Abstract: Raw coal, which contains coal and waste, is introduced into a sizing box having vertically spaced screens inclined rearwardly with the screens being vibrated to separate particles below a selected size from the raw coal. Raw coal is introduced into a washer box, which has a medium therein of a selected specific gravity to cause coal below a specific gravity to float to the top of the medium so as to be separated from the waste with the waste, which is of heavier specific gravity, falling to the bottom of the washer box. The medium and the separated coal therein flow along an inclined trough to a vibrating shaker, which has a plurality of vertically spaced screens inclined rearwardly. When flowing along the trough, at least half of the medium returns to a sump from which it is supplied by a pump to the washer box to maintain a desired level of the medium so that the medium will continuously flow from the washer box along the trough to the shaker.