of the crack and material dependent characteristics. The relation between these quantities
has been described in detail by Luyten et al. (1992).
Abrasion involves the fracture on the edges or surface-unevenesses of particles. This
type of attrition affects the particle size distribution. The fines produced are smaller than
the original pellet size and form an additional peak in the particle size distribution curve
(Fig. 2). Depe n d’m g on the amount of fines produced, bulk density may increase, since
small particles occupy space in the large voids in between pellets, thereby decreasing
pellet porosity.