The anisotropic adsorption of potassium cetyl phosphate on molybdenite surface and its implication for improving the flotation of molybdenite fines

Abstract

The flotation of molybdenite fines is a challenging task during mineral processing worldwide. In this work, potassium cetyl phosphate (PCP) was explored as a novel collector to enhance the flotation of molybdenite fines. The flotation performances were assessed by micro-flotation tests. The adsorption mechanisms were uncovered through Zeta potential, Fourier Transform Infrared Spectrometer (FTIR), X-ray Photoelectron Spectroscopy (XPS), atomic force microscopy (AFM), Tafel curves, cyclic voltammetry, contact angle and density functional theory (DFT) calculations. The flotation tests demonstrated that PCP could efficiently collect molybdenite fines. Zeta potential and contact angle results suggested that the adsorption of PCP significantly improved the hydrophobicity of molybdenite surfaces. AFM, Tafel curves and adsorption energy revealed that PCP had a preferential affinity to edges (Eads = -735.14 kJ/mol) than faces (Eads = 33.5 kJ/mol). FTIR, XPS, cyclic voltammetry and DFT analysis manifested that PCP chemisorbed on the edges via the hybridization of the O 2p orbital of P-O radical within phosphate groups with the Mo 4d orbital, forming two high ionicity bonds, which could replace kerosene to improve the flotation of molybdenite fines.