A process and apparatus for the manufacture of high-strength, low-salt
sodium hypochlorite. An aqueous solution that comprises certain weight
percentages of sodium hypochlorite and sodium hydroxide and that is
essentially free of sodium chloride (salt) crystals, an aqueous solution
that comprises a certain weight percentage of sodium hydroxide, and
chlorine in gas and/or liquid phase that may or may not include inerts
are reacted in a tank. This creates a solution having a precipitation
zone where salt crystals are precipitating out of solution and falling
downward to form a slurry, some of which is withdrawn, then cooled, and
then re-introduced into the precipitation zone. Above the precipitation
zone is a crystal-free mother liquor zone consisting essentially of
crystal-free mother liquor containing a weight percentage of sodium
hypochlorite greater than that of than the lower strength aqueous sodium
hypochlorite bleach being reacted.