1. Mineral Processing and Technology Research Centre, Department of Metallurgy, School of Mining, Metallurgy and Chemical Engineering, Faculty of Engineering and the Built Environment, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006, South Africa
2. School of Chemical & Metallurgical Engineering, University of the Witwatersrand, Private Bag X3, Johannesburg 2050, South Africa
3. Minerals Processing Division, Mintek, 200 Malibongwe Drive, Randburg, Johannesburg 2194, South Africa
4. Faculty of Engineering and the Built Environment, University of the Witwatersrand, 1 Jan Smuts Ave., Johannesburg 2000, South Africa