Energetics of collision between grinding media in ball mills and mechanochemical effects

Abstract

This paper describes the physical and chemical changes such as decomposition, double decomposition, oxidation, and phase transformation reported in the literature as a consequence of solid surfaces coming into contact under mechanical forces. These changes, generally termed mechanochemical and chemomechanical effects, occur in the near-surface regions when surfaces come into contact as in abrasion between solid surfaces and repeated collisions among grinding media in ball mills. For understanding mechanochemical effects in ball mills, the normal impact between two grinding balls is quantified in terms of collision force, contact radius, contact time, and collision energy. These measures are quantitied as a function of ball sizes (diameters varying between 1 and 4 cm), ball material (steel and alumina), and collision velocity (0.4–4 m/s), using expressions developed by previous investigators from the principles of continuum mechanics.