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 impac t crushing of rock. A power-law size-frequency distribution was used t o represent the cumulative progeny of single particle impact events. W ith the latter, the degree of subdivision imposed can be given as a si ngle quantity, i.e. the absolute value of the exponent, which is in es sence a measure of the degree of fineness of the daughter fragments. T he larger the value the greater the state of fragmentation of the part iculate system and conversely. However, this initial work involved the failure of individual cores of rock of carefully chosen fracture toug hness properties, and covered a narrow range of parent particle size o nly. This paper covers the latest research in this area in which repea ted single particle breakage experiments were performed on fragments o f naturally formed geometries. In addition, the initial particle size range covered has been expanded, and the proposed practical applicatio n of the size-frequency approach is discussed from the viewpoint of pr edicting the progeny of impact machines crushing relatively coarse mat erial. (C) 1998 Elsevier Science Ltd. All rights reserved.