Surface vs. bulk analyses of various feldspars and their significance to flotation

Cationic separation of Na-feldspar (albite) and K-feldspar (microcline) was earlier reported to be possible in the presence of monovalent salts. However, contrary to this result, the floatability of a series of K-feldspar minerals indicated that each microcline mineral exhibited different floatability and zeta potential patterns which in turn disputed the earlier results reported by our group. Comprehensive studies conducted on eight feldspar samples using ESCA and SEM/EDS probe analysis revealed the presence of nano spots on the surface of microcline; these nano spots with a dimension ranging anywhere from several nanometers to about 1000 nm not only distort the surface but also control the flotation behavior of the feldspar minerals. Interestingly, these spots shelter elemental impurities which could not be detected in the bulk analysis but assay several percents of Mn, Cu, Ba, Cr, Fe and Ni in the depth of 20 °A from the surface. These impurities are believed to be exposed upon preferential breakage of particles along the weak boundaries and modify the surface of microcline proportional with their numbers.