An improved screw feeder assembly is provided for interconnection between the outlet of a preconditioner and the inlet of an extruder barrel. The assembly includes an upright housing with a pair of elongated shafts equipped with auger flighting within the housing and driven by means of motor. Preferably, the housing is mechanically coupled to the outlet and inlet with the shafts extending through the preconditioner vessel and downwardly to a point within the inlet and closely adjacent the screw(s) within the extruder barrel the flighting is provided along the length of the housing, from a point closely adjacent the outlet and into the extruder inlet. This provides a positive conveyance of preconditioned material from the outlet to the inlet. Use of the assembly allows maintenance of superatmospheric pressures and temperatures above 212° F. within the preconditioner, which permits more efficient processing.
