Abstract
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%.
Highlights
Vanadium is a strategic rare metal element
After sodium roasting-water leaching of vanadium slag, only a little silicon is leached, which can effectively achieve the purpose of separating vanadium from silicon
When the amount of sodium carbonate is more than 20%, the leaching rate of vanadium decreases, mainly because too much Na2CO3 is easy to form a substance (NaFeSi2O6) with a low melting point with vanadium slag, which leads to melting and sintering of the sample, wrapping on the surface of roasting slag and reducing the leaching of vanadium
Summary
Vanadium is a strategic rare metal element. Because of its high melting point, tensile strength, hardness, and fatigue strength, vanadium is almost all used in the field of black or non-ferrous alloys [1,2,3,4,5,6,7]. It is difficult for vanadium to exist alone in nature. Vanadium is mainly symbiotic with other minerals or occurs in vanadium-titanium magnetite. Vanadium-titanium magnetites are smelted in a blast furnace to obtain vanadium-bearing hot metal, and vanadium is oxidized into the slag phase to obtain vanadium slag and semi-steel [8]. Vanadium in vanadium titanomagnetite is enriched into vanadium slag
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