A sustained drop in the grade of Mount Isa lead-zinc-silver ore occurred in mid 1980._x000D_
It was decided to increase concentrator throughput from 200 000 to 240 000 tonnes/four week period to maintain budget metal production. To achieve this increase whilst maintaining acceptable grinding and flotation performance, crushing plant final product size had to be reduced from 100%-13mm to 1000-11.2mm. The goal in the crushing plant was to achieve a 20% increase in throughput with a 20% decrease in the top size of the product._x000D_
This was achieved by operational changes to improve plant availability and optimisation of the existing crushing and screening equipment Performance.