Investigating the gas holdup in a gas-liquid cyclonic flotation column through the electrical resistance tomography

Abstract

ABSTRACT Gas dispersion characteristics are of significant importance in froth flotation. Studies show that cyclonic static microbubble flotation column (FCSMC) is an efficient device to recover fine minerals. In the present study, the gas holdup distribution and the mean gas holdup in a laboratory gas-liquid FCSMC are first quantitatively measured by electrical resistance tomography (ERT). Different flowrates of gas and liquid are considered. Performed experiments show that when the air flowrate increases from 1.1 L/min to 2.3 L/min, the mean gas holdups on measured planes increase to about 4 ~ 5 times the original value. The gas dispersion along the radial direction is poor, which is dense in the center and rare in the periphery. This uneven bubble distribution aggravates as the amount of the supplying air increases. As the circulating liquid flux increases, the corresponding measured gas holdup gradually decreases and the bubble shrinks to the center along the radial direction. When the liquid flux increases from 1.5 m3/h to 1.8 m3/h, the averaged decline of the mean gas holdup on measured planes reduces to 54 ~ 65% of the original value. Finally, it is validated that the sieve plate packing effectively reduces non-uniform radial and axial distributions of the gas holdup. The obtained results might lead to more effective operating of FCSMC, provide a reference for further numerical study and ERT application in other complicated devices.