Evaluation of Advanced Gravity and Magnetic Concentration of a PGM Tailings Waste for Chromite Recovery

Document Type: Research Article


1 Department of Chemical, Metallurgy and Materials Engineering Tshwane University of Technology, Pretoria, SOUTH AFRICA

2 Department of Materials Science and Engineering, Obafemi Awolowo University, Ile Ife, NIGERIA


This research was aimed at evaluating the efficiency of advanced gravity and magnetic separations on the recovery of chromite from the fine Platinum Group Metals (PGM) tailings consisting of particles 80% passing 75 µm with about 45% being >45 µm resulting in high chromite losses. The PGM plant tailings were subjected to X-ray fluorescence, scanning electron microscopy and particle size distribution analyses. The feed was then optimally classified with 60 mm diameter hydro-cyclone into underflow and overflow streams. The coarser underflow was further beneficiated using the spiral concentrator. The results obtained showed that the removal of fines increased the Cr2O3 grade for the spiral feed from 12.27% to 17.64% while spiral concentrate grade improved from 14.84% to 21.46% and recovery 69.85% to 95.53%. Magnetic separation efficiency was found to increase with particle size such that at >75 µm a concentrate with up to 17.13% grade and 61.5% recovery was achieved. The advanced Falcon concentration was also observed to be mainly particle size dependent and at 45 µm up to 17% grade and 60.3% recovery was achieved. The results obtained are based on particles >45 µm and the finer particles


Main Subjects

[1] Blignaut J.N., Hassan R.M., Assessment of the Performance and Sustainability of Mining Sub-Soil Assets for Economic Development in South Africa, Ecological Economics, 40(1): 89-101 (2002).

[2] Schouwstra R., Kinloch E., Lee C., A Short Geological Review of the Bushveld Complex, Platinum Metals Review, 44(1): 33-39 (2000).

[3] Visser M., An Overview of the History and Current Operational Facilities of Samancor Chrome, Southern African Pyrometallurgy, 285-296 (2006).

[4] Glastonbury R.I., Beukes J.P., Van Zyl P.G., Sadiki L.N., Jordaan A., Campbell Q.P., Stewart H.M., Dawson N.F., Comparison of Physical Properties of Oxidative Sintered Pellets Produced with UG2 or Metallurgical Grade South African Chromite: a Case Study, The Journal of The Southern African Institute of Mining and Metallurgy, 115: 699-706 (2015).

[5] Dawson N., Experiences in the Production of Metallurgical and Chemical Grade UG 2 Chromite Concentrates From PGM Tailingss Streams, South African Institute of Mining and Metallurgy. Journal, 110(11): 683-690 (2010).

[6] Güney A., Önal G., Atmaca T., New Aspect of Chromite Gravity Tailingss Re-Processing, Minerals Engineering, 14 (11): 1527-1530 (2001).

[7] Tripathy S.K., Rama Murthy Y., Modeling and Optimization of Spiral Concentrator for Separation of Ultrafine Chromite, Powder Technology, 221 (0): 387-394 (2012).

[8]Wills B.A., Napier-Munn T.J., Mineral Processing Technology, Elsevier Science & Technology Books, 7, (2006).

[9] Jones R., "An Overview of Southern African PGM Smelting", Nickel and Cobalt 2005: Challenges in Extraction and Production, 147-178 (2005).

[10] Cramer L., Basson J., Nelson L., The Impact of Platinum Production from UG2 Ore on Ferrochrome Production in South Africa,  Journal of the South African Institute of Mining and  Metallurgy, 104(9): 517-527 (2004).

[11] Tripathy S.K., Singh V., Ramamurthy Y., Improvement in Cr:Fe Ratio of Indian Chromite Ore for Ferro Chrome Production, International Journal of Mining Engineering and Mineral Processing, 1(3): 101-106 (2012).

[12] Simmons W.B., Pyroxene,Encyclopedia Britannica, inc, (2014).  Accessed March 05 2018,


[13] Özkan, S. G. İ., Concentration Studies on Chromite Tailingss by Multi Gravity Separator, International Mining Congress and Exhibition of Turkey, 765-768 (2001).

[14] Bhatti M.A., Kazmi K.R., Anwar M.S., High Intensity Magnetic Separation Studies of Low Grade Chromium Ore, Journal-Chemical Society of Pakistan, 30(1):42 (2008).

[15] Neizel B. W., "Alteration of Chrome-to-Iron Ratio in Chromite Ore by Chlorination", Doctoral Dissertation, North West University, (2010).

[16] El-Midany A. A.; Ibrahim S. S., Does Calcite Content Affect Its Weparation from Celestite by Falcon Concentrator, Powder Technology, 213(1–3): 41-47 (2011).

[17] Jordens A., Marion C., Langlois R., Grammatikopoulos T., Sheridan R. S., Ten, C., Demers H., Gauvin R., Rowson N.A., Waters K.E., Beneficiation of the Nechalacho Rare Earth Deposit. Part 2: Characterisation of Products from Gravity and Magnetic Separation, Minerals Engineering, (2016).

[18] Honaker R.Q., Wang D., Ho K., Application of the Falcon Concentrator for Fine Coal Cleaning, Minerals Engineering, 9(11): 1143-1156(1996).