| 摘要 |
PROBLEM TO BE SOLVED: To stably and inexpensively produce a high purity silicagel by only fundamental operations from a raw material of an aqueous solution of a normal alkali metal silicate, in which the concentrations of impurities are high and largely vary, without using a cation exchange resin or a chelating agent and a high pressure pump or the like. SOLUTION: The aqueous solution of the alkali metal silicate is directly extruded preferably under stirring into an aqueous solution containing a mineral acid in a specified concentration from a tube having a hole diameter of 1.0-4.0 mmψto form a granular silica hydrogel. Then, the formed silica hydrogel is washed and dissolved by using an aqueous sodium hydroxide solution. Thereafter, the obtained aqueous solution of the alkali metal silicate is again extruded into an aqueous solution containing a mineral acid in a specified concentration from a nozzle having a hole diameter of 1.0-4.0 mmψto form the granular silica hydrogel. The formed silica hydrogel is dipped in a mineral acid of a specified concentration and then washed. COPYRIGHT: (C)2005,JPO&NCIPI
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