Leading Scientific and Research Institute of Chemical Technology, Moscow, Russia

A. V. Kurkov, Head of the Project Office, e-mail: avkurkov@vniiht.ru
A. M. Egorov, Head of a Laboratory
I. V. Pastukhova, Leading Researcher
D. I. Krinov, Leading Researcher
E. V. Ovcharenko, Senior Researcher

A set of experimental researches on the extraction of gold and silver from unconventional sources, POX cakes of the complex uranium ores with low content of gold (~1 g/t), was performed. The complex composition of the initial crude ore determines the even more complex composition of the POX cakes. After pressure oxidation, a change in mineral composition and minerals surface parameters was revealed in the cakes. Major part of the pyrite grains is characterized by corroded surface. Compared with the original ore the concentration of iron oxides grains increases, due to the oxidation of pyrite during the pressure oxidation. The composition of these iron oxides (multiple hydrous oxides) indicates the presence of in water and hydroxyl groups in them. The surface of the iron hydrous oxides supplies cellular (porous) textures. Visible forms of precious metals were not found. Presumably, as a result of oxidation of auriferous pyrite the secondary gold is formed, which particles have nanometer size dimensions, and are closely associated with iron hydrous oxides. Despite the extraordinary complexity of the uranium crude ore that limits the possibility of its enrichment, the combination of the flotation process and hydrometallurgical processes allows to create quite an effective refractory complex uranium ores treatment technology. Throughout recovery in an enrichment of POX cakes — sorption cyanidation of the products obtained circuit were as follows: 72.3% of gold and 53.7% of silver. This is confirmed by pilot tests on bulk sample.

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