Large-scale reuse of copper tailings can mitigate environmental hazards and recover strategic elements; this work investigates the feasibility of producing foam glass-ceramics with high copper-tailing content (>70 wt%) by tuning the CaO/SiO₂ ratio to couple melt viscosity and crystallisation. The comprehensive utilisation of these tailings helps mitigate environmental pollution and enhance resource efficiency. In this study, foam glass-ceramics with varying CaO/SiO₂ ratios were synthesised through melt quenching followed by foaming heat treatment. The effects of different CaO/SiO₂ ratios on the foaming behaviour, crystallisation, and microstructure were investigated using DSC, FTIR, viscosity, XRD, SEM, and CT. The results indicate that increasing the CaO/SiO₂ ratio disrupts the three-dimensional network structure of the glass, which lowers the glass viscosity and influences the bubble size and distribution in the foam glass-ceramics. Additionally, the increased CaO content promotes crystal precipitation and enhances the compressive strength of the foam glass-ceramics. At a CaO/SiO₂ mass ratio of 0.22, the foam glass-ceramics exhibited the lower bulk density (240 kg/m³) and thermal conductivity (0.07 W/m·K). The materials also demonstrated good water absorption and compressive strength. This study highlights the potential of using copper tailings in foam glass-ceramics to improve their overall performance, offering promising energy-saving and environmentally friendly solutions.

The safe disposal and resource utilization of industrial fluoride-containing sludge represent a critical environmental challenge. In this study, high-performance fluorcanasite glass-ceramics were successfully synthesized from industrial sludge via a melt-quenching method followed by heat treatment. The effects of equimolar substitution of Al2O3 for SiO2 on the phase composition, glass network structure, crystallization behavior, mechanical properties, and fluoride leaching were systematically investigated. Structural analyses revealed that lower Al2O3 content (1–1.5 mol%) favored the formation of layered Q3 units, promoting the precipitation of an interlocking lath-like fluorcanasite main phase at 800 °C. Conversely, higher Al2O3 substitution (≥ 2 mol%) induced the precipitation of xonotlite. The optimized fluorcanasite glass-ceramic (1 mol% Al2O3) exhibited exceptional mechanical performance, achieving a maximum flexural strength of 296.71 ± 22.18 MPa, an elastic modulus of 75.33 ± 0.03 GPa, and a fracture toughness of 1.00 ± 0.14 MPa·m1/2. Furthermore, the fluorcanasite crystalline phase effectively immobilized F− ions, and its layered structure enhanced chemical durability. This work provides a promising method for the resource utilization of fluoride-containing sludge.