For metallurgical purposes, gold is often classified as ‘free milling’ if recoveries over 90% can be achieved by cyanide leaching, or ‘refractory’ if recoveries by leaching fall below 80%. A full investigation into gold recovery relies on a combination of beneficiation methods including gravity separation and cyanide leaching backed up with a gold deportment study.
Gold deportment studies are particularly valuable when recoveries are lower than expected, i.e. for refractory gold deposits. For this type of work GSL, have a procedure that relies on backscatter imaging of pre-concentrates combined with more detailed analysis of gold grains by SEM for mineral association and liberation analysis, electron microprobe (EPMA) analysis for elemental mapping and, if required, dynamic secondary ion mass spectroscopy (D-SIMS) for higher resolution elemental mapping or laser ablation induced coupled plasma mass spectroscopy (LA-ICPMS) for spot checks.
