Navoi Mining & Metallurgy Combine, Navoi, Uzbekistan:

K. S. Sanakulov, Chief Executive Officer
O. M. Mustakimov, Director of Central Mining Department
U. A. Ergashev, Chief Technologist of Northern Mining Department, e-mail: info-sevru@ngmk.uz
N. A. Akhatov, Director of Hydrometallurgical Plant No. 3 of Northern Mining Department in the period of 2010–2013

This paper considers the problems of modern global gold market in the light of deficiency of mineral raw materials. Considering the exhaustion of the reserves of deposits with high content and easily extractable gold, complex ores are more often processed. Solution of the problem of gold extraction from technologically refractory and high refractory ores is the urgent scientific task, important for national economy. Gold refractoriness is mostly connected with its dispersion in sulfide minerals with the particle size from the tenths to the thousands of parts of micrometers, in isomorphous or disperse form. The second reason of refractoriness is the presence of considerable amounts of carbonaceous substance (natural gold sorbent) in ore. These factors may be simultaneous, which complicates the processing technology. These ores are called the double refractoriness ores. Sulfide ores of Kokpatas and Daugyztau deposits may also be high refractory ones. Processing of these types of ores at Navoi Mining & Metallurgy Combine is carried out by biooxidation technology. Combined technologies are applied in global practice for rational mastering of gold ore deposits of high refractory ores. Taking into account the positive role of biooxidation process, the specialists of Navoi Mining & Metallurgy Combine investigated the possible combined sulfide concentrate oxidation methods. On the first stage, the oxidation of flotation concentrate is carried out according to biooxidation scheme, where the considerable amount of arsenic is dissolved and transferred in insoluble solid state. Biooxidation product with low content of arsenic is exposed to oxidizing roasting, where the gold, connected with carbonaceous substance, is obtained, and remained sulfide sulfur is oxidized. Oxidation roasting product is directed on sorption cyanidation of gold. The carried out scientific-research works show that roasting can significantly increase the gold extraction from biocake.

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