Abstract: Ultrafine tailings exhibit slow settling rates,low thickening efficiency,and high overflow water turbidity,necessitating the use of flocculants to accelerate fine particle sedimentation.However,flocculant residues remain in the thickened paste-like slurry,increasing its viscosity,reducing its concentration,promoting agglomeration,and raising pipeline transport resistance.This study employed theoretical analysis and field experiments to explore the mechanism by which flocculant residue influences the rheological properties of ultrafine ungraded tailings paste-like slurry.Results indicate that under flocculant restoration or shear damage,the floc network structure either encapsulates or releases water molecules,inducing migration and transformation between free and capillary water.This phenomenon is the fundamental cause of changes in the shear rheological properties of ultrafine ungraded tailings paste-like slurry.By optimizing flocculant selection,the study achieved a significant reduction in flocculant dosage and effectively mitigated its adverse effects.The findings hold substantial significance for systematically advancing the theory and methods of paste-like slurry shear rheology and pipeline transport.