Predicting the specific energy required for size reduction of relatively coarse feeds in conventional crushers and high pressure grinding rolls

In a previous paper (Morrell, 2009. Predicting the overall specific energy requirement of crushing, high pressure grinding roll and tumbling mill circuits. Minerals Engineering 22 (6), 544–549), an approach was described to predict the specific energy of a range of tumbling mill and crushing/high pressure grinding rolls (HPGR) circuits. In the case of crushing and HPGR circuits, recently acquired data have enabled this approach to be extended to coarser particle size reduction situations. This is achieved through the use of a size-dependent hardness parameter. Crushing and HPGR conditions are described where the use of this parameter should improve the accuracy of specific energy predictions. A worked example is also given.