Scale-up of a pharmaceutical granulation in fixed bowl mixer-granulators

Scale-up in fixed bowl mixer-granulators has been studied by applying the classical dimensionless numbers of Power, Reynolds and Froude to end-point prediction in a range of geometrically similar machines. The simple relationship of Power number/Reynolds number, as suggested by previous workers, has been found to be inappropriate for large-scale production machines where corrections have to be made for gross vortexing and powder bed height variation by the incorporation of the Froude number and a scaling factor. When corrections are made, data from 25-, 100- and 600-1 machines all fall on the same curve allowing predictions of optimum granulation end-point conditions to be made for production-scale equipment from measurements on laboratory-scale equipment and vice-versa.