Ural State Mining University, Ekaterinburg, Russia:

A. N. Matushkina, Post-Graduate Student, e-mail: annamat87@mail.ru
A. M. Amdur, Head of a Chemistry Chair, e-mail: engineer-ektb@rambler.ru
E. F. Tsypin, Professor, e-mail: Tsipin.E@mail.ru

The designed method for extraction of fine-graded gold from refractory carbonatesilicate ores was realized in laboratory conditions. In the base ore, gold is associated with pyrite and arsenopyrite, whilst it also present in quartz and minerals, and it is not extracted through cyanidation, the sizes of Au grains varied from fractions to 10 micrometers. The material was heated, melted, and after cooling it was grinded and enriched by using a centrifugal Knelson concentrator. After melting the material at the temperature of 1250 ^oC, drops of gold were floated — under the influence of interphase tension — by carbon oxide bubbles, which are formed during decomposition of carbonates. The process of flotation is accompanied by coagulation. The outcome is a concentration of gold on the surface of the formed oxide melt and enlargement of particles up to the sizes that allow extraction of Au through gravitational methods. In this way, during the process of heating and melting of ore mass, gold switches to a free state, while its particles are enlarged up to 100 micrometers. This enables a significant increasing of its extraction by gravitational methods. During the laboratory cyanidation in neutral and alkaline solutions, by adding KCN while mixing air with access of oxygen for 24–28 hours, the extraction of gold reaches 100% as a result of thermal treatment.
This work was carried out within the project part of the state task of the Russian Ministry of Education and Science and the grant of the Russian Foundation for Basic Research No. 16-08-00768\16.

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