Changes of surface and volume properties of calcite during a batch wet grinding process

An experimental study on the ultra-fine wet grinding of calcite in a batch stirred bead mill is reported. The evolution of the size distribution and of the specific surface area of the particles versus grinding time was measured revealing that an agglomeration phenomenon takes place during the comminution process. The X-ray diffraction profiles versus milling time did not show any polymorphic phase transformation but an intensity reduction and a broadening of diffraction peaks. The size distributions can be properly fitted by a linear combination of statistical log-normal laws, taking the agglomeration of particles into account. The analysis of theological properties of the ground suspensions revealed a plastic thinning behaviour which can be described by the Hershel-Bulkley equation. (C) 2002 Elsevier Science B.V. All rights reserved.