In this paper, we address the role that limestone impurities play in the morphogenesis of different CaO-based particle surfaces. During the thermal decomposition of 00., such impurities can be the source of a complex pattern of reactions that form heterogeneous CaO-based surfaces. Our study reveals that this phenomenon is experimentally measurable once the level of impurities in the starting limestone is approximately 1.7% and the decomposition temperature is 1300°C. In limestones with impurity levels of 1% or less, the reactivity between them and the host CaO/CaCO3 phases is reduced to a negligible level. To explore their average surface properties, we dispersed a set of heterogeneous lime powders in liquid paraffin and measured the correspondent exothermic wetting heat. Combining these results with Brunauer, Emmett and Teller (BET) measurements of the specific surface of the limes allows one to introduce a new parameter: the specific wetting enthalpy ξ (J/m2). Limes with nearly identical specific surface areas of approximately 1 m2/g can differ greatly in their ξ values, which range from -8±0.2 J/m2 to -1±0.2 J/m2. The specific wetting heats can be used as an intensive average thermodynamic parameter to characterise the chemical and physical properties of lime surfaces with specific surface energies that are experimentally undeterminable via calorimetric measurements.

Specific wetting enthalpies for investigating lime surface properties due to the high temperature reactivity of limestone impurities

Alberto Lagazzo;Rodolfo Botter;
2017

Abstract

In this paper, we address the role that limestone impurities play in the morphogenesis of different CaO-based particle surfaces. During the thermal decomposition of 00., such impurities can be the source of a complex pattern of reactions that form heterogeneous CaO-based surfaces. Our study reveals that this phenomenon is experimentally measurable once the level of impurities in the starting limestone is approximately 1.7% and the decomposition temperature is 1300°C. In limestones with impurity levels of 1% or less, the reactivity between them and the host CaO/CaCO3 phases is reduced to a negligible level. To explore their average surface properties, we dispersed a set of heterogeneous lime powders in liquid paraffin and measured the correspondent exothermic wetting heat. Combining these results with Brunauer, Emmett and Teller (BET) measurements of the specific surface of the limes allows one to introduce a new parameter: the specific wetting enthalpy ξ (J/m2). Limes with nearly identical specific surface areas of approximately 1 m2/g can differ greatly in their ξ values, which range from -8±0.2 J/m2 to -1±0.2 J/m2. The specific wetting heats can be used as an intensive average thermodynamic parameter to characterise the chemical and physical properties of lime surfaces with specific surface energies that are experimentally undeterminable via calorimetric measurements.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/882780
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