A self-driven centrifuge for separating particulate matter out of a circulating liquid includes a base plate and a rotor shell. The base plate has a center tube extending therefrom along a longitudinal axis. The center tube is constructed and arranged to deliver fluid containing particulate matter. A rotor shell has an inner cavity and a plurality of spiral vanes extending along the longitudinal axis within the inner cavity. The spiral vanes extend spirally around the center tube and the spiral vanes are integrally formed with the rotor shell. In one form, spiral vanes are also formed on the base plate and are nested in between the spiral vanes of the rotor shell.