Abstract: A cement board having bare surfaces and a woven mesh of reinforcing fibers underlying the top, bottom, and longitudinal edge surfaces is made continuously on an improved apparatus which comprises a pair of edger rails which slidably rest on a conveyor belt and define the path of the cement board being made on the conveyor belt and a means for folding and pressing outer margins of the bottom mesh into the edge surfaces and the top surface.

Abstract: A cement board having bare surfaces and a mesh of reinforcing fibers underlying the top, bottom, and longitudinal edge surfaces is made continuously on an improved apparatus which comprises a pair of edger rails which slidably rest on a conveyor belt and define the path of the cement board being made on the conveyor belt and a means for folding and pressing outer margins of the bottom mesh into the edge surfaces and the top surface.

Abstract: A calcining apparatus comprising a kettle, a heating chamber for heating the outside of the kettle, a stack for exhausting gas from the heating chamber, a duct connected at one end to the stack and having the other end extending for a limited distance into the contents of the reaction chamber of the kettle for introducing a portion of the stack gas directly into the calcining reaction mixture, and means for propelling the stack gas through the duct and into the reaction chamber of the kettle, thereby directly adding heat to the reaction mixture and accomplishing fuel conservation by recapturing and utilizing a portion of the heat from the stack gas.

Abstract: Naturally occurring or man-produced calcium sulfate dihydrate is subjected to a process which involves concomitant flash calcination, utilizing co-current contact of the gypsum with a gaseous heat source, and self-comminutation to produce the insoluble calcium sulfate anhydrite in relatively pure and finely comminuted form without the use of specially-sized feed rock and extensive mechanically motivated grinding of the product required by prior means known in this art.