Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow, Russia:

Yu. V. Zablotskaya, Senior Researcher, e-mail: Nboxclear@gmail.com
G. B. Sadykhov, Head of Laboratory
M. Sh. Khasanov, Postgraduate Student
V. B. Smirnova, Research Fellow

Oxidized nickel ores contain around 160 mln tons of nickel, and about 70% of it comes in the form of limonites. The concentrations of nickel and iron in limonites can vary within 0.8–1.3 and 35–45% and higher, respectively. Recent years have seen a global trend to raise the scope of oxidized nickel ore processing. However, the well-known hydrometallurgical techniques have serious drawbacks and do not prove to be feasible. Because of this, new hydrometallurgical techniques are being developed that use atmospheric pressure to selectively recover nickel into the solution using sulphuric, hydrochloric, nitric and other acids. This paper describes the results of a study that looked at the process of leaching a reduced limonite ore from the Buruktal deposit in the Orenburg Region with dilute sulphuric acid solutions under atmospheric pressure. The authors of the paper also defined the process kinetics and how the nickel contained in calcined ore tends to dissolve. The shrinking core model was used to analyse the dissolution kinetics of nickel. The experimental data obtained in the temperature range of 80–95 ^оС and with the solution pH of 1.8 and 2.0, can be adequately interpreted by the shrinking core model when nickel is leached from calcined ore in a pore diffusion mode, which can be described with the following equation: 1 – 3(1 – x)^2/3 + 2(1 – x) = k_dt. The authors used the Arrhenius equation to determine the activation energy at different pH levels, as well as the reaction order.
This research was carried out under the Governmental Assignment No. 007-00129-18-00.

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