Improving the flotation efficiency of Pb–BHA complexes using an electron-donating group

Abstract Lead complexes of benzohydroxamic acid (Pb–BHA) are metal-organic complex collectors having excellent selectivity. However, the flotation efficiency of Pb–BHA needs improvement. In this research, we report the introduction of an electron-donating group into the BHA ligand to improve the performance of Pb–BHA in mineral flotation; p-methyl-benzohydroxamic acid (MBHA) was synthesized and used as a new ligand to form the Pb–MBHA complex. The flotation behavior of Pb–MBHA in scheelite flotation was investigated using micro-flotation experiments. The adsorption mechanism of collectors at the solid–liquid interface was investigated via solution chemistry analysis, Fourier-transform infrared spectroscopy (FTIR), zeta potential, X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Froth stability tests were used to study the adsorption behavior of the collectors at the gas–liquid interface. Pb–MBHA had stronger collecting ability and pH adaptability than Pb–BHA. The Pb(MBHA)+, Pb(MBHA)2, and Pb(OH)MBHA were the main species of Pb–MBHA in solution. For oxygen atoms on the scheelite surface, Pb–MBHA has stronger chemical adsorption ability than Pb–BHA, and its adsorption made the scheelite surface more hydrophobic. The foaming ability and foam stability of Pb–MBHA were stronger than those of Pb–BHA in solution, and stable foam was more likely to form at the gas–liquid interface.