Modification of internal granule structure via spray-drying parameters
Abstract
Suspensions from alumina particles and water and in selected cases with a polymeric binder (polyvinyl alcohol) were spray-dried at varied process parameters. Besides suspension mass flow also nozzle gas mass flow and drying temperature were changed. The resulting granules were characterized concerning mechanical properties as well as changed internal structure parameters. If no polymeric binder is used, the changed process parameter suspension mass flow has only a marginal effect on the internal structures and resulting mechanical properties. If a polymeric binder is added to the suspension an effect on internal structure as well as mechanical properties can be found: Increasing fracture strengths were measured while reducing nozzle gas mass flow or drying temperature whereas the intensity varies. Parallel the shell thicknesses are increased and the micro porosity is changed. In additional single droplet drying experiments at different temperatures also an effect of this process parameter on the drying behavior can be documented.
