Methods for manufacturing a calcined gypsum and a gypsum board

Abstract

The present invention provides a method for manufacturing a calcined gypsum wherein the mixing water amount is reduced and the setting time does not increase. As a raw gypsum is compounded with a carboxylic acid-type material and calcined, a calcined gypsum can be manufactured wherein the mixing water amount is small and the setting time does not increase. Furthermore, a regular gypsum board can be manufactured without reducing the productivity of the gypsum board even if a large quantity of recycled gypsum causing increase of the mixing water amount is used as a raw gypsum, because the mixing water amount is small and the setting time does not increase for the calcined gypsum manufactured as described above.

Dependencies are inferred from the claim text.