METHOD OF PRODUCING GYPSUM Russian patent published in 2012 - IPC C01F11/46 C09C1/02 D21H17/67 

FIELD: chemistry.

SUBSTANCE: mixture is prepared from calcium sulphate semihydrate and/or calcium sulphate anhydrite and water with dry substance content of said mixture ranging from 34 to 84 wt %. The mixture is stirred until formation of a crystalline gypsum product. The reaction mixture can further be mixed with a calcium sulphate dihydrate or a crystal habit modifier selected from ethylene diamine amber acid, amino diamber acid, ethylene diamine tetraacetic acid, diethylene triamine pentaacetic acid, nitrilotriacetic acid, N-bis-(2-(1,2-dicarboxyethoxy)ethylaspartic acid, di-tetra- and hexaaminostilbene sulphonic acid and salts thereof, such as sodium aminotriethoxy succinate (Na₆-TCA), as well as akylbenzene sulphonates. Water is used at temperature 0-100°C. Crystallised gypsum is dispersed using a dispersant in amount of 0.01-5.0 wt %, treated with a biocide, sieved and bleached. The obtained gypsum product essentially consists of intact gypsum crystals with size 0.1-2.0 mcm, shape factor 2.0-5.0 and aspect ratio 1.0-10.

EFFECT: simple method.

23 cl, 33 dwg, 28 ex