The fluidized bed is an important process for the formulation of various products. To design and control such apparatuses and processes knowledge about the process kinetics is necessary. Previous models for the process dynamics extinguish size-independent particle growth, the formation of compact shells and a uniform distribution in the fluidized bed of the injected liquid. New measurements question all these assumptions. Therefore, an extended model is proposed that can detect the new experimental results well and it includes the earlier approaches as limiting cases.