Water-bentonite interaction in balling of iron ores

Abstract

The growth of granules in batch agglomeration of hematite iron ore powder with or without the presence of bentonite additive can be described by the non-random coalescence mechanism. The specific balling rate constant in the kinetic expression for median ball-size increases with increasing water content of the feed and decreases with addition of bentonite. It is suggested that, in so far as the gross kinetic behaviour is concerned, the role of bentonite in balling is to immobilize a fraction of the water present in the charge. The amount of bound water has been estimated from the balling rate constant data and the extent of immobilized water is found to be disproportionately higher for wetter feeds. Implications of these results in operation and control of industrial iron ore balling circuit are discussed.