| 摘要 |
PURPOSE:Calcined easily dispersible calcium carbonate having improved dispersibility, a specific surface area by BET method of >= a specific value, an oil absorption of >= a specific value, and high activity, obtained by calcining ultrafine colloidal calcium carbonate. CONSTITUTION:A water-soluble metal salt to form a colloidal metal hydroxide in a molar ratio of it to calcium hydroxide of 0.02-0.10:1 is blended in a spray state with a carbonic acid gas and reacted with it in such a way that the feed is finished in <=3% carbonization ratio [(CaCO3/Ca(OH)2X100wt%)]. When the carbonization ratio reaches 80%, soluble silicic acid (e.g., sodium silicate) is added to the reaction mixture, and the carbonization reaction is continued. The prepared calcium carbonate is dried by a conventional procedure, and calcined at 90-1,000 deg.C by a fluidized calcining furnace, to give calcined easily dispersible calcium carbonate having >=60m<2> specific surface area by BET method and 70ml/100g oil absorption.
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