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Chapter II <br />(3) Multi-Lift Mining. <br />Two panels of coal are cut, the second beneath the first, using the longwall mining <br />method. After the top panel of coal has been extracted and the caved area <br />reconsolidates, two dual entry developments are driven in the relaxed zone under. <br />the gob, just inside the top lift panel, to provide access for the lower retreating <br />panel. The lower panel of coal is then mined with the shearer. A coal and/or rock <br />band, left between the upper and lower panels, serves as the roof of the lower panel. <br />b. Support Activities -Underground. <br />(1) Ventilation. <br />A sophisticated ventilation system is required in the Coal Basin mines. <br />The mines are ventilated using an exhaust-type system. The exhaust fans create <br />negative pressure within the mine, causing fresh air to course in through the <br />intakes, across the faces, and out the returns. The air is directed to the faces by <br />means of temporary and permanent stoppings, overcasts and brattice cloth line <br />curtains. The main fans are located on the surface. <br />(2) Dust Suppression. <br />Dust in the working areas is controlled by cleanup procedures, including the <br />expeditious removal of loose and pulverized coal from the mine, by ventilation at the <br />working faces, by spraying face areas with water, and by the application of rock <br />dust (pulverized limestone) to the floor, roof and sides of underground workings. <br />(3) Roof Control. <br />The longwall equipment must be protected from the weight of the overlying rock as <br />mining progresses, and the roof must be supported above the workings of the <br />mine. <br />c. Major Equipment -Underground. <br />MINING <br />Shearers <br />Continuous miners <br />- COAL LOADING AND TRANSPORTATION <br />Face conveyor/Internal belt conveyors <br />Stage loaders <br />. Shuttle cars . <br />10 <br />_- <br />,~ _ ~_ <br />