(321f) Methods for the Reduction of Cycle Time in Intermediate Crystallization Steps | AIChE

(321f) Methods for the Reduction of Cycle Time in Intermediate Crystallization Steps


Redman, T. P. - Presenter, METTLER TOLEDO AutoChem

In recent years great attention and research focus has been paid to improving the final crystallization step in process development. The final crystallization step will typically define final product attributes such as purity, yield and particle size and is critical for delivering material that can be effectively processed and formulated into a final product fit for the market.

While focus on the final crystallization remains important it is apparent that an opportunity exists for the improvement of many non-optimized intermediate crystallization steps. Intermediate steps differ from the final crystallization in that the intermediate product is usually transferred to the next step where it is dissolved and processed. In most cases the final product attributes are less important that the speed and efficiency with which the intermediate product can be delivered to the next step.

The challenge for intermediate crystallization development is that increasing the speed of crystallization typically means running at higher supersaturation levels. Such operation can result in undesired crystallization mechanisms excessive secondary nucleation, phase separation (oiling out) morphology changes. Such mechanisms often lead to common downstream bottlenecks such as slow filtration rates, poor flowability and caking during transportation.

In this presentation techniques will be presented that focus on reducing the overall cycle time of intermediate crystallization steps. The application of in situ measurement and imaging tools will be shown to facilitate the choice of process parameters that ensure the fastest crystallization possible without sacrificing the speed of downstream separation and delivery to the next processing step.