1. Mining and Mineral Processing Engineering Department, Taita Taveta University, Voi, Kenya
2. Department of Mining and Metallurgical Engineering, University of Namibia, Windhoek, Namibia
3. School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
4. Department of Metallurgical and Materials Engineering, Federal University of Technology Akure, Nigeria
5. The School of Mining Engineering, University of the Witwatersrand, Johannesburg, South Africa