Comparison of adsorption capacity of water and hydroxide with collector reagents on geversite (PtSb2) mineral surface : a DFT-D insights

Abstract

The interactions of water, hydroxide and organic collectors with mineral surfaces are the key aspects that define the floatability behaviour of minerals. This study employed the density functional theory with dispersion correction (DFT-D) method to unravel the adsorption capacity and bonding behaviour of H2O, OH–, normalbutyl- xanthate (NBX–), butyl-dithiocarbamate (BDTC–), butyl-trithiocarbonate (BTTC–) and dibutyldithiophosphate (DBDTP–) with the PtSb2 (100) surface. The adsorption energy of hydration was found less exothermic than that of hydroxylation, indicating that the OH􀀀 had greater ability to interact with PtSb2 surface compared to H2O. The collector adsorption energies strength decreased in the order: BDTC > BTTC > NBX > DBDTP, and clearly the BDTC unveiled the superior exothermic adsorption. It was found that the collectors may easily displace water and OH􀀀 , and attach on the mineral surface during flotation due to their strong binding than water and OH􀀀 . However, since there was a greater probability of OH􀀀 attaching on the surface, operating at low pH may be decisive in the flotation of PtSb2 mineral. This study has compared the adsorption behaviour of various collectors with water and hydroxide and established the best conditions that may improve the flotation performance of PtSb2 mineral.