| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for precipitating calcium carbonate, having a low viscosity of pigment dispersion and grinding load and a high efficiency with a small amount of dispersant added by grinding a dispersion of precipitated calcium carbonate while directly blowing a carbon dioxide gas to the dispersion so as to adjust the dispersion to a specific pH region. SOLUTION: A carbon dioxide-containing gas having >=10% carbon dioxide gas concentration is directly blown into a water dispersion obtained by dispersing precipitated calcium carbonate produced by caustification process of a pulp manufacturing process preferably by a sulfate process or soda process into water to adjust the water dispersion of precipitated calcium carbonate to a pH of 8.0 to 12.0. The water dispersion of precipitated calcium carbonate is fed to a grinder packed with a medium having, for example, 0.1-10 mm particle diameter and ground in a wet state to give the water dispersion of precipitated calcium carbonate having <=0.6μm average particle diameter and >=70 wt.% solid content concentration. Consequently, pulverization can be carried out in a high concentration of pigment dispersion by mutual action such as stirring by a gas, etc., without causing impurities except calcium carbonate in neutralization.</p> |
