PURPOSE: To eliminate the influence of the contained water glass component at the time of reutilizing aq. sodium hydroxide used in the reaction to convert coal ash into zeolite.
CONSTITUTION: The concn. of the aq. sodium hydroxide to be reutilized and the concn. of silica contained as water glass are simultaneously measured, the measured sodium hydroxide concn. is corrected with the measured silica concn. based on the previously obtained relational expression, and the amt. of the original aq. sodium hydroxide to be supplied to a tank for supplying the aq. sodium hydroxide, the amt. of sodium hydroxide to be circulated and the supply of water are adjusted based on the corrected sodium hydroxide concn. Consequently, even though the content of the reaction product such as silica in the aq. sodium hydroxide circulated from the reaction system is changed, the concn. of the aq. sodium hydroxide supplied to the reaction tank is maintained as specified.
YOSHITAKE TOMOO
KATO HIDEO
