LAUSR

Abstract In order to improve the utilization efficiency of surfactants, a novel addition mode injects surfactant vapor into the bubbles has been proposed. The effect of the cationic surfactant dodecylamine (DDA) and the frothers methyl isobutyl carbinol (MIBC) and 2-octanol on the collision between bubbles and hydrophilic/hydrophobic quartz was evaluated under three surfactant addition modes namely as: 1) vapor in air, 2) dissolved in water, and 3) vapor in the air and dissolved in water. When the surfactants were added as vapor in the air the induction time and collision frequency were smaller than those when surfactants were dissolved in water and added partially dissolved in water and as vapor in air. This is independently of the surfactant sort and quartz surface property. Of these three surfactants, when added as vapor, DDA showed smaller collision frequency and induction time as compared to MIBC and 2-octanol. When the surfactants were dissolved in water and added partially dissolved in water and as vapor mixed with the air, the induction time and collision frequency were larger with DDA as compared to MIBC and 2-octanol. The induction time increased nearly linearly with the collision frequency, independently of the surfactant sort, surface property and surfactant addition mode. The contact angle decreased as the induction time increased on the hydrophobic methylated quartz surface while it was almost constant as the induction time increased on the hydrophilic quartz surface. The results may provide valuable insight into the development of surfactant utilization and waste mitigation in flotation.