LLC “Hypronickel Institute”

S. L. Tsapakh, Leading Researcher of the Laboratory of Hydrometallurgy, e-mail: sltsa@nickel.spb.ru

L. S. Lutova, Researcher of the Laboratory of Hydrometallurgy

A. Yu. Chetverkin, Junior Researcher of the Laboratory of Hydrometallurgy

Authors have carried out investigations on copper sulfide deposition from chloride solution with the use of elemental sulfur and different reducing agents. It was demonstrated that formation of sulfide ions can be achieved in a variety of reactions, where the reducing agent was presented as a metal (nickel, copper), copper (I) sulfide, copper (I) chloride complexes or compounds capable to reduce sulfur (hydroxylamine hydrochloride). The mechanism of sulfides formation was determined and patterns of the process of copper deposition into sulfide precipitate with nickel particles use as a reducing agent were defined. The ways of copper sulfide formation are: sulfur reduction resulting from the contact of nickel and sulfur particles followed by direct reaction of copper ions with sulfide ions adsorbed on the elemental sulfur particle, or displacement reaction with nickel sulfide formed as a result of colliding nickel and sulfur particles in a suspension, or three step reaction, starting with cement copper buildup on nickel particle with successive ionization as a result of copper and sulfur contact and formation of copper sulfide. All the described ways result in copper sulfide shell buildup on sulfur particles. The phase composition of copper sulfide depends on the ratio of the amounts of copper in a solution and elemental sulfur in a suspension. If sulfur is in deficiency the copper sulfide is mostly presented by djurleite, digenite, chalcocite and metal copper. If sulfur is taken in excess copper sulfide is presented by covellite. The conducted studies demonstrate that the residual concentration of copper in the nickel chloride solution purified by powdered nickel and sulfur is in the range of 0.005–0.060 grams per liter. The optimal charge of elemental sulfur in the range from 0.35–0.45 to 1 kg of copper in the solution provides formation of the sulfide precipitate with nickel content of 12–18%. Contacting the precipitate with a copper containing solution provides reduction of nickel content in it down to 1–2%. This semiproduct can be processed in copper production technology.

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