New Insights into a Vanadium Precipitation Process by Hydrolysis Based on Manganese Salt Pretreatment

Vanadium precipitation is the key step in producing vanadium products from vanadium solution. The sustainable development of the vanadium industry requires new environmentally friendly processes for vanadium precipitation. In this study, NaVO₃ solution was pretreated with manganese salt to preliminarily separate the vanadium and sodium components. The product of vanadium extraction by manganese salt was dissolved by acid to produce manganese vanadate solution. After vanadium precipitation by hydrolysis, manganese removal, and calcination, the target product V₂O₅ was obtained. Scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma emission spectrometry (ICP-OES), and atomic absorption spectrometry (AAS) were used to perform the characterization and analyses. The results showed that vanadium and manganese have a strong binding ability. The rate of vanadium extraction by manganese salt reached 99.75%, and the product of vanadium extraction by manganese salt was Mn₂V₂O₇, with a sodium content of only 0.089%, confirming the effective separation of vanadium and sodium. The acid dissolution rate of the vanadium extraction product reached 99.95%, and the rate of vanadium precipitation by hydrolysis reached 97.87%. After manganese removal and calcination, the purity of the V₂O₅ product reached 98.92%. In addition, the recyclability of manganese sulfate and ammonium sulfate was analyzed. The process reduced the production of ammonia-nitrogen wastewater, laying a foundation for researching new technologies for extracting vanadium from vanadium slag.