Chemical precipitation of copper from copper-zinc solutions onto selective sorbents

The selective sorption and multiple concentration of copper in the form of an ultradisperse precipitate from a diluted Cu2+-Zn2+-solution has been investigated. The selective sorption is accomplished by means of weakly basic anion exchangers in their free base forms. Regeneration of the sorbent and conversion of Cu2+ to Cu-0 is carried out by means of a chemical reduction in the resin phase. Thus the resins can be reused for sorption of further copper ions. The process has been investigated in both, batch and packed bed experiments. After multiple saturation-reduction cycles an accumulation of metallic copper on the surface and in the pores of the sorbent is observed. The presence of finely dispersed metallic copper leads to the additional sorption of the Cu2+ ions due to a synproportional reduction-oxidation reaction. The total uptake of copper after several cycles amounts to more than 300 % of the anion exchange capacity. (C) 2008 Elsevier B.V. All rights reserved.