Abstract: Device for the thermal treatment of bulk material with a screw conveyor transporting the bulk material which is equipped with infrared heat radiators in a tempering zone, characterized in that the infrared heat radiators are arranged in the screw conveyors in the central area of the rotation diameter. The device is also characterized in that the infrared heat radiators are mounted in a radiation-permeable screw shaft. The walls of a screw trough of the screw conveyor have an infrared-reflecting coating or are made of an infrared-reflecting material.

Abstract: A worm or screw conveyor for the thermal treatment of a bulk containing thermoplastics and which has an elongated housing along which the bulk material is conveyed by a worm or screw. The worm or screw has a certain peripheral diameter and is rotatable about the worm axis to displace the bulk material therealong and an infrared heater is located in the housing centrally of the peripheral diameter for directly exposing bulk material in the housing to infrared radiant energy to heat the bulk material.