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By D. S. Choi

Coal is expected to become an increasingly important source of energy in the future. Coal production has already increased from about 650 million tons in 2975 to about 875 million tons in 1984 (Wilkinson, 1985). The declining trend of labor productivity in the early seventies was a source of concern for Consolidation Coal Company (Consol). To improve productivity, a gradual change from room-and-pillar mining to longwall mining has been taking place within Consol. Consol produces 45 million tons of coal annually with about 70 percent of the production coming from underground mines. Consol introduced longwall mining in the early seventies and currently operates about 20 longwall faces. The longwall faces are in mines in the Appalachian region in the States of West Virginia, Pennsylvania, and Ohio. The successful operation of longwall faces has contributed to a recovery of productivity and to an improvement of mine safety.

Jan 1, 1985

By Benjamin K. Pocock

When considering alternative equipment choices in mill or process flowsheets, it is important to determine both capital and operating costs of such equipment as well as other possible savings related to downstream operations. This paper presents a few case studies and shows cursory guidelines for the selection of equipment for new installations or in the retrofitting of existing plants. Based upon recent plant experience, suggestions are given to improve the operation of clarifiers, thickeners and vacuum filters.

Jan 1, 1986

By E. A. Metz

Silicon dioxide, silica, is the most common oxide in the earth' s crust. The health effects of silicon dioxide dust have been known since Biblical times. Agricola's book, published in the mid 1500's on occupational medicine, described a lung disease that afflicted miners. He observed a disease in miners that caused shortness of breath, coughing and wasting. Add fever, chest pains and fatigue and we have the current symptom complex of silicosis. As we approached the 21stcentury, the Labor Department began an aggressive campaign to combat silicosis-a preventable disease. Unfortunately, many publications do not clearly differentiate the polymorphs of silica known to mineralogists. Crystalline silica, i.e., alpha quartz, tridymite and cristobalite need to be considered differently from the amorphous forms of silica. Freshly fractured surfaces of the silica and host specific responses will be examined. Recent research focuses on the biologic interactions of free radicals generated by mineral particles. This results in cell injury and DNA damage, in turn leading to fibrogenesis and possibly carcinogenesis. In addition to particle-cell interactions, emphasis is given to lung defense mechanisms.

Jan 1, 1998

By E. Jong, E. Watkins

"The application of passive tracer gas sources in underground mines is particularly useful for long-term tracer gas studies, as well as for studies in permissible areas of underground coal mines. The use of passive perfluoromethylcyclohexane (PMCH) sources have previously been demonstrated in mines, but this new work details the development and testing of multiple, distinct tracer compounds that can be used in passive sources. A description of their potential application in mine ventilation systems is also provided. Three tracer compounds are detailed, which are PMCH, PECH and PMCP. The release rates of these tracers were examined over a 180 day period at multiple temperatures. The advantages and disadvantages of these sources are presented, along with potential applications in understanding complicated ventilation circuits, flow through gob, and leakage. INTRODUCTION The use tracer gases for ventilation applications is an established practice, with various research projects being perform with Sulfur Hexafluoride (????6) in the past. Perfluorocarbon tracers (PFTs) however are relatively new compared to ????6, which is proven to be useful in ventilation and air modeling experiments along with other PFTs (Watson, Wilke, Dietz, Heiser, & Kalb, 2007). These liquid tracers are characterized by low background presence in air, inert behavior with other gases, high detectability with a gas chromatograph and low toxicity. A design was proposed called a permeation plug release vessel (PPRV), which initially introduced by Brookhaven National Laboratory to meet those requirements. The PPRV works by allowing the gaseous form of the tracer to diffuse through the permeable silicone stopper and evaporate into the open air on the other side. The PFTs inside the vessels are injected as a liquid but instantly begin to convert to their gaseous phases at room temperature due to high vapor pressures (Zhang, H., Cloud, A.,2006). Previous studies have detailed how release rates change based on plug thickness across various temperatures (Jong et al., 2015), but not on the release rate stability based on temperature across multiple tracers. For use in underground mines passive release sources need to be durable, be simple to manufacture, have customizable and reliable release rates as well as a long operating life. The PPRV vessel provides a steady release of tracer gas that is essential for long term passive release experiments, making it a viable vessel for the PFTs being tested. The PPRV design also allows for vessels to be bundled together to achieve release rates at detectable levels and allows for the capability to run ventilation surveys with multiple tracers simultaneously. The ability to conduct ventilation surveys with multiple tracers using the PPRV bundling design and detection of the PFTs makes testing the tracers and design together a promising potential for complex and long term mine ventilations studies."

