METHOD OF PREPARING CHEMICALLY PRECIPITATED CALCIUM CARBONATE Russian patent published in 2004 - IPC

FIELD: inorganic compounds technology. SUBSTANCE: invention provides preparation of product having commercial value in mechanical rubber, cable, perfumery, cosmetic, and paper industries, which as well can be used in preparation of fillers. Clarified distiller liquid from soda production is fed into reactor provided with heating system and stirrer. Temperature is raised to 60-80^o and 0.02 to 0.07 wt % of organic additive, namely oxyethylenated monoalkylphenols based on propylene trimer, is added, said additive having empirical formula C₉H₁₉C₆H₄O(C₂H₄O)_nH wherein C₉H₁₉ represents isononyl radical, n number of ethylene residues attached to one alkylphenol molecule, and n=9-12. Thereupon carbonate-bicarbonate solution, which is sodium bicarbonate production waste (filtration stage mother liquor) showing total alkalinity 130-400 g/l, is added in 0.3-0.5% stoichiometric excess with respect to calcium chloride. Treatment proceeds for 20-30 min until pH 7.2-7.4 is attained. Resulting precipitate is separated, washed, and dried. Precipitated calcium carbonate contains 0.002-0.006% chlorine, has whiteness 95.0-98.0% and bulk density 120-600 kg/m³. EFFECT: enabled utilization of soda production waste. 4 cl, 1 dwg, 1 tbl