Synergistic valorization of lithium mine tailings for lightweight foamed ceramics: Process optimization, pore...

The rapid expansion of the lithium-ion battery industry has generated massive quantities of lithium mine tailings (LMT), creating severe environmental and land-occupation challenges. This study presents a novel and sustainable approach for converting LMT into high-performance lightweight foamed ceramics by synergistically incorporating blast furnace slag, diatomite, pyrite tailings, and calcined kaolin. Batch compositions were rationally designed based on the CaO-MgO-Al₂O₃-SiO₂ phase diagram, and sintering parameters were systematically optimized. Comprehensive characterization using XRD, SEM-EDS, Micro-CT, mercury intrusion porosimetry, and mechanical testing revealed that at 1150 °C with 90 min holding time and 5 °C·min^-1 heating rate, the optimal formulation achieved a minimum apparent density of 0.75 g/cm³ while maintaining acceptable compressive strength. A uniform honeycomb-like pore structure with thick, continuous walls was formed through the ideal dynamic balance between liquid-phase viscosity and internal gas pressure. Gas generation originated primarily from SO₃ decomposition and residual carbon combustion, and structural reinforcement was provided by stable mullite crystals. Elemental mapping confirmed that moderate LMT addition optimized the Si/Al/Ca ratio in the glass phase, enabling superior pore uniformity and mechanical integrity. This study developed an efficient and low-carbon approach for the high-value utilization of hazardous lithium mine tailings, paving the way for sustainable lightweight insulation materials specifically derived from complex lithium-bearing wastes, and advancing circular economy development in the lithium battery industry.