On the gas dispersion measurements in the collection zone of flotation columns

This work shows the results of gas dispersion parameters in a fully controlled laboratory column flotation cell, namely gas hold-up (εg), superficial gas velocity (Jg) and bubble size distribution, measured directly by image analyses using the LTM-BSizer. Gas hold-up and bubble size (and their distribution) were found to be strongly dependent on Dowfroth 250 concentration and superficial gas velocity. A fairly linear relationship between experimental εg and bubble superficial area flux (Sb) was established, and results are compared to those calculated using drift flux analysis. Data obtained are discussed in terms of solution, hydrodynamics and interfacial phenomena. Possible implications on the role of the frother in the energy dissipation in bubble generation and on interfacial tensions are explored. ► Accurate measurements of gas dispersion parameters in a lab column flotation cell are reported. ► The parameters were: gas hold-up, εg, superficial gas velocity and bubble size distribution (BSD). ► εg and BSD strongly depended on Dowfroth 250 concentration and superficial gas velocity. ► A linear relationship between εg and bubble superficial area flux (Sb) was established.