Crystallisation kinetics of ultra-pure lactose

An ultra-pure lactose feed was produced from a patented process (Durham et al. 1997) and shown to be free of lactose phosphate (LP) and other impurities. The objectives of this work were to establish the crystallisation kinetics of the ultra-pure lactose during cooling seeded batch crystallisations and to compare the results with similar data obtained for commercial pharmaceutical grade α-lactose (PGα-L). Based on experimental data, a nonlinear least squares dynamic optimisation technique was used to define the growth rate constant K of a power law function. For all conditions studied, K was higher for the ultra pure feed than for the commercial feed. The use of the ultra pure feed, free of LP, produced smaller crystals with a narrow particle size distribution and in higher yield.