(325b) Effect of Aspect Ratio on Breakage Kinetics of Urea Crystals in Agitated Slurries

Previous research on paracetamol crystals investigated the effect on the particle size and shape distributions when the crystals were agitated in a nonsolvent. The initial parent crystals had aspect ratios near 2 in different size ranges. Experiments showed that the average aspect ratio in a given size range changed little as the residence time in the agitated was increased. Similar experiments were later performed with urea crystals that had higher aspect ratios. The urea crystals experiments in an agitated vessel also showed that the agitation residence time had little effect on the average aspect ratio of crystals in a given size interval.

While the urea crystal with the had a higher breakage rate than the paracetamol crystals, it is not clear that this was entirely due to the larger aspect ratio because the properties of the two substances are different. Additional urea crystal experiments were recently performed to provide more detailed information on the urea breakage kinetics. Specifically, the initial aspect ratios of the urea crystals used in the breakage experiments were narrower and more aspect ratios were used to aid in determining the effect of the aspect ratio on crystal breakage. These experimental results and the breakage distribution functions and parameters derived from the experiments are presented.