Influences of oil collector on surface air nucleation in fine graphite flotation

Abstract

This paper investigates the effect of an oil collector, namely diesel oil, on surface air nucleation and the influence of nucleation microbubbles on collector adsorption in froth flotation. In order to prepare the condition for air nucleation in flotation, air-oversaturated water was produced using tap water pressurized by high-pressure air in an autoclave. Micro-flotation, single bubble collision experiments, contact angle measurements, microscopic observations, and agglomerations analysis were combined to investigate the effects of the oil collector on air nucleation and agglomerates formation. Furthermore, the free energy changes in an ideal system were utilized to explain the mechanisms. The experimental results and free energy changes show that diesel oil can improve the air nucleation probability on graphite surfaces by decreasing the barrier for nucleation. Meanwhile, the oil collector can also significantly increase the fraction of agglomerates formed in air-oversaturated water to improve the recovery of fine particles. Besides, the results indicate that the formation of nucleation microbubbles before collector conditioning can occupy significant surface areas of the graphite particles and inhibit the collector adsorption on the mineral surfaces.