Исследования по переработке измельченного золотомедного флотоконцентрата методом сернокислотного атмосферного окисления

Abstract

The study is focused on the conditions of sulphuric acid atmospheric oxidation of crushed gold-copper flotation concentrate for obtaining a solid gold-containing product suitable for gold extraction by cyanidation. Additionally, the scope of the study includes the problem of maximising the transfer of copper into a sulphate solution for subsequent separation into a commercial product. The object of research consisted of a gold-copper concentrate with the main copper minerals represented by chalcopyrite and tennantite. Experiments on atmospheric oxidation of flotation concentrate were carried out in a laboratory reactor at a temperature of 90-95°C in a sulphuric acid medium using industrial oxygen and air as an oxidiser. In order to analyse the chemical composition of solutions, atomic absorption, inductively-coupled plasma atomic emission and titrimetric analysis methods were used. The composition of solid phases was studied by assay-gravimetric, assay-atomic absorption and chemical methods. In the course of research on the selection of optimal parameters for conditioning the flotation concentrate prior to cyanidation, the particle size of the material was revealed to be at least 80% of the class, i.e. -20 μm. This contributes to an increase in the subsequent gold cyanidation recovery by 56.0% and a decrease in reagent consumption by 21.0 kg/t (compared to direct cyanidation without pre-treatments). In order to reduce the oxygen consumption in the process of atmospheric oxidation, as well as to increase the extraction of copper, a three-stage scheme of the process was proposed including air bubbling for 8 h, oxygen oxidation for 2 h and air oxidation for 8 h. In this case, the extraction of copper and gold (with subsequent cyanidation) into solution comprised 90.1 and 95.4%, respectively, with the consumption of NaCN decreased to 8.1 kg/t. Atmospheric oxidation of gold-copper flotation concentrate pre-crushed to a particle size of 20 μm in a sulphuric medium by bubbling the pulp with oxygen and air results in high recovery rates for copper into a sulphate solution and gold during cyanidation of solid product following atmospheric oxidation with simultaneous decrease in cyanide consumption.