Foam growth dynamics in the presence of a rising bubble plume: Effect of surfactant concentration and gas superficial velocity

This study investigates foam formation dynamics in the presence of a rising bubble plume which has significant importance in mineral flotation process. Three surfactant systems - anionic (SDS), cationic (CTAB), and a CTABNaCl mixture were used to quantify the foam growth behaviour for different surfactant concentrations and gas superficial velocities (ug). High-speed imaging was used to measure the bubble size distribution and foam heights. The chemistry of the surfactant systems significantly influenced bubble sizes in the bulk affecting the foam growth behaviour. SDS systems produced smaller bubbles in the bulk compared to the CTAB systems which led to relatively spherical shape and polygonal bubbles in the bulk and foam, respectively. Foam stability was characterised using several parameters - equilibrium foam height, equilibrium time, foamability and foam halflife. In general, enhanced foam stability was observed when surfactant and electrolyte concentration was high, and gas superficial velocity was low up to a system specific threshold.