Influence of bubble diameter and solids concentration on bubble stability: Development of a novel analytical approach

Abstract

The properties and thickness of the bubbles in the froth control the flotation process. There is no work showing how to measure bubble film composition and thickness by a straightforward manner. In this work, a novel approach, a custom-designed bubble cell associated with layer interferometry (in the UV-vis region) and FT-IR spectroscopy was used to investigate the effect of solid particle type (hydrophilic vs hydrophobic), concentration and bubble diameter on stability of a bubble blown in air. Stability was quantified by measuring bubble lifetime and hydrated film thickness. Kerosene with silicone oil as a foaming agent was used to evaluate the impact of bubble diameter (test series I). Frother solutions (MIBC, Dowfroth 250, Hexanol and F-150) were used for the solid type concentration experiments (test series II). In the first series of experiments, it was determined that as the diameter of a bubble increased from 10 to 25 mm, so did the hydrated film thickness from 350 to 1000 nm. In the second series, as the silica concentration increased (0 to 10%), an increase in bubble lifetime and hydrated film thickness was resulted (130%–250%). An impact of solid hydrophobicity was found but to a lesser degree than expected. It is possible that the small particle size (<0.1 m) of silica was responsible for this behavior. The findings are used to interpret the effect of solids in flotation froth.

Keywords

bubble diameter / bubble lifetime / thin liquid film / UV-visible

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