Liquid ion exchangers are used in reactive extractions and the modelling of reactive-phase equilibria with Gibbs excess models takes into account complex formation in aqueous electrolytes or organic media. The chemical kinetics and effective diffusivity are evaluated in small-scale laboratory devices and applied in models using the chemical potential as the driving force. The simulation of lab-scale columns is performed on simple hydrodynamic models, whereas for industrially sized equipment droplet populance-based modelling is the challenge of the future. Parameter estimation regarding this is discussed and stirred column simulations are presented.