Jan 1, 2017

By L. Patts, J. Hummer

The use of diesel-powered equipment in underground coal mines has increased substantially during the last ten years in an effort to enhance mine safety and productivity. Pennsylvania and West Virginia are two of a number of states with regulations governing the use of such equipment. These states both developed and promulgated regulations before permitting diesel equipment in their underground coal mines because of concern for miners’ safety and health, especially with regard to the contamination of mine ventilation air with diesel exhaust emissions. The major components of diesel exhaust emissions are combustion gases and diesel particulate matter. The gaseous emissions consist of carbon monoxide, carbon dioxide, oxides of nitrogen, sulfur oxides and unburned hydrocarbons. The diesel particulate matter (DPM) is comprised of solid carbon particles, liquid and solid hydrocarbons, sulfates and moisture. The Federal Mine Safety and Health Administration (MSHA) also promulgated regulations in an effort to control diesel emissions in underground coal mines. MSHA has adopted threshold limit values (TLVs) for all gaseous components of diesel exhaust, which were established by the American Conference of Governmental Industrial Hygienists (ACGIH). MSHA (30 CFR Part 72 Subpart D) has established a tailpipe DPM emissions limit of 2.5 g/hr for diesel engines used in permissible equipment, heavy-duty non-permissible equipment, generators and compressors used in underground coal mines. A tailpipe DPM limit of 5.0 g/hr has been established for light-duty outby diesel-powered equipment. The rationale for the tailpipe emissions limit was that an ambient measurement of DPM in a coal mine was not feasible because there is no established sampling method able to distinguish between coal mine dust and DPM. The stringent tailpipe emissions limit mandates the use of exhaust aftertreatment devices for most diesel engines used in underground coal mines today. One method by which tailpipe DPM can be reduced to MSHA limits involves using an exhaust cooling device in conjunction with a high-temperature, disposable diesel particulate filter.

Jan 1, 2011

By Hugh McMillan

To protect the water supply for the Metropolitan Chicago area, the Illinois legislature, in 1889, created the Metropolitan Sanitary District of Greater Chicago. To insure the quality of the water supply, the Sanitary District collected and diverted the wastes of 750,000 people away from Lake Michigan. Today, the Sanitary District collects and treats the wastes from a domestic population of 5 ¼ million people and an industrial waste load equivalent to 4 ¼ million people. The District serves Chicago and 120 other cities and suburbs in an 858 square mile area. An average of 1300 million gallons of wastewater is treated each day, producing as a by- product about 700 dry tons of solids which contains more than $10,000 worth of plant nutrients when equated to the value of commercial fertilizer purchased in the retail market. The Sanitary District considered several alternatives to past methods for disposing of these solids, and chose land application as a technique to utilize the solids produced by the wastewater treatment process in a beneficial manner.

Jan 1, 1973

By S. S. Klima, A. L. Mazzella, J. S. Driscoll, T. W. Beck

Previous testing was performed by researchers at the National Institute for Occupational Safety and Health (NIOSH) to improve longwall dust control using underside shield sprays with a longwall directional spray system. This testing provided encouraging results toward respirable dust exposure reductions for longwall personnel, achieving as high as 99% dust reduction at some sampling locations along the longwall personnel walkway. Additional laboratory testing was conducted to test these underside shield sprays in conjunction with a shearer-clearer spray system located on the longwall shearer body. The purpose of this testing was to determine if the underside shield sprays interacted positively or negatively with the shearerclearer sprays. Results from this testing indicate that while the shearerclearer system influences where the respirable dust particles are directed, underside shield sprays can still lower respirable dust exposure for longwall personnel.

Mar 2, 2022

By A. K. Sinha

Research shows that continuous mining sections can normally produce around 950 tons per shift in a seam 5 or 6 ft. thick. The shuttle cars as well as the continuous haulage systems are able to match with the continuous miners in capacity. However, in practice both of the two systems seem to be averaging at around 450 to 500 tons per shift in production. Continuous haulage systems are preferred in thin seams particularly where the floor is soft.

Jan 1, 1981

By K. S. Olson

My reaction when first asked to present this paper was; "What could I possibly say that would hold the audience?s attention for 15 minutes? What could I offer that anyone familiar with the Nevada Barite Industry wouldn't already know?" Well, quite frankly I can't. The industry has certainly been anything but exciting for the past 10 years and, in fact, quite depressing. The challenge, for those few of us left in it, has been to keep it alive. At times it has felt like a doctor must feel with a terminally ill patient. All I can do is recap the past ten years, review the present state of the industry, and offer a few personal opinions and observations as to where I think we are headed.

Jan 1, 1993

By A. Wallace Mitchell

Barite deposits in Nevada occur as bedded and vein-types along a north-northeastern -trending zone which parallels the Antler orogenic belt The bedded deposits of Nevada are the most significant economically. They are presently supplying eighty-five percent of the domestic barite production which is used primarily as a weighting agent in the petroleum drilling industry. The ore bodies are controlled both structurally and stratigraphically, occurring along regional and local structural breaks in siliceous eugeosynclinal rocks of mid-Paleozoic age. Evidence for origin of the barite includes sedimentary and hydrothermal features indicating that localization probably took place along fractures in the seafloor.

Jan 1, 1980

By Edgar W. Sawyer

Attapulgite and sepiolite are the clay minerals used to thicken ionically contaminated watzrs in the preparation of drilling fluids. They are nonsweliing clays that can be dispersed and reflocculated by mechanical means to increase the viscosity of fresh water and salt and gypsum contaminated waters. Those gelled in fresh water do not become excessively thick when contaminated with high salt concentrations or polyvalent cations encountered during drilling. Gels formed exhibit thixotropy and yield pseudoplastic rheological behavior due to the particle interactions and mechanical interferences of the flocculated gel structure.

