JOURNAL PAPER

Calcium and magnesium rejection from sulphate solutions in lateritic nickel solvent extraction using Versatic 10 acid-LIX^®84-IC system

B. Ndlovu; T. Mahlangu

Department of Materials Science and Metallurgical Engineering, University of Pretoria, South Africa

SYNOPSIS

The world mineral industry has over the years experienced growth in the production of nickel (Ni) due to its use not only in the catalytic industry but mainly also to its demand in the stainless steel production industry. Hence there is a need to produce more pure and marketable grades of Ni through the use of efficient purification routes such as solvent extraction. The V10-LIX^®84-IC system resulted in nickel (Ni) extraction isotherm shifting to lower pH levels. The pH window of opportunity for the extraction of Ni subsequently increased in solution containing magnesium (Mg) and calcium (Ca) even though the system also resulted in slight shifts to less positive pH values for Mg and Ca curves. Results showed a synergistic effect of LIX^®84-IC when added to V10 for all elements, Ni, Mg and Ca. The pH₅₀ values for elements Ni, Mg and Ca in the V10-LIX^®84-IC system were 2.95, 8.10 and 7.70 respectively. Comparing results obtained when using V10 alone produced ΔpH₅₀for Ni, Mg and Ca being 3.35, 0.15 and 0.70 respectively, which was a confirmation of the synergistic shifts for all the elements. The ΔpH₅₀^(Mg-Ni) value was 1.95 with no synergism and 5.15 with synergism and that for ΔpH₅₀^(Ca-Ni)was 2.10 with no synergism and 4.75 with synergism. This showed that the Ni-Mg separation factor was relatively larger than the Ni-Ca. Improved loading and stripping kinetics were also observed.

Keywords: Nickel solvent extraction separation, magnesium, calcium, versatic 10 acid and LIX^®84-IC

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References

1. CHENG, C.Y. Solvent extraction of nickel and cobalt with synergistic systems consisting of carboxylic acid and aliphatic hydroxyoxime, Hydrometallurgy, 2006, vol. 84, pp. 109-117.         [ Links ]

2. DENEGAN, S. Direct solvent extraction of nickel at Bulong operations, Minerals Engineering, 2006, vol. 19, pp. 1234-1245.         [ Links ]

3. GOONAN, T.G. and KUCK, P.H. Nickel statistics, U.S. Bureau of Mines and U.S. Geological survey-Minerals Yearbook, October 2006.         [ Links ]

4. KARADAKIS T., AGTZININI-LEONARDOU, S. and NEOU-SYNGOUNA, P. Removal of magnesium from nickel leach liquors by chemical precipitation using calcium hydroxide and the potential use of the precipitate as a filler material, Hydrometallurgy, 2005, vol. 76, pp. 105-114.         [ Links ]

5. MACKENZIE, M., VIRNIG, M. and FEATHER, A. The recovery of nickel from high-pressure acid leach solutions using mixed hydroxide product-LIX84-INS technology, Minerals Engineering, 2006, vol. 19, pp. 1220-1233.         [ Links ]

6. PRESTON, J.S. Solvent extraction of nickel and cobalt by mixtures of carboxylic acids and non-chelating oximes, Hydrometallurgy, 1983, vol. 56, no. 1, pp. 105-124.         [ Links ]

7. PRESTON, J.S. and DU PREEZ, A.C. Separation of nickel and calcium by solvent extraction using mixtures of carboxylic acids and alkylpyridines, Hydrometallurgy, 2000, vol. 58, pp. 239-250.         [ Links ]

8. SCHEKERS, M.J. and DUPREEZ, H. Solvent extraction for separation of groups of base metals, United States Application, June 2006.         [ Links ]

9. SOLE, K.C. Solvent extraction in modern based-metal hydrometallurgy, 6th World Congress of Chemical Engineering, Melbourne, Australia, 23-27 September 2001.         [ Links ]

10. SOLE, K.C. Short course: Solvent extraction and ion exchange, Anglo Research and Matomo Projects. 2007.         [ Links ]

11. TSAKIRIDIS, P.E. and AGATZINI, S.L. Process for the recovery of cobalt and nickel in the presence of magnesium and calcium from sulphate solutions by Versatic 10 and Cyanex 272, Minerals Engineering, 2004, vol. 17, pp. 535-543.         [ Links ]

12. TSAKIRIDIS, P.E. and AGATZINI-LEONARDOU, S. Process for the recovery of cobalt and nickel in the presence of magnesium from sulphate solutions by Cyanex 272 and Cyanex 302, Minerals Engineering, 2004, vol. 17, pp. 913-923.         [ Links ]

Paper written on project work carried out in partial fulfillment of B Eng (Met. Eng.) degree