Nucleation and growth kinetics of barium sulphate in batch precipitation

Precipitation kinetics of barium sulphate were determined from a series of batch experiments. The thermodynamic supersaturation ratios were calculated from conductivity measurements while the crystal size distributions were measured by means of an electrical zone sensing particle size analyser. Using the measured crystal size distributions the nucleation and growth rates were determined by the moments method. Observed nucleation rates were strongly affected by the thermodynamic supersaturation ratio as well as by the stirrer speed and magma density and indicated the occurrence of both primary and secondary nucleation. The nucleation kinetics were therefore expressed as a combination of primary and secondary nucleation terms. The dependence of the growth rates on the thermodynamic supersaturation ratio and the stirrer speed suggested that both the diffusion and surface integration processes influenced the kinetics.