Calcium vanadate (CaV₂O₆), a new product of vanadium precipitation, was obtained from vanadium slag by sodium roasting-water leaching and calcium precipitation. The separation behavior of vanadium and silicon in vanadium slag during sodium roasting and water leaching was systematically studied, and micro-morphology and valence migration behavior of vanadium and Fe in vanadium slag, roasting slag, and residue were revealed. The Na₂CO₃ was added to the vanadium slag at 20% mass fraction, roasted at 790 °C, and kept for 120 min, the roasted sample was added to the deionized aqueous solution with a liquid-solid ratio of (L/S) 5mL/g, and then heated at 90 °C for 60 min, 89.54% vanadium and 1.96% chromium were extracted. Sodium carbonate tends to combine with vanadium to form sodium vanadate, while silicon is easy to combine with Fe and Na to form acmite (NaFeSi₂O₆). When the molar ratio of N (Ca/V) is 0.6 and CaO, is added to adjust the pH of vanadium leaching solution to 6.7 ± 0.1 and precipitate 90 min at 90 °C, vanadium is precipitated in the form of CaV₂O₆ with a purity of 95.69%, under these conditions, the precipitation ratio is 95.03%.

In NaCl-KCl-NaF-V₂O₃ molten salt, used graphite as an anode and carbon steel plate as a cathode, vanadium was successfully prepared by molten salt electrodeposition. The reduction mechanism of molten salt electrodeposition vanadium is discussed, and the influence of NaF content, current density, electrodeposition temperature, and electrodeposition time on the electrodeposition vanadium are studied. The optimum electrodeposition conditions are obtained: the composition of molten salt is X_NaCl = 0.4, X_KCl = 0.4, X_NaF = 0.2, V₂O₃ is 15%; adopt bidirectional pulse current (pulse period T = 1000 ms, positive and negative current ratio i_p/i_n = 6:1, positive and negative time ratio t_p/t_n = 3:1); the current density is 200 mA·cm⁻². The electrodeposition temperature is 973 K, and the electrodeposition time is 30 min.