Multi-scale investigations on mechanisms of transport, mixing and energy input in continuous two-stage planetary roller melt granulation

• Applicant: Dr.-Ing. Jens Bartsch
• Subject Area: Mechanical Process Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 555533312

Melt granulation is by nature a promising alternative in terms of sustainability compared to the standard wet granulation. In particular, an energy intensive, subsequent drying of the product is not required and the resource water is not consumed, while a continuous operation in addition minimizes product quality fluctuations. Despite these various advantages, continuous melt granulation is still considered a less preferred granulation method. This is due to the lack of understanding the process mechanisms resulting in a reduced process control for the typical execution with twin-screw systems, which also struggle with a dominant mechanical energy input. In contrast, a planetary roller granulator favors crucial aspects of melt granulation as the ratio of heated surface to processed volume is enhanced and particle-particle interaction is promoted by the multiple transition events of the material. However, in order to establish planetary roller melt granulation as a continuous method for powder processing, a sophisticated design and enhanced control level are required enabling a process optimization focusing on quality assurance and sustainability. The aim of this project is therefore to reveal on a fundamental level the correlations of product attributes to process settings in planetary roller melt granulation. The central task is to elucidate the mechanisms of transport, mixing and energy input and to quantify independently the resulting material modification and corresponding energy consumption within segments of the processing zone (local scale). Initial work will be dedicated to the process design, which will decouple spatially the melting of the binder and the granulation of a model compound. Thereby, the material modification in terms of particles size and temperature and the affiliated energy consumption will be examined independently. Hereby, the radial and axial material distribution in the processing zone will be characterized as preliminary investigations highlighted that transport, mixing and energy input during processing are related to the accumulated mass in the granulator. Finally, the processing zone will be divided in parts as the discharged granules are a product of the mechanisms and affiliated rate processes along the granulation stage. The unification of these investigations will lead to a model and process map for the whole processing section (global scale) with a focus on quality assurance and minimal power consumption.

• DFG Programme: Research Grants