Phase evolution, microstructure and properties of glass-ceramics derived from municipal solid waste incineration bottom ash and molybdenum tailings

Abstract

Municipal solid waste (MSW) incineration bottom ash (BA) and molybdenum tailings (MTs) are bulk solid wastes that have low added value and is of a serious environmental concern. Hence, it is imperative to develop technology that potentially as convert these wastes into potential products that are safe to handle. In the present work, the goal is to synthesize glass-ceramics from BA and MTs without addition other supplement materials. The study attempts to assess the influences of raw material ratio and sintering temperature on the phase transformation, microstructure and properties of glass-ceramics. The synthesized product shows that diopside ferroan and anorthite were the dominant crystals, and the content of diopside ferroan and anorthite increased with an increase in the proportion of MTs. It was observed that the presence of Fe2O3 and TiO2 inside solid wastes promote nucleation facilitating growth of crystals. Diopside ferroan and anorthite distribute uniformly and are well interweaved, densifying the structure with favorable properties of glass-ceramics. At the optimal processing temperature the presence of Na2O and K2O in the raw materials act as fluxing agents that facilitate formation of liquid phase, that enhance diffusion and rate of crystallization. The optimal mass ratio of BA to MTs was 45:55 and the sintering temperature of 1000 °C, exhibited the best comprehensive properties of the glass ceramics. At the optimal conditions the flexural strength, Vickers hardness, bulk density and water absorption were observed to be 76.00 MPa, 5.77 GPa, 2.69 g/cm3 and 0.32 %, respectively. The leaching test proved stability of the glass ceramics, and hence can serve to be a potential way of utilizing the waste into a valuable product benefiting the environment and promoting sustainable growth.