Preparation and characterization of glass-ceramics from oil shale ash: Effect of basicity and sintering temperature on crystallization behavior, properties, and environmental risk

Oil shale ash is an inorganic by-product generated from the combustion and refinement of oil shale. In this study, it was used as main raw material to produce glass-ceramics. The crystalline phases, crystallization mechanism, bulk density, compressive strength and microstructure of glass-ceramics were studied. Specifically, the leaching characteristics and ecological risk assessment of heavy metals in glass-ceramics were emphasized. The results showed that the increase of basicity reduced the crystallization activation energy , but the surface crystallization mechanism of different samples has not changed. Anorthite and diopside were identified as the main crystalline phases in glass-ceramics despite varying basicity and sintering temperatures . The compressive strength and bulk density increased with the increase of sintering temperature. The compressive strength of VS2 (basicity = 0.3) was higher than that of VS1 (basicity = 0.2) for the same sintering temperature due to more crystals and denser microstructure. Independent of the basicity, a higher sintering temperature promoted the sintering and densification of products. The highest compressive strengths of VS1 and VS2 were 219.14 ± 12.8 and 255.57 ± 15.6 MPa, respectively. In addition, the reliable stability and low potential ecological risk index of heavy metals in the final products make it to be a competitive eco-friendly construction material.