National Gypsum Company

National Gypsum Properties, LLC

Robert J Piasecki

Larry W Kingston

Edward A Burkard

Frank H Campbell

A composition for accelerating the setting reaction of an aqueous calcined gypsum slurry, and a method of making the same are disclosed. The composition includes a vibratory ball milled mixture of calcium sulfate dihydrate and a surfactant. The composition is prepared by subjecting the mixture to the high-frequency, low-impact grinding action of a vibratory ball mill. The resultant composition has a potency superior to that of conventional gypsum set accelerators.

Gypsum set accelerator and method of making the same

An apparatus for continuously calcining gypsum includes a flash calcining impact mill, a feed bin adjacent the impact mill for holding gypsum, and a gypsum feed control mechanism for supplying gypsum from the feed bin to the impact mill at a substantially constant rate. A method for continuously producing calcined gypsum includes the steps of providing a flash calcining impact mill and providing a feed bin adjacent the impact mill, the feed bin containing gypsum to be calcined. A gypsum feed control mechanism is provided for supplying gypsum from the feed bin to the impact mill. Gypsum is supplied from the feed bin to the impact mill at a substantially constant rate, and the impact mill is operated to dry, grind, and calcine the gypsum.

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Charlotte, NC, United States of America

Robert J Piasecki