Increased Vertimills Productivity by Applying MPC & Advanced Control Systems at Minera Los Pelambres

Abstract

The implementation of a successful control operation for a vertical regrinding mill (vertimill) should be capable of processing a variable rougher flotation feed without becoming a process bottle neck. It should also deliver an adequate quality product to the process downstream while keeping an adequate circulation load and making an efficient use of the available grinding power. On the same line it should maintain adequate control of the cyclone's pressure and density while maintaining an adequate pump box level with only a few manipulated variables. Thus, it becomes a non-linear multi-variable type of process with multiple control objectives to satisfy simultaneously.To achieve this, many operations have implemented basic or conventional control or even better yet, expert systems. But due to the fast changing nature of vertimill's process conditions, Minera Los Pelambres believes that better and faster results can be achieved using a combination of MPC (model-based predictive control) and advanced control. Thus, such strategy was successfully implemented in its two vertimill circuits, reducing considerably process variability while maintaining high throughput and keeping the process well within constraints limits. Regardless of their differences in processing capacity, a unique approach and stabilizing-control strategy was developed, tested and tuned. Their control philosophy, implementation process, main results and their key performance indicators are discussed here.