Multidimensional separation due to selective spherical agglomeration—Evidence of shape separation via X-ray microtomography

Abstract Objective of this work was to develop a novel method for characterizing real 3D shapes of particles smaller than 20 μm by X-ray microtomography (X-RMT). Multidimensional separation of heterogenous solids through agglomeration in suspension will improve recycling processes as the particle shape and the agglomerate size are used for shape-selective separation. In the present paper we discuss the fundamentals of X-ray tomography and the experimental setup for selective spherical agglomeration in suspension. A specific preparation method of the particulate sample for X-RMT followed by 3D image processing, are essential for the shape analysis expressed as sphericity. We also discuss the limitation of this method due to the so-called Partial Volume Effect and particle clusters in the order of magnitude of X-RMT resolution. As proof of concept, we used a mixture of graphite platelets and spheronized graphite particles for a shape selective-agglomeration in suspension. The remaining fines were analyzed and showed more platelets than in the mixture. This indicates that spheronized particles are preferably bound in the agglomerates. These findings show that, based on the discussed sample preparation and a 3D image analysis in connection with X-RMT, particle shapes of micronized particles can be discriminated.