| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for treating a deteriorated electroless nickel plating soln. by which Ni<2+> and a phosphorous acid compd. are separated and recovered from the deteriorated soln. industrially, inexpensively and effectively and the soln. is made pollution-free so as to be discharged as such state. SOLUTION: A deteriorated electroless nickel plating soln. is brought into contact with a nickel powder to bring about an electroless plating reaction, and the nickel ion in the soln. is separate and recovered as metallic nickel in a first separation stage. Gypsum or a mineral acid and slaked lime are then allowed to react with the separated mother liquor, and the desired phosphorous acid compd. is separated and recovered as calcium phosphate in a second separation stage.</p> |
