Abstract: Particulate material to be calcined is conditioned and then introduced into a stream of flue gases which transport the material along a sloping drying duct while drying the material. The dried material is then introduced into the same stream of flue gases upstream of the drying duct, and the flue gases transport the dried material along a sloping preheating duct while preheating the material. The preheated material is fed tangentially into the lower end of a vertical calcine reactor and calcined product is withdrawn tangentially from the upper end of the reactor. The flue gases used for drying and preheating are produced in the calcine reactor and are cooled during the drying and preheating.

Abstract: A self-contained calcination plant is enclosed in a feed-storage silo. The plant consists of a vertical reactor, a separation cyclone and a pair of heat exchangers connected by appropriate piping and immersed in the feed material stored in powdery form in the silo. A positive displacement blower creates an air stream that is preheated in one of the heat exchangers and fed in part to a gas burner and in part to a feed pipe at the bottom of the reactor. The feed material is kept in a fluidized state in the silo by air heated in the other heat exchanger and blown upward from the bottom of the storage compartment, from where the material is dropped into the feed pipe through rotary valves prior to injection into the reactor. The feed pipe is connected tangentially to the reactor so as to produce an upward swirling flow around the burner's flame.