2015-3-15 · At present, HPGRs are (still) applied in combination with ball milling, either as a pre-grinding stage or as a regrinding of the ball mill discharge in integrated milling-pelletizing plants (Van Der Meer, 1997, Saralaya et al., 1997), Also, HPGR is applied to regrind mixtures of ore concentrates bought from different sources in stand-alone ...