| 摘要 |
PURPOSE:To obtain a product of high purity consisting of uniform fine crystal grains in the titled production by the hydrothermal synthetic method, by specifying factors such as composition and concentration of a raw material a solution, method for forming a slurry, alkalinity in the production process and crystallization conditions, etc. CONSTITUTION:(A) (a) An aqueous solution containing NaAlO2 and NaOH, (b) a suspension of ultrafine particulate SiO2 in an aqueous solution of NaOH and (c) an aqueous solution of NaOH are prepared. The alkalinities of the respecitve solution and suspension are 1.4-3.5N for the solution (c) and within [alkalinity of the solution (c)] + or -0.3N range for the fluctuation in alkalinity of the aqueous solution phase in the following stages (B)-(C) for the solution (a) and suspension (b). The composition ratio of the solution (a) and suspension (b) satisfies the molar ratios of formulas I -III. (B) The solution (a) and suspension (b) at <=45 deg.C are injected from separate injection holes always simultaneously into the solution (c) under stirring at <=45 deg.C to form a slurry. (C) The resultant slurry is then stirred and aged at <=45 deg.C. (D) The slurry is further heated to >=70 deg.C with stirring and heated at the temperature to form sodium aluminosilicate, which is crystallized. (E) The resultant crystals are finally separated, washed with water and dried.
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