Effect of B2O3 on the Melting Characteristics of Model Municipal Solid Waste Incineration (MSWI) Fly Ash

This paper presents the melting characteristics of the multicomponent system of CaO-SiO2-Al2O3-Fe2O3-MgO under the influence of B2O3. Experiments on modelled ash fusibility were conducted in which mixtures of SiO2, Al2O3, CaO, Fe2O3, MgO, and B2O3 were investigated using a high-temperature stage microscope (HTSM) and ash fusion temperature (AFT) test. Thermodynamic calculations combined with X-ray diffraction (XRD) were used to obtain the reaction mechanisms that contributed to the melting process. The results showed that the temperature at which the particles agglomerated and melted decreased as the B2O3 content increased. B2O3 decreased the melting temperatures of the model ash samples, which could be related to the formation of the minerals Ca11B2Si4O22, Ca2B2O5, and CaB2O4 as well as the decrease of refractory minerals such as melilite.