Effect of surface roughness on the flotation performance of coarse glass beads

Surface roughness plays a pivotal role in bubble-particle interactions and flotation characteristics. In this study, the effect of surface roughness on the flotation performance of coarse particles has been fundamentally investigated. Surface roughness of coarse glass beads (with a median diameter of 429.91 μm) with varying etching times was characterized by a 3D optical microscope. The micro-flotation results showed that surface roughness can improve the flotation recovery of coarse particles. The fundamentals of surface roughness in assisting coarse particle flotation were investigated in terms of contact angle, bubble-particle attachment and detachment. It was found that surface roughness increases the particle hydrophobicity due to the Cassie-Baxter state on rough surfaces. The induction time decreased with increasing surface roughness, indicating that less time is required for the attachment between a bubble and a rough particle. Surface roughness facilitates the bubble-particle attachment. The measurements of attachment tenacity and detachment probability indicated that the stability of bubble-particle aggregates improves as surface roughness increases. Surface roughness helps prevent the bubble-particle detachment. Ultimately, the combination of increased bubble-particle attachment and reduced bubble-particle detachment improves the flotation recovery of coarse particles.