Method for the Treatment of a Gypsum Recyclate

Abstract

The present invention relates to a method for treating gypsum comprising siliconates, the treatment including the steps of stirring an aqueous gypsum suspension with a solution of an alkali metal and/or alkaline earth metal hydroxide having a pH of 10 or higher and separating the solid components from the aqueous gypsum suspension. By the treatment with alkali metal and/or alkaline earth metal hydroxide, the detrimental effects of siliconates on a later foam, which is prepared with the thus treated gypsum, is significantly reduced. The present invention further relates to methods of preparing foamed gypsum compositions and gypsum boards including such method, correspondingly prepared gypsum and gypsum boards, and a use of alkali metal and/or alkaline earth metal hydroxide solutions for inactivating siliconates in gypsum recyclates.

Dependencies are inferred from the claim text.