Slurry pooling and transport issues in SAG mills

Slurry pooling, excessive accumulation of slurry in the mill, and the associated loss of throughput and grind, are well recognised on lowaspect, single-stage SAG mills. However, it is becoming apparent that a wide range of the high-aspect mills also suffer from pooling issues. This is associated with the high throughput of mills treating less competent ores, excessive pebble porting, and large (>36ft) mills being closed with cyclones. Data are presented from a number of mills operating in different applications to support this contention. The issue raised is that mill throughput is controlled by discharge capacity, and a better understanding of this is required to enable higher mill throughputs.