Decoupling the mechanisms in chalcopyrite flotation with high sodium bentonite content when using saline water containing divalent cations

This study revealed the underpinning mechanisms in chalcopyrite flotation with high sodium bentonite content when using saline water containing divalent cations, Ca2+ and Mg2+. It was found that at a divalent cation concentration of 0.1 mol/L, the decrease of pulp viscosity significantly enhanced the copper recovery and grade. Entrainment still played a role as the salt concentration increased further. When pulp viscosity and entrainment were excluded, the non-selective aggregation of chalcopyrite and bentonite was also found to affect the copper grade. The change of flotation solution chemistry further influenced the electrostatic interaction between chalcopyrite and bentonite. The underpinning mechanism was the ion exchange reaction between sodium bentonite and saline water through which altered the elemental distribution and inner structure of bentonite. The findings in this work suggest that when using saline water containing Ca2+ and Mg2+ in flotation, the ionexchange interaction makes the control of divalent cations concentration in industry flotation more complex, particularly for sodium bentonite-ore. However, within an appropriate range of divalent cations concentration, both copper grade and copper recovery can be enhanced, instead of removing Ca2+ and Mg2+.

Automated summary

This study identified the mechanisms of chalcopyrite flotation with high sodium bentonite content using saline water with divalent cations, Ca2+ and Mg2+. The decrease in pulp viscosity significantly enhanced copper recovery and grade at a certain concentration of divalent cations, while non-selective aggregation of minerals also affected copper grade. The findings suggest that the ion exchange interaction complicates the control of divalent cations concentration in industry flotation, but within a suitable range, both copper grade and recovery can be enhanced.