METHOD AND APPARATUS FOR PRODUCING HIGH MOLAR RATIO ALKALI SILICATE AQUEOUS SOLUTION
PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a high molar ratio aqueous alkali silicate solution where the problem that, by the addition of acid to a low molar ratio aqueous alkali silicate solution, its molar ratio can be increased, but, the gelling time of the resultant...
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Zusammenfassung: | PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a high molar ratio aqueous alkali silicate solution where the problem that, by the addition of acid to a low molar ratio aqueous alkali silicate solution, its molar ratio can be increased, but, the gelling time of the resultant aqueous alkali silicate solution whose molar ratio is increased is made short and unstable by the coexistence of the by-produced salt is solved by efficiently separating and removing the by-produced salt from the aqueous alkali silicate solution whose molar ratio is increased with a pressure-driven type semi-permeable membrane, and the stable high molar ratio aqueous alkali silicate solution having a long gelling time is produced. SOLUTION: The kind of acid for making the by-produced salt into the one permeable as much as possible is selected; concentration is performed using a pressure-driven type semi-permeable membrane which does not permeate silicon oxide of the object as little as possible and permeates the by-produced salt as much as possible; the aqueous solution including the by-produced salt is permeated therethrough while being concentrated, and simultaneously or intermittently, water is added for dilution; and the concentration and dilution are suitably and continuously performed. Thus, the by-produced salt is removed to the filtrate (permeated water) side. On the other hand, the silicon oxide is left in the aqueous alkali silicate solution which is increased in a concentration and a molar ratio. COPYRIGHT: (C)2004,JPO&NCIPI |
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