Application of selectrodialysis for the removal of As from metallurgical process waters: Recovery of Cu and Zn

Abstract

Abstract In this work, selectrodialysis (SED) was used to separate arsenic (As(V)) from copper (Cu(II)) and zinc (Zn(II)) of acidic metallurgical process streams by integrating non-selective and selective membranes. The separation process is determined by the chemical speciation of the involved elements. In this case, As(V) is mainly present as anionic species (H2AsO4−), while Cu(II) and Zn(II) are mainly present as cationic species although partially complexed as neutral complexes (CuSO4 and ZnSO4). A lab set-up was used to conduct the experimental tests with different type of standard and monovalent selective ion-exchange membranes. The results obtained showed that by SED configuration it was possible to recover around 80 ± 0.2% of Cu(II), 87 ± 0.2% of Zn(II) and 95 ± 0.3% of As(V) from the feed solution to the rich-product streams with an energy consumption of 2.6 ± 0.2 kWh/kg CuSO4+ZnSO4. Furthermore, a Cu/Zn-rich stream with a purity of both divalent cations of 99.8% (0.02% of As(V)) was achieved by means of SED. Overall, the results herein gathered suggest that SED is an efficient separation technology for Cu(II) and Zn(II) recovery from mining and metallurgical acidic streams.