GOLD AND SILVER ELECTRODEPOSITION FROM THIOSULFATE SOLUTIONS IN A RECTANGULAR REACTOR WITHOUT MEMBRANE SEPARATION

摘要

Obtaining gold and silver by leaching with thiosulfate solutions has received widespread attention for some decades. This is mainly because this system has only a moderate environmental impact, while it is possible to treat minerals and materials that are refractory to the traditional cyanidation process. On the other hand, the separation of Au(I) and Ag(I) ions from the thiosulfate solutions has been performed using cementation with copper, and more recently, through an electroseparation process in a rotating cylinder reactor (RCR). In this type of reactor, a membrane is usually employed to separate the cathodic and anodic compartments, in order avoid the redissolution of the deposited metal, as well as to decrease the anodic oxidation of the thiosulfate. The present research used a rectangular batch reactor without a separating membrane, analyzing the effect of anode and cathode materials on the consumption of thiosulfate, cell voltage, as well as the current efficiency of the selective gold and silver deposition.