Supervisory expert control for ball mill grinding circuits

Stable control of particle size in ball mill grinding circuits is of great importance for the recovery of the valuable minerals, and the maximization of mill capacity is another main consideration in concentration plants. A supervisory expert control strategy is proposed to control product particle size and to improve fresh ore feed tonnage in grinding circuits. Expert control in supervisory level is developed to optimize the set-points for controllers in regulatory level. Mill solid concentration variable-ratio control, sump dilution water flowrate single-loop control and sump level loose control are carried out in regulatory level to reach the control targets. While the set-point modification by expert control for dilution water controller demonstrates good dynamic performance, the set-point adjustment for feed rate controller ensures a long-term stableness of particle size even ore hardness has changed. An increase of 10% in feed tonnage was achieved relative to other grinding circuits of similar capacity, running in parallel. More than four year's operation demonstrates the control strategy's practicality and reliability. (c) 2007 Elsevier Ltd. All rights reserved.