Abstract: In a calciner of the type having a radiant heat source and a screw conveyor for advancing material to and through a calcining reaction chamber by means of mated, intermeshing, rotating conveyor screws, an improvement comprising scraper means attached to and rotating with the conveyor screws for preventing agglomeration of material in the conveyor and for absorbing heat and conducting the heat to the material and lifter means attached to and rotating with the conveyor screws for increasing exposure of the material to the radiant heat and for absorbing heat and conducting the heat to the material.

Abstract: In a calciner of the type having a screw conveyor for advancing material to and through a calcining reaction zone, and wherein the screw conveyor comprises an internally cooled support shaft which is provided within an outer screw flight shaft, an improvement comprising means for controlling the bending stress between the inner and outer shafts is provided. Further, means are also provided for allowing axial movement of one of the shafts relative to the other. The bending stress ranges between the inner and outer shafts are controlled by means of a plurality of bearing members which extend in a generally radial direction with respect to the shafts and which extend between the shafts. The bending stress range is also controlled by the axial position of the bearing members along the shafts. Axial movement of one shaft relative to the other is permitted by the provision of bearing cages around the inner shaft with axial slots formed in the cage.

Abstract: A partition of high thermal conductivity is provided to separate a furnace heating zone from a furnace reaction zone, the reaction zone being at least partially heated by radiant heat from the heating zone. In a preferred embodiment, the partition means comprises a plurality of individual panels which are arranged in horizontally extending rows across the furnace. A ceramic seal plate is secured over the longitudinal interface between the adjacent panels in the same horizontal row. The seal plates in one horizontal row which extend across the width of the furnace are slightly offset from the seal plates in adjacent rows to compensate for thermal expansion forces which may tend to move the panels and sealed expansion spaces are provided between adjacent panels in the width-wise and longitudinal direction.