A pre-adsorption system: The application of 8-hydroxyquinoline in the separation of specularite and chlorite

Abstract

The conventional methods of separating closely related minerals like chlorite and specularite present challenges. This study delved into the pre-adsorption effect of 8-hydroxyquinoline (8-HQ) in a reverse flotation system using dextrin as a depressant and dodecylamine as a collector through single mineral flotation experiments, contact angle tests, Zeta potential determination, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The aim was to facilitate reverse flotation by pre-introducing 8-HQ to create specific adsorption with Al/Mg elements on the chlorite surface, thereby enhancing chlorite's flotation ability. Single mineral flotation experiments demonstrated that 8-HQ effectively heightened the disparity in floatability between the two minerals. When 15 mg/L of 8-HQ was added at a pH of 8, chlorite recovered 82.15 percent, while specularite only produced 19.2 percent. Results from artificial mixed minerals substantiated the feasibility of single mineral flotation. Further investigation into adsorption mechanisms revealed that 8-HQ forms steric hindrance via chelation and hydrogen bonding, preventing dextrin from adhering to the metal elements on the chlorite surface. The inherent hydrophobicity also promotes the formation of DDA hydrophobic flocs. Conversely, there was no notable adsorption between 8-HQ and specularite. Specularite could be specifically depressed by dextrin, enabling the selective separation of the two minerals. Finally, a model depicting the potential adsorption of 8-HQ on the mineral surface was proposed.