Preparation of glass–ceramics from high-chlorine MSWI fly ash by one-step process

Municipal solid waste incinerated (MSWI) fly ash contains heavy metals and chloride, which is urgent to be disposed via an effective method. Herein, glass–ceramics, one of the recycling waste materials based on MSWI fly ash with high chloride content, have been developed from one-step process. MSWI fly ash and waste glass have been utilized as calcium and silicon sources, respectively. Glass–ceramics were successfully prepared by the one-step process. It is found that the increase in MSWI fly ash promotes the fracture of glass mesh (Si–O) and the generation of non-bridging oxygen, reducing the polymerization degree of glass network structure, which leads to the decrease in glass stability. The difference between glass transition temperature (Tg) and crystallization temperature (Tc) was narrowed, and crystallization activation energy of basic glass was reduced, which promoted crystallization. With lower crystallization activation energy (E = 217.56 kJ·mol−1) and high utilization rate of 50 wt% MSWI fly ash, the optimal glass–ceramics with spherical diopside, cuspidine and glass phase, excellent hardness of 7.97 GPa and bending resistance of 114.86 MPa are achieved. It is worth mentioning that most of the high content of chlorine in MSWI fly ash will evaporate during vitrification process; the residual chlorine as well as heavy metals can be present steadily in crystalline grains. Therefore, this study not only increases the attachment value of MSWI fly ash, but also eliminates the problems caused by high chlorine and heavy metals in MSWI fly ash.