Developments in the understanding of South African style SAG mills

The South African style SAG (RoM) mills operate in a window that is almost exclusive from the operation of the Australian and North American mills tha t have been used for the development of SAG mill models. Combining good qua lity, test data from the RoM mills is extending and improving these models, and assisting in a practical manner in improving our understanding of SAG/ AG milling. Data from high mill loads, both in absolute filling and ball loading, have been used to extend and improve the JK SAG mill model. This improved unders tanding has been successfully applied to increasing the throughput of a mil l by 8%. Data is presented on relationships between power and load for high mill loading. Slurry pooling is common in closed-circuit RoM mills, and th e detrimental effect of this has been dramatically demonstrated at ALCOA wi th a mill throughput increase of over 20%. Techniques for calculating the e ffects of slurry pooling have been developed and a new pulp lifter system d esigned to give optimal slurry discharge. The influence of mill speed in sh ifting the product size distribution has also been measured. (C) 2001 Elsev ier Science Ltd. All rights reserved.