Fundamental insights into the effect of bubble size on the bubble-particle detachment

Bubble size plays a pivotal role in froth flotation. The effect of bubble size on bubble-particle collision and attachment has been well identified, but how it affects bubble-particle detachment is still unclear. In this study, the effect of bubble size on bubble-particle detachment was fundamentally investigated, with a special focus on force behavior. The theoretically calculated forces, based on the parameters obtained from the image process, showed good agreement with the measured forces by the bimorph. The interaction force between the bubble and particle was first increased and then decreased during the detachment process, which was attributed to the dynamic competition of the capillary force and Laplace pressure force. The maximum value of the interaction force was defined as the critical detachment force. It represents the minimum detachment force required to detach a particle from a bubble. The critical detachment force was increased with bubble size, which suggested that the detachment between a particle and a larger bubble was more difficult. This was further confirmed by the study of detachment probability. It was found that the detachment probability of the bubble-particle aggregate with a smaller bubble size was higher than that with a larger bubble size.