Centrifuge apparatus

Decanter centrifuge for separately discharging light and heavy phase materials from a mixture thereof, comprising a rotating, imperforate, cylindrical centrifuge bowl having one end thereof conically tapered, discharge ports for light phase material at the end wall of said cylindrical portion, and discharge ports for heavy phase material at the conical portion, the weir surfaces of the discharge ports for the light phase material having a shorter radial distance from the rotational axis of said bowl than the weir surfaces of the discharge ports for said heavy phase material, further comprising a screw conveyor coaxially mounted within the bowl for rotation relative thereto, the helical flights of the screw conveyor mounted coaxially with a feed cone and an annular baffle on a hub, with said feed cone being disposed radially outward of an outlet in the hub for the mixture, said helical flights being adapted to the contour of said bowl, with cylindrical and conical portions of the flights extending to the inner surface of corresponding cylindrical and conical portions of the bowl, thereby forming a chamber for said mixture helically wound around the rotational axis within the bowl, said chamber including a cylindrical separating zone and a conical discharge zone on opposite sides of said baffle, the outer edge of said baffle being spaced from the inner surface of said bowl to provide a restricted passageway between the separating zone and the discharge zone, characterized in, that said annular baffle is rigidly mounted on the outer surface of said feed cone in a position normal to said axis, and that the radial distance from said axis to the larger end of said feed cone is about equal to the radial distance from said axis to the weir surface of the discharge ports for the light phase material.