SRC Hydrometallurgy (LLC), Saint Petersburg, Russia:
T. Yu. Kositskaya, Senior Researcher, Candidate of Technical Sciences, e-mail: kositskaya-t@gidrometall.ru
A. Yu. Lapin, Principal Researcher, Candidate of Technical Sciences, e-mail: lapin-a@gidrometall.ru
Ya. M. Shneerson, R&D Director, Doctor of Technical Sciences, Professor, e-mail: shneerson-y@gidrometall.ru

Oxidized nickel ores (ONO) constitute nearly half of the world’s reserves of Ni. The study of ONO processing is a relevant task for today. The present paper provides the flowsheet of nickel and cobalt concentrates production using atmospheric sulfuric acid leach of calcine after reducing roasting of ONO. The high-quality concentrate of non-ferrous metals production route includes preliminary solution purification providing high-grade Ni and Co solution and iron precipitate. The flowsheet is based on triple-operation technology of selective hydrolytic precipitation of iron and non-ferrous metals. For the first and second operations limestone is used, for the third – highquality magnesium oxide. For each operation the optimal conditions are offered, as well as maximum achievable indicators are set. The key factors that determine the effectiveness of each stage of the process and therefore the technology as a whole are established. The consumption of neutralization agent CaCO₃ at the first processing stage is found to be 10 to 13 kg/m³ of solution. The duration of t he operation is at least 4 hours with intensive aeration of the slurry. The degree of iron precipitation reaches 50–53%, nickel and cobalt less than 0.5%. The resulting precipitate is a waste cake. The pH value is the key factor for the second processing stage where the recycled cake is formed. The value of pH should be in the range of 4.1–4.3. In this case at least 98% of iron and only 10–15% of non-ferrous metals are precipitated by CaCO₃. The activity of a neutralizer is the key factor for the third stage of the process. The recommended reagent is MgO. High-quality concentrate (more than 30% Ni+Co) can be produced only with at least 75% of the main substance in this reagent.

1. Reznik I. D., Ermakov G. P., Shneerson Ya. M. Nickel. In 3 volumes. Vol. 2. Oxidized nickel ores. Ore characterization. Pyrometallurgy and hydrometallurgy of oxidized nickel ores. Moscow : Mashinostroenie, 2001. 468 p.
2. Global Nickel Long-term Outlook Q1 2020, March 2020. Wood Mackenzie Ltd. Available at: https://www.woodmac.com/reports/metals-globalnickel-long-term-outlook-q1-2020-397363 (Accessed: 1.09.2020).
3. Talovina I. V., Lieberwirth H., Alexandrova T. N., Heide G. Supergene oxide-silicate nickel deposits: mineral-geochemical composition and peculiarities of processing. Eurasian Mining. 2017. No. 1. pp. 21–24. DOI: 10.17580/em.2017.01.06.
4. Anne Oxley, Nursun Sirvanci, Simon Purkiss. Calda Nickel Laterite Atmospheric Heap Leach Project. Metallurgija – Journal of Metallurgy. 2006. Vol. 13, No. 1.
5. Stopi S., Friedrich B. Hydrometallurgical processing of nickel lateritic ores. Military Technical Courier. 2016. Vol. 64, No. 4. pp. 1033–1047.
6. Kolmachikhina O. B., Naboychenko S. S., Boshnyak M. V., Galimyanov A. R. Oxidized nickel ore leaching with preliminary chloridizing roasting. Tsvetnye Metally. 2019. No. 2. pp. 21–25. DOI: 10.17580/tsm.2019.02.03.
7. Sosnovskiy M. G., Gulyaev S. V., Zarkov A. V. Possible processing of nickel-cobalt ores of the buruktal deposit at Southern Urals nickel plant. Tsvetnye Metally. 2019. No. 3. pp. 21–27. DOI: 10.17580/tsm.2019.03.02.
8. Kalashnikova M. I., Tsymbulov L. B., Naboychenko S. S., Kolmachikhina O. B. Innovative processing applicable to the oxidized nickel ores found in the Urals Region. Tsvetnye Metally. 2019. No. 8. pp. 4–12. DOI: 10.17580/tsm.2019.08.01.
9. Zablotskaya Yu. V., Sadykhov G. B., Khasanov M. Sh., Smirnova V. B. Kinetics of sulphuric acid leaching of nickel from reduced limonite ore of the Buruktal deposit. Tsvetnye Metally. 2018. No. 12. pp. 27–31. DOI: 10.17580/tsm.2018.12.04.
10. Dobrokhotov G. N. Precipitation of metal hydroxides from sulphuric acid solutions and pH values. Zhurnal prikladnoy khimii. 1954. Vol. XXVII, No. 10. pp. 1056–1066.
11. Maslenitskiy I. N., Dolivo-Dobrovolskiy V. V., Dobrokhotov G. N., Sobol S. V. et al. Pressure oxidation processes in non-ferrous metallurgy. Moscow : Metallurgiya, 1969. 348 p.
12. Posnjak E., Merwin H. E. The system Fe₂O₃ – SO₃ – H₂O. Journal of the American Chemical Society. 1922. Vol. 44, No. 9. pp. 1965–1994.
13. Luriye Yu. Yu. Reference book in analytical chemistry. Moscow : Khimiya, 1971. 456 p.