WO 2016/115398 A1

Controlled process for precipitating calcium carbonate and vaterite precipitated calcium carbonate compositions formed by said process

(22) 14.01.2016

(43) 21.07.2016

(57) A process for converting gypsum into precipitated calcium carbonate including reacting a mixture comprising gypsum and a seed, a mineral acid, or both with at least one carbonate source, whereby precipitated calcium carbonate is produced in the form of calcite and/or aragonite directly without conversion from a vaterite poly-morph. Also, a process for converting gypsum into precipitated calcium carbonate including providing a mixture comprising i) gypsum ii) a seed, a mineral acid, or both iii) at least one additive selected from the group consisting of ammonium sulfate, an organic acid, or an iron material, and reacting the mixture with at least one carbonate source to produce precipitated calcium carbonate in the form of vaterite. The precipitated calcium carbonates having desired and unique compositions, polymorph and crystal size characteristics formed by these processes.

(71) Imerys Pigments, Inc., 100 ­Mansell Court East, Suite 300, Rosewell, GA 30076 (US)

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