(243a) How Granule Characteristics Change When High Shear Granulators Are Scaled up?

Size enlargement of powders by granulation is widely used to improve the macroscopic and microscopic structures, flowability, bulk density, appearance, and behaviour during storage and transport. Granulators used in industry can be broadly divided into two categories: low shear mixer granulators (e.g. rotating drums and pans), and high shear mixer granulators. High shear mixer granulators are typically found in pharmaceutical and detergent industries, and are capable of reducing processing time and producing granules with high strength and density. Generally, several granulation scaling-up stages are involved before reaching the production scale. This is conducted to exert better understanding, control and optimisation at the smaller scales before proceeding to the larger scales in terms of geometric, kinematic and/or dynamic similarities. However, there is no previous work on the effect of equipment scale on the evolved granule structure, properties and strength. The aims of this paper are to identify and analyse the factors that affect the structure and physical properties of granules as a function of operating scale in the Cyclomix high shear granulator, manufactured by Hosokawa Micron B.V.

This paper highlights the effects of different feed particles on the evolved structure and the breakage mechanism of granules produced at various granulator scales. Calcium carbonate particles of different size ranges were selected as the feed materials with PEG 4000 used as the liquid binder. The granules produced from different granulator scales and formulations were studied by x-ray microtomography to ascertain their internal structure. The granules were also subjected to quasi-static and impact testing to elucidate the effects of strain rates and different loading conditions on their breakage behaviour.

Future work consists of incorporating the internal structure of the granules obtained from the x-ray microtomography in the computer simulation by Distinct Element Method (DEM) in order to realistically ascertain the microscopic growth and breakage of granules at various operating conditions. The results obtained from quasi-static and impact testing will be used to validate the computer simulation results.