Development of a size-frequency based model of the impact size reduction of coarse material

Recent single particle breakage work has outlined a possible basis for constructing a size-number, rather than size-mass, model of the impact crushing of rock. A power-law size-frequency distribution was used to represent the cumulative progeny of single particle impact events. With the latter, the degree of subdivision imposed can be given as a single quantity, i.e. the absolute value of the exponent, which is in essence a measure of the degree of fineness of the daughter fragments. The larger the value the greater the state of fragmentation of the particulate system and conversely. However, this initial work involved the failure of individual cores of rock of carefully chosen fracture toughness properties, and covered a narrow range of parent particle size only. This paper covers the latest research in this area in which repeated single particle breakage experiments were performed on fragments of naturally formed geometries. In addition, the initial particle size range covered has been expanded, and the proposed practical application of the size-frequency approach is discussed from the viewpoint of predicting the progeny of impact machines crushing relatively coarse material. (C) 1998 Elsevier Science Ltd. All rights reserved.