Patent ID: 6984300

Claim:
A method for recovering useful components in an electolytic phosphate chemical treatment bath, wherein, by contacting a metal material article having electrical conductivity with a phosphate chemical treatment bath and by subjecting the metal material article to be treated to electrolytic treatment in said phosphate chemical treatment bath, a film containing a phosphate compound is formed on the surface of said article to be treated, and then the treated article having phosphate chemical treatment liquid adhered thereto after chemical treatment is contacted with an aqueous solution for dilution and washing, characterized in that: (a) a phosphate chemical treatment bath which contains phosphate ions and phosphoric acid, metal ions that form a phosphate crystal to provide a film, metal ions that are reduced from cations in the solution to form a film as metals, and ions that are involved in the reaction of the above-mentioned phosphoric acid and various metal ions to form a film, but which does not substantially contain ions that are not involved in film formation, is used as the phosphate chemical treatment bath, and (b) the aqueous solution in the washing water tank with which phosphate chemical treatment liquid adhered to the treated article after chemical treatment is contacted for dilution and washing, is subjected to electrodialysis, and useful components in said aqueous solution is thereby recovered and returned to the chemical treatment bath.