Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
CLERK, D.J. de and VAAL, P.L. de. A holistic approach to control and optimization of a PGM concentrate flash drying unit. J. S. Afr. Inst. Min. Metall. [online]. 2012, vol.112, n.1, pp. 45-53. ISSN 2411-9717.
Global trends stipulate the need to optimize existing assets while reducing environmental impacts. This paper illustrates the procedure that was followed to achieve such goals at one of the coal burning flash dryer units at an Anglo American smelter. An indepth study of the process and related literature led to the development and installation of a revised control philosophy. This system includes modifications to the existing regulatory control structure as well as a hybrid rule-based and model-predictive advanced process control (APC) layer. Since commissioning of the APC, this flash dryer's average throughput has increased by more than 6%, despite higher feed moistures. Furthermore, even though coal consumption has increased slightly, operating efficiency has improved by close to 5%. This was made possible by improving stability of the drying column outlet temperature by approximately 40%, which in turn enabled selection of a more optimal setpoint. Recent data has shown that APC utilization now exceeds 95%. This is indicative of a successful controller installation with good site acceptance. The same philosophy has therefore since been rolled out to most of the other flash dryers in the group.
Keywords : flash dryer; platinum processing; model predictive control; expert system.