National University of Science and Technology “MISiS”, Moscow, Russia:
I. R. Boboev, Junior Researcher

¹National University of Science and Technology “MISiS”, Moscow, Russia ; ²Irkutsk State Technical University, Irkutsk, Russia:

L. S. Strizhko, Professor (Chair of Non-Ferrous Metals and Gold)¹, e-mail: sls_2007.47@mail.ru, Consultant of a Chair of Metallurgy of Non-Ferrous Metals²

Ministry of Industry and New Technologies of Republic of Tajikistan, Dushanbe, Republic of Tajikistan:

Sh. Bobozoda, Minister

“Yuzhuralzoloto Group of Companies” JSC, Plast, Chelyabinsk Oblast, Russia:
B. R. Berger, Acting Deputy Executive Officer

Literary studies were carried out together with definition of main factors, restricting the use of direct cyanidation process, both at low and exorbitant cyanide concentrations in processing of goldcopper raw materials. There are shown the main cyanide copper compounds, which were formed during cyanidation process. There is also described the effect of these compounds on gold recovery. On the basis of earlier researches, there was made a conclusion that ammonia cyanidation is the most promising method of hydrometallurgical extraction of gold. However, the research literature has no data about the chemistry and conditions of application of this method. For the first time, there were studied the kinetics and mechanism of ammonia-cyanide leaching of gold from gold-copper materials. The gold dissolution process was studied in two systems: Au – [Cu(CN)₂]^– – NH₄⁺ – OH^– – O₂ and Au – CuCN – NH₄⁺ – OH^– – O₂. It is shown that gold is dissolved in the presence of cyanide compounds of copper, even in absence of free cyanide. Basic reactions in ammonia-cyanide leaching were offered on the basis of physical-chemical analysis. Series of additional tests showed that ammonia cyanidation process in the pH range of 10.5–11.5 is introduced simultaneously to sedimentation of ammonia complexes of copper, which has a positive effect on subsequent sorption process. The obtained results allow to expand and refine the understanding of reactions, occurring in the process of ammoniac cyanidation. Finally, the following benefits can be achieved: involving in the processing of refractory gold-copper ores; increasing of gold recovery; reduction of cyanide consumption; reduction of solution copper concentration; utilization of dangerous cyanide compounds.

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