DEM simulation of single bubble flotation: implications for the hydrophobic force in particle-bubble interactions

A 3D Discrete Element Method simulation model for a single bubble was developed in order to investigate the capture of hydrophobic particles. The bubble was considered stationary at the centre of the working space. Particle-particle and particle-bubble contacts were simulated using a linear spring-dashpot model. Gravitational, buoyancy, drag and hydrophobic forces were taken into account. The hydrophobic force was estimated through a single exponential decay law which depends on a pre-exponential parameter K and a decay length λ. It was observed that when λ was less than 10. nm, the number of the particles that were collected was independent of the strength of the hydrophobic force. In contrast, for values of λ within the range of 10-500. nm, the capture efficiency increased significantly with the strength of the hydrophobic force and λ. We have also demonstrated how these two parameters affect the particle trajectory around the bubble and thus produce a significant difference in particle collection when the strength and range of the hydrophobic force were varied