Implementation of a Yukawa force model in polymer-induced bridging flocculation of hematite particles using CFD-DEM

• Yukawa force model is implemented in the polymer bridging flocculation. • The experimental polymer dose correlates to the simulated force model magnitude. • The interaction range of Yukawa force relates to the polymer molecular weight. • An enhanced aggregation rate is proposed for polymer bridging flocculation. Polymer-induced bridging flocculation of hematite particles under laminar shear flow is simulated using a coupled Computational Fluid Dynamics – Discrete Element Method (CFD-DEM). The attractive interactions between the polymer-coated particles are represented by a Yukawa force model, parameterised through benchmarking the CFD-DEM-derived cumulative chord length distributions (CLDs) against experimental measurements. By introducing a power-law dependency of the interaction constant on polymer dosage, the model accurately predicts the experimentally observed steady state mean aggregate chord length across a polymer dose range of 50–250 g/t. At steady state, the mass mean aggregate size, D 4 , 3 ¯ , scales linearly with the average chord length, CL ¯ , establishing a quantitative relationship between particle size and chord length. The flocculation kinetics are described using a modified shear-induced aggregation rate that incorporates an enhancement factor, γ , based on the effective volume fraction that includes both the particles and their polymer layers. The proposed flocculation rate captures the influence of the interaction range introduced by polymer extension and enables accurate prediction of polymer-induced flocculation in mineral suspensions.