Multiphysics coupling particle dissolution in aluminum electrolysis cells based on computational fluid dynamics and discrete element model

Particle dissolution is a common phenomenon in the metallurgical and chemical industries, involving heat and mass transfer. A user-defined solver toward the computational fluid dynamics and discrete element model method with particle dissolution sub-models integrating was developed based on the open-source software OpenFOAM-LIGGGHTS, which can simulate the alumina and spent refractory material (SRM) dissolution in electrolysis cells. This approach solves the fluid phase in the Eulerian framework and the particle motion in the Lagrangian framework, comprehensively considering the particle size shrinkage, bath temperature response, and concentration diffusion during particle dissolution. The model's accuracy was verified against experimental results. The dissolution of the alumina and SRM mixture at different mixing ratios was simulated. The results show that as the proportion of SRM in the mixture increases, the mixture's dissolution rate decreases, and the remaining undissolved mass increases significantly. The SRM content in the mixture will not affect the operation stability of aluminum electrolysis cells when it is 10%, and the maximum content cannot exceed 30%. The mixture particles and the dissolved alumina and silica first move around along the inter-anode gap and center channel and then gradually transport and diffuse to the anode–cathode distance region to replenish the consumed alumina and silica. The established model and method could provide guidance for optimizing the process parameters and feeding strategies of the electrolysis cell, further improving the dissolution rate of the mixtures and increasing the SRM consumption.