The role of surface mobility in enhancing froth drainage and reducing entrainment in flotation

• Low-dosage glycerol in wash water increases froth drainage and concentrate grade. • Drainage improvement by glycerol varies with bubble size and particle properties. • Fine, well-liberated particles form small, rigid bubbles that hinder drainage. • Coarse particles promote mobile bubbles, facilitating faster drainage but risk yield drop. • Outcomes highlight roles of hydrogen bonding and surface mobility in froth drainage. Improving froth drainage is crucial for reducing gangue entrainment and increasing concentrate quality in flotation. Advancing our previous work on promoting foam (particle-free) drainage via modulating interfacial mobility through hydrogen bonding networks at the air–water interface, this study extends the investigation to particle-laden froths under industrially relevant conditions. Laboratory-scale flotation experiments were performed in a Microcel™ column with industrial samples of varying but controlled particle size distributions and regrinding. Froth imaging was employed to assess froth bubble behaviour. Results reveals that low-dosage glycerol significantly enhances flotation froth drainage, underscoring the role of interfacial hydrogen bonding in modulating interfacial mobility and froth drainage in three-phase systems. The extent of water drainage improvement depends on bubble size, which is influenced by particle characteristics. Fine, well-liberated particles generate small, rigid bubbles that hinder water drainage, whereas coarser particles promote larger, more mobile bubbles that facilitate faster drainage but may reduce concentrate mass yield due to bubble coalescence. These findings provide new insights into tailoring froth structure and surface mobility for improved flotation performance.