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2006-12-01 - Colloque/Présentation - poster - Anglais - 1 page(s)

Sciamanna Valérie , Spagna Paul, Andrew Alexis, de Haan André, Dupuis Christian , "The burnability of white cement raw materials" in BCerS 06, Mol, Anvers, Belgique, 2006

  • Codes CREF : Matériaux céramiques et poudres (DI2744)
  • Unités de recherche UMONS : Géologie fondamentale et appliquée (F401), Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)

Abstract(s) :

(Anglais) In white cement production, the raw materials must be relatively low in Fe2O3 and other colouring oxides such as manganese, titanium and chromium oxides which contribute to the colour. These impurities are indeed of the fluxes whose importance is related to the need of a liquid phase for the rapid formation of C3S. Consequently, the production of white cement requires much more energy than that of gray cement. Also, it is important to control the parameters affecting the reactivity of the raw materials. The major problem encountered in the white cement plant with which we work, is the excessive formation of dust. In the industrial kiln, dust is responsible of losses of heat and materials. That’s why the reasons of dusting must be clarified. One of the causes is the formation of particularly friable kiln rings but the granulometry of the siliceous materials seems to have its share of responsibility in these disturbances. This work reveals that the granulometry of quartz has an essential role on the burnability . When the percentage of quartz larger than 50 µm is too high, clusters of belite (C2S) are generated and the alite (C3S) formation is partially compromised. As a result, the content of free lime of the clinker is too high. These observations were already pointed out in gray cement studies. The authors showed that the proportions of calcite particles larger than 125 µm, and of quartz particles larger than 44 µm are particularly important to assess burnability at 1400°C. From our investigations it seems that siliceous materials are not only responsible of high free lime content of clinker but also of dust formation. When coarse quartz is present in quantity in the raw mix, the polymorphic transition of ß-C2S to ?-C2S occurs, involving a great increase of specific volume.