Liner designs, materials and operating practices for large primary mills

"Significant increases in mill liner life and plant availability can be achieved by following guidelines that have evolved from over twenty years of practical experience with autogenous grinding (A0) and semi-autogenous grinding (SA0) mills. A0 and SA0 mill liner functions, performance criteria, designs, wear-resistant materials and maintenance procedures are reviewed. Operating practices that can lead to accelerated wear and breakage are discussed.IntroductionEfforts to improve the performance of liners for autogenous grinding (AG) and semi-autogenous grinding (SAG) mills began as soon as the modern, large-diameter versions of these comminution machines were first intalled in commercial plants twenty years ago . While concentrators with conventional circuits were typically running at 95010 or better mill availability, many of the new autogenous and semi-autogenous circuits were struggling to achieve 80% availability. Liner maintenance, which involves not only material and labour costs but also loss of production, was quickly identified as one of the major reasons for downtime.Today, liner designs and materials have evolved to the point where virtually maintenance-free liner life of two to three years is possible in autogenous mills and one year in the more severe operating conditions encountered in semi-autogenous mills. Of concern, however, is that hard-won lessons from the past sometimes seem to be forgotten or ignored during the design of new mills and the operation of existing mills. As liner suppliers, we are often confronted with performance problems that could have been avoided by applying well-publicized guidelines for liner design and materials selection.This paper provides an overview of AG and SAG mill liner functions, criteria for evaluating performance, designs, wear-resistant materials and maintenance procedures. Also, operating conditions that can lead to accelerated wear and liner breakage are discussed in detail."