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PGR has been used for many years and is emerging as an energy-efficient alternative to conventional and AG/SAG comminution circuits. One of the interesting features of HPGR is its capability to produce a particle size distribution with a greater than typical amount of fines, thus reducing the power requirement for the downstream ball mill. This makes the use of standard ball mill analyses based on the K80 inadequate, unless appropriate corrections are made. (This problem is shared by AG/SAG mill circuits.)
The most appropriate way to get around this data problem is to run the entire circuit at pilot-scale and analyze the data based on the overall power applied in kWh/t. This requires a fair quantity of sample, and the difficulties inherent to performing such a pilot plant make it difficult to come up with reliable conclusions.