Analysis of Granulation Rate Processes and Implications for Scale-Up

ANALYSIS OF GRANULATION RATE PROCESSES AND IMPLICATIONS FOR SCALE-UP 

Many of the required granule product attributes are directly related to the size, size distribution, and density of the granule product. These granule properties develop as a result of three classes of rate process in the granulator (Fig. 1)  

Each of these processes is analyzed in depth in Litster and Ennis (5). In this section, we will summarize each rate process in turn, particularly highlighting the main formulation properties and process variables. Wherever possible, we will define dimensionless groups that can be used in scale-up. 

The first step in granulation is the addition of a liquid binder to the powder to form nuclei granules. Within the granulator, the key region for wetting and nucleation is the spray zone where liquid binder droplets contact the moving powder surface. The nucleation process is considered to consist of four stages (Fig. 2)  

Droplet overlap and coalescence at the bed surface (i) Wetting Nucleation 

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