Effect of comminution on particle shape and surface roughness and their relation to flotation process

The essential physical characteristics of the distinction of particles are size, shape and surface roughness. Particle shape and surface roughness are considered important parameters in the prediction of the behavior of particles individually or collectively. These parameters are of great importance to industries employing various materials in a powder form. These parameters have not been currently reviewed satisfactory in the mineral processing field. Therefore, this research is concerned with the different methods used to estimate the particle shape and surface roughness and also to relate these parameters with the behavior of some mineral processing operations, especially comminution and flotation processes. The surface roughness of mineral particle influences the fundamental processes of particle-bubble attachment and the other sub-processes in froth flotation. The contact angle is dependent on the surface roughness. The modification of the wettability due to surface roughness can be greatly enhanced in the fractal surface: that is the fractal surface will be superrepellen (superwettable) to a liquid when the contact angle is greater (less) than 90 degrees. Correlations were found between the shape properties, surface roughness values and wettability. The dry grinding produces relatively rough particle surfaces with a high concentration of microstructural defects while the wet grinding produces smoother cleaner surfaces. The dry ground samples exhibited more stable, higher loaded froths and faster flotation kinetics. (C) 2010 Elsevier B.V. All rights reserved.