A PRELIMINARY FINITE ELEMENT ELECTROCHEMICAL MODEL FOR MODELLING IONIC SPECIES TRANSPORT IN THE CATHODE BLOCK OF A HALL-HEROULT CELL

摘要

A first 2D transient isothermal model was developed for the modelling of bath penetration in a Hall-Heroult cell cathode block. The model simulates the 'non convective' ionic species transport. The molten cryolite solution system is defined with an ionic model. The migration and diffusion of the ionic species is followed in the cathode block pores and in an overlying bath layer. The evolution of the potential is simultaneously obtained using charge conservation equations. The model includes a linear kinetic model for the electrochemical formation of metallic aluminium. The porous cathode behaviour is modelled using volume averaging based methods. The aluminofluoride ionic equilibrium is implemented by the penalty method and the electroneutrality criterion as a constraint on the FEM weak form. This is the first application of porous electrode theory, adapted for a molten salt, to Hall-Heroult cell cathodes. The results show the early stage evolution of voltage and ion distributions.