Electrochemical extraction of water-reactive silicon from coal fly ash in molten CaCl2-CaO

Coal fly ash (CFA), a major byproduct of coal-fired power plants, poses significant environmental challenges due to landfill accumulation and air pollution. Traditional recycling methods, primarily focused on construction materials, are limited by low efficiency, marginal economic returns, and potential ecological risks. This study proposes a high-value and eco-friendly strategy for CFA utilization based on molten salt electrochemistry. In this novel process, CFA is leached in molten CaCl 2 –CaO, and soluble silicate ions are subsequently reduced electrochemically to produce water-reactive silicon. The resulting silicon powder features a loosely agglomerated, submicron structure, showing high reactivity with water at temperatures near its boiling point and enabling on-demand hydrogen generation. This approach enables the efficient extraction of high-value silicon from CFA, offering a promising pathway for the clean and sustainable utilization of CFA in energy-related applications.