El Hagrasy et al. () identified the inadequacy of the kneading elements in distributing the granulation liquid as a potential cause for the wide PSD observed and stated that improving the liquid distribution inside the granulator would enhance the properties of the granules obtained, especially with respect to size. However, Vercruysse et al. () used NIR chemical imaging to monitor the moisture distribution for granules produced by TSG and described that although moisture uniformity could be achieved by implementing a sufficient number of kneading elements on the granulator screws, PSD results showed wide and bimodal profiles. Based on this observation, it was concluded that the typical bimodal PSD for granules produced by TSG was not mainly related to the insufficient mixing of powder and liquid phase during the short residence time of material inside the barrel, but rather to the granulation mechanism inherent to the technique. Furthermore, Fonteyne et al. () visualized the binder distribution in granules produced by TSG. No binder-rich zones were detected, indicating that the binder was homogenously distributed within the granules. So, the results from Fig. 7 are in agreement with the statements made by Vercruysse et al. () and Fonteyne et al. (). Granulation with tooth-mixing-elements (TME) and screw mixing elements (SME) Alternative to the conventional conveying and kneading elements, the feasibility of tooth-mixing-elements (TME) (Fig. 1c and d) and screw mixing elements (Fig. 1e) for TSG was investigated. TMEs used in this study were neutrally conveying. PSD results of granules produced at L/S ratio of 0.045 with various narrow TMEs (0, 1, 2 and 3) are shown in Fig. 8 (Fig. 3, screw configuration A, F, G and H). If multiple TMEs were used, they were separated by a conveying element (Length = 1.5D). By incorporating a TME in the screws, the amount of fines at an L/S ratio of 0.045 was lowered from 46.4 to 19.3%. Increasing the number of TMEs did not further reduce
El Hagrasy et al. () identified the inadequacy of the kneading elements in distributing the granulation liquid as a potential cause for the wide PSD observed and stated that improving the liquid distribution inside the granulator would enhance the properties of the granules obtained, especially with respect to size. However, Vercruysse et al. () used NIR chemical imaging to monitor the moisture distribution for granules produced by TSG and described that although moisture uniformity could be achieved by implementing a sufficient number of kneading elements on the granulator screws, PSD results showed wide and bimodal profiles. Based on this observation, it was concluded that the typical bimodal PSD for granules produced by TSG was not mainly related to the insufficient mixing of powder and liquid phase during the short residence time of material inside the barrel, but rather to the granulation mechanism inherent to the technique. Furthermore, Fonteyne et al. () visualized the binder distribution in granules produced by TSG. No binder-rich zones were detected, indicating that the binder was homogenously distributed within the granules. So, the results from Fig. 7 are in agreement with the statements made by Vercruysse et al. () and Fonteyne et al. (). Granulation with tooth-mixing-elements (TME) and screw mixing elements (SME) Alternative to the conventional conveying and kneading elements, the feasibility of tooth-mixing-elements (TME) (Fig. 1c and d) and screw mixing elements (Fig. 1e) for TSG was investigated. TMEs used in this study were neutrally conveying. PSD results of granules produced at L/S ratio of 0.045 with various narrow TMEs (0, 1, 2 and 3) are shown in Fig. 8 (Fig. 3, screw configuration A, F, G and H). If multiple TMEs were used, they were separated by a conveying element (Length = 1.5D). By incorporating a TME in the screws, the amount of fines at an L/S ratio of 0.045 was lowered from 46.4 to 19.3%. Increasing the number of TMEs did not further reduce
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