Navoi Mining and Metallurgical Company, Public Company, Navoi, Republic of Uzbekistan:

K. Sanakulov, General Director, Professor, Doctor of Technical Sciences, e-mail: info@ngmk.uz
U. A. Ergashev, Deputy Head of the Process Department, Doctor of Technical Sciences, docent
I. O. Khamroev, Deputy Chief Geologist, Candidate of Geology & Mineralogy Sciences

Navoi State Mining and Technology University, Navoi, Republic of Uzbekistan:
O. U. Fuzaylov, Associate Professor at the Department of Metallurgy, Candidate of Technical Sciences

It is of relevance for the gold industry to have a classification of refractory gold ores that would determine the choice of an optimum recovery process. There exist quite a few classifications of gold ores, which specify different factors of their refractoriness. It should be noted though that none of the mentioned classifications highlights the presence of submicroscopic gold as the cause of the refractory nature of ore. However, the experience of the Navoi Mining and Metallurgical Company of dealing with refractory ores of Kyzylkums shows that it is the recovery of submicroscopic gold that ensures high process performance. Gold coarseness is one of the essential parameters that determines how the ore should be processed. Processing of gold ores containing submicroscopic gold is a challenging task. There is a size threshold for gold particles, which go to waste when using classical processing schemes. Submicroscopic gold particles should be considered as a separate cause of gold ore refractoriness, and such ores should be distinguished into a separate type. The second most common factor that causes the under-recovery of gold when relying on the standard cyanide process includes the sorption activity of ore (i.e. preg-robbing). This phenomenon manifests itself in hydrometallurgical processes both in the form of gold adsorption on the surface of carbon and clay minerals (surface gold) and as gold that is initially incorporated in carbonaceous matter (carbonaceous gold). This paper offers a simplified classification of refractory gold ores. Based on that classification the authors selected a combination processing scheme that implies a successive (stage-by-stage) recovery of submicroscopic gold (due to breaking the crystal lattice matrix of minerals) followed by the recovery of gold that is prone to preg-robbing and was initially contained in the carbonaceous matter. It may well be that the proposed processing scheme can claim to be universal and can be used for the processing of refractory gold ores from many different deposits while ensuring high process performance.

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