Force analysis of bubble-particle detachment colliding with a solid surface

Abstract

This is the second in a series of papers concerned with bubble-particle detachment colliding with a solid surface. Part I [22] explored, experimentally, the detachment of a particle from the surface of a bubble colliding with a solid surface in mimic of the pulp-froth interface. Detachment was seen to be dependent on interactions between the bubble-particle aggregate and the solid surface, which is characterized by the inclination angle. A neck was formed during the detachment process between a particle and a bubble. Zoom in images of bubble-particle aggregate are used to extract parameters on contact angle and three-phase contact, which can be used to calculate forces acting on the particle.

Part II presents calculations of the forces in the particle detaching processes, which is essential to the modelling of coarse particle flotation processes. It is found that advancing contact angle serves as a prerequisite for the particle detachment in both particle detachment modes, i.e. rebound detachment and slip detachment. The advancing contact angle makes the three-phase contact line contract and move over the location of the maximum capillary force. After which the particle is likely on the track of detachment.

This study provides detailed experimental observations and calculations of the forces acting on particles during separation, analyzes the forces between particles attached to bubbles when aggregates collide with a flat wall, and provides the first quantitative analysis of the impact of contact angle hysteresis on the separation mechanism, providing new insights for applications in the field of transportation and beneficiation.