A screen of some native Australian flora and exotic agricultural species for their potential application in cyanide induced phytoextraction of gold

The phytoextraction of gold is an exciting new area of research involving the use of plants to extract gold from a low grade ore and waste products. The aim of this study was to screen some Australian native plant species and exotic agricultural species for their potential use in cyanide-induced phytoextraction of gold from a crushed ore body. Plants were grown in an ore body with a gold grade of 1.75 g/ton gold and treated with 0.1 g/kg and 1 g/kg cyanide as aqueous NaCN. The above-ground biomass was harvested one week after treatment and the gold concentration determined. Mean gold concentrations of up to 27 g/ton (d.w.) were found in the plant tissue of Trifolium repens cv. Prestige. Higher gold concentrations were generally found in the stems and older leaves with the lowest gold concentrations in the young leaves. Plants grown in the 1 g/kg cyanide treatment generally had higher concentrations of gold in the plant tissue than plants grown in the 0.1 g/kg cyanide treatment. This study demonstrates the potential use of plants to extract and concentrate gold from a low grade ore and waste products.