FR2284557A1 - Continuous prodn of chlorine dioxide - by reduction of alkali metal chlorate in strong mineral acid soln (SF300476) - Google Patents

Abstract

Continuous process for prodn. of chlorine dioxide comprises (a) maintaining a reaction medium contg. an alkali metal chlorate, a reducing agent and a strong mineral acid, (b) forming ClO2 and Cl2 dioxide and continuously evaporating water at b.pt. of the medium; (c) removing from the reaction zone a gaseous. mixt. of ClO2 and Cl2; (d) adding to the reaction zone an alkali metal salt of the, anion of the strong acid; (e) removing from the reaction zone a suspension contg. the deposited alkali metal salt and part of the reaction medium; (f) forming a recycle mixt. having a reduced alkali metal salt content and contg. a sufficient amt. of alkali metal chlorate and reducing agent for replenishment; (g) heating the recycle mixt. to the b.pt. at the press. prevailing in the reaction zone; (h) accelerating the heated mixt. to establish a back-press. at least equal to the difference in satn. vapour press. of the heated mixt. and the reaction medium; (i) adding a strong mineral acid to the heated mixt. at the max. speed achieved by the mixt. due to the acceleration to form a feed matl. to the reaction zone; (j) allowing the gaseous matl. in the feed to undergo expansion to maintain a low level of acceleration; (k) adding the expanded mixt. to the reaction zone, the sum of the amt. of water evaporated from the reaction medium, the amt. of water withdrawn from the reaction medium in the suspension and the water or crystallisation in the solid matl. recovered from the suspension being equal to the amt. of water added to the reaction medium in the feed mixt. so that the level of liq. in the reaction zone is constant.