METHOD OF DECOMPOSING SODIUM HYPOCHLORITE IN SOLUTION OF CHLORATE

摘要

An aq. NaCl soln. is electrolysed to produce a chlorate soln. (I) leaving the electrolysis cell. Ammonia or an ammonium salt is added to soln. (I) to decompose Nacl before the soln. is fed to a crystallisation vessel for the chlorate. The addn. of NH3 provides a molar ratio (MR) of hypochlorite:NH3 of less than 1.5, and a pH after adding the NH3 of 6-6.5. Soln. (I) has pref. been previously held 1-8 hours in a tank, and has pH 4.5-5.5; and the pref. dacompsn. agent is NH3; alternatively, soln. (I) is adjusted to pH 7-8.5 and NH4Cl is used as the decompsn. agent. The pref. reaction temp. is above 40 deg.C. The amt. of active chlorine present as either Nacl or NH2Cl in soln. (I) is reduced to a very low value, so corrosion of the crystalliser is eliminated.