PRODUCTION OF CALCIUM CARBONATE HAVING CONTROLLED PARTICLE DIAMETER

PURPOSE:To regulate the amount of calcium carbonate deposited on the surface of a seed crystal and enable production of a product having controlled average particle diameter, by adding a calcium carbonate seed crystal as a specific ratio to an aqueous solution of a Ca salt and introducing carbon dioxide into the aqueous solution. CONSTITUTION:A calcium carbonate seed crystal is added to an aqueous solution a Ca salt so as to provide the weight ratio of the weight of the Ca salt in the above-mentioned aqueous solution expressed in terms of Ca to the calcium carbonate seed crystal within the range of 10:90-99:1. CO2 is then introduced into the afore-mentioned aqueous solution to deposit Ca in the aqueous solution as calcium carbonate on the surface of the seed crystal and form calcium carbonate having the average particle diameter of 1.1-5 times based on that of the seed crystal. In the process, the amount of the seed crystal added into the aqueous solution of the Ca salt is varied to change the amount of calcium carbonate deposited on the surface of the seed crystal. Thereby the aimed calcium carbonate having a controlled average particle diameter within the above-mentioned range can be readily obtained.