Dr. Oscar G. Olvera, Dr. Yeonuk Choi, Dr. Peter Kondos
Refractory sulfidic ores consist of materials in which gold occurs finely disseminated within metallic
sulfides or forming solid solutions, with pyrite and arsenopyrite being the two sulfides most
commonly associated with gold. Given that gold in this type of ores is not readily accessible to
leaching solutions, typical cyanide operations yield poor performance and oxidative pretreatments
are usually required to increase gold recovery in these ores.
Due to the characteristics of refractory sulfidic ores, in order to increase gold recovery it is necessary
to break or modify the sulfide matrix encapsulating the gold. Pretreatment alternatives include
ultra-fine grinding, roasting, pre-aeration, acidic and alkaline high pressure oxidation, and bacterial
oxidation. The presence of arsenic, however, introduces a serious disadvantage to the use of roasting
and bacterial leaching, while high pressure oxidation involves high capital costs.
In this work we have evaluated the addition of a carbon resin as an elemental sulfur collector upon
the oxidation of an arsenopyrite-pyrite sulfidic concentrate under atmospheric tank leaching (ATL)
conditions. The ATL residues were further tested for gold recovery under standard cyanide carbonin-
leach (CIL) and calcium thiosulfate (CaTS) leaching conditions.