Calcified roasting followed by dilute sulfuric acid leaching is a promising process for cleaner vanadium extraction from converter vanadium slag. However, some impurities, like Ca, Mg, Mn, Si and Al, also transfer into the leaching solution, accompanying V during the dilute sulfuric acid leaching, leading to the product of vanadium pentoxide prepared from this acidic vanadium-bearing solution, inferior to the product from the traditional process of sodium roasting and water leaching. A chemical precipitation method was firstly proposed to purify this acidic vanadium-bearing solution with a new prepared remover of MnNH₄F₃, which combines neutralization and fluoride precipitation into one operational step to remove impurities of Ca²⁺, Mg ²⁺, Al³⁺ and Si⁴⁺ in an acidic pH range, simultaneously. Effecting factors involved in the purification process were investigated. It was found that removals of Ca, Mg and Al were all over 95% and around 55% of Si was removed as well at stirring speed of 200 rpm, adding coefficient of 1.6, temperature of 50 °C, reaction time of 30 min and pH of 4.50 ± 0.05, while the loss of vanadium was kept lower than 5%, which was attributed to the reason that the purification reactions mainly proceeded on the surface of the remover. Adding flocculant of polyacrylamide was conductive to accelerating sedimentation of the precipitate and reducing the loss of vanadium. Meanwhile, the filter aid of diatomaceous could improve the filtration performance of the slurry. Ammonium persulfate could effectively oxidize and separate Mn²⁺ in the form of MnO₂ from the vanadium-bearing solution which had been treated by MnNH₄F₃, but performed less selectivity over Mn²⁺, and the loss of vanadium was unacceptable. The product of vanadium pentoxide prepared from the purified vanadium-containing solution satisfied the requirements for the standard of grade 98.

中文翻译：

---

新型化学沉淀法纯化酸性含钒溶液

用钙焙烧然后稀硫酸浸出是从转炉钒渣中提纯钒的有前途的方法。但是，在稀硫酸浸出过程中，一些杂质（如Ca，Mg，Mn，Si和Al）也随V一起转移到浸出溶液中，导致由这种酸性含钒溶液制备的五氧化二钒的产品劣于该产品来自传统的钠焙烧和水浸工艺。首先提出了一种化学沉淀法，用一种新制备的MnNH ₄ F ₃去除剂来纯化该酸性含钒溶液，该去除剂将中和和氟化物沉淀结合到一个操作步骤中，以去除Ca 2 ⁺，Mg ^2+的杂质。，Al ³⁺和Si ⁴⁺同时在酸性pH范围内。研究了纯化过程中涉及的影响因素。发现在200 rpm的搅拌速度，1.6的添加系数，50°C的温度，30分钟的反应时间和200 rpm的搅拌速度下，Ca，Mg和Al的去除率均超过95％，Si的约55％也被去除。 pH为4.50±0.05，而钒的损失保持在5％以下，这是由于纯化反应主要在去除剂表面进行的缘故。添加聚丙烯酰胺絮凝剂有助于加速沉淀物的沉淀并减少钒的损失。同时，硅藻土助滤剂可提高浆料的过滤性能。过硫酸铵可有效氧化并分离Mn ²⁺MnNH ₄ F ₃处理过的含钒溶液以MnO ₂的形式生成MnO ₂，但对Mn ^2+的选择性较小，钒的损失是不可接受的。由纯化的含钒溶液制备的五氧化二钒产品满足98级标准的要求。