Conceptual designs of entry systems for mining thick coal seams by the longwall top-slicing method were investigated. Based on a 100-foot thick seam, covering four square miles and dipping at 10 degrees, an entry concept was designed using ten slices and present-day equipment. Using five main entries driven downdip and located in rock beneath a central barrier pillar on the property centerline, the design utilizes four longwall units at full production for a rate of 2.62 million tons per year. Laterals and inclines are driven off the mains to serve single entry panels in each slice. Face lengths are typically 570 feet in length and panels are staggered to provide a smooth subsidence contour. An all-retreat layout is used with longwall operations retreating from the property boundaries to the central barrier pillar on strike. The entry concept is described in detail relative to the geometric layout, panel sequencing, production and development equipment, material handling requirements and ventilation requirements.
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