Combined PID and Predictive Control of Sag Mill Feed Size Distribution

The control of the operation of a semi autogenous grinding mill is mainly based on power and bearing pressure measurements. Image based sensors can provide on-line measurements of the size distribution of the ore feeding a SAG mill allowing the control of this variable that impacts the operation of this equipment. This paper investigates the potential of using the information from such type of sensor to maintain a SAG mill feed target size distribution by manipulating the speed of the ore extractors below an ore stockpile. A PID and adaptive predictive controller for the size distribution are studied using a simulator for a stockpile and the equipments used for ore withdrawing from the pile. The proposed controller is found to give a good performance while remaining easy to tune.