Enhancing Lithium Extraction from Coal Fly Ash via Ammonium Chloride Activation and Water Leaching for Li2CO3 Crystal Production

This study investigates the optimization of lithium extraction from coal fly ash (CFA), a promising secondary resource, through ammonium chloride (NH4Cl) activation and water leaching. Despite advancements in lithium recovery methods, the suboptimal conditions for NH4Cl activation and non-acidic leaching processes remain a challenge. This research utilizes controlled experiments varying CFA/NH4Cl ratios, activation temperatures, and leaching parameters to address these gaps. The crystallization process of lithium carbonate (Li₂CO₃) was conducted by reacting the lithium-rich solution with sodium carbonate (Na₂CO₃) at a controlled temperature to produce high-purity Li2CO3 crystals. The findings indicate that an optimal CFA:NH₄Cl ratio of 1:1.5, combined with an activation temperature of 155°C, significantly enhances lithium extraction, achieving a lithium concentration of 1.643 mg/L with a yield of 89.14%. Morphological analyses using SEM and FTIR reveal structural alterations in CFA, including breakdowns of aluminosilicate matrices, which increase lithium accessibility. FTIR results also show chemical modifications in CFA post-activation, confirming the removal of less stable components during leaching. Additionally, the study achieved the formation of high-purity Li2CO3 crystals with a recovery efficiency of 65.4%, as confirmed by SEM and XRD analyses. Comparisons with existing literature highlight the environmental benefits and efficiency of the proposed method over conventional acid leaching. The study demonstrates the potential for scalable lithium recovery, contributing to the growing demand for sustainable energy storage solutions. This research advances the field by providing a cost-effective and environmentally friendly alternative for lithium extraction, with implications for industrial scalability. Future studies could refine this process by exploring alternative reagents, operational variables, and the applicability of the method to other industrial by products.