ACTIVE ANHYDRITE MANUFACTURING PROCESS Russian patent published in 2007 - IPC C04B11/05 

FIELD: manufacture of building materials.

SUBSTANCE: invention relates to calcium sulfate-based cements, namely to processes for manufacturing anhydrite from gypsum-containing mineral materials, and can be applied in manufacture of building materials and products therefrom. In the process according to invention, ground gypsum-containing mineral stock is treated with 98% sulfuric acid at mineral stock-to-acid weight ratio (5-20):1 and then neutralized by calcium-containing material (selected from CaO, Ca(OH)₂, CaCO₃, and CaSiO₃) to reach mixture pH at least 7.

EFFECT: avoided heat energy supply.

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