SODIUM ALUMINIUM SILICATES WITH CRYSTALLINE LAYER-CONSTRUCTION AND USE OF THESE FOR WATERSOFTENING AND METHOD FOR WATERSOFTENING

摘要

Crystalline lamellar aluminium silicates of general formula Na2y[Si(2-x)AlxO(4+y-x/2)] (I) are new. y = 0.75-1.25 and x = 0.01-0.8. The sodium-aluminium-silicates are prepared by mixing an aqueous water-glass-solution that contains sodium and silica in the region of 0.9-1.1 with a required quantity of an aqueous alkaline aluminate solution pref. of sodium-aluminate in a concentration corresponding to Si/Al > 2 atomic ratio. The mixture is dried, pref. comminuted and heated at 600-800 deg C until the development of a desired crystalline structure. Granules of preferred sizes are obtained by grinding.