ENERGETICS OF COLLISION BETWEEN GRINDING MEDIA IN BALL MILLS AND MECHANOCHEMICAL EFFECTS

This paper describes the physical and chemical changes such as decompo sition, double decomposition. oxidation, and phase transformation repo rted in the literature as a consequence of solid surfaces coming into contact under mechanical forces. These changes, generally termed mecha nochemical and chemomechanical effects, occur in the near-surface regi ons when surfaces come into contact as in abrasion between solid surfa ces and repeated collisions among grinding media in ball mills. For un derstanding mechanochemical effects in ball mills, the normal impact b etween two grinding balls is quantified in terms of collision force, c ontact radius, contact time, and collision energy. These measures an q uantified 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 th e principles of continuum mechanics. (C) 1998 Elsevier Science S.A. Al l rights reserved.