Abstract: [Objective]This study aims to enhance flocculation-sedimentation performance by optimizing parameters such as slurry mass concentration,specific flocculant consumption, and agitation rate,thereby addressing issues like slow sedimentation speed and low dewatering efficiency during the filling of geotextile tubes with ultra-fine tailings.The ultimate goal is to improve the mechanical strength and storage stability of dewatered tailings. [Methods]Cylinder sedimentation tests were conducted using"flocculation efficiency"as the core evaluation metric.Single-factor analysis was employed to investigate the effects of slurry mass concentration,specific flocculant consumption,and agitation rate on flocculation performance.A three-factor, three-level Box-Behnken design(BBD)was utilized for response surface methodology(RSM)experiments.Design-Expert software was applied to establish a quantitative model between flocculation efficiency and various factors,analyzing multi-factor interactions and underlying mechanisms. [Results]Single-factor tests indicated that higher flocculation efficiency was achieved within the following ranges:slurry mass concentration of 4%-8%,specific flocculant consumption of 0.5-1.5 mL,and agitation rate of 300-500 r/min.Variance analysis of the response surface optimization model revealed the significance of factors affecting flocculation efficiency in descending order:square of agitation rate>square of slurry mass concentration>specific flocculant consumption>interaction between slurry mass concentration and specific flocculant consumption>slurry mass concentration>square of specific flocculant consumption>agitation rate>interaction between specific flocculant consumption and agitation rate>interaction between slurry mass concentration and agitation rate.The optimal parameter combination was identified as slurry mass concentration of 5.45%,specific flocculant consumption of 0.5mL,and agitation rate of 415r/min,yielding a predicted flocculation efficiency of 8.086%/ppm.The measured values aligned closely with predictions,exhibiting less than 5% error. [Conclusion]The established flocculation efficiency model effectively predicts the sedimentation performance of ultra-fine tailings.The response surface methodology successfully elucidates the mechanisms of multi-factor interactions,and the optimized parameters significantly enhance flocculation efficiency.This study provides a theoretical foundation and technical support for the dewatering process of geotextile tubes.