| 摘要 |
PURPOSE:To efficiently obtain the titled CaCO3 having excellent water retentivity, having excellent coating property and useful for coating material or pigment, etc., by treating a heavy CaCO3 suspension having a prescribed solid- concentration with sand mill so as to have a desired specific surface area. CONSTITUTION:The suspension is obtained by suspending the heavy calcium carbonate such as lime stone into water so as to have 30-85wt.% solid- concentration and mixing kaolin, etc., if necessary. Then, the suspension is treated with sand mill so that the specific surface area of the heavy CaCO3 satisfies the condition expressed in an inequality I (A is the specific surface area m<2>/g of the heavy CaCO3 before the sand mill treatment), an inequality II (B is the specific surface area m<2>/g of the heavy CaCO3 after the sand mill treatment) and an inequality III at the same time by adding natural (synthetic) fine particles (e.g. mineral fine sand) having mean particle size of <=5mm, filling up in a container and mechanically agitating. Thereafter, the heavy CaCO3 for coating material is formed in the treated suspension. |
