Media type effect on Grinding Efficiency

The consumption of energy in the grinding process is significant in both the amount used and the cost involved. Both imply that it is important to maximise the throughput for a given grinding task; which in turn implies it is important to maximise mill power draw, which is related to the efficiency whereupon this power is used.

In order to optimise the process it is first necessary to know the effects of the operative parameters on the ore grindability because it is the grinding efficiency that is to be evaluated; that is to say, the efficient use of the energy from the metallurgical point of view in conventional ball grinding, recognising that such concepts and criteria also apply to other types of applications such as semiautogenous grinding (SAG) and vertical mills.

It was demonstrated that it is possible to optimise the grinding process by means of the correct selection of grinding media that allows maximising the effectiveness (power draw) and the power efficiency of the process (correct use). For example, simulations demonstrate that using forged steel grinding balls (high density) [compared to cast steel (lower density) balls and to high chromium white cast iron (lowest density) balls] increases throughput by 2.2 - 4.4 per cent and reduces the specific energy consumption by 2 - 3 per cent (at constant feed size and product size).