This paper proposes an integrated coupling process of alkali leaching, HBTA-TOPO synergistic extraction, and carbonation for the resource utilization of spent carbon anode (SCA), a typical lithium-bearing industrial solid waste from electrolytic aluminum production, whose lithium content exceeds the ore grade. Compared with conventional acid leaching methods, the adopted alkaline leaching approach features mild reaction conditions, low equipment corrosion risk, and eliminates the volatilization of toxic hydrogen fluoride (HF) gas, thus showing prominent environmental safety advantages. Under the optimal alkaline leaching conditions (NaOH concentration of 10 mol/L, reaction temperature of 90 °C, liquid-to-solid ratio of 10:1, and reaction time of 120 min), the maximum Li+ leaching rate reaches 89.46%. As the leaching process proceeds, lithium in the carbon slag rapidly migrates to the alkaline leaching solution. The Na–Al–F bonds of cryolite (Na3AlF6) and lithium cryolite (Na2LiAlF6) present in the SCA gradually break, and soluble ions such as Na+, Li+, Al3+, and F− enter the solution. High-concentration Na+ reacts with free F− to form sodium fluoride (NaF), which adheres to the SCA, leading to an increase in the sodium-aluminum ratio (Na/Al) of the SCA. The HBTA-TOPO synergistic extraction system is proposed for the extraction and enrichment of lithium in the lithium alkaline leaching solution, and the extraction residue is used to repair and regenerate cryolite. The extraction efficiency of Li+ reaches and the yield of cryolite reaches 81.54% and 76.54%. The molecular ratio of sodium fluoride to aluminum fluoride in synthetic cryolite products is relatively high. This integrated process realizes the efficient recovery of lithium and the high-value regeneration of cryolite from SCA, providing a sustainable technical route for the clean utilization of electrolytic aluminum solid waste. This integrated closed-loop process realizes the simultaneous recovery of lithium and high-value regeneration of cryolite from SCA, which not only mitigates the environmental pollution caused by SCA stacking and the scarcity of lithium resources, but also provides a sustainable technical route for the clean and high-value utilization of electrolytic aluminum solid waste.
