FIGURE E.2 Schematic showing underground coal mine workings. The coal seam is accessed by both a slope and a shaft, shown on the right. The ventilation fan arrangement is shown adjacent to the surface opening of the shaft. The shaft has an elevator for lowering and raising miners and materials. Coal gathered from the workings by various conveyors is transported to the surface by the slope conveyor. The surface features shown are the raw coal storage silo fed by the slope conveyor, the coal preparation plant (the building on the left), the clean coal storage silos in the front, and the train load out. A longwall section and a room-and-pillar continuous miner section are shown. The room-and-pillar section is a five-entry development with rows of four pillars. The longwall face is between two three-entry developments. SOURCE: CONSOL Energy Inc.

will require thick-seam underground mining methods such as large longwalls or multiple slice and/or caving techniques that have not been used in the United States. This will require improvements to mining equipment and practices that are likely to entail research and development (R&D) on mine design, ground control, mine automation, and new systems for protecting worker health and safety.

Room-and-Pillar Mining. In the room-and-pillar method, a set of entries, usually between three and eight, are driven into a block of coal. These entries are connected by cross-cuts, which are usually at right angle to the entries. The entries are commonly spaced from 50 to 100 feet apart, and the cross-cuts are usually about 50 to 150 feet apart. The pillars formed by the entries and cross-cuts may be extracted or left standing depending on mining conditions. In the

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