Preparation of high-quality glass-ceramics entirely derived from fly ash of municipal solid waste incineration and coal enhanced with pressure pretreatment

Abstract The disposal and high-volume reutilization of municipal solid waste incineration fly ash into environmentally friendly construction materials have been gaining significant interest over the years. This study proposed a new method to produce glass-ceramics with enhanced mechanical properties and chemical leaching characteristics from fly ash and coal fly ash with mechanical pressure pretreatment. A series of co-sintering experiments were conducted by varying proportions of fly ash and coal fly ash, the pretreatment mechanical pressures and sintering temperatures, and the effectiveness was measured by analyzing the thermal behavior, compressive strength, leaching behavior of heavy metals, mineralogical and microstructural characteristics of sintered samples. The results showed that the obtained glass-ceramics exhibited distinguished physicochemical properties, a maximum compressive strength of 51.00 ± 0.86 MPa was obtained. The leaching concentrations of five heavy metals in sintered samples were much lower than the standard limitation. The morphology results showed the coal fly ash addition positively enhanced the stabilization of heavy metals and the formation of new mineral phases. And the compressive strength was evidently improved with the increase of pretreatment pressure, which was attributed to the microstructure transition and increased crystalline degree. These findings suggested that the production of glass-ceramics entirely from fly ash and coal fly ash with pressure pretreatment is a promising method by minimizing the energy consumption together with the co-disposal of two solid waste streams.