Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 41 for “"Longwall"”.
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Classification and analysis of longwall delays
… rates have been achieved by certain U.S. longwalls, and yet a large number of longwall operations have failed to meet anticipated production targets. This study attempts to identify the primary factors which contribute to the production shortcomings of many marginal longwall operations. …
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GASMAK2 model for longwall gob gas emission
… describes methane control requirements for the longwalling coal in gassy areas. This is not a theoretical model; it uses an empirically determined gas emission rate as an input. The computer program divides Longwall panels into segments, keeps track of the face advance and generates emission …
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Factors considered for increasing longwall panel width
Longwall mining is the preferred method in coal mining to maximize production and reserve recovery by extracting large blocks of coal that have been outlined with a set of continuous miner development entries. In the US, technological advances and system enhancements have steadily improved …
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An optimal determination of longwall panel dimensions
The optimal dimensions of a longwall panel are investigated using four different objectives of minimum average unit cost, internal rate of return, profitability index and present value of average unit cost. The two main variables, production and cost are analyzed into different parameters. …
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Stress transfer between multi-seam longwall mines
The future of most underground coal mining in the USA will entail the extraction of coal under multi-seam mining conditions. Mine design in such an environment will require the accurate prediction of stress transfer between adjacent seams. The available knowledge on criteria controlling stress …
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Rock mechanics instrumentation applied to longwall coal mining
Includes bibliographical references.
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Longwall weighting events at Phalen Colliery, Nova Scotia, Canada
… in mines where coal is extracted using the longwall mining method. Weightings are characterized by high convergence rates within the powered supports which maintain roof stability along the longwall face. Rapid convergence is induced by ground pressures that exceed the load capacity of the …
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Stochastic availability analysis and modeling of longwall mining operations
… assessment and prediction of the availability of longwall mining systems. After a functional analysis of longwall mining operations, the longwall production system is divided into four subsystems: coal—cutting, face—conveying, roof—support, and outby—haulage. The operating characteristics of the …
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A study of longwall subsidence in the Appalachian coalfield
… is to develop characteristic relationships of longwall subsidence and its related parameters from case studies gathered from the Appalachian coalfields. Furthermore, based on this information, an empirical, predictive capability will be developed which can be used to provide accurate and …
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Four-Dimensional Passive Velocity Tomography of a Longwall Panel
… mine in the western United States, utilizing longwall mining. The mine has experienced rockbursts. Seismic data were collected over a nineteen day period, from July 20th, 1997 to August 7th, 1997, although only eighteen days were recorded. Instrumentation consistsed of sixteen receivers, …
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Design and stability of barrier pillars in longwall mining
… this study to model single- and double-entry longwall systems. The influence of the geology, mining depth and mine-layout on barrier pillar stability was examined and design guidelines for determining sizes for such pillars were established using the "pillar core concept". The yield zone was …
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Numerical analysis of coal yield pillars at deep longwall mines
Includes bibliographical references.
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Layout design for interactive zones in longwall multiple seam mining
… for the increasingly popular multi-seam longwall method. Entry layouts often depart from the ideal when finally developed. The thesis examines the occurrence of ground control problems, and possibilities for improvements in strata control, in a variety of undermining situations. The …
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Longwall mining, subsidence, and protection of water resources in Virginia
… numerous hydrologic investigations indicate that longwall mining is likely to alter the hydrologic regime in the vicinity of the mine. The knowledge base for regulation of hydrologic impacts has been inadequate but is being improved in Virginia. Both DMLR and some coal companies recognize the need …
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Investigation, Analysis, and Modeling of Longwall Face-to-Face Transfers
… efforts to investigate, analyze, and model longwall face-to-face transfers through the use of operations research techniques. The purpose is to reduce overall transfer time and the variation of transfer times among operations within the U. S. longwall industry. The research includes: (1) …
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CFD modeling of a tailgate ventilation condition in a longwall bleeder system
Face ignitions at the longwall are a serious hazard in underground coal operations and can lead to a major mine explosion. Despite having methane monitoring systems mounted on the shearer and at various locations on the longwall face, undetected methane accumulations can still occur and result in …
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A Study of Mine-Related Seismicity in a Deep Longwall Coal Mine
… until April 7, 2011 during the mining of three longwall panels and the data was telemetered to Blacksburg, Virginia. A correlation equation was developed to relate local magnitude estimated by automatic data processing software in near real-time to seismic moment for well-recorded events. Local …
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AN IMPROVED ROCK MASS BEHAVIOR NUMERICAL MODEL AND ITS APPLICATIONS TO LONGWALL COAL MINING
… BEHAVIOR NUMERICAL MODEL AND ITS APPLICATIONS TO LONGWALL COAL MINING The rock mass constitutive models should include elastic moduli, strength and stiffness of intact rock as well as those of joints and geometric properties of joints. The post-failure behavior of intact rock and joints must also …
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Preventing spontaneous combustion in gob areas of retreating longwall panels by ventilating without bleeders
… of fire occurrence. The focus is directed to longwall gobs. The changing gob characteristics, especially the varying degree of consolidation at different parts of a gob as the face moves, is considered. Analytical studies and computer modeling show that bleederless ventilation in retreating …
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