Filtration mechanism of copper tailings: Influence of initial solids content and flocculation

Cake filtration is increasingly applied in tailings management to achieve high solids contents for backfill preparation, dry stacking, and co-disposal with waste rock; however, the combined effects of initial solids content and flocculant dosage on filtration kinetics and cake development remain insufficiently understood. In this study, laboratory-scale vacuum filtration tests were conducted on copper tailings to systematically investigate the influence of initial solids content (60%–69%) and flocculant dosage (0–30 g/t) on filtration performance. Filtrate mass was continuously measured, and filter cake samples were collected to determine final solids content. The filtration process was classified into two distinct stages based on filtrate removal rate, and the underlying filtration mechanisms were interpreted. The results show that increasing initial solids content significantly reduces the average filtrate removal rate during the rapid-dewatering stage from 0.75 g/s to 0.44 g/s due to increased hydraulic resistance, while higher flocculant dosages enhance filtrate removal rates within each solids content group. Despite pronounced differences in filtration kinetics, the final solids content of the filter cake converges to similar values of approximately 81% within each solids content group, indicating that the final cake state is primarily governed by particle packing. Classical filtration models can describe the general filtration behavior; however, modifications are required to explicitly incorporate the influence of initial solids content.