The current vanadium extraction process from sodium roasted vanadium slag poses risks such as ammonia pollution. This study proposes a novel calcium-based vanadium extraction and hydrolysis precipitation process

achieving clean and efficient vanadium recovery. The introduction of CaO facilitates the targeted reconstruction and conversion of vanadium and calcium in the solution

forming acid-soluble calcium vanadate intermediates. Under optimal conditions

n

(Ca)/

n

(V) ratio of 1.75

extraction temperature of 90 ℃

and extraction time of 90 min

the vanadium extraction ratio reached 99.83%. This process also separates vanadium from sodium and silicon

enabling one-step purification of the vanadium solution. Subsequent sulfuric acid leaching

conducted at pH of 4.0

90 ℃

and 60 min

achieved a vanadium leaching ratio of 99.72%

further separating vanadium from calcium and other impurities. Finally

the purified vanadium solution underwent hydrolysis precipitation at pH of 2.1 and 95 ℃ for 60 min

achieving a precipitation ratio of 98.69%. The calcined product yielded V

2

O

5

with a purity of 98.60%. Compared to the conventional sodium roasting-water leaching along with ammonium salt precipitation process

this innovative method eliminates ammonia-nitrogen wastewater emissions. This study provides a foundation for the development of new vanadium extraction technologies from vanadium slag.