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

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.