Gas dispersion properties: bubble surface area flux and gas holdup

Abstract

Bubble surface area flux has been related to flotation performance and advocated as a key “machine variable”. Analysis of available data suggests that bubble surface area flux (S b) and gas holdup ( ε g) are related by S b ∼ 5.5 ε g. This was the case for flotation columns and mechanical cells, both laboratory and plant scale, over the approximate range S b < 130s −1 and ε g < 25%. A relationship is expected given their similar dependence on gas rate and bubble size (both increase as gas rate increases and bubble size decreases). Reasons that a relationship may be obscured, especially in full size units because of the difficulty in defining the overall S b and ε g, are discussed. The possibility to replace S b by ε g as the machine variable has the advantage that gas holdup is easier to measure.