Emerging valorization pathways for coal fly ash: carbon capture, strategic element recovery, and polymer composites

Coal fly ash (CFA), a massive by-product of coal-fired power generation, poses significant environmental and health risks if improperly managed. Conventional bulk utilization of CFA in construction, environmental remediation, and agriculture is largely confined to relatively low-value-density sectors and is subject to inherent limitations. This review summarizes the physicochemical properties of CFA and discusses both conventional and emerging utilization pathways, with particular emphasis on three potential high-value routes: CFA-derived materials for CO 2 capture, selective recovery of strategic elements, particularly lithium, gallium, and rare earth elements (REEs), and CFA-based polymer composites. Key mechanisms, performance characteristics, and persistent challenges such as limited long-term stability, low extraction efficiency, and poor interfacial compatibility, are discussed. Comparative considerations of technological maturity, scalability, economic feasibility, and environmental implications are further highlighted based on available literature evidence. Future development requires improved material design, scalable processing strategies, and comprehensive life-cycle and techno-economic assessments to facilitate the transition of CFA from a waste by-product to a valuable resource for sustainable technologies.