Shell porosity in spray fluidized bed coating with suspensions

An experimental study regarding spray fluidized bed coating with aqueous suspensions is presented. The dependency of coating shell morphology on drying parameters, atomization pressure and composition of suspension is investigated. The results are compared to existing work regarding spray fluidized bed coating with aqueous solutions of crystalline material. Contrary to coating with solutions, coating shell smoothness and porosity does not depend on drying conditions. Nevertheless, atomizing pressure and mass fraction of solids in suspension have large influence on coating shell morphology. High atomization pressures, leading to small droplets, result in smooth coating surfaces and low shell porosities. A similar trend is observed for a low mass fraction of solids in the suspension. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.