Study on the effect of flocculation morphology on the floatability of talc flocs and the adhesion mechanism with air bubbles

Abstract

This study investigates the impact of floc morphology on flotation by preparing two types of flocs with similar apparent particle sizes but different aggregation degrees through varying the stirring speed. Flotation tests were conducted on the two flocs, revealing that flocs with higher aggregation degrees demonstrated superior floatability and higher flotation rate constants. Fractal dimension and AFM analysis indicated that flocs with higher aggregation degrees exhibited higher fractal dimensions, displaying a more circular and compact overall morphology, as well as a more regular and uniform surface morphology. XPS and contact angle tests showed that, for flocs with comparable particle sizes, an increase in fractal dimension led to increased adsorption of flocculant (PEO) on the surface, accompanied by enhanced hydrophobicity. Further analysis of the induction time for particle-bubble attachment and coverage angle demonstrated that flocs with higher fractal dimensions had shorter induction times and larger coverage angles, indicating faster attachment between flocs and bubbles. These findings suggest that flocs with higher fractal dimensions can acquire greater kinetic energy in a flow field, enabling them to more effectively disrupt the hydration film on the bubble surface and adhere to the bubble surface, thereby enhancing floatability.