A Mechanistic Model for Attrition of Particles in Flow Systems

Abstract

Particle-particle contact affects many industrial systems such as powder processing, particle handling, and slurry flows. The control of fracture processes during contact is the key to the success of these systems. Many investigators have studied fracture of materials due to the contact between particles (Shipway and Hutchings, 1993). There are many correlations between the contact load and the amount of damage observed. However, until recently, the specific mechanism of damage was still unknown. This paper reports the experimental results and analytical models for the contact of brittle spheres in several contact configurations. Fracture analysis is used to determine the cause of failure and the stress at the failure site. The mechanism of failure is primarily Mode I (tensile) crack propagation. The location of failure is shown to be influenced by Young’s modulus, the radius of curvature and the method of contact. The fracture origin for a single glass sphere compressed by two flats is at the equat or and for a single glass sphere compressed by three spheres or by either a flat or sphere is at the contact points. Fracture originates from the contact point for alumina spheres for all testing configurations. The experimental stress is in agreement with theoretical predictions once the location of the primary fracture origin is known. Results for soda-lime-silica and borosilicate glasses and alumina balls are reported. The significance of the location of failure origin to the processing of particles are discussed.