Surface Energy Heterogeneities - New Insights to the Microprocesses of Flotation Separation of Minerals

Especially the modern fine grained and polymetallic deposits call for a continuation in process development and even more so in better understanding the flotation process which is based on the selective hydrophobization/hydrophilization of minerals. This poster will present novel insights on the hydrophobization of various mineral particles, i.e. silicates, semi-soluble salt type minerals and metal oxides with different collector molecules. We investigate the effect of the collectors on the surface energy distribution which is determined with inverse gas chromatography. With this method it is possible to assess the wettability of particles without the difficulties encountered with the conventional sessile drop and penetration methods. By applying inverse gas chromatography we can show that it is due to the collector adsorption the reduction of the highly energetic moieties which only make up less than 10 percent of the particle surface. Furthermore we can present the effect of collector adsorption on the different surface energy components, i.e. disperse and specific interactions. By calculating the free energy of interaction between a particle and a bubble immersed in water using the complex surface energy information we can find a good correlation to the flotation response, i.e. recovery determined with classic microflotation experiments in the Hallimond tube. The minerals used are: quartz, apatite and magnetite. The collectors assessed are cationic and different anionic surfactants at various pH and collector concentration.