Recovering precipitated calcium carbonate - by filtering and washing with water containing dissolved carbon di:oxide to convert any residual hydroxides

摘要

Recovering precipitated calcium carbonate (PCC) comprises: (i) separating PCC by filtration; (ii) collecting the filtrate and washing to separate by-products; and (iii) washing with water containing dissolved CO2 to convert hydroxy compounds present to carbonate. Also claimed is apparatus for recovering PCC comprising: (a) a pressure filtration unit; and (b) a wash liquid tank which includes a CO2 input line.