Role of bubble size in flotation of coarse and fine particles - A review

Froth flotation is the dominating mineral beneficiation technique and has achieved great commercial success. This process has also found many applications in other industries where physical separation of materials is needed. However, its high process efficiency is often limited to a narrow particle size range of approximately 10-100 mum. Considerable efforts have been made to extend this size range to the lower limit of a few microns, even submicrons, and the upper limit of 1 - 2 mm, in response to increased needs for higher process efficiency and expanded applications of flotation. The particle-bubble collision, attachment, and detachment are the most critical steps in the flotation process. These individual elementary processes (microprocesses) and their effects on flotation efficiency are discussed and the most recent findings are reviewed. The low flotation recovery of fine particles is mainly due to the low probability of bubble-particle collision, while the main reason for poor flotation recovery of coarse particles is the high probability of detachment of particles from the bubble surface. Fundamental analysis indicated that use of smaller bubbles is the most effective approach to increase the probability of collision and reduce the probability of detachment.