PURPOSE: Low concentration aqueous caustic soda solution is reacted with chlorine to provide chlrinated solution containing no precipitated NaCl. To this chlorinated solution, high concentration aqueous caustic soda solution is added to precipitate NaCl, and then chlorinated, providing a low NaCl-content, aqueous sodium hypochlorite solution of high concentration.
CONSTITUTION: NaOH in the concentration of 18 to 22 wt%, preferably an aqueous low concentration caustic soda solution of 19 to 20 wt% is reacted with chlorine at a temperature below 40°C, preferably 20 to 35°C to provide chlorinated solution of greater than 80 chlorination and having 0.1 to 2% NaOH concentration. This chlorinated solution is added with a 40 to 60 wt% or preferably 45 to 50 wt% concentrate NaOH, in a rate of 0.5 to 0.5 1/hr, per 1 l of chlorinated solution, precipitating NaCl crystal. The addition of caustic soda solution is stopped when NaOH concentration is reached to 18 to 30 wt% and chlorine is fed at a rate of 25 to 35 Nl/hr per 1 l of chlorinated solution until the chlorination is reached to 80% or preferably to 97 to 99%. During this process, NaCl crystal precipitates, which is removed to provide a highly concentrated squeous sodium hypochlorite solution (20 to 30 wt%).
KAWANAMI KOUJI
HIRATA SUEICHI
| JPS4947292A | 1974-05-07 |