Surface modification of hemimorphite with lead ions and its effect on flotation and oleate adsorption

Abstract

This paper proposed the surface modification of hemimorphite using lead ions as a promising method for increasing its flotation recovery with sodium oleate as collector. The floatability of lead-modified hemimorphite was significantly improved and the flotation recovery of hemimorphite in the presence of lead ions reached up to 90.3% at 5 × 10−5 mol/L sodium oleate. The experimental results of zeta potential showed that lead ions could adsorb on the hemimorphite surface in the form of Pb2+ and Pb(OH)+, and the adsorbed lead species rendered the hemimorphite surface positively charged at pH < 8.5, facilitating the electrostatic interaction of the negatively charged collector with the mineral surface in addition to chemical adsorption. XPS measurement revealed that O atoms were the reactive sites on the hemimorphite surface interacted with lead ions, and it existed on the hemimorphite surface in the form of ZnO, SiO and OH species. O atoms on the hemimorphite surface interacted with Pb2+ and Pb(OH)+ in the flotation pulp to form a new active product, i.e., OPb complex through electrostatic interaction and chemical adsorption, which greatly increased the number of reactive sites on the hemimorphite surface. The adsorbed lead species on the mineral surface exhibited strong reactivity towards sodium oleate, so more hydrophobic species were formed on the hemimorphite surface, thus enhancing the floatability of hemimorphite.