non continuous two-stage chlorination methods for the production of neutral calciumhypochlorit advantage.

摘要

1. Discontinuous process for the preparation of neutral calcium hypochlorite hydrate, in the form of an aqueous slurry, according to which gaseous chlorine is reacted, in two chlorination stages, with an aqueous slurry with a calcium hydroxide content of 160 to 360 g/l and the reaction medium is kept stirred, characterized by the fact that, in the first step, a chlorination operation is effected at a temperature below 40 degrees C and preferably of between 20 and 35 degrees C, and continued until the calcium hydroxide content of the reaction medium has been lowered to between 45 and 80 g/l, the temperature of the reaction medium is lowered to between 0 and 12 degrees C in less than 30 minutes and preferably less than 20 minutes and, in the second step, a chlorination operation is then effected at a temperature of between 5 and 22.5 degrees C, the rate of flow of chlorine being regulated in such a way that the duration of the said chlorination operation, necessary to lower the calcium hydroxide content of the reaction medium to below 16 g/l and preferably between 5 and 10 g/l, is between 10 and 25 minutes, and the temperature of the reaction medium is lowered to or maintained at below 20 degrees C and preferably between 12 and 15 degrees C, the maximum temperatures theta 1 and theta 2 reached in the course of, respectively, the first and the second steps being such that the difference theta 1 -theta 2 is at least equal to 15 degrees C, and that it is applied to calcium hydroxide in the form of particles with a diameter of between 0 and 200 mu m.