Interactions of Anionic Collectors in Flotation of Semi-Soluble Salt Minerals

Our recent studies on the interaction of oleate with salt-type mineral surfaces have been summarised and discussed in the light of the published literature. The mechanism of oleate adsorption on these minerals was evaluated based on adsorption, zeta potential and infrared studies as well as theoretical thermodynamic calculations. In contrast to earlier knowledge, a quantitative evaluation of oleate adsorption in systems forming a monolayer coverage as in the case of calcite and a bilayer formation in the cases of fluorite, apatite, scheelite and baryte, preceding the precipitation of metal soap is presented. The monolayer coverage is shown to correspond to a condensed state of oleate with a molecular coverage area of 33 Å2 (liquid crystal state). Depending on the surface potential and its magnitude at basic pH values, oleate is either chemisorbed on the surface calcium or monocoordinated through counter sodium and calcium ions for the monolayer filling. The results have been discussed in terms of the existing adsorption models.