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The solids which have settled to the bottom of <br /> the coarse classifier (the underflow) discharge <br /> to raw coal sumps and are taken into the normal <br /> preparation cycle, wherein coal is separated <br /> from non-coal refuse. The coal is prepared for <br /> sale; non-coal refuse goes to disc filters to <br /> be dewatered, then to the refuse conveyor belt <br /> to be conveyed to the approved refuse disposal <br /> area. <br /> Thickener <br /> The overflow from the coarse classifier gravity <br /> flows either to the feed well of the <br /> preparation plant's existing 55' diameter <br /> refuse thickener, or directly to the inclined <br /> plate clarifier. <br /> Use of the thickener is an option which can be <br /> employed for treatment of overflow in order to <br /> reduce the solids loading to the clarifier. <br /> If the overflow from the coarse classifier goes <br /> to the thickener, the water is flocculated to <br /> promote settling of solids, and the overflow <br /> from the thickener moves by gravity to the <br /> inclined plate clarifier for further removal <br /> of solids. <br /> The coarse classifier overflow can by-pass the <br /> thickener feed well, advancing directly to the <br /> inclined plate clarifier. The presence of <br /> coarser solids promotes settling of finer flocs <br /> in the clarifier, so the thicker may be by- <br /> passed to improve function of the clarifier. <br /> The solids removed in the thickener (underflow) <br /> go to the plant disc filter, (the disc filter <br /> de-waters the underflow) then to the refuse <br /> conveyor belt to be conveyed to the approved <br /> refuse disposal area. <br /> The fine solids removed from the clarifier <br /> underflow, and the backwash of the mixed media <br /> filters, report back to the thickener to be <br /> mixed with larger size particles in the <br /> thickener underflow. This allows for better <br /> handling and disposal of very fine particles. <br /> As indicated, thickener underflow goes to the <br /> disc filters for dewatering, then to the refuse <br /> conveyor belt. <br /> 2 <br />