Bubble-particle detachment in flotation: A comparative study of the tangential and vertical direction

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Bubble-particle detachment plays a crucial role in flotation, affecting the recovery of coarse particles. This study investigated the detachment of bubble-particle aggregates in both tangential and vertical directions using experimental and numerical simulation methods. Bubble-particle aggregates stability was evaluated using a bubble-particle oscillatory detachment test system and an interaction force test system. A high-speed camera and the lattice Boltzmann method (LBM) were used to compare detachment processes in both directions and determine similarities and differences. Results indicate that the stability of bubble-particle aggregates is significantly lower in the tangential direction than in the vertical direction, making them more prone to detachment in the tangential direction during flotation. The detachment process of aggregates in both the vertical and tangential directions can be divided into three stages: bubble stretching, bubble sliding, and bubble necking. The contact angle reaches the advancing contact angle as a prerequisite for the contraction of the contact line, and a tiny bubble is left on the particle surface at the end of the detachment process in both directions. However, there are differences in specific processes, with simultaneous increases in contact angles on both sides of the aggregates in the vertical detachment process and “cross” variation in contact angles in the tangential detachment process. These findings further our understanding of the bubble-particle aggregates mechanism and have significant implications for the flotation industry, particularly for coarse particle flotation.