The energy of interactions between bubbles and particles – specific surface free energy distributions and microflotation

In fundamental flotation studies typically the contact angle is used to describe wettability and correlated with floatability. However, a more fundamental parameter is the specific surface free energy, related to the contact angle via Young’s equation. Inverse gas chromatography (iGC) is a suitable method to determine specific surface free energy components and their distributions on particulate surfaces. In this study the pure minerals quartzite (SiO2), fluoro-apatite (Ca5[F,(PO4)3]) and magnetite (Fe3O4) are examined for microflotation floatability and surface energy considering different methods of sample treatment and the effect of the collectors sodium oleate and dodecyl ammonium acetate. The parameter of specific net free energy of interaction between bubbles and particles immersed in water ΔGpwb derived from the complex surface energy analysis is introduced and used to evaluate the hydrophobicity of the mineral surface correlated with microflotation floatability. Results lead to the provocative hypothesis that only small fractions of the surface and their change by flotation reagent adsorption will inherently define floatability of minerals.