| 摘要 |
PURPOSE:To produce a basic hydrated silicic acid having high oil-absorption, by adding and reacting a mineral acid to an aqueous solution of an alkali metal silicate, separating produced hydrated silicic acid by filtration, contacting with a weakly alkaline compound and drying in air stream. CONSTITUTION:A mineral acid such as sulfuric acid, hydrochloric acid, etc., is dividedly added to and reacted with an aqueous solution of an alkali metal silicate such as sodium silicate to precipitate hydrated silicic acid in a state of fine powder. The produced hydrated silicic acid is separated by filtration. The wet cake of separated hydrated silicic acid or a slurry produced by dispersing said wet cake in an aqueous solution is made to contact with a weakly alkaline aqueous solution (preferably an aqueous solution of sodium carbonate or sodium acetate). Basic hydrated silicic acid produced by this process is separated by filtration and rapidly dried with air stream.
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