An ampholytic surfactant of flotation separating quartz from silicate minerals: Insights from experiments and theory

Due to the analogous crystal structure, the efficient separation of quartz from silicate minerals presents significant challenges. In this study, we reported a quartz collector, referred to as C-01, which incorporates an ampholytic group for the reverse flotation separation of quartz from various silicate minerals, including albite, potassium feldspar, and kyanite, at a pH of 7. A series of flotation experiments demonstrated that collector C-01 exhibited a high degree of selectivity in adsorbing to the quartz surface, achieving an assay grade and the recovery exceeding 90%. Specifically, atomic force microscopy (AFM) and surface tension tests demonstrated that the collecting capacity of the ampholytic collector surpassed that of traditional mixed collectors for quartz, suggesting that innovative molecular design can enhance the intramolecular multi-group synergistic effect, which is superior to the intermolecular multi-group effect. Furthermore, the adsorption mechanisms on quartz were comprehensively investigated through Fourier-transform infrared (FT-IR) spectroscopy, zeta potential measurements, and density functional theory (DFT) calculations, indicating that collector C-01 selectively adsorbed to the quartz surface via electrostatic interactions and hydrogen bonding. Overall, this research offers a valuable framework for designing multi-group molecules with intramolecular synergistic effects as mineral collectors and for evaluating surface interactions in selective separation processes, with broader implications for the development of novel chemical additives in various engineering and environmental applications.