Image analysis was used to characterise quantitatively the shapes of single
crystals impacted against a target. The conditions of impacts are created
to simulate the impacts undergone by the crystals in an industrial crystall
iser. The change of particle morphology due to attrition enables to underst
and the abrasion and breakage mechanisms of the crystals after one or sever
al collisions. The projected area, the elongation, the robustness, the conc
avity characterise the evolution of the crystal shape as a function of the
number of impacts. The crystal becomes rounded and its shape irregular. The
quantification of the length and of the propagation of the created cracks
is done. Cracks are initiated by the impacts and propagate to join one anot
her, creating a fragment finally removed from the particle. (C) 2000 Elsevi
er Science S.A. All rights reserved.