2013-11-13_PERMIT FILE - C1981018A (2)

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The mining system selected for the Deserado Mine is primarily the longwall mining method. Some part of the deposit may be worked in part by the room and pillar, with pillar extraction mining method. III.A.2.a Room and Pillar Mining Room and pillar mining or continuous mining has long been the backbone of the United States' underground coal mining industry. The advantages of the continuous mining system are due to its adaptability and flexibility. This system easily adapts to changes in the geological and physical conditions of the mine. Using this system, it is possible to exclude in part any poor sections of the deposit and it is possible to negotiate geologically disturbed areas of the mine and easily adapt to variations in the seam. The continuous mining system has great flexibility. The equipment can be easily moved around to different locations in the mine and the overall system is only minimally affected by a stoppage of any one unit. The production from each continuous miner section is relatively small and this mining system is generally more hazardous and more expensive to operate than a longwall system. The overall coal reserve recovery from room and pillar mining seldom exceeds 55 percent because all of the pillars cannot always be safely extracted. III.A.2.1b Longwall Mining. Longwall mining has gained great acceptance in the United States because of its three apparent advantages; 1) High recovery, 2) High production, and 3) High safety. In longwall mining, coal is extracted from panels that are several thousands of feet long and several hundreds of feet wide. The shearer which is a powerful cutting machine with a huge drum on each end rips a strip of coal from the longwall face. The coal falls onto a face conveyor consisting of flexible steel pans which transfers the coal away from the longwall. As the shearer passes, the roof supports are advanced immediately and the roof behind them is allowed to cave. When the shearer returns on the cleanup pass, the face conveyor is pushed forward and the cycle is ready to be repeated. Because longwall mining usually extracts the entire seam height in a solid block of coal, coal reserve extraction is usually extremely high. Extraction as high as 90 percent has been achieved with longwall mining methods, and 70 -80 percent recovery is average. The average production from longwall faces is about 5,000 tons per shift. However, many new faces including the face started by BME have exceeded 7,000 tons without difficulty and new equipment and technology promises to raise future production even higher. Because longwall mining is believed to be the only true continuous mining system the tonnage mined by this method is expected to climb during Permit Revision #8 (02/2013) III -4