Role of crystal structure in flotation separation of diaspore from kaolinite, pyrophyllite and illite

Wettability and electrokinetics of kaolinite, illite, pyrophyllite and diaspore were measured in the context of reverse flotation using cationic collectors. The results were interpreted by crystal structure analysis of the minerals. The point of zero charge (PZC) was calculated using crystallographic parameters of the minerals and compared well with the corresponding iso-electrical point (IEP) determined experimentally. The decreasing order of the measured IEP or calculated PZC from diaspore to kaolinite, illite and finally pyrophyllite correlated well with decreasing the number of broken Al–O bonds and the ratio of broken Al–O to Si–O bonds. The electrostatic interaction was identified as the main driving force for cationic collector adsorption on the minerals. Satisfactory separation of aluminosilicates from diaspore was achieved by reverse flotation.