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Réactivité à haute température de l’hexa-aluminate de calcium au contact des cendres de biomasse

Abstract : High-temperature corrosion by alkali (salts or oxides of sodium and/or potassium in solid, liquid, and vapor state) and slag is a serious problem that affects the service life of refractories used in incineration plants. In order to contribute to a better knowledge of this attack, a laboratory study was carried out during this research to study alkali corrosion of different raw materials: fireclay, andalusite, mullitized andalusite, mullite, fused zirconia mullite, bauxite, white corundum, β-alumina and compared to calcium hexa-aluminate.Moreover, the reactivity of calcium hexa-aluminate and alumina with CaO-SiO2 and CaO-Al2O3 slags is studied to evaluate their resistance. The reaction kinetics is determined from ex-situ corrosion tests by XRD after cooling, on CA6/Al2O3 grains mixed with slag synthesized and milled in varying proportions. For both alumina and calcium hexa-aluminate grains, the dissolution is fast, followed by a slow precipitation of an intermediate compound. This is in agreement with thermodynamic predictions.As a result, calcium hexa-aluminate shows both high thermochemical stability in contact with alkali and high dissolution resistance to liquid oxides. Industrial trials are underway in an American hazardous waste incinerator located in Houston. The results after a trial period of 7.5 months show that calcium hexaluminate castable is resistant.
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Submitted on : Thursday, May 6, 2021 - 12:10:20 PM
Last modification on : Friday, May 7, 2021 - 3:22:05 AM


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  • HAL Id : tel-03219294, version 1



Mouna Sassi. Réactivité à haute température de l’hexa-aluminate de calcium au contact des cendres de biomasse. Science des matériaux [cond-mat.mtrl-sci]. Université d'Orléans, 2019. Français. ⟨NNT : 2019ORLE3101⟩. ⟨tel-03219294⟩



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