A clean metallurgical process for vanadium precipitation from chromium-containing vanadate solution

Abstract

The conventional process of sodium carbonate roasting-water leaching for vanadium extraction cannot be applied to high chromium bearing vanadium slag, and the production process will produce a large amount of V-Cr-bearing reducing slag and wastewater containing sulfate and ammonium salt. To avoid these questions, this work proposes a novel process for the extraction of vanadium and chromium from vanadium slag. In the current research, the vanadium precipitation part of the novel process was studied in detail. The experiment results show that weak basic ammonium bicarbonate precipitation method can realize the selective precipitation of vanadium from chromium-containing vanadate solution. The presence of Cr(VI) in the solution has a great influence on precipitation, crystallization as well as product purity of NH4VO3. Chromium can increase the solubility of NH4VO3 and reduce the supersaturation degree of NH4VO3. Furthermore, it can change the crystal morphology of NH4VO3 and affect the precipitation of NH4VO3. The precipitation of NH4VO3 increased with the increase of N/V molar ratio, but decreased with the increase of chromium concentration in the solution. The content of chromium in V2O5 increased with the increase of N/V molar ratio as well as the chromium concentration in solution. For vanadate solutions containing 2.0, 5.0, 10, 20 and 25 g/L Cr, under the most suitable vanadium precipitation conditions, the precipitation of vanadium is 83.5%, 80.1%,73.8%, 61.2% and 60.3%, respectively.