An alternative strategy to compensate for screw wear in gravity induced stirred mills

Abstract

In fine grinding applications, gravity induced stirred mills have a demonstrated higher energy efficiency compared to conventional tumbling ball mills, leading to their increasing utilisation in unlocking value from fine grained and low-grade ore deposits. The efficiency of the current strategy for compensating for wear of the agitator screw, by maintaining constant power draw through increasing mill media filling during the liner lifecycle, has not been evaluated. This paper provides a laboratory evaluation of the alternative strategy of maintaining constant mill filling in batch wet grinding. The comparison is based on the size specific energy (SSE) approach. It was established that the grinding efficiency improves when maintaining a constant filling, whereas it decreases when running at a fixed mill power. These results encourage continuing work with continuous and full-scale mills, and potentially utilising increasing mill speed to compensate for the loss of power draw, and thus throughput, with screw wear.