Granulation mixer-granulator

Fig. 5. Double-shaft mixer used in fertilizer granulation. Courtesy of Reimeburg Division of Heyl Patterson.

These mixers are particularly suited for rapid mixing of powders and granules with liquids, for dissolving resins or solids in liquids, or for removal of volatiles from pastes under vacuum. Scale-up is usually on the basis of maintaining constant peripheral velocity of the impeller. 

Batch planetary mixers are used extensively in the pharmaceutical industiy for powder granulation. A typical batch size of 100 to 200 kg has a power input of 10 to 20 kW. Mixing times in these granulators are quite long (20 to 40 min). 

Scale-Up and Operation Scale-up of pharmaceutical mixer granulators is difficult because geometric similarity is often not preserved. Kristensen recommends constant relative swept volume ratio... 

FIG. 20-85 (a) Horizontal and (h) vertical high-shear mixer granulators for pharmaceutical granule preparation for subse-... 

For successful tableting, a material must have suitable flow properties to allow it to be fed to the tableting machine. Wet or dry granulation is used to improve the flow properties of materials. In the case of wet granulation, agitative granulation techniques such as fluidized beds or mixer granulators as discussed above are often employed. 

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