Experimental investigation of reagent feeding point location in a semi-batch precipitation process

This research is dedicated to a study of BaSO4 crystallization process in a batch stirred reactor. The temporal development of the precipitation process is measured by conductivity at global and local levels. The effect of the macromixing on temporal evolution of local conductivity is shown in the experimental results obtained by EIT. The effects of the mixing intensity and the BaCl2 feed location on the CSD and morphology are considered. Morphology of the crystals was found to be independent from mixing intensity in the studied range. The CFD simulations of the mixing hydrodynamics were used to estimate the influence of turbulent dispersion on crystal size. The correlation of mean crystal size and TR number proposed by (Torbacke and Rasmuson, 2001) has been checked against d90 in the range of 103-105 and showed reasonable agreement. The scatter of the results plotted can be explained by the macromixing scale and critical time of the crystallization not included into TR number. The combined effect of mixing at meso and macro scales onto crystal size is proposed.