熔融钒渣纯氧氧化钙化提钒(英文)

在实验室条件下对熔融态钒渣直接氧化钙化提钒新工艺进行研究。在反应过程中利用纯氧氧化,CaO作为添加剂,硫酸浸出熟料。采用XRD、XPS、SEM及EDS等手段对钒渣熟料进行分析,考察不同CaO/V2O5质量比与硫酸浓度对熟料中钒浸出的影响,并与现行焙烧工艺在能耗方面进行对比。结果表明:钒渣熟料中形成了钒的富集相,钒渣的氧化钙化产物主要为CaV2O5和Ca2V2O7,并对钒酸钙的形成机理进行了阐释;XRD和XPS分析得出熔渣中钒的氧化反应在供氧充足的情况下存在一定限制,CaO的增加能促进五价钒在熔渣中的稳定;在优化的实验条件下(CaO/V2O5质量比0.6,粒度120~150μm,浸出时间2 h,浸出温度90°C,液固比5:1 mL/g,H2SO4浓度20%,搅拌强度500 r/min),钒的浸出率能达到90%;能耗计算得到每处理1000 kg钒渣,利用新工艺可以节约能量1.85×106 kJ。实验与计算结果验证新工艺是一种节能减排的提钒手段。

Extraction of vanadium from molten vanadium bearing slag by oxidation with pure oxygen in the presence of CaO

A novel process of vanadium extraction from vanadium slag in its molten state was conducted at the laboratory scale by oxidation with pure oxygen in the presence of CaO. The effect of mass ratio of CaO to V₂O₅ on the recovery of vanadium was studied. The sintered samples were leached by H₂SO₄ solution and characterized by XRD, XPS, SEM and EDS techniques. Compared with the roasting process, the energy saving effect of the proposed process was also discussed. The results showed that vanadium-rich phases were formed and vanadium mainly existed in the forms of CaV₂O₅ and Ca₂V₂O₇. The formation mechanism of calcium vanadates in the molten vanadium bearing slag was explained. The XRD and XPS results implied that there was a limit to the oxidation reaction of V(IV) to V(V) under the high temperatures even though oxygen-supply was sufficient. An increase in the CaO content led to an increase in the formation of Ca₂V₂O₇. About 90% of the vanadium recovery was obtained under optimal experiment conditions (mass ratio of CaO to V₂O₅ of 0.6, particle size 120 to 150 μm, leaching temperature 90 °C, leaching time 2 h, H₂SO₄ concentration 20%, liquid to solid ratio 5:1 mL/g, stirring speed 500 r/min). The energy of 1.85×10⁶ kJ could be saved in every 1000 kg of vanadium bearing slag using the proposed process from the theoretical calculation results. Recovery of vanadium from the molten vanadium bearing slag and utilisation of its heat energy are important not only for saving metal resources, but also for energy saving and emission reduction.