Dynamic agglomeration profiling during the drying phase in an agitated filter dyer: Parametric investigation and regime map studies

Understanding effect of filtration and washing on dried product: Paracetamol case study

“…A similar effect is reported for widening the particle size distribution. As reported by Wakeman 14 and later by Beckmann 4 , particle shape affects filtration rate, cake porosity and cake resistance.…”

“…9 Drying is the activity within the isolation step that is most frequently responsible of particle size variation (either by breakage or agglomeration or sometimes both) and in extreme cases even large lump formation. [10][11][12][13][14] Washing, on the other hand, has an essential role in delivering cake purity. By selection of appropriate filtration and washing strategies drying can be improved to facilitate production of pure product particles with comparable size as to the material produced in the crystallizer.…”

“…When granules are formed during isolation further processing to disrupt the granules and attain the desired size distribution is usually necessary, typically this is accomplished by introducing a milling step. 14 Wash solvent selection can also lead to dissolution of small particles which may narrowing the PSD and/or reduce the isolated yield. This can occur either because the API has appreciable solubility in the wash solvent or in mixtures of the wash solvent and the crystallization solvent.…”

“…[34][35] Drying performance and the impact of drying on product attributes is influenced by both particle and process properties including; input particle size distribution and crystal shape, the flow rate of the drying gas (typically nitrogen) through the cake, the residual solvent content and composition at the start of drying, the heat applied and the design and operation of the drying device. [10][11][12][13][14]36 Many researchers have reported and examined possible causes of agglomeration during drying. 33,36,37 Common hypotheses suggest that if the API solubility in the wash solvent is high and sufficient solvent is present then interparticle bridges of polycrystalline material are deposited at the points of contact between particles due to the evaporation of solvent saturated with dissolved API.…”

“…39 An appropriate solvent selection can have a larger impact on particle clustering than initial particle size. Birch and Marziano (2013) 35 , Zhang and Lamberto (2013) 40 and Tamrakar et al (2016) 14 have all studied the effect of solvent choice on drying, analysing the role of solvent polarity in the formation of strong granules. Generally, the higher the solubility of the product in the wash solvent, the greater the chance of solid bridge formation.…”