Reactive crystallization is when a solid phase crystalline material results from the reaction of two components. This type of reaction can often be performed more profitably in a crystallizer than in a separate reactor. An example of reactive crystallization is the production of ammonium sulfate from liquid or gaseous ammonia and concentrated sulfuric acid.
The draft tube baffle crystallizer is particularly suited for reactive crystallization. The reactants are mixed in the draft tube of the DTB unit where a large volume of slurry is mixed continuously with the materials to minimize the driving force (supersaturation) created by the reaction. Removal of the heat produced by the reaction is accomplished by vaporizing water or other solvents as in a conventional evaporative type crystallizer.
Reactive crystallization can also be performed in a forced circulation type crystallizer where the reactants are mixed in the circulation piping.