Downstream Processing
Typically, after industrial crystallization, a series of subsequent processing steps are employed, including milling, filtration, washing, drying, and formulation. The efficiency of these downstream processing steps is influenced by the characteristics of the crystal population. For instance, during filtration and washing, a low packing density can lead to elevated pressure drop, while in the tableting process, poor powder flowability can result in blockages. The Particle Size and Shape Distribution (PSSD) of crystals significantly impacts powder properties, such as the flowability and packing density. To visually demonstrate the contrast in flowability and packing density between needle-like and equant crystal shapes, a video has been provided where the same mass (5g) of the same material, L-Glutamic acid, but with different shapes, is poured into beakers.
Despite its significance, the impact of Particle Size and Shape Distribution (PSSD), specifically the effect of crystal shape, on powder properties like flowability and filterability has been overlooked, primarily due to the previous unavailability of methods capable of accurately characterizing the size and shape of non-equant crystals, such as needle-like and plate-like crystals, in large quantities.
The objective of this project is to investigate the relationship between the PSSD and powder properties relevant to downstream processes in crystallization. By understanding this connection, the project aims to facilitate the optimal design of both crystallization and downstream operations.
This project is funded by an ETH Zurich Research Grant.