Yoshino Gypsum Co., Ltd.

Shizuo Taira

Masahiro Wada

Tomoya Hasegawa

Michio Nishi

Takehiro Tanaka

Tsuneo Tsuruzawa

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.

Methods for manufacturing a calcined gypsum and a gypsum board

There are provided a method of recovering a base paper for gypsum board for continuously and efficiently recovering a base paper for gypsum board from a waste material of gypsum board including a gypsum core and the base paper for gypsum board adhering thereto. The method of recovering a base paper for gypsum board includes steps of breaking the waste material of gypsum board, separating a gypsum component and a paper piece of the base paper for gypsum board from the broken waste material of gypsum board, and washing the separated paper piece with water using a rotary drum-type washing device so as to eliminate a gypsum component adhering to the paper piece.

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Tokyo, Japan

Shizuo Taira