Integrated Upstream and Downstream Application of Wet Milling with Continuous Mixed Suspension Mixed Product Removal Crystallization

The integration of rotor-stator wet mill and continuous mixed suspension mixed product removal crystallizer (MSMPRC) is studied in this work. The wet mill is applied in two different configurations: (1) downstream in a recycle loop to continuously reduce particle size via controlled secondary nucleation and breakage; and (2) upstream as a high shear nucleator to continuously generate seed crystals in situ. These two novel approaches are compared to continuous MSMPRC without wet mill. In addition, the influences of wet mill operating conditions (i.e., tip speed, number of turnover per residence time) on five important product and process qualities, including average particle size, particle number, width of size distribution, yield, and startup duration are identified for both configurations. The paper demonstrates that desired average crystal size, narrow size distribution, high yield, and very short startup duration can be achieved at the same time by applying the rotor-stator wet mill upstream as a continuous in situ high shear seed generator followed by continuous MSMPRC.