Co-adsorption mechanism of NaOL/OHA mixed collectors and its contribution to surface hydrophobicity of micro-fine ilmenite: An experimental and molecular dynamics simulation study

The efficient flotation of microfine ilmenite is attracting growing interest in the field of mineral processing. In this study, the flotability of microfine ilmenite (18–37 μm) with a single collector (NaOL or OHA) or mixed collector (NaOL/OHA) was studied by micro-flotation tests, and the molar ratio of the two collectors to maximize ilmenite flotation was determined. The positive synergistic effect between the two collectors was confirmed by a surface tension calculation. Zeta potential, adsorption experiment, and X-ray photoelectron spectroscopy measurements (XPS) showed that the mixed collector could co-adsorb at the Ti and Fe sites on the surface of ilmenite and the adsorption strength of the mixed collector was stronger than that of either single collector. The adsorption morphology of flotation reagents on the mineral surface was observed by atomic force microscopy (AFM), which confirmed that the mixed collector had high coverage on the ilmenite surface, indicating the existence of co-adsorption. The results of molecular dynamics (MD) simulations indicated that the relative concentration of water in the hydration film on the ilmenite surface decreased considerably and the hydrophobicity increased after exposure to the mixed collector.