Are barium sulphate kinetics sufficiently known for testing precipitation reactor models

Barium sulphate precipitation, widely used to validate micromixing models, requires the knowledge of nucleation and crystal growth kinetics under non stoichiometric conditions, which is generally the case when two fluids are mixed. Therefore, the spontaneous precipitation of barium sulphate was studied under both stoichiometric and non stoichiometric conditions. A new method was developed to derive the nucleation and crystal growth rates based on the simultaneous measurement of concentration and crystal size distribution. Two expressions were proposed describing well nucleation and crystal growth kinetics. The kinetic parameters were determined as a function of the initial concentration ratio, showing the crucial effect of stoichiometry on the nucleation and crystal growth kinetics. Consequently, attention should be paid to the use of kinetic laws of barium sulphate precipitation to validate micromixing models.