In recent years, non-destructive X-ray microscopy (XRM) has become a common method to characterize particle systems in various scientific fields: Besides the size and shape of particles in bulk powders, the insight into filter cake structures provides additional information about micro processes during filtration and dewatering. Distributed particle properties mainly influence the porous network build-up with possible local deviation in vertical and horizontal alignment. This article focusses on the model-based correlation between the distributed particle properties and characteristic network parameters like tortuosity, pore radii and preferred capillaries for dewatering, using tomography data as model input. Therefore, cake-forming filtration experiments were carried out with a down-scaled, self-constructed in-situ pressure nutsch. The entire tomographic dataset consists of seven individual scans at certain desaturation steps at different pressure levels. For the experiments, a lognormal distributed particle system (crushed Al2O3) in the range of 55 to 200 μm inside an aqueous suspension was used, containing additives for contrast enhancement. Image data processing based on reconstructed 360° projections allows the identification of the background, solid particles and liquid phase by a two-step segmentation. The subsequent modelling uses experimentally verified particle size distributions from laser diffraction measurements (integral value), 2D- (limited number of particles) as well as tomographic analysis, based on calculated single-particle volumes given by the voxel-dataset (all particles within the scanned volume). To characterize the porous network, a developed tetrahedron model is first applied to follow the shortest way through the porous matrix, then again to calculate the widest capillary related to the pore entrance. Furthermore, with information about the pore throat distribution and the wetting line from the tetrahedron side faces, the force balance is evaluated. This results in an entrance pressure distribution, the capillary pressure curve. Experimental data according to VDI 2762 built filter cakes and mercury intrusion tests are taken as reference for validation. https://opara.zih.tu-dresden.de/xmlui/handle/123456789/1944 2026-04-07T11:51:41Z 2026-04-07T11:51:41Z Löwer, Erik https://opara.zih.tu-dresden.de/xmlui/handle/123456789/1965 2021-08-23T15:11:43Z 2021-01-01T00:00:00Z

X-ray tomography scan of partially dewatered filter cake Löwer, Erik X-ray tomography image of a partially dewatered filter cake. The initial slurry contains Al2O3 particles suspended in a potassium iodide-glycerol solution, which were separated by cake-forming filtration with subsequent dewatering. All filtration and dewatering experiments took place in an in situ apparatus within the Zeiss Xradia 510 X-ray microscope. The filter cake is dewatered by gradually increasing the pressure. A scan is taken in the equilibrium state after one pressure step. The data set contains seven pore filling grades S1-S7 (= seven pressure steps). see note parameter.png in each measurement file for further measurement and reconstruction parameters

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