Preparation of additive-free glass-ceramics from MSW incineration bottom ash and coal fly ash

Abstract

An additive-free glass-ceramics was prepared entirely from municipal solid waste incineration bottom ash (BA) and coal fly ash (CFA), which provided new sight for the synthesis of waste-derived glass-ceramics and reduced its production cost. By varying temperature and proportion of BA and CFA, the thermal behaviour, crystalline species, microstructure, physical-mechanical-chemical properties, and metals leaching of glass-ceramics were studied. The results showed that the variation of temperatures did not change the crystal types of glass-ceramics, but affect the crystal volume and morphology. With the basicity increasing from 0.15 (G1, BA/CFA = 30/70) to 0.41 (G5, BA/CFA = 70/30) at 950 °C, the main crystalline phases evolved from single anorthite to coexisting anorthite and diopside, and the compressive strength showed a volcano trend. Among different glass-ceramics, G3 with 50% BA and 50% CFA sintered at 1000 °C demonstrated the most promising properties with density of 2.55 ± 0.02 g/cm3, water absorption of 0.1 ± 0.01%, and compressive strength of 299.09 ± 21.19 MPa, as well as good corrosion resistance to strong acid/alkali solutions. Besides, the metals leaching and ecological risk assessment results of the additive-free glass-ceramics demonstrated a low risk for the metal contamination in the final products and heavy metals were well fixed into the coexistence system of amorphous and crystalline phases. The achieved additive-free glass-ceramics showed competitive properties and environmentally friendly features. Therefore, the preparation of additive-free glass-ceramics from BA and CFA can be considered as a feasible and promising method to realize their efficient utilization and simultaneously reduce the cost of waste-derived glass-ceramics.