Enhancement of gold recovery during lead fire assay by salt-roasting

摘要

The aim of this study was to investigate the effect of a simple and economical salt-roasting method on the gold recovery of a conventional lead fire assay. An enhanced gold recovery of 30.99 g/ton (16.82%) was obtained by roasting a gold concentrate at 750°C, but this was further enhanced to 40.44 g/ton (21.95%) at the same temperature with the addition of 20% salt. The fact that the maximum recovery was obtained at a roasting temperature of 750°C was attributed to the fact that pyrites within the concentrate contained invisible gold, with the addition of salt enhancing the decomposition of these pyrites. Thus, by treating the gold concentrate with a combination of conventional and salt roasting, its gold content was increased and the loss of gold to the glass slag was reduced. Finally, it was also observed that the amount of gold loss with an amorphous specimen was less than that of samples containing galena.