had been treated. The United States Radium Co., which continued to treat carnotite for several years, has recently shut down its plant.Although there is probably a large profit derivable from the treatment of Congo ore, it is not likely that the Belgium Syndicate will meet sufficient competition to cause any reduction in the present quotations. It is not known how long the high-grade ore will last, but when exhausted the price of radium may be expected to advance. According to K. L. Kithil3 it is the opinion of interested parties that, so far as can be forseen, radium will in future years never again be obtained at the present low price.Carnotite contains the valuable element, vanadium, which is not present in the Congo ore. The recovery of-vanadium is an important factor in the cost of extracting radium from carnotite, and under favorable conditions carnotite can be profitably treated for the vanadium alone. Vanadifecous sandstones are found ranging all the way from roscoelite (vanadium mica), containing little or no uranium; to a high-uranium and low-vanadium carnotite. Ores containing 2 per cent or more U308 are classed as radium ore and are sold on the basis of the uranium content, which is proportional to the radium content. Only in exceptional cases have ores been evaluated on the basis of both the radium and vanadium contents, although the presence of vanadium has undoubtedly influenced the price of radium ore."

May 1, 1928

By T. O. Llewellyn

The Bureau of Mines conducted laboratory batch beneficiation tests on a waste granite sludge from New Hampshire to determine the feasibility of recovering a reusable silicon carbide product. The granite sludge responded to attrition scrubbing, desliming, and flotation in either alkaline or acid circuits using fatty acid as a collector. Recovery of over 80 percent of the contained silicon carbide at grades of up to 96 percent SiC was obtained.

Jan 1, 1975

By Clarence O. Babcock

This Bureau of Mines report presents the initial development of a two-dimensional method of analysis for inclusions in plates in which the deformed shape of an open hole and the separate structural behavior of inclusion and plate with hole are used to obtain the stresses and strains in the inclusion only. In this report the solution for a circular inclusion is presented because a direct verification of the results with previous solutions was possible. The numerical results were in exact agreement with those obtained with the equations of Sezawa and Donnell. The equations developed are less complex than those of Sezawa and more general, for a circular inclusion, than those of Donnell. Stresses and strains in the inclusion are in terms of the elastic constants of the inclusion and the plate and the biaxial stress field applied far away. The elastic constants can be all different. An important conclusion from this work is that a difference in Poisson's ratios between inclusion and plate may be as important as a difference in Young's moduli between inclusion and plate in producing the inclusion effect. Many problems in mining and rock mechanics can be treated as inclusion problems. The understanding of inclusion behavior on a physical basis should provide the solutions to some of these problems.

Jan 1, 1974

By L. M. Chan, D. R. Carlson, J. H. Johnson

"This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program.The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.INTRODUCTIONDiesel-powered mining vehicles are gaining Popularity in underground coal mines and are almost universally used in underground non-coal mines due to their mobility, flexibility, and higher productivity. However, noxious gases and particulate matter in diesel engine exhaust are a concern because of the potential for being harmful to the health of miners. Diesel exhaust pollutant concentrations out the tailpipe of a mine vehicle change with time due to engine wear, inadequate maintenance, improper adjustments and other factors. This deterioration in pollutant concentrations, if not properly controlled, may adversely affect the air quality in an underground mine. To provide assurance that a clean and healthful work environment are maintained, a program is needed to identify and repair diesel engines that contribute to poor air quality. Also, earlier detection of deteriorated engines will make preventive maintenance possible, thereby eliminating further deterioration and possibly complete breakdown. Preventive maintenance also increases engine life and equipment availability in production which in turn will result in decreased operating costs."

Nov 1, 1995

By Walter R. Storms

This paper , which describes the mining methods and costs at the Atwood copper mine in the Lordsburg ( Virginia ) Mining District of Hidalgo County , N. Mex . , is one of a series being prepared by the Mining Division of the Bureau of Mines on mining practices , methods , and costs in various mining districts of the United States . The mine and surface plant are situated in the west half of sec . 7 , T. 23 S. , R. 18 W. , about 3 miles by road southwest of the center of Lordsburg , near the old abandoned townsite of Valedon ( see fig . 1 ) . The main line of the Southern Pacific Railroad passes through Lordsburg , as does the paved eastwest U. S. Highway 70-80 . A spur line of the Southern Pacific ends near the mine . A good graded road connects the mine with Lordsburg . The following pages present a brief history of the district , describe the geology , and outline methods of prospecting and exploration, including sampling and estimations of tonnages and values . Development, and mining methods are explained , and transportation , ventilation , drainage ,. safety measures , and organization are described . The wage scale and costs of development and mining comprise the corrcluding sections of this circular .

May 1, 1949

By V. Castranova, K. VanDyke

"INTRODUCTION A soluble mediator has been described which is released from activated rabbit leukocytes and induces histamine secretion from rabbit platelets (Barbaro and Zvaifler, 1966; Siraganian and Osler, 1971). This factor has been isolated, characterized and named platelet activating factor, PAF (Bcnveniste et. al., 1972). PAF has since been chemically identified as l-0-alkyl-2-acetyl-sn-glyceryl-3-phosphocholine (Benveniste et. al., 1979; Demopoulous et. al., 1979).PAF is a lipid mediator of broad biological activity. It causes smooth muscle contraction, contraction of lung tissue and decreased FEV 1; while enhancing capillary permeability thus causing edema (Pinkard, 1983). In addition, PAF is a chemoattractant and can lead to inflammation.PAF has been reported to stimulate the release of lysosomal enzymes, leukotriene B,, and lipid metabolites from neutrophils (Smith et. al., 1983; Shaw et. al., 1981; Lin et. al., 1982; O'Flaherty et. al., 1984). The objective of the present investigation was to further characterize PAP-induced stimulation of granulocytes and to develop a bioassay, i.e. chemiluminescence, for screening PAF receptor antagonists and inhibitors of PAP-induced activation of granulocytes. The possible use of the chemiluminescence assay to monitor PAF synthesis by human granulocytes is also described.METHODSBlood was drawn from healthy volunteers into a blood storage bag containing CPD anticoagulant. Granulocytes were partially purified by dextran sedimentation and further purified by centrifugal elutriation as described previously (Jones et. al., 1980). Granulocytes obtained by this procedure were approximately 95 percent pure. The number of granulocytes in this preparation was determined using an electronic cell counter (Coulter Model Z1, Coulter Instrument Co., Hialeah, FL). Isolated granulocytes were used to monitor membrane potential, hydrogen peroxide and superoxide release, oxygen consumption, calcium uptake and, in some cases, chemiluminescence. Studies of PAF receptor antagonists were conducted using neutrophils isolated by density centrifugation. Briefly, blood was layered onto Mono-Poly-Resolving Medium (Flow Laboratories, McLean, VA) and centrifuged at 22 °C and 300 g for 30 min. Neutrophils collected from the second band of this gradient were at least 90 percent pure."

Jan 1, 1989

By Yael Miron

Coal mines that undergo self-heatings, and specifically mines that sustain both floor heave and self-heatings, would benefit from the use of sealants to minimize air ingress to susceptible areas. The U.S. Bureau of Mines (USBM) evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gel. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the USBM Safety Research Coal Mine. Two for-mulations resulted in stable gels that lasted for at least 12 months in the mine. Semicontinuous preparation of gel using an eductor was evaluated and appears feasible. Although guar gum gel is expensive, selective use to prevent heatings in specific areas would be cost-effective, both in terms of productivity and enhanced mine safety.

Jan 1, 2010