Influence of bubble size on performance of apatite flotation of different particle sizes

The main mechanism of flotation is bubble-particle interaction, which is strongly dependent on the particle size and the bubble size distribution (BSD). It is known that air bubbles are responsible for collecting and delivering hydrophobic particles from the pulp to the foam zone. Controlling the size and distribution of bubbles generated is essential to promote greater bubble-particle interaction. The aim of this study was to investigate the influence of bubble size on the flotation performance of apatite of a low-grade phosphate ore for different particle sizes: fine (d32 = 13.95 µm), intermediate (d32 = 50.86 µm), and coarse (d32 = 108.96 µm). Through the results, it was possible to identify the best bubble size range for each particle size studied. The fine particles showed a better flotation performance when medium-sized bubbles (800–1,000 µm) were used, while the coarse particles had an improved performance when large bubbles (d32 > 1,000 µm) were used. However, the best flotation result was obtained with intermediate particles, which accepted a large range of bubble size distribution under different operating conditions since the collision and attachment mechanisms are favored in this particle size range.