Extraction and separation of nonferrous and precious metals from waste of electrical and electronic equipment through ferric sulfate leaching and electrolysis

Abstract

AbstractBACKGROUNDThe continuous generation of waste electrical and electronic equipment (WEEE) causes serious environmental problems as it is disposed in landfills, because of its hazardous content. In most electronic equipment, there are important components which contain large amounts of nonferrous metals and precious metals.RESULTSSeparation of silver using sieving proved to be efficient; silver was almost entirely collected in the finer fraction (<0.5 mm size). Separating gold from silver and palladium was achieved through leaching the metallic fraction in a 0.5 mol L–1 aqueous ferric sulfate solution at room temperature. A good yield of metal extraction was obtained after leaching using ferrous sulfate. The composition of the cathode deposits points to an almost complete recovery of silver and copper by electrolysis and a partial recovery of tin. Also, cyclic voltammetry tests in the solution (pH adjusted at 0.5) identified cathode peaks at ∼ −0.3 V Ag−1 ref. ascribable to Cu reduction, at ∼ − 0.783 V Ag−1 ref. ascribable to Ni reduction, as well as a plateau in the range −0.75 ↔ −1.0 V Ag−1 ref. ascribable to a simultaneous reduction of several ionic species.CONCLUSIONLeaching from WEEE was carried out by an environmentally friendly procedure using nonpolluting ferric sulfate, and using electrolysis some metals were extracted in good condition. © 2018 Society of Chemical Industry