Biomineralisation - gold nuggets from tailings waste

In various gold mines, large quantities of gold (in some cases >20 %) are non-recoverable. The reasons range from gold being contained in the rocks at too low grade or, based on its mineralogy, the gold is refractory or too fine to be captured by gravity circuits. This has significant economic ramifications and impacts on the lifespan of the mine. Recent advances in our understanding of bio-geochemical gold cycling suggest that gold lost to waste tailings could be recovered through the employment of novel low-cost bio-geochemical approaches. Specifically, it has been shown that microbiota (Cupriavidus metallidurans) mediate the formation of secondary gold grains (nuggets) at sites such as the Prophet Gold Mine in Queensland. Further, laboratory tests have confirmed that recoverable gold grains are formed within month time scales, therefore suggesting potential viability of this processing route for mine tailings. The opportunity therefore exists for Newcrest to be part of this project that will provide a low cost, low tech, environmentally sustainable solution for problem ores, in particular carbonaceous ores that are pre-robbing during cyanidation.