Hydrocyclone separator

A hydrocyclone separator forming a closed end construction including a conical body and a cylindrical portion, and having an inlet provided at the circumference of said cylindrical portion for introducing a slurry of solid material in a liquid tangentially into said cylindrical portion for separation into underflow and overflow slurry fractions, an underflow nozzle connected to the apex terminus of said conical body and an overflow finder mounted on the base end of the cylindrical portion, said separator comprising a forced discharge means in the form of a screw conveyor extending axially through said underflow nozzle into said conical body for forcibly discharging concentrated heavy extraneous slurry components through said underflow nozzle, said screw conveyor being rotatingly driven by a variable speed drive means and having a hollow rotational axis comprising means for providing at least a portion of a passage of air to be fed into said conical body for maintaining an air column therein, said means enabling said passage of air to extend into said conical body a sufficient distance to minimize resistance to the flow of the slurry and to encourage the separating action of the hydrocyclone separator.