Preparation and characterization of glass-ceramics via co-sintering of coal fly ash and oil shale ash-derived amorphous slag

A novel preparation method of glass-ceramics from coal fly ash (CFA) and oil shale ash-derived amorphous slag (OSAS) was developed in this study. Effects of important factors such as OSAS/CFA ratio and sintering temperature on the crystalline phase compositions, microstructure, mechanical-chemical properties, heavy metals leaching characteristics, and potential ecological risk assessment of glass-ceramics were investigated. The results showed that the properties of glass-ceramics increased with increasing OSAS/CFA ratio and sintering temperature, and S4 glass-ceramics (100% OSAS) showed the most superior product performances, followed by the S3 (80%OSAS-20%CFA), S2 (60%OSAS-40%CFA), and S1 (100% CFA). As for the products from the mixed sources, the best product properties of S2 glass-ceramics (density, 2.00 +/- 0.04 g/cm(3); water absorption, 3.11 +/- 0.22%; and compressive strength, 106.67 +/- 28.42 MPa) were achieved at 1085 degrees C. S3 glass-ceramics showed the highest density of 2.16 +/- 0.04 g/cm(3), and lowest water absorption of 0.22 +/- 0.01%, and highest compressive strength of 195.99 +/- 23.85 MPa at 1085 degrees C. Specially, the overall energy consumption for preparing S2 and S3 glass-ceramics was estimated to be reduced 23.66-27.00% and 11.67-13.50%, respectively, compared to that of S4 glass-ceramics. In addition, the good chemical stability, low heavy metals leaching concentrations and low potential ecological risk of OSAS-CFA-derived glass-ceramics further confirmed its potential and feasibility as building material in engineering application.