METHOD FOR OBTAINING WATERPROOF AND ENVIRONMENTALLY SAFE GYPSUM BINDING MATERIALS Russian patent published in 2008 - IPC C04B11/26 

FIELD: chemistry.

SUBSTANCE: invention concerns building material industry, particularly gypsum-containing waste processing, and can be applied in production of gypsum binding materials, in particular of phosphogypsum. The method for obtaining environmentally safe gypsum binding material based on phosphogypsum involves processing phosphogypsum by sulfuric acid with concentration of 62.5-95.0%, heated to 40-70°C, heating suspension obtained to 95-105°C and its further maturing at the same temperature until fluoride content of not over than 0.05 wt %, two-stage neutralisation by adding carbonate-containing additive and then calcium hydroxide powder to the suspension, drying the mix till total removal of non-bound water, and autoclave processing with obtaining high-strength gypsum binding material, or burning with obtaining anhydrite binding material. Prior to neutralisation fluorine gas is stripped by compressed air, and fluorides are removed, carbon dioxide being removed at the first neutralisation stage.

EFFECT: obtaining environmentally safe binding materials with improved water resistance and durability.

3 cl, 16 ex, 2 tbl