Innovative dispersant for reducing heterogeneous coagulation of pentlandite and serpentine and new insight for their dispersion

Abstract

Serpentine is easily muddy and has a high zero electric point of zero charge (PZC), which leads to heterogeneous coagulation with pentlandite, which seriously affects the flotation of pentlandite. To solve this problem, from the new perspective of reducing the heterogeneous coagulation of pentlandite-serpentine and dispersing them, this study explored the influence of sodium tungstate as a dispersant on the dispersion of between pentlandite and serpentine using flotation tests, zeta potential tests, scanning electron microscope-energy dispersive spectrometer (SEM-EDS) examination, molecular dynamics simulation (MS), and calculations of the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory. The results show that −20 μm fine serpentine seriously deteriorates the flotation of pentlandite, while adding sodium tungstate can significantly promote the flotation separation of pentlandite and serpentine. MS simulation results showed that sodium tungstate could be chemisorbed with iron ions on the surface of pentlandite and mainly physisorbed with serpentine. EDLVO theoretical calculations show that after adsorption of sodium tungstate, the interaction between the two changed from attraction to repulsion at pH less than 10, and the mutual attraction was weakened at pH more significant than 10, thus weakening the heterogeneous coagulation between pentlandite and serpentine and causing serpentine to desorb from the surface of pentlandite, thus restoring the floatability of pentlandite, which SEM-EDS also confirmed. This provides a new insight into the dispersion mechanism of sodium tungstate as the innovative dispersant that is different from other dispersants for reducing heterogeneous coagulation of pentlandite and serpentine.