Designing a lactose crystallization process based on dynamic metastable limit Original Research Article

In the dairy industry, lactose crystallization during refining typically generates a large number of fines (<100 μm), which greatly reduces the efficiency of downstream processes. To overcome this problem, a strategy to minimize fines production was developed. On lab scale units, lactose crystals were produced from three crystallizers (draft-tube baffled, anchor and paddle) operated with three cooling profiles (at different region inside metastable zone (MSZ)). Computational fluid dynamics was used to simulate the flow profile. Among all combinations investigated, anchor crystallizer (lowest shear) operated at slow cooling rate (in upper MSZ) produces the largest crystals with minimal fines. Then, the design strategy was applied in industrial scale crystallizer. The 13 h cooling profile created for operation in the medium MSZ region successfully produced crystals with 28% less fines than the typical process. Therefore, depending on the crystallizer design and operational region (in MSZ), production of fines can be minimized.