Relating the attrition behaviour of crystals in a stirred vessel to their mechanical properties

The attrition behaviour of eight different crystalline materials in a stirred vessel was investigated applying similar fluid dynamic conditions, i.e. just suspending the crystals off-bottom. Despite the rather gentle stirring, all crystalline materials underwent remarkable attrition, generating, in 1 h, an amount of fragments ranging from 3.9 to 28.7% of the original mass. The attrition behaviour of the crystals was characterised basing on the size distribution of the fragments, which was analysed and modelled, confirming that they were mainly produced by abrasion mechanism. The morphological analysis of the fragments showed that the size of the main axes of the coarse residue got closer. while the fragments became more elongated as their size decreased. Two different approaches relating the attrition resistance of the materials to their hardness and to their stress resistance were examined and discussed in order to relate the attrition behaviour to the mechanical properties of the materials. (C) 2003 Elsevier Science B.V. All rights reserved.