Advanced Simulation for Semi-Autogenous Mill Systems: A Simplified Models Approach

Abstract

Modelling and simulation of semi-autogenous (SAG) mills are valuable tools for helping to design control laws for a given application and subsequently to optimise its performance and process control. SAG mills (see Figure 1) are presently one of the most widely used alternatives in the field of mineral size reduction as a result of their advantages such as higher processing capacity, lower physical space requirements, and lower investment and maintenance costs, as compared to conventional circuits (Salazar, et al., 2009). Due to the size of SAG mills, pilot plants are usually used for research purposes to improve the control strategies. In cases where a pilot-scale is not available for test, simulations using models based on data from a wide range of full-scale plants are helpful and can significantly reduce risks for process control purposes. Simulations also provide an additional and very valuable crosscheck against the pilot results (Morell, 2004). Fig. 1. Typical semi-autogenous (SAG) mills This chapter presents a dynamic simulator of a semi-autogenous grinding operation deduced from first principles coupled to an on-line parameter estimation scheme able to simulate industrial operations for future control purposes. The proposed procedure for simulation purposes is as follows: Model equations are based on a conventional non-stationary population balance approach to develop the necessary dynamic model of the semi-autogenous mill operation. The presented models are able to predict the time-evolution of key operating variables such as product flow rate, level charge, power-draw,