Some equipment selection criteria for granulation and compaction processes are discussed. In wet granulation, agglomeration is promoted by the addition of binders and solvents. Proper gas-distributor design is required to maintain solids mixing, heat and mass transfer, and to prevent unstable operation that could cause the bed to defluidize or collapse. Gravimetric feeding often improves granulation performance due to smaller fluctuations in feedrates. Differences in equipment, impeller and chopper geometry result in very wide variations in shear rate and powder flow patterns among manufacturers. It is vital to keep in mind the high degree of interaction between granulation mechanisms, formulation properties and process equipment in making equipment selection. One-pot processing, encompassing mixing, granulation and drying make both fluidized beds and mixers attractive choices. Lastly, materials of low permeability can present limitations in continuous processes, especially in dry compaction.
