Abstract: Improved apparatus for separating mixed solids of different specific gravities by means of a liquid medium comprising rotatable means defining a frustro-conical separation chamber having a lighter solid outlet at one end and a heavier solid outlet at the other end; a generally fan-shaped wall normal to the axis of rotation stationarily mounted in the chamber dividing a lower portion of the chamber generally into a lighter solid zone and a heavier solid zone, the wall having a substantially arcuate lower surface complementary with, and adjacent, the surface of the chamber; means for supplying mixed solids and liquid medium to the chamber; a vertical opening in the lower arcuate surface of the wall for passage of solids through the wall; and means for removing solids accumulating in the heavier solid zone.