| 摘要 |
A process for the production of finely-dispersed precipitated calcium carbonate having a disturbed calcite lattic, a specifice surface area (according to Brunauer, Emmett and Teller) of more than 80 sq. m./g. and containing silicic acid in an amount corresponding to an SiO2 content of 0.1 to 20% by weight, which process comprises reacting an aqueous suspension of calcium hydroxide of not more than 1.0 molar concentration, at a starting temperature of not more than 20 DEG C., with gases containing carbon dioxide, with the addition of active silicic acid in an amount of 0.179 to 35.8% by weight SiO2, based on the CaO content of the suspension, and in the presence of sulphuric acid, a water-soluble salt thereof in an amount of 0.179-35.8% by weight based on the CaO content of the suspension, the supply of carbon dioxide-containing gases to the suspension being interrupted when reaching a pH value of 8.0 to 10.0 therein. Citric acid, tartaric acid, or the sodium, potassium lithium or ammonium salts of these are referred to. |
