The synergistic solvent extraction system consisting of Versatic 10/LIX63/TBP was used for the separation and purification of nickel and cobalt from synthetic laterite leach solution after iron removal. Very encouraging results were obtained for separating nickel and cobalt from manganese, magnesium and calcium._x000D_
In batch tests, the organic composition of the synergistic system was optimised and very large synergistic shifts for nickel and cobalt were observed. The pH50(Mn-Co) and pH50(Mn-Ni) values were as large as 1.65 and 2.40, respectively. The extraction and stripping kinetics of nickel and cobalt wasfast._x000D_
Semi continuous extraction tests were conducted with a pH profile of 5.5/6.1/6.5 in three stages at 40C. The nickel and cobalt extractions reached 99.9 per cent with only 5 mg/L Ni and <1 mg l co left in the raffinate. with two stages of scrubbing, only 2 mg l mn and less than 1 mg l mg and ca were left in the scrubbed organic solution. with two stripping stages, the stripping efficiencies of ni and co reached over 95 per cent._x000d_>
A fully continuous pilot plant operation was conducted successfully for 280 hours. With an O/A ratio of about 2 and a pH profile of 5.5/5.8/6.0/6.3 for the four stages EX1/EX2/Ex3/EX4, both nickel and cobalt were almost completely extracted. Using a pH profile of 5.4/5.0 for SC1/SC2, the manganese scrubbing efficiency was over 96 per cent. Using three strip stages, over 98 per cent Ni and 99 per cent Co were stripped with only 64 mg/L Ni in the stripped organic solution. The nickel concentration in the loaded strip liquor reached 83 g/L, resulting in a Ni of over 28 g/L._x000D_
The chemical stability of the system was also assessed over 12 weeks under proposed industrial operating conditions. Operation exclusively under strip conditions at 50C and 40C resulted in LIX63 oxime half lives of 1.1 and 2.1 years, respectively. Operation exclusively under extract conditions at 50C and 40C resulted in oxime half lives of 0.26 and 0.82 years, respectively. Losses of Versatic10 were less than four per cent._x000D_
CITATION:Cheng, C, Boddy, G, Zhang, W, Godfrey, M, Barnard, K, Robinson, D, Pranolo, Y, Zhu, Z, Zeng, L, Wang, W, Turner, N, Shiers, D and Hill, T, 2010. Separation of nickel and cobalt from manganese, magnesium and calcium by synergistic solvent extraction - From batch tests to pilot plant operation, in Proceedings XXV International Mineral Processing Congress (IMPC) 2010, pp 285-298 (The Australasian Institute of Mining and Metallurgy: Melbourne).