Steady-state and dynamic simulation of a grinding mill using grind curves

Abstract

A dynamic non-linear model was fitted to the grind curve data of an industrial semi-autogenous grinding (SAG) mill by means of a step-wise procedure. Grind curves give the steady-state values of the performance variables throughput, power draw, and grind in terms of the mill filling and critical mill speed. The grind curves indicate the operable region of the grinding mill. An analysis and dynamic simulation of the model show that the model captures the main dynamics of the grinding mill. Further simulations demonstrate that the model represents the full range of steady-state conditions defined by the grind curves. In other words, the dynamic model is quantitatively accurate as it settles at the correct steady-state for the operable region of the grinding mill. Therefore, the model is suitable as a simulator to test and develop optimizing control strategies for global operating conditions rather than only for local operating conditions.