Estimation of Bubble Size and Gas Dispersion Property in Column Flotation

This study investigates bubble size measurements, bubble characteristics, and the relationship between key operating variables and gas dispersion properties in column flotation. As the frother concentration increased to 120 ppm, the bubble size distribution (BSD) transformed from bimodal to unimodal and achieved a minimum bubble size of 0.62 mm. The critical coalescence concentration (CCC) was identified as 120 ppm. Gas velocity and wash water velocity significantly influenced bubble size, with gas holdup peaking at 27% at 1.08 cm/s a gas velocity. The bubble-rising velocity increased as the bubble size increased, indicating that the bubble size and bubble-rising velocity were proportional. The bubble surface area flux decreased linearly with increasing bubble size and was significantly affected by the gas velocity. A strong correlation (R2 = 0.86) between measured and calculated bubble sizes was achieved, with an average size of 0.64 mm and an estimation error of ±13%. The study demonstrated that bubble size and distribution could be effectively controlled under specific operational conditions (Jg = 0.65–1.3 cm/s, JW = 0.13–0.52 cm/s, frother = 30–120 ppm). These findings highlight the importance of optimizing key variables to enhance column stability, regime maintenance, and flotation performance.