Method for metal and cyanide recovery from plating baths and rinse waters

摘要

A method for recovery of metal and cyanide from plating baths and rinse waters includes formation of hydrogen cyanide by acid treatment of such solutions, followed by HCN removal through diffusion across a microporous membrane. The method is applicable in a system wherein soluable metal cyanides and metal cyanide complexes are concentrated through use of a basic anion exchange system. Free hydrogen cyanide is released from the anion exchange system by means of an acid regenerant. In a preferred application of the invention, HCN, once having diffused through the microporous membrane, is neutralized with sodium hydroxide, to form a sodium cyanide solution that can be returned to a plating bath.