SciELO - Scientific Electronic Library Online

vol.109 issue11'Necessity the mother of invention' - a reflection on the requirements for successful innovation in the metallurgical industries author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Journal of the Southern African Institute of Mining and Metallurgy

On-line version ISSN 2411-9717
Print version ISSN 0038-223X

J. S. Afr. Inst. Min. Metall. vol.109 n.11 Johannesburg Nov. 2009




Skorpion zinc solvent extraction: The upset conditions



J.M. Musadaidzwa; E.I. Tshiningayamwe

Namzinc (Pty) Ltd, Rosh Pinah, Namibia




Skorpion Zinc is located 25 km north-west of the small settlement of Rosh Pinah in southern Namibia. Commissioned in early 2003, Skorpion Zinc became the first mine-to-metal operation to commercially apply a purely hydrometallurgical process route to exploit a zinc oxide orebody. The novel technology, known as The Modified ZincexTM Process patented by Tecnicas Reunidas, comprises sulphuric acid atmospheric leaching, zinc solvent extraction (SX) and electrowinning (EW) to produce London metal exchange (LME) Special high grade (SHG) zinc. Forming the core of the process, the SX step has thrived in its role as a barrier to impurities and also in the upgrading of the pregnant liquor solution (PLS), converting it into a loaded electrolyte (LE) sufficiently rich and pure for EW. Against this successful run, a number of challenges have, however, been encountered in SX due the emergence of upset conditions largely emanating from upstream processes. This paper outlines some of the major deviations that have beset the SX process in its first five years of continuous operation. Impurity excursions, temperature depressions, changes in phase continuity, excess aqueous entrainment, the effect of colloidal silica and the accumulation of rare earth elements on the organic phase will be discussed in detail.

Keywords: skorpion zinc, solvent extraction, the Modified ZincexTM Process (MZP) DE2HPA, aqueous entrainment (AE), loaded electrolyte (LE), standard liquid validation (SLV) test, organic continuity, aqueous continuity (AC), electrowinning, colloidal silica, phase disengagement time (PDT), rare earth elements (REE)



“Full text available only in PDF format”




1. GNOINSKI, J. Skorpion Zinc: Optimisation and Innovation, Africa's Base Metals Resurgence, Southern African Institute for Mining and metallurgy, Johannesburg, 2007, pp. 329-342.         [ Links ]

2. GNOINSKI, J., BACHMANN, T. and HOLTZHAUSEN, S. Skorpion Zinc: Defining the cutting edge of zinc refining, Proceedings of the International Symposium on Lead and Zinc Processing, Koto, Japan, 2005, pp. 1315-1325.         [ Links ]

3. ROUX, E.A., SECHEMENE, M.J., and HOLZHAUSEN, S. Iron Removal in the Skorpion Process, Iron Control technologies, J.E. Dutrizac and P.A. Riveros, (eds.), Canadian institute of Mining, Metallurgy and Petroleum, Montreal, 2006, pp. 491-500.         [ Links ]

4. GNOINSKI, J. and SOLE, K.C. The influence and benefits of an upstream solvent extraction circuit on the electrowinning of zinc in sulphate media: the Skorpion Zinc Process.         [ Links ]

5. SOLE, K.C., STEWART, R.J., MALULEKE, R.F., and RAMPERSAD, A. and MAVHUNGU, E. Removal of entrained organic phase from zinc electrolyte: Pilot plant comparison of CoMatrix and carbon filtration, Hydrometallurgy, vol. 89, 2007. pp. 11-20.         [ Links ]

6. GNOINSKI, J. Investigation into the nature and cause of impurity spikes through the SX circuit at Skorpion Zinc, Report No. SKP-2211 Rev 0.         [ Links ]

7. GNOINSKI, J., SOLE, K.C., SWART, D.R., MALULEKE, R.F., DIAZ, G., and SANCHEZ, F. Highlights and hurdles in zinc production by SX: The first fours years at Skorpion Zinc. International SX Conference ISEC2008, B. Moyer (ed.), Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, in press. 2008.         [ Links ]

8. MORAIS, C.A. and CIMINELLI, V.S.T. Process development for the recovery of high-grade lanthanum by solvent extraction, Hydrometallurgy, vol. 73. 2004. pp. 237-244.         [ Links ]

9. SOLE, K.C. Preliminary assessment of the options for reconfiguration of the Skorpion Zinc solvent extraction circuit in the event of failure of one mixer settler stage, Anglo American Research Laboratories, Project No. A200500144, Report No. 1.         [ Links ]

10. Skorpion Zinc Project, Metallurgical Piloting and Test work, Final Report, 2000.         [ Links ]

11. Modified Zincex Process, Skorpion Project, Training course handbook, Solvent Extraction Plant, Tecnicas Reunidas, Report No. ITR/P- 4554/047/2001.         [ Links ]

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License