Effect of surface chemical heterogeneity on kinetics of three phase contact formation

Abstract

Bubble–particle interaction is a major focus for froth flotation research that has widespread use in mineral separation and concentration. The formation of a stable three phase contact (TPC) line is key to successful flotation. In industrial flotation processes, nearly all surfaces of particles are heterogeneous. Thus, the investigation of the influence of surface heterogeneity on the kinetics of TPC formation is important for understanding these processes. In this study, four types of heterogeneous surfaces were prepared by hydrophobization of glass slides followed by partial coverage with different mesh grids and oxidization with UV light. Interactions between bouncing bubbles and heterogeneous surfaces were investigated using a high-speed video camera. The results showed that the interval times between consecutive collisions with the patterned slide surface (before rupture) are almost independent of the surface. However, the behavior of the TPC line differed on various heterogeneous surfaces after bubble rupture. The terminal diameter was measured on different heterogeneous surfaces. It was found that the terminal diameter increased with the decrease in the mesh spacing of the grid. The slope of each curve is used to characterize the TPC line expansion velocity. The TPC line initial expansion velocity is inversely correlated with the grid mesh spacing. The surface heterogeneity had insignificant effect on the collision interaction between the bubble and the surface before the bubble rupture. However, after bubble rupture, the behavior of the expansion of TPC line was affected by the surface heterogeneity.