Incorporation of calcium in glasses: a key to understand the vitrification of sewage sludge
Résumé
The quantity of sewage sludge generated daily in water decontamination represents a major environmental problem. Remediation strategies focus on using the wastes as raw materials to reduce storage costs and minimize the need for mining. An approach by vitrification reduces the volume of waste and inertizes hazardous elements by binding them to the structure of chemically stable glasses and glass-ceramics. The valorization process of sewage sludge by vitrification has been simulated by producing a glass and a glass-ceramic from a basalt enriched in calcium that lies between the stability fields of pyroxene and melilite in the system CaO-MgO-SiO2-Al2O3. Nucleation at the temperature of maximum nucleation rates (650 and 675 ºC) of this glass causes the formation of a biphasic system (crystal + glass) that constrains its rheological behavior enhancing the formation of a large amount of nuclei that result in a fine microstructure, forming a glass-ceramic. The microhardness of the glass (8.2 GPa) and the glass-ceramic (8.6 GPa) and leaching tests (in the ppb range) place both the glass and the glassceramics at the high end of the mechanical properties and chemical resistance of ceramic tiles for the building industry.
Domaines
Sciences de l'environnement
Origine : Fichiers produits par l'(les) auteur(s)