Pressure cyanidation of the minus 10 micron slimes fraction of the
Fimiston flotation concentrates for the recovery of gold values has been
evaluated as an alternative processing route to the roasting and
atmospheric cyanide leaching of the calcine. Laboratory and pilot trials
have demonstrated that gold extractions of greater than 94 per cent can be
achieved at cyanide consumptions of 12-24 kg/t and oxygen
consumptions of 0.1-0.3 Nm3/t with total pressures of 1000-2000 kPa.
Economic and operational assessment of several reactor configurations
suggests autoclaves may be preferred over pipe reactors at treatment rates
of 10 t concentrate/h.