Understanding interaction mechanisms between pentlandite and gangue minerals by zeta potential and surface force measurements

Understanding the interaction between valuable and gangue minerals is of both fundamental and practical importance in the field of flotation. In this study, we investigated the interactions between valuable (i.e. pentlandite) and gangue minerals (i.e. serpentine, olivine, and magnesite) in an aqueous solution by directly measuring the zeta potential distributions. In addition, interaction force measurements using an atomic force microscope (AFM) were performed between a silicon nitride tip and gangue mineral surfaces, and the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to fit the interaction force between the silicon nitride tip and gangue mineral surfaces. In the case of serpentine and pentlandite mixture system at pH 10.1, only a single zeta potential distribution was obtained, as compared to two distinct distributions for the two individual minerals, indicating an attractive interaction is present between the two minerals. For olivine and pentlandite mixture system, a single distribution with two distinct spikes was obtained in the zeta potential distribution of the mixture, indicating repulsive interaction between the two minerals. Similarly, a single distribution with two distinct spikes was also observed in the zeta potential distribution of magnesite and pentlandite mixture system, indicating repulsive interaction between the two minerals. Repulsive interaction between silicon nitride tip and olivine surface, and slight attractive interaction between silicon nitride tip and magnesite surface, were observed and consistent with the DLVO model. The zeta potential and AFM force measurements show good agreement regarding the surface charge properties and interactions of the minerals, and provide complementary information and new insights into the interaction mechanism of valuable and gangue minerals. (C) 2014 Elsevier Ltd. All rights reserved.