Jan 1, 1983

By Rudolf Fahn

Bentonites are best suited for the preparation of acid activated clays with efficient adsorption properties. They are weathering products of acid volcanic ashes and their natural deposits are world-wide spread. The main constituent of bentonite is the aluminium hydrosilicate nontmorillonite with a high ability to swell. Süd-Chemie owns bentonite deposits in Germany and subsidiaries in Italy, Mexico and Arizona.

Jan 1, 1979

During foundry sand reclamation process development, molds formed from reclaimed chromite sand showed a rapid decline in tensile strength during thermal cycling tests. Because this characteristic could limit reuse of chromite sand in the foundry, the sand was examined in detail. Scanning electron microscopy, x-ray mapping, magnetic susceptibility, and x-ray diffraction were utilized to evaluate processed chromite sand. It was found that process variables such as binder composition, reclamation temperature, and processing method had a significant effect on the chromite sand particle surface. X-ray diffraction indicated a crystallographic change in the processed sands. Magnetic susceptibility also increased after processing. Diffusion of iron to the particle surface and increased surface roughness were identified as potential causes of the decreased tensile strength in the molds.

Jan 1, 1993

By Mr. Peter J. Huck

Recent research has developed procedural control and geophysical test methods that can greatly enhance quality control in rock grouting. Confidence that design objectives will be made In construction requires that grout monitoring efforts be carefully designed and integrated into the overall project. Parameters that should be monitored are identified and documentation/review procedures that permit effective evaluation of the grouting effort are discussed.

Jan 1, 1980

By Allan M. Johnson

The Sherwood Mine is being monitored to determine the nature and extent of changes in the mine and its environs which result from the closing and the cessation of pumping. Of particular interest was the possibility of piping-induced subsidence occurring as the mine flooded. Previous experience in the district indicated that this possibility was very real. A monitoring system, including acoustic sensors, extensometers, surface subsidence monuments, and ground water observation wells was installed in July 1978, just prior to the mine closing. Late in 1979, three piping-induced subsidence events occurred. The monitored data, and related laboratory studies are being applied to a quantitative description of piping-induced subsidence.

Jan 1, 1980

By R. Q. Honaker

Recent studies conducted at Virginia Tech have shown that ultrafine coal particles can be selectively coagulated and separated from mineral matter without the use of traditional agglomerants or flocculating agents. This technique utilizes hydrophobic interaction forces to induce coagulation of coal particles, while particles of mineral matter are dispersed using pH control. After selective coagulation, the coal coagula can be recovered by a sedimentation technique. In the present work, factors such as pH, particle size, and solids concentration have been examined. A wide range of coal samples have been successfully upgraded using this technique.

Jan 1, 1991

By R. F. Merwin

Advancement in automation intensifies the need to remove tramp iron from bulk materials being processed and carried on belt conveyors. Although magnets have long been employed for this purpose, it becomes increasingly necessary that magnetic equipment of appropriate types and sizes be selected and advantageously installed -- if maximum benefits are to be derived Tramp iron present in bulk materials consists of ferrous trash, such as wire, bolts, nails, equipment parts, tools, and machine cuttings. The results, if the iron is not removed, are damaging to equipment having close clearances, explosions, or fire, En the case of flammable materials, production downtime losses, and contaminated products.

Jan 1, 1966

By Charles G. Zink

Early anthracite "deep mining" methods, production, manpower. underground transportation, labor, safety and reserves are reviewed and compared to the present and to future requirements which must be met in order to economically win the fourteen million tons of untapped reserves and to keep the product competitive in the market place.

Jan 1, 1971

By Odin Wilhelmy

Agriculture in the United States today is becoming more and more a business, rather than a way of life. In the light of this, it behooves the farm-supply industries that provide the American farmer with his tools of production--feed, fertilizer, machinery, and the like--to give even greater attention than they have in the past to meeting the needs of the farmer-businessmen they are serving. Increasing competition among the companies that make up these industries merely accentuates this need for better service. An opportunity for such improved service, not yet fully realized, exists in the fertilizer industry today. That opportunity lies in the increased transportation of fertilizer ingredients by water. However, before the benefits inherent in this increased water movement of fertilizers can be fully realized, certain obstacles must be met and overcome. It is the purpose of this paper to outline the nature and magnitude of this opportunity, to point out some of the roadblocks and the steps that can be, or are being, taken to remove them, and to indicate some of the rewards that would logically stem from success in these efforts.

Jan 1, 1961

By G. Babut

The restructuring of mining operations in Valea Jiului coal basin imposed by the transation to the market economy calls for an increased coal production. Under the circumstances, the role of drainage networks grows ever more important. The paper describes an original mathematical model and software developed on its basis, with enables the ventilation engineer to assess the configurations of different systems, as well as to test their reliability and prognose their future performance before conceiving another methane drainage system or changing the existing one. The paper also includes the underlying principles of an optimization program for methane drainage networks, which will enable the detection of the optimal methane drainage system, both from a technical and an economic point of view.

Jan 1, 1996