The design and evolution of SAG mill liner trails
Development of SAG liners has always been of considerable interest to mill operators as liners significantly affect plant performance (throughput, grind size), material costs and plant downtime. Thus, operators commonly trial different liner shapes, profiles, and configurations. However, there is little to be found in the way of guidance on how to conduct such trials and evaluate the benefits. Conducting liner trials involves a significant investment and the risk is usually considered high. There is potential for loss of production if the trial liners underperform or if they need to be removed prematurely due to reduced wear life or poor performance.
In terms of data analysis to evaluate the benefits of trial liners there are some inherent difficulties. Firstly, it is impractical to conduct an on-off trial, hence there is generally only one data set for analysis. Furthermore, the liner shape is dynamic due to wear, with the progression in wear yielding differing mill performance in terms of throughput, power draw, and size reduction over the life of the liner. Thus, a before and after comparison may provide an overly simplified and erroneous result. Finally, the fact that the service life of a liner is in the order of months means that both the wider plant and the ore being processed are often subject to significant variation over the course of a trial. This means that comparisons between liners can only be made by rigorous statistical analysis or process modelling if reliable conclusions are to be drawn.
This paper aims to provide guidance for conducting SAG liner trials and tools and techniques to evaluate the results. This will allow mill operators to minimize the risk associated with liner trials and provide increased confidence in any conclusions and recommendations.