Strategy for Stepwise Removal of Silicon and Tungsten from Alkaline Solution Containing Vanadium and Preparation of High-Purity Nh4vo3

Abstract

Vanadium-containing alkaline solution, which obtained directly from vanadium-containing secondary resources, is a kind of precursor solution for preparing high purity vanadium-based materials. However, the solution still contains trace impurities, especially tungsten (W) and silicon (Si), after separation and enrichment, which present severe challenges in the manufacture of high-purity vanadium products. This study introduces a stepwise impurity removal technique, realized the efficient separation of vanadium from tungsten and silicon in alkaline solution and successfully prepares NH4VO3. The AlCl3 was introduced to separate Si impurities according to the chemical precipitation method, which formed stable aluminosilicate precipitates and achieved high-efficiency removal of Si with a removal rate of 99.05%, while the loss of V is maintained at a low level of 0.61%. Based on the difference of binding ability of V2O74-, HVO43-, WO42- and Ca2+, the separation of V and W is achieved by precisely precipitation and followed by ammoniation transformation process, while the recovery efficiency of vanadium reaches as high as 87.96%. The uniform crystal morphology and size NH4VO3 can be directly separated by cooling crystallization in the impurity removal solution without adjusting pH, and the purity of the final NH4VO3 product reaches 99.88%. This study developed a new technology for the resource utilization of vanadium containing alkaline solutions, providing strong support for building a green, low-carbon, and sustainable high purity vanadium product.

Keywords: Spent SCR catalysts, Vanadium, Impurity removal, Recycling, NH4VO3