Froth transport characterization in a two-dimensional flotation cell

Abstract

A study of the froth bubble transport in a two-dimensional (2D) flotation cell was performed. Experiments were developed as a 2×2 factorial design, in which the effect of superficial air rate (1.2–1.8cm/s) and froth depth (2–4cm) on the froth transport for a two phase (air–water) system was characterized.Using image analysis techniques, bubble residence times, air recovery, bubble path and bubble size increase through the froth were obtained. This information was complemented by froth surface velocity measurements using the Visiofroth system.It was found that bubbles transported from the pulp–froth interface up to the overflow, showed a minimum residence time for bubbles entering the froth near the lip wall. Also, the air-recovery significantly changes in a range of 7–20% at different operating conditions.Higher residence times promoted bubble size increase by coalescence for bubbles transported from the interface. Conversely, for lower residence times, a smaller increase in bubble size was observed.