Pilot plant pressure oxidation of refractory gold-silver concentrate from Eldorado Gold Corporation's Certej Project in Romania

Abstract

A pilot plant campaign has been conducted by Sherritt Technologies in support of Eldorado Gold Corporation's evaluation of pressure oxidation (POX) technology for the treatment of refractory gold concentrates from the Certej deposit in Romania. Preliminary batch tests indicated that gold extraction from the oxidised concentrates in subsequent cyanide leaching was adversely affected by the presence of organic carbon in the POX feed when chloride in solution was at an elevated level. As such, the process conditions tested were selected to either counteract the negative impact of the organic carbon, or to deactivate it during POX. Both routes proved feasible, yielding gold extraction of 95–98% in cyanide leaching of the oxidised concentrates. Silver extraction was typically in the range of 80–90%, provided that the oxidised concentrates were also processed in a lime boil step before cyanide leaching.