LLC “Institute “Gipronikel”, Saint Petersburg, Russia:

P. M. Saltykov, Senior Researcher
M. I. Kalashnikova, Head of Hydrometallurgy Laboratory, e-mail: MIKal@nikel.spb.su
E. G. Saltykova, Leading Engineer
O. A. Trubina, Leading Engineer

JSC “Norilsk Nickel” MMC, Moscow, Russia:
S. B. Kotukhov, Head of Technical Board Department

There were studied the upstream circuits of hydrometallurgical process flowsheet for treatment of nickel sulfide concentrates of Australian deposits. The content of basic components in analysed sulfide concentrates shows wide-range variation: 6.93–16.48% of Ni; 9.54–34.2% of Fe; 10.4–35.1% of S; 3.74–13.6% of Mg. Pentlandite, millerite and polydymite were the dominating substances among nickel-bearing phases of various concentrates. Pyrite content in concentrates also varied within a wide range of 0.2–51.0%. In spite of the compositional difference, the process of nickel concentrates’ oxidative leaching is subject to the common mechanisms. Increased level of refractory minerals (polydymte, violarite, purrhite) in the concentrate requires the severisation of leaching process parameters. Preferential progress of reactions, responsible for elemental sulfur production, leads to sulfur shielding of sulfide particles and inhibiting of sulfide particles’ oxidation. In such a case, temperature should be increased for acceleration of leaching process. Optimum autoclave oxidative leaching process parameters, ensuring maximum non-ferrous metals passing into the solution for all tested concentrates, are within the following ranges: 190–210 ^оС temperature; oxygen partial pressure of 0.5–0.7 MPa; L/S ratio of 4.5–5.5. At the same time, 95.7–97.8% of Ni is recovered into solution. The process flowsheet for sulfide concentrates treatment is offered, including the following principal circuits: pressure leaching; oxidised slurry’ neutralisation; oxidised slurry’ counter-current washing; iron removal; hydrolytic sedimentation of nickel concentrate. sulfide concentrates from various ore deposits can be used as the plant's feed.

1. Rossiyskiy proizvoditel, globalnyy igrok : godovoy otchet (Russian manufacturer, global player : annual report). JSC “Norilsk Nickel” MMC. 2012. Available at : http://www.nornik.ru/_upload/GO_s_priloz.pdf.
2. Novaya strategiya, novye vozmozhnosti : godovoy otchet (New strategy, new possibilities : annual report). JSC “Norilsk Nickel” MMC. 2013. Available at: http://www.nornik.ru/_upload/2014/NN_AR_2013_rus_EGO.pdf.