As from the mixed solution of the sulfuric acid second iron which includes ferrous sulfate as

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently regenerating a ferric sulfate soln. used to pickle off the oxide scale depositing on a stainless steel, etc., to the ferric sulfate soln., and to provide a regenerator used therefor. ;SOLUTION: An excess of ferrous sulfate is previously removed from a mixed soln. of ferrous sulfate and ferric sulfate as the original soln., and the ferrous sulfate in the mixed soln. is regenerated to ferric sulfate. In this case, the original soln. is cooled to a specified temp. below the temp. at which the ferrous sulfate in the original soln. is crystallized, hence the ferrous sulfate is crystallized, and a mixed soln. contg. a crystal nucleus is formed. Subsequently, an excess of ferric sulfate is separated from the mixed soln. in the crystallization tank 40 to obtain non-excess mixed soln. Further, hydrogen peroxide and sulfuric acid are added to the non-excess mixed soln. to regenerate the ferrous sulfate in the mixed soln. to ferric sulfate.;COPYRIGHT: (C)1998,JPO