METHOD OF PRODUCTION OF PURIFIED CALCIUM CARBONATE Russian patent published in 1995 - IPC

FIELD: production of pure calcium carbonate. SUBSTANCE: source natural or synthetic CALCIUM carbonate is dissolved by nitric acid at its consumption within 1.13 to 1.28 kg per of dry CALCIUM carbonate, the obtained pulp is cleaned of impurities by its treatment by CALCIUM carbonate (7.7 to 31.0 % of the mass of source CALCIUM carbonate) during 20 to 50 minutes, and impurities are separated. The purified solution is treated by a carbonizing reagent-ammonium carbonate - in two stages, the first stage takes 9.4 to 21.0 % of the total consumption of ammonium carbonate with subsequent separation of precipitate. After the second stage the product is separated. The method provides for use of natural or synthetic CALCIUM carbonate in the stage of purification, in this case the precipitate separated after the first stage of treatment of purified solution by ammonium carbonate can be used as synthetic CALCIUM carbonate. The content of the main substance in the product is within 98 to 99%. EFFECT: facilitated procedure. 3 cl, 4 tbl