Hydrocyclones

A hydrocyclone which includes a main body having a chamber therein, the chamber including an inlet section, and a separating section, the separating section having an inner side wall which tapers inwardly away from the inlet section, the hydrocyclone further including a feed inlet feeding a particle bearing slurry mixture into the inlet section of the chamber, an overflow outlet at one end of the chamber adjacent to the inlet section thereof, and an underflow outlet at the other end of the chamber remote from the inlet section of the chamber, the hydrocyclone further including an overflow outlet control chamber adjacent to the inlet section of the chamber of the hydrocyclone and in communication therewith via the overflow outlet, the overflow outlet control chamber including a tangentially located discharge outlet and a centrally located air core stabilising orifice which is remote from the overflow outlet, said stabilising orifice having a generally conical shaped inlet section having tapering side walls which extend into the overflow outlet control chamber, said stabilising orifice, overflow outlet and underflow outlet being generally axially aligned, and said overflow outlet control chamber having an inner surface which is generally in the shape of a volute for directing material entering the overflow outlet control chamber from the separation chamber towards the discharge outlet.