Abstract
This paper presents the results of a Ph.D. research program undertaken by the Author at the Mining Engineering Department of Oporto University. This was a part of a continuing team effort to develop modelling and computational ideas and tools for the mineral processing industry, based on mathematical descriptions of the state of liberation of a comminuted mineral mass. It focuses on the effects of air friction on the metallurgical parameters affecting an electrostatic separation process and on their practical implications, mainly as regards the needs for previous sizing of the feed.