MSc (Eng) Project title Effect of HPGR on Platinum Bearing Ores and the Flotation Response
(Supervisors: A/Prof AN Mainza, Dr M Becker, A/Prof J Petersen, Prof J-P Franzidis) Graduated: 2011
The application of comminution devices such as the ball mill in the beneficiation of platinum group minerals (PGMs) makes this a highly energy inefficient process. Excessive energy is required to sufficiently liberate the very fine grained PGMs.In a time when energy costs are rapidly increasing, some operations including the platinum industry have opted to investigate the possibility of applying more energy efficient processing methods, particularly in the comminution stage. One such way is the application of alternative comminution devices such as the high pressure grinding rolls (HPGR). The addition of the HPGR in copper, diamond, and gold circuits has resulted in benefits such as improved throughput, recovery and energy consumption. Therefore, this project sought to determine if the same benefits can be achieved for the platinum ores through the application of the HPGR as an alternative to the ball mill. Breakage tests were carried out on three Lonmin platinum ores using a pilot-scale HPGR and a pilot ball mill, under different milling conditions. The energy consumption and the particle size distribution of the resulting product were assessed; flotation tests were performed on selected products to compare the PGM recoveries obtained. Energy savings of up to 30% were obtained when the HPGR was used to grind the ore at a lower pressure. The ore ground in the ball mill appeared to have a superior flotation response compared to that ground using the HPGR under different operating conditions. No significant differences were observed in the mineral liberation profiles of the materials comminuted in the two mills.
Peer-reviewed journal publications
Solomon, N., Becker, M.E., Mainza, A.N., Petersen, J. and Franzidis, J.-P. 2011. Understanding the influence of HPGR on PGM flotation behavior using mineralogy. Minerals Engineering, 24: 1370-1377
Peer-reviewed conference proceedings
Solomon, N., Mainza, A., Becker, M., Petersen, J., and Franzidis, J.-P. 2010. Effects of high pressure grinding rolls on the flotation response as compared to the conventional ball mill., XXV International Mineral Processing Congress (IMPC), Brisbane, Australia, 5-10 September, 2010
Oral conference presentations
Solomon, N., Becker, M., Mainza, A., Petersen, J., Franzidis, J.-P.and Ross, V. 2010. Comparison of the effect of grinding device on mineral liberation and flotation behaviour in PGM ores. Process Mineralogy 2010, Cape Town, 10-12 November 2010.