Optimization of flocculation and settling parameters of tailings slurry by response surface methodology

High-efficiency flocculation and settling is required for solid-liquid separation in cemented paste backfill, which is one of the best approaches for tailings management and green mining. The optimization of flocculation and settling parameters of tailings slurry was carried out by response surface methodology (RSM) with Box-Behnken design. The solid fraction, flocculant dosage, flocculant concentration, and shear rate were selected as the factor. Likewise, the maximum square-weighted mean chord length of tailings floc, initial settling rate of the suspension-supernate interface, and turbidity of supernate were selected to characterize the flocculation and settling process. For individual response, a quadratic polynomial regression model was proposed and optimal parameters were achieved by RSM. Multiple response optimization by the overall desirability function approach was applied successfully to estimate the optimal parameters, i.e., solid fraction of 10.29%, flocculant dosage of 25%, flocculant concentration of 0.15%, and shear rate of 51.60 s(-1). The validation experiments demonstrated that the Box-Behnken design in RSM is an appropriate and powerful approach for the optimization of flocculation and settling parameters of Nickel tailings slurry. More importantly, the optimal parameters achieved provide valuable information for the flocculation settling process of unclassified Nickel tailings slurry in Jinchuan Nickel Deposit, which will contribute to tailings management and water recycling, avoiding air pollution, water pollution, and soil pollution in mine.