Abstract: A separator tank has a pressurized separating medium of a selected specific gravity introduced through one of its two end walls adjacent the top of the level of the medium, which forms the bath, in the tank. The other end wall of the tank has weir discharge openings to enable the coal, which is separated from the waste of the raw coal through floating to the top of the medium while the waste falls to the bottom of the medium, to flow therethrough with the medium to a weir chute and to maintain a selected level of the medium within the tank. The tank has a paddle wheel assembly to pick up the waste on a semi-cylindrical bottom wall of the tank and remove it therefrom. The paddle wheel assembly has a plurality of equally angularly spaced arms with each including an outer arm, which is resiliently biased to pass over obstructions, having its tip ride along the bottom wall of the tank.