Abstract:
Vanadium slag and sodium peroxide (Na2O2) were mixed, briquetted, roasted, and leached to rich vanadium into V2O5. The effects of roasting temperature, briquetting pressure, roasting time, Na2O2 content, and leaching temperature on the vanadium leaching rate were studied. The results showed that the vanadium leaching rate first increased and then decreased as the molar ratio of Na2O2 to V2O5 increased from 0.5∶1 to 4∶1, the roasting temperature increased from 700 ℃ to 1000 ℃, and the briquetting pressure increased from 1 MPa to 25 MPa. The vanadium leaching rate reached the maximum 95.57% with the Na2O2/V2O5 of 3∶1, the roasting temperature of 850 ℃, and the pressure of 5 MPa. As for the roasting time in the range of 0.5–2.5 h and the leaching temperature of 60–100 ℃, the vanadium leaching rate fluctuated and reached the maximum at 2.5 h and 80 ℃. Under the optimum conditions, the vanadium leaching rate reached 95.57%. Meanwhile, the phases during roasting were analyzed and characterized by X-ray diffraction and electron probe microanalysis. The results showed that the main phases were Fe2O3, Fe3O4, Ca(TiO3), Na3VO4, Mg0.165Mn0.835O. Finally, ammonium salt was added into the leaching solution containing vanadium, and 96.84% V2O5 was obtained through precipitation and calcining process.