Parallel Switching Regulatory Control of Iron Ore Flowrate from Multiple Feeders with Time Delay

The suitable performance of an industrial process needs regulatory control loops to adjust the main process variables to their especified reference values (set-points), and to compensate eventual load disturbances on the process. Regulatory control is fundamentally used in the industry for stabilizing process variables, and it’s generally implemented through the SCADA architeture of the plantwide control system. The absence or inefficiency of control in an industrial process generally implies in losses of productivity so that regulatory control is a key issue for improving process performance. In this context, this article presents the development and implementation of a control strategy for regulating the output mass flow (in t/h) of a crushing plant in the Carajás Iron Ore Processing Factory. The plant has eight feeders in parallel, and the goal was to control such feeders so that the resulting output flow matches a specified production set-point (in t/h). The article first explains the process, the control problem, and the transfer function model of the process. Subsequently, one’s presented the control strategy, which was based on a switching between a constant and a PI control action. The suitability of the strategy was investigated through computational simulations. Finally, the results and conclusions are discussed