Modelling the motion of a collected particle over a bubble surface

Froth flotation is a process that utilizes the surface properties of mineral particles to separate them from unwanted gangue materials. Usually, the mineral particles are either naturally hydrophobic, or surfactant-treated hydrophobic and thus, they are prone to adhere to bubbles. Once attached, the capillary force is dominant in the control of the particle bubble aggregate stability. Capillary force is a function of surface tension and contact angle, which is a measure of particle hydrophobicity. In this paper, the Discrete Element Method has been applied to simulate the interaction between particles and a central bubble in a quiescent liquid with the aim of describing: (1) the motion of the particle sliding over the bubble surface, and (2) the formation of the three phase contact line. Simulation results for particle-bubble separation distance versus time showed excellent agreement with experimental observations. Moreover, the simulations correctly predicted the time when the particle contacted the bubble. Additional simulations were carried out for multi-particle attachment that highlighted the interaction between particles, including collision and rebounding phenomena. These simulations correctly captured experimental observations reported in the literature and have provided valuable insight into the particle loading capacity of bubbles being utilized in mineral flotation devices