¹Chair of Non-Ferrous Metals and Gold, National University of Science and Technology “MISiS”, Moscow, Russia; ²Irkutsk State Technical University, Irkutsk, Russia:

L. S. Strizhko, Professor¹, Consultant of a Chair of Metallurgy of Non-Ferrous Metals², e-mail: sls_2007.47@mail.ru

Chair of Non-Ferrous Metals and Gold, National University of Science and Technology “MISiS”, Moscow, Russia:

I. R. Boboev, Post-Graduate Student
E. S. Shigin, Post-Graduate Student
E. P. Gorbunov, Candidate for a Master's Degree
S. A. Gavrilov, Post-Graduate Student

This article describes the method of gold extraction from pyrite and pyrrhotite-containing flotation concentrates, which are one of urgent problems of modern gold mining industry. As a rule, the presence of iron reduces the efficiency of the following technological processes:
— indices of gold extraction and its dissolution rate are decreased due to the sharp reduction of concentration of dissolved oxygen in cyanide solutions and accumulation of soluble sulphides and sulphates of alkaline metals in these solutions;
— the consumption of cyanide is increased, which makes it necessary to use additional operations of iron sedimentation and to force the cyanidation process.
In connection with this, there were analyzed the existing technologies of elimination of adverse effect of iron sulphides on cyanidation process. At the same time, on the basis of these technologies, there was proposed a new intensification method of processing of similar concentrates, using the “fan-type” sonar radiator. The main parameters of this radiator are given. There were carried out the researches of preliminary alkaline processing of auriferous flotation concentrate on laboratory facility, provided with the “fan-type” sonar radiator for increasing of the dissolved oxygen content and formation of additional oxidizing agents, such as OH radicals and hydrogen peroxide. There was studied the influence of oxygen on the rate of iron transition to insoluble form of cyanide solutions. On the basis of the given data, it was found that this type of sonar radiator also reduces the thickness of the diffusion layer, and consequently, increases the rate of oxidation of Fe (II) to Fe (III). This foundation confirms the theoretical relationship, according to which, the diffusion layer thickness is inversely proportional to the square root of the relative velocity of the phases. It is noted that during the final analysis, application of sonar radiator in the process of alkaline treatment leads to increasing of gold recovery, decreasing of cyanide consumption and reduction of leaching duration.

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