PURPOSE: To simply prepare pure aragonite CaCO3 suitable for paper coating agents, etc., by adding a divalent or trivalent metal salt to the aqueous suspension of variable calcium carbonate and thermally treating the suspension to cause a crystal transition reaction.
CONSTITUTION: Vaterite calcium carbonate is prepared by a method in which carbon dioxide is introduced to an emulsion containing calcium hydroxide and calcium acetate. The vaterite calcium carbonate aqueous emulsion is mixed with a divalent or trivalent metal salt (e.g. magnesium hydroxide or chromium chloride) and subsequently heated at a temperature of ≥40°C to transfer the crystal of the vaterite calcium carbonate into the crystal of aragonite calcium carbonate. The produced aragonite calcium carbonate is filtered and washed with methanol to provide the pure calcium carbonate.
TODAKA AKIMOTO
SATO KAZU
IKEBE YUTAKA
SUGIHARA HISAO
TODAKA AKIMOTO