Effect of particle shape on bubble-particle attachment behavior: Roles of surfaces, edges, and vertexes

It has been understood through many studies that particle shape is important in terms of particle adhesion to air bubbles in flotation. However, there are many questions yet to be answered. Whether the surface of the particle or its sharp corners is effective is only one of the issues that need to be better understood. Therefore, this study aims to delve deeper into the fundamental studies on the role of particle's geometry (surface, edges, and vertex) in their flotation behavior by investigating the attachment of spherical, cylindrical, triangular prismatic, and cubic particles to air bubbles based on their attachment efficiency, settling velocity, collision efficiency, and induction time. Bubble-particle attachment test results inferred that the attachment efficiency was in the order of cubic > triangular > cylindrical > spherical. In addition, it was found that the induction time of the spherical surface decreased from 37 ms to 15 ms with increasing collector concentration, while the induction time of the edged cubic particle decreased from 8 ms to 2 ms. This was attributed to the fact that the edge facilitates the drainage, thinning, and rupture of the water film between the bubble and the particle, thereby increasing the attachment efficiency. Finally, it has also been observed that the three-phase contact line of the cube particle is larger than that of the spherical particle, which improves the attachment stability and reduces detachment efficiency. The results obtained in this study shed light on the fact that the shape of the particles fed to flotation can be produced by using a suitable mill and thus higher flotation efficiency can be achieved with lower collector concentration.