Fluorine-containing silicon residue (FCSR) is a silicon-rich industrial solid waste whose high fluorine content hinders its direct resource utilization. This study aims to develop an efficient and energy-saving strategy for the high-value conversion of FCSR, enabling the simultaneous recovery of silicon resources and removal of fluorine and aluminum impurities.FCSR and carbon black were used as the silicon and carbon sources, respectively, with Fe(NO₃) ₃ serving as a catalyst. Flash Joule heating (FJH) was employed to induce an ultrafast carbothermal reduction reaction at a heating rate of approximately 1000 °C s^-1, producing 3C-SiC and SiC@C composites. The effects of flash temperature, Fe(NO₃) ₃ loading, and the number of FJH cycles on SiC formation and impurity removal were systematically investigated. The lithium-storage performance of the resulting SiC@C composites was evaluated through electrochemical measurements. In addition, a simplified life cycle assessment (LCA) and techno-economic analysis (TEA) were conducted to assess the energy consumption and economic feasibility of the proposed process.The optimal flash temperature was determined to be 2000 °C, and the addition of Fe(NO₃) ₃ at 5 wt% relative to the mass of FCSR significantly promoted SiC formation. After four FJH cycles, the SiC content reached approximately 97%, while the removal efficiencies of Al and F reached 95% and 100%, respectively. The resulting SiC@C composites exhibited favorable lithium-storage performance and rate-cycling stability. Specifically, the SiC@C composite obtained after two FJH cycles delivered a discharge specific capacity of 247.8 mAh g^-1 at the 75th cycle when the current density returned to 50 mA g^-1, corresponding to a capacity retention of approximately 94% relative to the fifth cycle. The simplified LCA and TEA indicated that the total energy consumption of the FJH process was approximately 13.22 MJ per kilogram of FCSR, substantially lower than the 365.40 MJ reported for conventional wet chemical pretreatment, while the processing cost was reduced by approximately 86%.Fe-assisted FJH enables the rapid conversion of FCSR into 3C-SiC while simultaneously removing fluorine and aluminum impurities. With its short reaction time, low energy consumption, and efficient resource utilization, this approach offers a promising strategy for the environmentally sound treatment and high-value valorization of fluorine-containing industrial solid waste.
 

Fluorine-containing silicon residue,Flash Joule heating,3C-SiC,lithium-ion battery