Abstract: An apparatus for separating granular material such as crushed coal or ore that includes particles of different specific gravity. The apparatus includes an elongated frame defining a receiving chute and a discharge chute. A plurality of hydraulic cells are supported in tanden on the frame, each cell including a wave chamber, a screen forming a material supporting floor submerged in the wave chamber, plungers for cyclically raising and lowering the water level in the wave chamber and a refuse bin adapted to receive heavier particles that are separated out in the wave chamber and that collect above the screen. The wave chambers define a flow channel extending from the receiving chute to the discharge chute and adapted to contain a suspension or slurry of the crushed particles.