Effect of surface modification by lead ions on flotation behavior of columbite-tantalite

Ta and Nb are listed in the category of strategic metals. Columbite-tantalite is the most abundant Nb- and Ta-containing mineral. The flotation is a promising method for fine columbite-tantalite recovery. However, few studies have been performed on the surface modification and enhanced flotation recovery of columbite-tantalite in presence of benzohydroxamic acid (BHA). This study systematically investigates the surface modification of columbite-tantalite by Pb2+ ions and its effect on columbite-tantalite flotation with BHA as collector. The results show that the Pb2+ modification enhances the adsorption of BHA on the columbite-tantalite surface, increases its hydrophobicity, and consequently improves floatability. Zeta potential measurement and X-ray photoelectron spectroscopy (XPS) analysis reveal that the Pb ionic species (Pb2+ and PbOH+) interact with the columbite-tantalite surface via electrostatic attraction and chemical interaction, generating new active products on the mineral surface, i.e., -O-Pb complexes. The -O-Pb complexes exhibit strong reactivity toward BHA subsequently introduced into the flotation pulp. This leads to a significant improvement in the chemisorption of BHA on the Pb2+-modified columbite-tantalite surface. As a surface modification method, introducing Pb2+ ions can effectively activate the columbite-tantalite surface and increase its floatability.