Abstract: To address the challenges of high additive cost,substantial impurity dissolution,significant environmental pol lution,and high energy consumption in existing vanadium extraction processes from vanadium-bearing steel slag,this study pro posed a clean vanadium extraction process based on blank roasting followed by ammonium bicarbonate leaching.Using a vana dium-bearing steel slag with a V2 O5 content of 0.95% as the raw material,the effects of key roasting and leaching parameters on vanadium leaching efficiency were systematically investigated,and the phase evolution and selective leaching mechanism were elucidated by means of XRD and SEM-EDS.The results showed that under the optimal conditions of blank roasting at 950 ℃ for 3 h,ammonium bicarbonate concentration of 140 g/L,leaching temperature of 80 ℃,leaching time of 2 h,and liquid-to solid ratio of 10∶1 mL/g,the vanadium leaching efficiency reached 43.96%.After concentration,the vanadium concentration in the leachate reached 9.21 g/L,while the contents of impurities such as Ca,Fe,Mg,Al,and Mn were all below 0.01 g/L,dem onstrating the excellent selective leaching capability of this system for vanadium.Mechanistic studies revealed that vanadium was primarily hosted in silicate matrices and calcium-aluminum-iron composite oxide phases.During the leaching process, CaCO3 was newly formed,accompanied by the transformation of some silicate phases,while spinel and aluminate structures such as Ca2 Fe2 O5 ,MgFe2 O4 ,and Ca12 Al14 O33 remained stable,revealing from the phase perspective the mechanism of efficient impurity suppression and selective vanadium release.This process requires no roasting additives,operates under mild condi tions,and yields a leachate with low impurity content that can serve as a high-quality feed for subsequent vanadium precipitati on.This study provides a promising technological pathway for the green utilization of low-grade vanadium-bearing steel slag.

Key words: vanadium-bearing steel slag,blank roasting,ammonium bicarbonate leaching,vanadium leaching efficiency