Yes / Granulation is commonly used as an enlargement process of particles produce granules with desirable characteristics and functionality. Granulation process transforms fine powders into free-flowing, dust-free granules with the presence of liquid binder at certain operating conditions. The main focus of this research is on seeded granulation of detergent powders, a new phenomenon of granulation in which a layer of fine powders surround the coarse particle. This is already proven for calcium carbonate (Rahmanian et al., 2011). Here, detergent granules were produced in a 5 L high shear Cyclomix granulator using different fine/coarse powder ratio (1/3, 1, 3) and different binder ratio of 10 %, 20 % and 30 %. The granules were then characterized for their particle size distribution, strength and structure. It was found that a high percentage (70 wt. %) of granules in the desired size range between 125 - 1,000 µm were produced using the powder ratio of 1/3 and a binder content of 10 %. Low mean crushing strength (3.0 N) with a narrow distribution was obtained using this condition. Structure characterization of the detergent granules produced in the granulator shows that consistent seeded granule structures are produced under the optimum process and formulation conditions of 1/3 powder ratio with 10 % binder.

Yes / It has been shown that seeded granules of calcium carbonate can be produced in commercial batch high shear granulators such as the Cyclomix high-shear impact mixer. Seeded granules are attractive to the pharmaceutical industry due to their high uniformity and good mechanical properties which can assist efficient tablet manufacture. In the current study, attempts to produce seeded granules of Durcal 65 and PEG 4000 binder using hot melt granulation are reported, in response to the recent shift towards continuous pharmaceutical manufacturing. Various screw configurations and rotation speeds were investigated in a series of experiments to determine the relationship between process conditions and granule properties. Particle size analysis, strength measurement and structural characterisation were used to quantify granule properties. It was found that using a series of kneading elements arranged at a 60° staggering angle located near to the feed section of the extruder screw generated strong, spherical granules. From structural characterisation approximately 5–15% of extruded granules were found to be seeded. Twin screw melt granulation is therefore considered to be a promising technique for continuous production of seeded granules, although a more detailed investigation is required to optimise yield and quality.

The effect of the operating conditions of three continuous high shear granulators on the internal structure and strength of granules has been investigated and the possibility of seeded granulation has been explored. In a recently concluded programme of research on the scale-up of a high shear granulator, Cyclomix (manufactured by Hosokawa Micron B.V., The Netherlands), a novel method of granulation called seeded granulation was introduced, where each granule contained, at its core, a large particle from the upper tail end of the feed particle size distribution. Seeded granulation is particularly useful for process control of continuous granulators as there is the potential to control granulation by the flow rate of the seed particles. Hence, the performance of three different types of continuous granulators in terms of granule strength and structure has been evaluated here; these are Extrudomix, Modulomix (manufactured by Hosokawa Micron, UK and The Netherlands, respectively) and the Nica M6 Turbine continuous granulator (manufactured by GEA, UK). Calcium carbonate (Durcal 65) powder was granulated using an aqueous solution of polyethylene glycol (PEG) as binder in the same ratio as used previously in our batch granulation, to allow comparison between the continuous and batch processes. The crushing strength was characterised by quasi-static side crushing between two platens using a mechanical testing machine. The internal structure and morphology were evaluated by scanning electron microscopy and the extent of seeding quantified. Granules produced in all the three continuous granulators were significantly weaker than those of the batch granulator tested previously. Among the continuous granulators only the Modulomix granulator produced some seeded granules. It is considered that longer residence time is necessary to produce seeded granules.