Patent ID: 8251695

Claim:
A gypsum dryer/calciner comprising: a calcining space; a first pipe having an inlet connected to a source of hot gases and an outlet emerging in the calcining space; a second pipe having an inlet connected to a source of gypsum and an outlet emerging in the calcining space, the second pipe being concentric with the first pipe; a force-feeding screw positioned at least partially in the second pipe, the screw carrying the gypsum along in the calcining space; a burner positioned in a top part of the reactor, an outlet of the burner being placed in the first pipe for transfer of hot gases; and an inlet for gypsum emerging in the space between the first pipe and the second pipe, so the gypsum to be burned is located in the space between the first pipe and the second pipe, wherein the hot gases outlet is located at the bottom of the first pipe and the first pipe emerges approximately at the bottom of the receptacle.