<p>Hydrogen fluoride is an important basic chemical raw material that is widely applied in semiconductor manufacturing and electronic device processing. Aluminum electrolyte slag containing Na₃AlF₆ is a good candidate for producing hydrogen fluoride. In this study, we discussed the effect of pre-delithiation on the evolution of hydrogen fluoride for the concentrated sulfuric acid leaching method. Through systematic single-factor experiments, the effects of leaching temperature, liquid-to-solid ratio, and reaction time on the fluorine removal efficiency were investigated. Additionally, kinetic analysis clarified the rate-controlling steps of leaching. Furthermore, SEM morphology analysis, particle size distribution testing, and BET specific surface area measurements were utilized to reveal the mechanism of fluorine removal under low-temperature conditions. As a result, the fluorine removal efficiency increased from ~ 55% to ~ 100% owing to the formation of the active phase and smaller particle size. This study demonstrates that pre-delithiation treatment activates the material, and a high efficiency of fluorine removal can be obtained.</p>