The relationship between the flotation behaviour of a mineral and its surface energy properties using calorimetry

Surface energy defines the wettability of a mineral surface, which is of great importance in separation by flotation. Surface energies can be calculated and separated into their polar and non-polar components by measuring the enthalpy of immersion of a finely divided mineral powder in a number of probe liquids. In this study, the enthalpies of immersion of different isolated pure minerals in water, formamide and n-hexane were determined using a precision solution calorimeter. The van Oss-Good-Chaudhury (VGC) model was applied to systematically characterise the surface energy components of the minerals. A microflotation system was also employed to determine the flotation responses of the different minerals. The enthalpy of immersion technique was capable of differentiating the surface energies of isolated pure minerals. The relative strength of the surface energies and their components was dependent on the mineral type. The work of adhesion of water and the interfacial energy of interaction between particles and bubbles immersed in water correlated well with the enthalpy of immersion in water and were both inversely related to the flotation response of the minerals. The results are intended to provide a firm foundation for the investigation of the wettability of mineral mixtures, composite particles and simple ores using the enthalpy of immersion technique.