Selective leaching of vanadium from vanadium-chromium slag using sodium bicarbonate solution and subsequent in-situ preparation of flower-like VS2

A novel leaching method for selectively separating vanadium from calcification roasted vanadium-chromium slag (V-Cr slag) was proposed, using sodium bicarbonate (NaHCO3) as the leaching medium. Vanadium disulfide (VS2), which can be used as an energy storage material, was prepared in-situ by a hydrothermal reaction from the vanadium-containing leaching solution, without purification. VS2 was characterized by XRD, SEM, XPS, and BET. Results show that the leaching extent of vanadium was 92.98% when the calcification roasted materials were treated with 80 g/L NaHCO3 solution and leached at 100 degrees C for 120 min. Additionally, only 1.84% silicon, 0.05% chromium, 0.06% iron, and 0.05% manganese were co-leached along vanadium, meaning that an effective selective vanadium extraction was achieved. The leaching solution was treated with thioacetamide (FAA) in a hydrothermal reaction at 140 degrees C for 16 h, which resulted in a vanadium recovery of 96.00%. The reaction generated flower-like VS2, with vanadium and sulfur in the form of V4+ and S2-. The BET specific surface area of the flower-like VS2 was 21.63 m(2)/g. As an anode material for Li-ion batteries, the initial discharge capacity of the flower-like VS2 reached 1119.83 mAh/g at current density of 100 mA/g, which was favorable for ion storage. This process not only achieved the selective extraction of vanadium, but also provided a new mechanism to shorten the preparation process of VS2 while generating a product with added value.