Method and arrangement for producing pcc

Abstract

The present invention relates to a method and arrangement for producing precipitated calcium carbonate (PCC) from ground calcium carbonate (GCC). The method comprises the following steps: a) an aqueous process liquid (1), carbon dioxide CO2 (3) and GCC (2) are mixed together and the pressure is set, b) carbon dioxide dissolves, whereby the pH decreases, c) under the said conditions GCC or part of the GCC dissolves: CaCO3 (s) + 2 H+ (aq) → Ca2+(aq) + CO2 (g) + H2O(l), d) a pressure reduction is carried out, e) carbon dioxide is released as gas, whereby the pH increases and Ca2+ and CO2 crystallize into PCC, f) degassing is carried out, CO2 is led back to process step a via a recycling line, g) precipitated calcium carbonate (PCC) or its derivatives, such as PCC agglomerates, GCC+PCC -clusters or PCC / GCC mixture, are passed on.