Exploring the mechanism of a novel cationic surfactant in bastnaesite flotation via the integration of DFT calculations, in-situ AFM and electrochemistry

Abstract

Effectively separating bastnaesite from calcium-bearing gangue minerals (particularly calcite) presents a formidable challenge, making the development of efficient collectors crucial. To achieve this, we have designed and synthesized a novel, highly efficient, water-soluble cationic collector, N-dodecyl-isopropanolamine (NDIA), for use in the bastnaesite-calcite flotation process. Density functional theory (DFT) calculations identified the amine nitrogen atom in NDIA as the site most susceptible to electrophilic attack and electron loss. By introducing an OH group into the traditional collector dodecylamine (DDA) structure, NDIA provided additional adsorption sites, enabling synergistic adsorption on the surface of bastnaesite, thereby significantly enhancing both the floatability and selectivity of these minerals. The recovery of bastnaesite was 76.02%, while the calcite was 1.26%. The NDIA markedly affected the zeta potential of bastnaesite, while its impact on calcite was relatively minor. Detailed Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results elucidated that the ―NH― and ―OH groups in NDIA anchored onto the bastnaesite surface through robust electrostatic and hydrogen bonding interactions, thereby enhancing bastnaesite’s affinity for NDIA. Furthermore, in situ atomic force microscopy (AFM) provided conclusive evidence of NDIA aggregation on the bastnaesite surface, improving contact angle and hydrophobicity, and significantly boosting the flotation recovery of bastnaesite.