Prediction of micro processes, filter cake build-up and porous media flow is a key challenge to describe macroscopic parameters like filter cake resistance. This is based on a precise description, not only of the disperse solid fraction, but the distributed properties of the voids between the particles. Lab-experiments are carried outwith alumina and limestone,which differ in particle size distribution (PSD) and resulting filter cake structure. Filter cakes of bothmaterials are characterized by standardized lab tests and additionally, alumina cakes aremeasured with X-ray microscopy (XRM). Focusing on distributed process key parameters, the data gives a deeper understanding of the laboratory experiments. The solid volume fraction inside the feed strongly influences the particle sedimentation and leads typically to a top layer formation of fine particles in the final filter cake,which has a negative influence on subsequent process steps. The top layers seal the filter cake for washing liquid and increase the capillary entry pressure for gas differential pressure de-watering. The influence on cake structure can be seen in a change of porosity, particle size and shape distribution over the height of the filter cake. In all measurements, homogenous filter cake structures could only be achieved by increasing the solid volume fraction inside the suspension above a certain percentage, at which particle size related sedimentation effects could be neglected and only zone sedimentation occurred. XRM offers the chance to quantify these effects, which previously could only be described qualitatively.

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Recent Submissions

  • X-ray tomography scans of filter cakes (feed slurry: variation in solid volume fraction)Open Access Icon 

    Löwer, Erik (Technical University Bergakademie Freiberg - Institute of Mechanical Process Engineering and Mineral Processing, 2021)
    X-ray tomography measurements (Zeiss X-radia Versa 510) of in-situ and in a VDI pressure nutsch built filter cakes (Al2O3 crushed particles in 25 mmol/l KI brine with 24 m.-% glycerol). The filter cakes are measured ...