Manufacture of high purity silica

Abstract

Abstract PURPOSE:To manufacture high purity silica having a low impurity content by treating a purified aqueous soln. of a crystalline alkali silicate with ion exchange resins to prepare silica sol, converting the silica sol into silica gel, and heat treating silica gel. CONSTITUTION:A recrystallized product of a crystalline alkali silicate such as sodium metasilicate having 0.5-1.5 molar ratio of SiO2/Na2O is dissolved in water. This aqueous soln. is purified by ultrafiltration or coprecipitation with a finely-divided insoluble substance, and the purified aqueous soln. is successively treated with a cation exchange resin, an anion exchange resin and a cation exchange resin to prepare acidic silica sol. Silica gel is deposited in the purified silica sol by adding a coagulant, and it is heated at about 500 deg.C to manufacture high purity silica contg. <=1ppb U and <=10ppb Th.

Inventors

• 👤 Toshihiko Morishita
• 👤 森下　敏彦
• 👤 Hitoshi Koshimizu
• 👤 仁 輿水
• 👤 Kazuyoshi Torii
• 👤 鳥井　一義

Bibliographic Details