A review of techniques for measurement of contact angles and their applicability on mineral surfaces

Knowledge of the wetting characteristic of mineral surfaces is paramount in enhancing the efficiency of separation of valuable minerals from gangue using froth flotation. The contact angle value is a useful indicator providing the hydrophobic characteristic of the solid mineral surfaces due to a close relationship between this parameter and the floatability of minerals.In this paper, techniques for contact angle measurements and their applicability on mineral surfaces are reviewed. Two main groups of techniques for contact angle measurements are available; one group is applicable to flat and smooth surfaces while the other one has been especially developed for non-ideal surfaces or particles. Capillary penetration methods have been found to be more applicable than the other methods cited in measuring contact angles on real mineral surfaces. The major challenge with this technique is the modification required to overcome the difficulties in the experimental packing technique needed, and more importantly, to obtain the receding contact angle values. The coupling of accurate contact angle measurements with real (batch) flotation data would seem to be area which has had limited attention.