Dorr-oliver Incorporated

David W Leyshon

Peter A Angevine

Phosphate rock is calcined under conditions calculated to completely oxidize the carbon and sulfur in the rock. Calcination is also conducted at elevated temperature to eliminate cadmium metal, a poisonous substance in fertilizers, from the calcined rock product. A fluid bed system for eliminating cadmium metal in the calcination of phosphate rock involves a two-vessel system in which an independent cadmium removal vessel served by a separate fluidizing air stream carries out volatilization of cadmium, while preheating, precalcining and cooling is conducted in another multi-bed reactor which is served by a separate fluidizing air stream.

Fluid bed calcination process

Hot gases for fluidizing the preheat compartment of a multi-bed fluid bed reactor are cooled by injection of water, or cool air and water, to reduce scaling of the ducts, hot cyclone, hot windbox and the tuyeres in the constriction dome separating the hot windbox from the preheat compartment.

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Westport, CT, United States of America

David W Leyshon