Simulation of Semibatch Precipitation of Sodium Perborate Tetrahydrate in an Industrial Crystallizer

A model of an industrial semibatch sodium perborate tetrahydrate (SPT) precipitation process, based on mass, population, and energy balances, is presented. The model parameters of growth, nucleation, and agglomeration were obtained by nonlinear parametric optimization from the experimental data for the sodium perborate tetrahydrate concentration in the mother liquid, the mass of the solid phase, the crystal size distribution, and the suspension temperature as a function of time. A combined integral-differential strategy was used to determine the kinetic parameters. The original set of five kinetic parameters was reduced to two subproblems, each of which was solved consecutively, and in this way, the parameters were calculated much faster. The model was verified by comparison with measurements obtained in precipitation experiments, which were carried out under process conditions different from those used in the reference run. A rather good agreement between the model predictions and the experimental data was found.