In Mechanical Hydrocyclone, the spiral flow is induced by an internal rotor. Feed is introduced through a top axial inlet. The overflow leaves via a vortex finder pointing upwards through the apex of the cone.
The underflow discharges through an annulus around the vortex finder. This design is used clarification, thickening or classification.
The rotary hydrocyclone has rotating walls so is a cross between a centrifuge and a hydrocyclone. It is cylindrical and feed enter axially and passes through rotating blades.
Both products are removed at the opposite end. The light product passes through and axial tube and the heavy product passes through a radial orifice. Shear rates are lower than in conventional hydrocyclone.
The rotary design has been used mostly for liquid separation but could find application for small fragile solids.