This paper is about sweet whey protein (α-lactalbumin and β-lactoglobulin) recovery by a fluidized ion exchange chromatographic process. Simplified models are proposed for both main steps of this cyclic process: a model with intraparticle diffusion for the adsorption of proteins (fixation step) and a lumped kinetic model for their desorption (elution step). The validity of these models and their physical background are discussed. They are then used for an economical optimization algorithm in order to determine operating conditions (fixation and elution steps durations, elution effluent recycling and liquid-phase velocity). Recycling the elution effluents leads to a slight improvement in the process but it was found to be less advantageous than an optimization of the liquid-phase velocity.