Influence of electrochemical solution activation on kinetics of pyrite flotation: Experimental and theoretical investigations

Abstract

This study modeled the molecular structure of adsorbed water films on the pyrite (100) surface using density functional theory (DFT) to investigate the effects of hydronium ions on the surface bonding interactions. Adding hydronium ions to the water films weakened the Fe–O interaction, increasing the Fe–O bond distance from 2.145 to 3.245 Å and, consequently, reducing hydrogen bonding among water molecules within a 5.5-Å range of the FeS₂ surface. Molecular dynamics simulations further revealed the proton transfer dynamics from the subsurface to upper water layers, aligning with experimental observations of the kinetics of pyrite particle attachment to air bubbles. Electrochemical activation of a sodium bicarbonate solution enhanced the pyrite particle loading on the bubbles by up to 32 % compared to a nonactivated solution. These results suggest that hydronium-mediated surface modifications intensify the flotation process, providing insights into optimizing mineral separation techniques.