LLC Research Center Hydrometallurgy, Saint Petersburg, Russia

S. I. Lyakh, Chief Engineer, Candidate of Technical Sciences, e-mail: lyakh-s@gidrometall.ru
I. V. Fomenko, General Director, Candidate of Technical Sciences, e-mail: fomenko-i@gidrometall.ru

JSC Chelyabinsk Zinc Plant, Chelyabinsk, Russia
M. S. Varganov, Head of the Technical Administration, e-mail: mkv@zinc.ru
S. A. Zagrebin, Deputy Head of the Technical Administration, Candidate of Chemical Sciences, e-mail: saz@zinc.ru

The article presents the results of laboratory studies on the technology of direct atmospheric leaching of the sample of the Russian zinc concentrate, containing, %: 49.1 Zn; 32.8 S; 8.4 Fe; 2.5 Pb; 2.3 Cu; 1.8 SiO₂. The results describe two-stage atmospheric leaching of the concentrate with a sulfurous solution similar to a composition of the spent zinc electrolyte (170 g/l H₂SO₄ and 50 g/l Zn). Leaching of the zinc concentrate in atmospheric conditions (temperature is 95–100 ^oC) is shown as highly efficient in transferring up to 98–99 % Zn and 90–95 % Cu to a liquid phase of sludge. It has been determined that the amount of iron, precipitating to a liquid phase of sludge during oxidation of iron-containing sulfide minerals (pyrrhotite, chalcopyrite and partial pyrite) is enough for a deep oxidation of sphalerite and zinc leaching. In conditions of atmospheric leaching, the degree of oxidation of sulphide sulphur achieved 90±5 %, and the rate of conversion of sulphide sulphur to elemental sulphur was 80±5 %. The article presents the results of laboratory studies on the operation of refining of a production solution after the first state of atmospheric lea ching from hydrolysable impurities (Fe, As and Sb) before electrolytic deposition of zinc. Key parameters are determined to influence hydrolytic refining of the solution. The studies showed a rationale for a technological need for the deposition of copper from the solution as a copper-chloric cake before hydrolytic refining to minimize its losses with a waste hydrated cake.

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