Etude de la fragmentation de milieux granulaires : modélisation numérique à l'échelle du grain et analyse expérimentale du broyage de matières minérales et végétale

Abstract : Although grinding is a widespread operation in industrial processes, it remains poorly understood. The difficulty to model grinding not only lies in the complexity of the fragmentation, which depends on material properties and loading dynamics, but also on the stress transmission from the grinder to the particles. The development of grinding technologies has led to an empirical know-how, and much more effort is still needed to understand the the mechanisms of the comminution of particles. This objective can be achieved only by increasing knowledge on the phenomena involved at different scales (sub-particle heterogeneities, particle, powder bed and boundary conditions of the process).In this PhD work, we investigate the key parameters influencing comminution mechanisms and the energetic efficiency of grinding. A numerical model of particle breakage including a subparticle distribution of cleavages was developed. This model allowed us to analyze the cracks patterns, fragment sizes and probability distribution of failure. At the scale of the process, an extensive experimental study of comminution was carried out using a laboratory mill. An energy evolution inspired by Rittinger model but taking into account the agglomeration phenomena was proposed. This model was then extended to other grinding technologies to compare the energy efficiency for grinding minerals, vegetal particles and their comilling.
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Nicolas Blanc. Etude de la fragmentation de milieux granulaires : modélisation numérique à l'échelle du grain et analyse expérimentale du broyage de matières minérales et végétale. Génie civil. Université Montpellier, 2018. Français. ⟨NNT : 2018MONTS039⟩. ⟨tel-02096278⟩

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