Patent ID: 8012443

Claim:
A method for producing spherical calcium carbonate comprising blowing a carbon dioxide gas or a carbon dioxide-containing gas into an aqueous suspension containing calcium hydroxide for reaction to a carbonation ratio of 2 to 10% and further comprising: step (a) after the carbonation ratio reaches 2 to 10%, adding an aqueous solution or suspension of a water-soluble phosphoric acid compound or a water-soluble salt thereof to the reaction mixture and continuing to introduce the carbon dioxide gas or carbon dioxide-containing gas into the aqueous suspension, at a blowing rate of not greater than 1.0 NL/minute, as 100% by volume carbon dioxide, per 1 kg of calcium hydroxide while stirring with a stirrer peripheral speed of at least 10 m/sec., and step (b) after step (a), adding an aqueous suspension containing calcium hydroxide and an aqueous solution or suspension of a water-soluble phosphoric acid compound or a water-soluble salt thereof to the reaction mixture and introducing a carbon dioxide gas or a carbon dioxide-containing gas for reaction, while stirring with a stirrer peripheral speed different from that in step (a) to produce spherical calcium carbonate having a mean particle diameter of 10 μm or larger.