United States Gypsum Company

Usg Corporation

Otto L Dozsa

Larbi Bounini

Richard F Stone

Donald R Janninck

Hydrodynamic pumping of the fluidized calcining mass in a kettle is set up by the continuous flow of the mass to and from heating rods immersed therein which are constantly emitting at least about 1 British Thermal Unit of heat per minute per square inch of the surface of the rods. The transfer of heat from the walls and bottom of the kettle is enhanced so that more of the available heat is actually absorbed than in a kettle lacking such heating rods. The rate of calcination may be increased while the rate of heat input is decreased.

Highly efficient calcination of gypsum to hemihydrate

A setting accelerator for calcined gypsum plaster and a process for its preparation are disclosed. The accelerator comprises finely ground calcium sulfate dihydrate having composite coatings on the particles of firstly a calcination inhibiting material such as sugar and secondly a coating of aluminum sulfate hydrate. The accelerator is particularly useful in the formation of gypsum wallboard.

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Palos Heights, IL, United States of America

Otto L Dozsa