Bubble characteristics play an important role during mineral flotation process. With the application of ultrasound in flotation process, the mechanism of ultrasound on enhancing flotation performance has been paid more attention. However, the bubble rising characteristics under ultrasound action are not clear. This work aims to investigate the effect of ultrasonication on bubble rising behaviors in deionized water and MIBC (Methyl Isobutyl Carbinol) solution. The high-speed dynamic video technology was used to record the bubble rising process and analyze bubble rising behavior. The possible mechanism of ultrasound on bubble was explored by COMSOL software. Ultrasound has a similar effect as surfactant, increasing the bubble sphericity and decreasing the bubble rising velocity. A roughly negative linear relationship was found between the bubble aspect ratio and rising velocity, and the ultrasonication diminished this relationship. Marangoni effect was considered as the cause of MIBC affecting the bubble motion. The perturbations of cavitation bubbles around the observation bubble and the observation bubble surface oscillations were observed in the experiments. The acoustic radiation pressure from the pressure gradient around the bubble, bubble surface wave driven by the acoustic pressure fluctuations and the violent disturbance of cavitation bubble were considered as the explanation of the effect of ultrasound on bubble rising behaviour.

Air bubble; Ultrasound; Aspect ratio; Rising velocity