2011 – AusIMM Metplant Conference 2011, Perth, WA
Silver and gold bearing ore from the Troy Resources NL Casposo Gold-Silver Project,
located within the San Juan Province of Argentina contains a complex mix of gold, silver,
electrum and silver sulphides in the ore. Casposo is a typical low sulphidation epithermal
style gold–silver deposit where mineralisation is hosted within rhyolite – andesite flows and
breccias. Veins are typically banded quartz–chalcedony colloform – crustiform banded with
quartz – carbonate infill. Mineralisation is associated with an assemblage consisting of
quartz, chalcedony, adularia, calcite, illite, sericite and trace sulphides. Gold and silver occur
as electrum, native silver, sulfosalts and silver sulphides. This paper presents a case study
that describes the process selection, development and engineering of a tailored process
plant for the recovery of gold and silver from this ore.
The original feasibility study, modelling, metallurgical testwork and engineering studies are
outlined. The final flowsheet was based on minimising capital cost, operability, recovery and
minimising technical risk.
The process flowsheet uses the traditional Merrill Crowe route because of the high silver to
gold ratio in the feed and achieves maximum gold and silver recovery while providing a
common facility for future ore body treatment.