Effect of separation angle on bubble-particle detachment behavior and detachment force

Abstract

The study of bubble-particle detachment is crucial for enhancing the flotation effect of coarse particles and increasing the upper limit of flotation particle size. At present, there is a wide consensus on the normal direction detachment behavior of bubble-particle and the detachment force model. However, bubble-particle detachment may occur at arbitrary separation angle (ω) in actual flotation. Therefore, this study conducts an in-depth investigation into the effect of the separation angle on bubble-particle detachment. Firstly, using a self-made bubble-particle detachment testing system, the detachment behavior and detachment force of bubble-particle at different separation angles were tested. At the same time, the distribution of contact angles along the contact line in the normal direction (ω=0°) and non-normal direction (ω≠0°) detachment cases was tested, and the relevant models were revised. Finally, based on the revised contact angle distribution model, the detachment force model at arbitrary separation angle was derived, and the model prediction results were consistent with the experimental values. The study shows that with the increase of separation angle, the contact line in the bubble-particle detachment process successively shows the regularity of "two-way synchronous contraction, two-way asynchronous contraction, one side contraction and one side fixed, one side contraction and one side spreading", the contact angle changes from "synchronous change" to "cross change", and the detachment force decreases accordingly. In addition, it was found that when bubble-particle non-normal direction detachment occurs, the distribution of contact angles along the contact line is not the traditional step or linear model but shows a third-order distribution model. Based on this, the detachment force model at arbitrary angle was derived. This study not only helps to optimize the quantitative analysis of the bubble-particle detachment process but also provides strong support for the improvement of the bubble-particle turbulent detachment theory in the flotation process.