Recycling of granite sludge for the preparation of high‐strength glazed glass‐ceramics using stepwise sintering

Abstract The reutilization of granite sludge generated in granite cutting and processing possesses economic and ecological benefits. In this study, high‐strength glazed glass‐ceramics were prepared entirely from granite powder using dense sintering and instantaneous glaze firing. The densification and glaze formation are clarified in terms of phase evolution to study their effects on the flexural strength and surface glossiness of the glass‐ceramics. The milling process promotes particle refinement and the removal of colored minerals, thus increasing the powder whiteness and sinterability. After dense sintering at 1100°C, instantaneous glaze firing at high temperatures decreases the flexural strength while greatly increases the surface glossiness of the glass‐ceramics due to the dissolution of quartz and feldspars in the liquid phase. After the acid‐leached powder was densely sintered and fired with a rapid heating of 50°C/min to 1300°C, the pinhole‐free glazed glass‐ceramic has a flexural strength of 112.5 MPa and a surface glossiness of 54.7 GU (glossiness unit), meeting the quality requirements of the bright glazed tiles in the market. The stepwise sintering process provides a simple processing route for recycling granite sludge into decorative construction tiles and high‐temperature glazes, promising the scalable and value‐added utilization of granite sludge.