The influence of bimodal particle systems on filter cake structures using micro tomography

E. Löwer*, F. Pfaff, T. Leißner, U. A. Peuker, Technical University Bergakademie Freiberg, Germany

The use of X-ray microscopy (XRM) for characterizing particle systems offers more and more applications in particle technology: With raising voxel resolution the size and shape of particles in bulk powders e.g. the analysis of filter cake structures allows more information about micro processes during filtrbimation and de-liquoring, supporting an enhanced understanding of industrial process characteristics. Tomography measurements provide information about the build-up of porous systems, quantified by using key parameters and distribution functions.

The solid-separation of wide spread particle properties make the prediction of filtration processes difficult. Besides broadly distributed properties like size, shape and wetting behavior the location, the dispersion range and the shape of the distribution has to be taken into account. Multimodal distributed particle properties described in literature originate from a change in bulk structure at which the fine fraction starts to dominate the force transmission and the interparticular contact number. Investigating the change and its influence on cake filtration, the use of X-ray microscopy makes an insight into the substructure on micro-level basis possible.

For tomography experiments, filter cakes according to VDI 2762 are built with respect to the measurement volume. Particle systems of self-similar fractions (crushed Al2O3) between 20 and 200 µm are mixed to bimodal distributions. The volume fractions of fines between 20 and 60 % are compared with the monomodal fine and coarse fractions with regard to global and local porosity, permeability, geometric tortuosity and coordination number...

Session: L2 - Particle, Slurry and Cake Characterization
Day: 22 October 2019
Time: 14:45 - 16:00 h

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