Understanding the roles of high salinity in inhibiting the molybdenite flotation

De-ionized water (DI water) and simulated sea water were applied to float molybdenite in this study. Results showed that the flotation recovery of molybdnite was sharply reduced in simulated sea water at pH above 9.5. To find out the exact mechanisms of depression, several advanced apparatuses were applied for surface characterization. Based on the measurements by the scanning electron microscopy (SEM), two kinds of precipitates (colloidal precipitates and crystallized precipitates) were observed on the molybdenite surface which was immersed in the simulated sea water during flotation. It was found that the colloidal precipitates overspread on the surface while the crystallized precipitates randomly scatted on the surface. With the detection by auger electron spectrum (AES), it was found that magnesium and calcium were the main components in the colloidal precipitates and crystallized precipitates, respectively. According to the X-ray photoelectron spectrum (XPS) tests, it was testified that the colloidal precipitates were Mg(OH)(2) and the crystallized precipitates were CaCO3, which was confirmed by ToF-SIMS results. These precipitated Mg(OH)(2) and CaCO3 particles on the molybdenite surfaces play an important role in inhibiting the flotation of molybdenite in the simulated sea water. (C) 2016 Published by Elsevier B.V.