Electrodialysis of solutions obtained by elution of cyanide complexes from anionic exchange resin by means of acidic thiourea

Electrodialysis of copper-thiourea solutions is not recommended because of the presence of formamidine disulphide which constitutes a poison for the cation exchange membrane. In this paper, it has been shown that the electrodialysis of copper in a thiourea medium becomes possible when the solutions are obtained by means elution of cuprocyanides by thiourea. A new mechanism of both the elution of cuprocyanides and the ion transfer across the anion exchange membrane has bee formulated. The process studied provided evidence for the recovery of acid used for the elution and its concentration in the cathode compartment as a pure product which can be reused. Applications to leaching solutions of an Algerian gold ore have also been performed. (C) 1997 Elsevier Science B.V.