Effect of surface chemical heterogeneity on bubble attachment probability: Implications for coarse particle flotation

Abstract

Coarse particle flotation for gangue rejection at an early stage has received extensive attentions in mineral processing. Coarse particles often bear chemically heterogeneous surface with low exposure rate of valuable minerals. To date, the bubble attaching behavior at such heterogeneous surface remains unclear, which hinders the process optimization for coarse particle flotation. Therefore, this study investigated the attachment probability of bubbles of three sizes on four inclined hydrophilic surfaces containing discretely distributed hydrophobic dots. Note that these surfaces had the same area fraction of hydrophobic phase but different distribution pattern in terms of hydrophobic dot size and their distribution density. For small bubble of 550 μm in diameter, it was observed that the distribution density of the hydrophobic dots dominated the attachment probability. As the bubble size increased to 750 μm and 950 μm, bigger hydrophobic dot size could improve the bubble attachment probability. Further study found that the surface chemical heterogeneity and bubble size jointly determined the bubble adhesion force which is directly related to the attachment probability. This study reveals the matching mechanism between the exposed features of heterogeneous surface and bubble size, which would facilitate the process optimization for coarse particle flotation.