Metal recovery method and system for electroplating wastes

摘要

The present invention relates to a method of completely recovering nickel and zinc metal from multiple plating process waste streams by first separating the waste streams into a clean, relatively constant flow and/or concentration fraction and a dirty, variable flow and/or concentration fraction. Metal is recovered from the clean fraction by ion-exchange so as to concentrate the extracted metals for direct return to the plating bath. The effluent from the ion-exchange step is then blended with the dirty, variable flow and concentration fraction. This blended flow is first neutralized and then precipitated in a two-stage process using a sodium hydroxide solution. The resultant slurry containing the metal precipitate is filtered to yield a filter cake containing recovered nickel and zinc. This filter cake can then be further processed to recover the metal for reintroduction into the plating bath or for other uses.