On the surface wettability heterogeneities in fine particle separation technologies - inverse Gas Chromatography investigations and interface interaction studies


On the surface wettability heterogeneities in fine particle separation technologies - inverse Gas Chromatography investigations and interface interaction studies

Rudolph, M.; Sygusch, J.

Fine particle separation is a challenging task and relies on a proper understanding of interfacial properties. In our research the focus lies on the process of flotation, which is a heterocoagulation separation method for fine particles in aqueous dispersions (size range approx. 5 µm < x <200 µm). It has been used in large extent for several decades and with billions of tons of particles processed per annum in the mining industry to separate valuable mineral particles from worthless ones. The main principle of separation is the particles' differences in wettability. This wettability is influenced by controlled selective adsorption of amphiphilic molecules rendering most typically the valuable containing minerals hydrophobic. Usually the particle property "wettability" is being quantified with a water contact angle. However, this value is not only difficult to assess for particles but furthermore through Young's equation a function of the surface free energy, which is a complex parameter as a result of various interatomic/intermolecular interactions. Using iGC we show how to characterize these complex wettability properties of particles assessing the heterogeneity of disperse and acid base specific surface free energies. These complex values are used in accordance to an approach by van Oss to formulate a new wettability parameter for flotation which is the specific free energy of interaction between a particle and a gas bubble immersed in water. We are presenting the general approach and results from various mineral collector systems and give insights to the boundary conditions and the general calculation scheme. In a recent trial we show the predictive power of the results. Furthermore we show how iGC can be put in context to other interaction investigations using flotability, contact angle measurements and colloidal probe atomic force microscopy.

  • Invited lecture (Conferences)
    1st European Symposium on Sorption Science, 05.-07.09.2018, Wien, Österreich

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Publ.-Id: 28381