Study on surface physical and chemical mechanism of nanobubble enhanced flotation of fine graphite

Abstract

It has been concluded in a recently published investigation that the nanobubble flotation process significantly reduces the number of fine flake graphite flotation stages and improves the flotation performance. The present study was conducted to explore the mechanisms of surface nanobubbles enhancing flake graphite flotation by investigating effects of nanobubbles on surface properties of graphite and interactions between particles and bubbles by use of contact angle analyzer, zeta potential analyzer, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The study results show that nanobubbles can improve the surface properties of graphite and enhance the adsorption effect of collector, which increased the contact angle of the graphite surface by 11.93° compared with conventional flotation. Infrared spectroscopy and potential analysis showed that the nanobubbles could enhance the hydrophobic attraction and reduce the electrostatic repulsion between the collector and the graphite surface, which was beneficial to enhance the hydrophobic surface of the graphite and enhance the agglomeration of fine graphite particles. XPS analysis showed that the nanobubbles covered polar hydrophilic groups (such as CO, CO, COOH) on the graphite surface, which enhanced the adsorption of collector to improve the hydrophobicity of graphite surface.