Effect of air flow rate and froth depth on the flotation performance : an industrial case study in a 10 m3 cell

The main purpose of the froth zone in flotation is to transport all the valuable particles from the pulp zone into the concentrate. However, in practice, a complete recovery of these particles is rarely achieved since some of them are detachment from the bubbles and return to the pulp zone. While this is an important topic in the mineral flotation industry, the previously published papers are mainly limited to small laboratory scales. Therefore, this study aimed to examine the effect of two main flotation variables (air flowrate and froth depth) on the flotation of iron ore in a 10 m3 industrial scale cell. It was found that, when the air flowrate increased from 45 to 146 m3/h, the velocity of the bubble coalescence also increased. In addition, when the froth depth increased from 5 to 30 cm, the product grade showed on average 2 unit increase (for instance, from 12% to 14%) due to the detachment of particles and liquid drainage. It was also found that the flotation concentrates recovery decreased with the increasing froth depth and air flowrate.