Compréhension des mécanismes de fragmentation par analyse granulométrique et morphologique

Abstract : aComminution is an important process in powder technology, in which progress can still be made, to improve the operation of existing equipments or to design new systems. To understand better the phenomena taking place in the grinding chambers, the classical approach based on the examination of size distributions has been combined with the distributions of the shape of the fragments, observed by scanning electron microscopy and characterised by image analysis. The particle morphology has been assessed through the use of a set of seven parameters, six of them describing the 2D shape and one the pseudo 3D shape. In complement statistical tools (tests, principal component analysis) have been used. Comminution experiments have been run with different materials exhibiting either welldefined initial morphology (gibbsites obtained by crystallisation) or not (natural rocks) in a stirred bead-mill with different suspension concentrations, and beads diameters and filling rates. After a preliminary study of the particles before grinding, the analysis of the size reduction phenomena from the size distributions only has shawn its limits. The method finally proposed is based on a joint analysis of the shape and size parameters. If a better understanding of the phenomena can help to control the product quality, a possible pollution by fines produced by wear of the grinding bodies should be taken into account. A method based on the analysis of their surface by scanning electron microscopy is proposed to monitor this wear.
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Karima Bélaroui. Compréhension des mécanismes de fragmentation par analyse granulométrique et morphologique. Alimentation et Nutrition. Institut National Polytechnique de Lorraine, 1999. Français. ⟨NNT : 1999INPL131N⟩. ⟨tel-01749897⟩

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