Separation and recovery of reusable heavy metal hydroxides from metal finishing wastewaters

摘要

A method is disclosed for the elimination of hazardous metal wastewater and sludges by recovering the non-ferrous metals zinc, nickel, copper (II), cadmium or chromium (III) present in an aqueous sludge comprising mixed metal hydroxides by selectively precipitating the ferrous metal ions present while maintaining the non-ferrous metal ions in solution, isolating the precipitate and then precipitating the non-ferrous metal ions from solution.