Efficient Separation of Silicon and Vanadium by Sodium Roasting-Water Leaching from Vanadium Slag and CaV2O6 Preparation

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 degrees 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 degrees 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 degrees C, vanadium is precipitated in the form of CaV2O6 with a purity of 95.69%, under these conditions, the precipitation ratio is 95.03%.

Automated summary

Calcium vanadate (CaV2O6), a new product obtained from vanadium slag, was successfully synthesized by sodium roasting-water leaching and calcium precipitation. The study systematically investigated the separation behavior of vanadium and silicon during the process, and achieved a purity of 95.69% for the precipitated CaV2O6 under specific conditions.