To achieve the clean extraction of vanadium from iron vanadate spinel minerals, vanadium has been successfully leached as [V(C₂O₄)₃]³⁻ complex by using oxalic acid as a leaching agent in our previous study. However, the precipitation of vanadium from the V-bearing oxalic acid leaching solution has never been reported. Therefore, an environment-friendly hydrothermal precipitation method was applied in vanadium precipitation process in this study. Firstly, vanadium was effectively precipitated from the V-bearing oxalic acid leaching solution by hydrothermal decomposition of [V(C₂O₄)₃]³⁻ complex ions at the temperature above 200 °C to obtain a mixture of vanadium oxides. Based on the vanadium precipitation, to further obtain high purity vanadium oxide product, the hydrothermal precipitation of VO₂ from the V-bearing oxalic acid leaching solution was investigated. Before the hydrothermal reaction, an excess hydrogen peroxide solution was employed to oxidize the [V(C₂O₄)₃]³⁻ complex ions to form VOC₂O₄ in advance. Then, the effect of temperature, the quantity of added V₂O₅, and reaction time on the VO₂ product preparation and vanadium precipitation extent were investigated. Finally, the uniform and well-crystallized VO₂ (B) with 97% purity was obtained, and higher than 99% of vanadium precipitation extent was achieved under the optimum precipitation conditions.

为了从钒铁尖晶石矿物中清洁提取钒，钒在我们先前的研究中已成功通过使用草酸作为浸出剂浸出为[V（C ₂ O ₄）₃ ] ³⁻络合物。然而，从未报道过从含V的草酸浸出溶液中钒的沉淀。因此，本研究在钒的沉淀过程中采用了一种环境友好的水热沉淀法。首先，通过[V（C ₂ O ₄）₃ ] ^3-的水热分解，从含钒的草酸浸出溶液中有效地沉淀出钒。在高于200°C的温度下生成复杂的离子，以获得钒氧化物的混合物。在钒沉淀的基础上，为进一步获得高纯度氧化钒产品，研究了从含钒草酸浸出液中水热沉淀VO ₂的方法。在水热反应之前，先使用过量的过氧化氢溶液将[V（C ₂ O ₄）₃ ] ^3-络合离子氧化以预先形成VOC ₂ O ₄。然后，温度的影响，添加V的数量₂ ø ₅上的VO，和反应时间₂研究了产物的制备和钒的沉淀程度。最终，获得了纯度为97％的均匀且结晶良好的VO ₂（B），在最佳沉淀条件下，钒的沉淀程度达到了99％以上。