«Institute of Metallurgy and Ore Beneficiation» JSC (Almaty, Republic of Kazakhstan):

Dyusenova S. B., Leading Engineer, dusenova_s@mail.ru
Kenzhaliev B. K., General Director, Doctor of Engineering Sciences
Abdulvaliev R. A., Head of Laboratory, Candidate of Engineering Sciences, rin-abd@mail.ru
Gladyshev S. V., Leading Researcher, Candidate of Engineering Sciences, gladyshev.sergey55@mail.ru

The urgency of solving the problem of processing concentration waste products is not only due to environmental considerations, but also to the demand for increased chromium production. The advanced gravity concentration technologies used for chromite ores enable effectively obtaining chromium concentrates from coarse and medium fractions, while the fine slimes remain practically unprocessed due to the challenges of separating complex minerals into concentrates and waste rock. The possibility of comprehensive processing of concentration tailings for the purpose of recovering rare metals and rareearth elements is also not being considered. This paper presents the processing results for tailings obtained from the fine fraction of –0.2 mm using a complex hydrochemical technology, including leaching in a solution of NH₄HSO₄. It was established that, during leaching in a solution containing 10 % NH₄HSO₄, no aluminum, silicon, iron or chromium were recovered into the solution. Upon leaching solution neutralization with an ammonia solution to pH 5.5, a product containing REE and the rare metals of gallium and vanadium was isolated. Further neutralization of the solution to pH 8.5 resulted in isolation of a nickel-cobalt concentrate with the NiO content of 19.9 % and the Co₃O₄ content of 2.74 %. Subsequent removal of impurities and evaporation of the solution rendered a magnesium sulfate double salt of (NH₄)₂(Mg(H₂O)₆)(SO₄)₂ with the nitrogen content of 6.7 % and the magnesium oxide content of 10.59 %. Alkaline treatment of the leaching cake rendered a chromite concentrate with the Cr₂O₃ content of 51.3 %. The recovery rates of rare-earth elements and rare metals in the final products were as follows: 73.83 % for rare-earth elements; 63.25 % for Ga₂O₃; 82.0 % for V₂O₅; 60.0 % for NiO; and 32.1 % for Co₃O₄.

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