Effects of emulsifier concentration in a high-internal-phase, W/O emulsion binder on particle agglomeration

Abstract The kinetics of hydrophobic particle recovery by flotation declines with particle sizes below 20 µm. This work investigated a much-faster novel process, agglomeration, which utilises a high-internal-phase, water-in-oil emulsion as the binder. The effects of changes in the binder composition were studied by varying the emulsifier:oil ratio from 0.2:1 to 100:1, while maximizing the concentration of the dispersed aqueous phase within the binder. The oil consumption was assessed as an inferred film thickness surrounding the individual hydrophobic particles captured by the agglomeration. This film thickness decreased from 156 nm to as little as 4.5 nm by increasing the emulsifier concentration. This result is consistent with an increase in the emulsifier concentration causing an increase in the internal oil–water interfacial area within the binder. Water permeation into the binder, which reduces the viscous resistance to particle capture, decreased to an asymptotic level beyond a 5 wt% emulsifier concentration.