METHOD FOR RECOVERING NOBLE METAL COMPOUND

摘要

PURPOSE:To recover only the noble metal compd. at a high concn. in the form of a concd. liquid by separating the noble metal compd. in a treating liquid with a reverse osmosis membrane and concentrating the compd. by electrodialysis utilizing both anion and cation exchange membranes. CONSTITUTION:The treating liquid of plating contg. the noble metal compd. is separated by a reverse osmosis membrane apparatus 6 utilizing the reverse osmosis membrane 6a consisting of cellulose acetate. The liquid 3a permeated through said membrane is concentrated by an electrodialysis apparatus 9 provided with diluting chambers 10 and concentrating chambers 11 formed by alternate partition with the anion exchange membranes A and the cation exchange membranes K. The concd. liquid 13 is returned successively by a pump 21 to a plating cell 1 where said liquid is used to prepare the plating liquid. The liquid 13 is further dried by a dryer 22 and the noble metal compd. is recovered in the form of crystal or powder. Only the noble metal compd. is recovered in the form of crystal or powder at the high concn. by the above- mentioned method.