Patent ID: 8470282
Filing Date: 2013-06-25
Classification: C01F,C01P

Abstract:
1. A method of producing calcium carbonate from lime comprising the steps of: (i) providing an aqueous solution comprising 10% to 35% by weight of dissolved polyhydroxy compound and 1% to 5% by weight of dissolved calcium hydroxide (expressed as Ca(OH) (ii) treating the solution prepared in step (i) to remove solids including suspended solids; (iii) dispersing carbon dioxide through the solution of step (ii) so as to form a mixture containing calcium carbonate, said dispersing initially producing a reduction in the pH of the mixture, and subsequently producing a rise in the pH of the mixture; (iv) terminating the dispersion of carbon dioxide and adding an alkaline agent at a time after the beginning of the rise in the pH of the reaction mixture in step (iii) but before any subsequent reduction in the pH of the reaction mixture to 9.5, the alkaline agent being added to maintain a pH for the mixture of at least 9.5, and (v) recovering precipitated calcium carbonate.