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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 tower 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 />