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

Abstract

In this work, selectrodialysis (SED) was used to separate arsenic (As(V)) from copper (Cu(II)) and (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 mono-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.