Analysis of dynamic interactions in a bubble-particle system in presence of an acoustic field. (15th January 2019)

• Record Type: Journal Article
• Authors: Yasmin, Dilruba; Mitra, Subhasish; Evans, Geoffrey M.
• Is Part Of: Minerals engineering. Volume 131(2019)
• Page Start: 111
• Page End: 123
• Publication Date: 2019-01-15
• Subjects: Bubble-particle interaction -- Acoustic field -- Bubble oscillation -- Rayleigh-Plesset model -- DEM -- Collision -- Attachment; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2018.11.008
• Languages: English
• ISSNs: 0892-6875

Abstract

Graphical abstract: Highlights: 3D model developed for bubble-particle interactions in an acoustic field. Bubble oscillation enhances collision in surface clearance range from 1 to 10.6%. Collision efficiency (20–100%) predicted in Bo number range from 0.01 to 0.5. No attachment predicted in below resonance frequency regime (35–79 Hz). Attachment efficiency (10–50%) predicted in above-resonance regime (3.61–14.4 kHz). Abstract: Use of an acoustic field in flotation is known to improve mineral recovery. However, studies in this area are rather limited and in general there is a lack of a mechanistic description of the collision and collection efficiency of particles in presence of an external acoustic field. This study aims to contribute to this knowledge gap by developing a simplified 3D numerical model of single bubble-particle interactions based on a discrete element method (DEM) based approach. Volume mode oscillatory behaviour of the bubble was modelled within the theoretical spherical shape limit (0.1 ≤ Bo ≤ 0.5) using 1D Rayleigh-Plesset equation in a quiescent liquid medium and one-way coupled to particle motion obtained through DEM. Interaction dynamics were simulated for various operating conditions involving three parameters, namely oscillation amplitude ratio ( ε ≤ 0.1), excitation frequency (below and above resonance frequency) and bubble-particle surface-to-surface distance (∼1.0 to 10.6% of bubble radius). Regime maps were constructed to establish suitable combinations of these three operating parameters to represent the collision and attachment behaviour of a particle with the oscillating bubble. While conventional flotation models predict particle collision efficiency based on the nearest streamline adjacent to the bubble surface, application of an acoustic field on a bubble was shown to incur collision with a particle in the far field away from the interface due to oscillatory motion. It was noted that although such collisions occurred in the below-resonance-frequency regime (∼35 to 79 Hz), particle attachment did not occur due to weakening of the attractive capillary force. In the above-resonance-frequency regime (3.61–14.4 kHz), however, particle attachment was predicted and attachment probability increased in the vicinity of the bubble resonance frequency.