Throughput and product quality control for a grinding mill circuit using non-linear MPC

• Proposal of a nonlinear model-based control architecture for a grinding mill circuit.
• Use nonlinear MPC for the overall grinding circuit and dynamic inversion control for the fast sump dynamics.
• Achievement of independent control of throughput and product quality.
• Full-state feedback not assumed.
• Observers make use of real-time continuous measurements commonly available on industrial plants.

A non-linear model-based control architecture for a single-stage grinding mill circuit closed with a hydrocyclone is proposed. The control architecture aims to achieve independent control of circuit throughput and product quality, and consists of a non-linear model predictive controller for grinding mill circuit control, and a dynamic inversion controller to control the fast sump dynamics. A particle filter is used to estimate the mill states, and an algebraic routine is used to estimate the sump states. The observers make use of real-time continuous measurements commonly available on industrial plants. Simulation results show that control objectives can be achieved by the controller despite the presence of measurement noise and disturbances.