New insights into the interaction between low-rank coal particles and clay minerals and its role in flotation responses

This study investigates the adverse effects of fine clay minerals on low-rank coal (LRC) flotation. Zeta potential analysis, X-ray photoelectron spectroscopy, flotation experiments, and the particle-bubble attachment index (PBAI) were employed to assess these effects. Results indicate that quartz and chlorite particles are more prevalent in the flotation concentrate than kaolinite and montmorillonite, likely due to their preferential adsorption of flotation collectors, which inhibits the hydrophobicity of the LRC surface. Montmorillonite, however, exhibits greater adhesion to LRC surfaces due to its positive charge. Extended DLVO theoretical analysis reveals that polar surface interaction energy is a primary driving force in coal-mineral interactions and is crucial in overcoming the energy barrier posed by electrostatic double-layer forces. The impact of clay minerals on LRC flotation is highly dependent on clay type.