Ural Federal University named after the First President of the Russian Federation B. N. Eltsin (UrFU), Institute of New Materials and Technologies, Department of Non-Ferrous Metallurgy, Ekaterinburg, Russia:

A. V. Kritskii, Postgraduate Student, Engineer, Assistant Lecturer at the Department of Non-Ferrous Metallurgy, e-mail: a.v.kritsky@urfu.ru
S. S. Naboychenko, Visiting Professor at the Department of Non-Ferrous Metallurgy

Due to the reduction in sulfide massive ores reserves in the Urals region, a volume of disseminated ores production is increasing, in particular at the Mikheevsky Mining and Processing Plant (South Urals). Froth flotation of copper-porphyry ores at the Mikheevsky enrichment plant allows to obtain chalcopyrite concentrates of the following chemical composition, %: 21.5 Cu, 24.5 Fe, 26.5 S, 0.4 Pb, 17.6 SiO₂, 1.85 CaO, 5–7 Au (ppm), 12–16 Ag (ppm). Current technology of the concentrate processing includes autogenous smelting, matte desulfurization and blister copper refining. Operating technology is characterized by well-known disadvantages. Alternative method for the processing of concentrates using oxidative autoclave leaching (POX) was investigated. POX process was studied in the following interval of technological parameters: t = 150–220 ^oC, pO₂ = 2–6 bar, [H₂SO₄] = 10–60 g/l. Graphical and mathematical description of the process was created. Autoclave leaching of chalcopyrite concentrate at proposed parameters (t = 190 ^oC; pO₂ = 5 bar; [H₂SO₄] = 10–20 g/l;  = 120 min) allows to achieve copper extraction at the level of 98.5%. A comparison of POX kinetics at the recommended parameters and total oxidation conditions is given. At elevated temperatures (220 ^oC) the duration of the POX is reduced from 120 to 90 min, while the Fe²⁺ ions are more complete oxidized to Fe³⁺ ions, which are quantitatively hydrolyzed, reducing the total iron content in solution. A double-stage POX allowed to obtain copper-rich solutions (up to 70 g/l), however, this increased the final concentration of iron in solution and the final acidity of the solution. Most of the zinc and nickel, 60–70% magnesium, 30–40% calcium and 30–40% aluminum were extracted into the solution; precious metals in the solution were not detected; most of the arsenic remains in the cake. Mass loss of the cake was 37–44%; the cake contains, %: not more than 0.5 Cu, up to 40 Fe, 25–35 SiO₂, 5–7 S. The choice of its utilization method requires targeted research.
This research was funded by the Government of the Russian Federation following Decree No. 211, Contract No. 02.A03.21.0006.

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