The paper presents findings from collaborative research on fine grinding, coordinated by the Australian Mineral Industries Research Association. The data reported here were collected from a tower mill circuit in the low grade mineral section of Mt. Isa Mines＇ Hilton Concentrator, Multi-component modelling, based on assays of size fractions, showed that the circuit was capable reducing the fresh feed from 110 to 15 mu m at the desired throughput using about 22 kWh/t, provided classification at around 27 mu m was installed. A benefit of about 3% recovery of both lead and zinc was indicated, A new simplified method of modelling grinding and liberation together is explained and verified by using parameters from the normal grind to predict, quite accurately, the size reduction and liberation achieved in a finer grind.