In refractory ores, a substantial part of the gold content may be present as a sub‐microscopic
component within the mineral matrix of the various carriers. This type of gold may be present as
finely disseminated colloidal size gold particles (<0.5μm) or as a solid solution within the
sulphide mineral matrix. Such ores are not amenable to gold recovery by direct cyanidation. In
order to liberate the sub‐microscopic gold, the ore has to be oxidized before being subjected to
gold cyanidation and extraction. Autoclave pressure oxidation (AC POX) of the sulphide ore and
subsequent cyanidation is a common technology used to liberate the gold in such refractory ores.
The additional presence of active carbonaceous matter in such ores (double refractory ores)
represents another major obstacle for efficient gold recovery during the process of pressure
oxidation and cyanidation. This carbonaceous matter (c‐matter) can adversely affect the gold
recovery due to its ability to adsorb, or pre‐grob gold from the cyanide solution.
Advanced micro‐beam analytical techniques such as Dynamic Secondary Ion Mass Spectrometry
(D‐SIMS) and Time‐of‐Flight Secondary Ion Mass Spectrometry (TOF‐SIMS) have become
powerful tools for characterization of different forms and carriers of gold for the needs of the
mineral processing industry. Major advantages of these techniques are related to their ability to
analyze individual mineral particles and provide quantitative analysis with detection limits in the
low ppm/ppb concentration range. This paper describes various micro‐beam techniques and
procedures implemented at Surface Science Western (SSW) for quantification and
characterization of the sub‐microscopic gold and the preg‐robbed surface gold as part of full gold
deportment studies in feeds and process stream products.