Mo(Ⅵ)-V(Ⅴ)-H_2O体系的热力学分析  

Thermodynamic analysis of Mo(Ⅵ)-V(Ⅴ)-H_2O system

作　　者：廖宇龙[1] 李江涛[1] 

机构地区：[1]中南大学冶金与环境学院,长沙410083

出　　处：《粉末冶金材料科学与工程》2016年第5期678-684,共7页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金青年项目(51304246)

摘　　要：通过热力学计算,绘制Mo（Ⅵ）-V（Ⅴ）-H2O体系中不同Mo,V浓度下各物质随p H值变化的平衡图（25℃）,为现行的钼钒分离技术提供理论依据。对计算结果分析可知,碱性溶液中Mo元素以单钼酸根形式存在,而V元素在弱碱性条件下即聚合为同多钒酸根。由于聚合阴离子与吸附剂的结合能力通常强于单核阴离子,故可从p H=7-8的溶液中实现Mo,V有效分离。当溶液p H值降至中性时,单钼酸根开始聚合成同多钼酸根;而p H值降至弱酸性时,同多钒酸根和同多钼酸根转变成多种钼钒杂多酸根。由于p H=6.5-7的溶液中杂多酸根的比例较少,添加试剂促进杂多酸根的解聚有助于钼钒的分离;p H=2-6的溶液中两者难以分离的原因在于杂多酸根的比例很大。The thermodynamic equilibrium diagrams of Mo（Ⅵ）-V（Ⅴ）-H_2 O system on the distribution of substances at different p H and concentrations of Mo and V at 25 ℃ were drawn to provide theoretical explanation for the current separation technology of them. It is shown that Mo exists as single molybdate in alkaline solution, while V can be aggregate into isopoly vanadates in weak alkaline conditions. The binding power of polymeric anions and adsorbents is usually better than that of single anions and adsorbents, so the effective separation of Mo and V can be achieved in the p H=7-8 aqueous solution. When the p H is lowered to neutral, single molybdate begin to aggregate into isopoly molybdates; as the p H value is lowered to weak acid, isopoly molybdates and isopoly vanadates transform into a variety of heteropolyanions. Because the ratio of heteropolyanions is little in p H=6.5-7 solution, the addition of reagents which can promote the depolymerization of heteropolyanions may contribute to the separation. However, it is difficult to separate Mo and V in the p H=2-6 solutions, owing to a large proportion of heteropolyanions.

关 键 词：Mo(Ⅵ)-V(Ⅴ)-H2O系 钼 钒 分离 杂多酸 热力学分析 

分 类 号：TF841.2[冶金工程—有色金属冶金]