Formation and breakage of chalcopyrite aggregates produced by anionic polyacrylamides: Influence of polymer molecular weight and shear conditions

Flocculation-flotation is an important process for the treatment and recovery of fine particles. This study investigates the influence of polymer molecular weight (MW) and shear environment on the aggregation behaviour of fine chalcopyrite particles treated with anionic polyacrylamides (APAM), under a typical range of flocculation-flotation conditions. High-resolution in-situ images were obtained to measure aggregate size using Image Derived Chord Length Distributions (ID-CLD). The relationship between polymer MW and shear-induced forces was analysed along with aggregate formation and breakage kinetics, breakage reversibility and aggregate regrowth. The results indicate that the aggregates typically reached maximum sizes about 1 min after polymer addition and break over time. Higher MW polymers produced larger aggregates that could better withstand breakage effects. Lower shear rates enhanced floc growth, whereas higher shear rates promoted comparatively hindered aggregate growth and increased particle breakage. The shear-induced breakage process was found to be mostly irreversible for the chalcopyrite particles, with minor aggregate regrowth following subsequent shear reduction. These findings provide key insights into the role of polymer characteristics and shear conditions in controlling the size and integrity of aggregates, which is essential for optimising aggregation performance in separation processes and industrial plants.