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.)