SYSTEM FOR PRODUCING PRECIPITATED CALCIUM CARBONATE FROM CALCIUM CARBONATE SLURRY WASTE; METHOD FOR CALCIUM CARBONATE SLURRY WASTE RECOVERY, PROCESSING AND PURIFICATION AND THE CALCIUM CARBONATE PRODUCT THEREOF

摘要

System for producing precipitated calcium carbonate from calcium carbonate slurry waste; method for calcium carbonate slurry waste recovery, processing and purification and the precipitated calcium carbonate product thereof”. The application defines a system for producing precipitated CaCO3, said system having separation (m1), recovery (m2), processing (m3) and purification (m4) modules; a method for calcium carbonate slurry waste recovery, processing and purification, wherein additives (dispersants) and lime are added to the slurry, said slurry being subjected to the following steps: hydration (20-70% solids), separation using a sieve, acidulation/carbonation using CO2 from the boiler (step wherein phosphoric acid is added along with chelating acidulants such as sulfuric acid, hydrogen peroxide and citric acid), decanting, delaminating, homogenization (with dispersants being added), separation using a sieve, stabilization (pH adjusted to between 8 and 9.5) and drying (1.0% average humidity); and the precipitated calcium carbonate that has an average PSD of 3.0 pm, a minimum ISO purity of 92%, a total carbonate content of 95% and iron (Fe2O3) content200 ppm. The application further describes the use of CO2 from paper-production boilers for adjusting the pH of the water used in the method, and the use of a limestone waste that is rich in organic components (obtained from the first separation step of the calcium carbonate slurry using a sieve) for correcting soil.