Role of Agitation in Electrokinetics and Carrier Flotation of Clay Using Calcite and Oleate

A detailed study of carrier flotation of kaolin clay using calcite showed the major beneficiation mechanism to be enhanced aggregation between anatase and calcite under intense agitation conditions. To develop an understanding of this selective aggregation, surface charge characteristics of kaolinite, anatase, and calcite were studied under simulated flotation conditions. Zeta potential of all these minerals tended towards a constant negative value in oleate solutions under certain conditions possibly due to adsorption or precipitation of oleate on them. However, whereas the zeta potential of anatase in the oleate solutions was not influenced by the agitation level, that of kaolinite was found to be strongly dependent on the agitation intensity. The effect of oleate on zeta potential of kaolinite was reduced by an increase in agitation intensity. It is suggested that oleate is much more firmly bound to the surface of the anatase and that this preferential attachment is responsible for the enhanced selective aggregation of the anatase with calcite. Agitation level plays a major role in carrier flotation since intense agitation is considered to enhance both the chemisorption of oleate on anatase and preferential detachment of calcium oleate precipitate from the kaolinite surface, all of this producing a large difference in the surface Properties of anatase and kaolinite, and hence in their tendency to aggregate with calcite.