Patent ID: 8491864

Claim:
A method for the continuous manufacture of higher-strength, lower-salt, aqueous sodium hypochlorite bleach from lower-strength aqueous sodium hypochlorite bleach that has some sodium hydroxide and that is essentially free of sodium chloride (salt) crystals, the method comprising: A) in a tank that has a bottom wall and a sidewall extending upward from the bottom wall to bound an interior of the tank, sustaining a continuous reaction that produces a slurry of higher-strength bleach and solid salt crystals by introducing into the tank interior in a generally upward direction a solution comprising a mixture of the lower-strength aqueous sodium hypochlorite bleach that has some sodium hydroxide and is essentially free of salt crystals, aqueous sodium hydroxide solution having a concentration by weight within a range from about 45% to about 51%, and a recycle solution, and introducing into the tank interior chlorine in gas and/or liquid phase that may or may not include inerts, so that the mixture and chlorine begin to mix with slurry already in the tank at a level above the bottom wall of the tank; B) continuously withdrawing slurry from the tank at a level below the location where the mixture and the chlorine begin to mix with slurry already in the tank; C) cooling a first portion of the withdrawn slurry and using the cooled first portion as the recycle solution; D) processing a second portion of the withdrawn slurry to separate substantially all salt crystals from the residual liquid; and E) recovering the residual liquid as the higher-strength lower-salt, aqueous sodium hypochlorite bleach.