Abstract

This technical note presents results of gas dispersion measurements carried out in industrial mechanical flotation cells from Chilean concentrators. Results showed that superficial gas rate, gas holdup and bubble size were within ranges found in literature. The bubble surface area fluxes (S-B) were computed using the superficial gas rates and the Sauter mean diameters, obtaining approximate S-B ranges from 20 m(2)/s/m(2) to 60 m(2)/s/m(2) for both self-aerated and forced-air flotation cells. Despite the different cell types, sizes and wide range of operating conditions, an exponential relationship between superficial gas rate (JG) and Sauter mean diameter (D-32) was obtained: D32 =D-0 center dot e(7JG). D-0 = 0.77 +/- 0.11. gamma = 0.77 +/- 0.09 This result allows predicting D-32 as a function ofk. Data on gas holdup (epsilon(G)) as a function of Sauter mean diameter were also presented: For J(G) < 1.2 cm/s, gas holdup increases as superficial gas rate increases, indicating a dominant effect of superficial gas rate; for J(G) > 1.2 cm/s, gas holdup decreases as D-32 increases, indicating a predominant effect of bubble coalescence. (C) 2013 Elsevier Ltd. All rights reserved.