(中南大學(xué) 冶金與環(huán)境學(xué)院，長沙 410083)
摘 要: 通過熱力學(xué)計算繪制25 ℃時W(Ⅵ)-V(Ⅴ)-H2O系中存在的離子隨pH、鎢、釩濃度變化的熱力學(xué)平衡圖，并總結(jié)其變化規(guī)律。通過熱力學(xué)分析，從理論上尋找到鎢、釩在混合溶液中存在形式上的差異，并據(jù)此提出鎢釩分離的技術(shù)路線。釩形成聚合離子的能力強于鎢。在pH約為8.5~9.0的條件下，溶液中絕大部分的釩以聚合離子形式存在，而鎢則幾乎全部為單核離子，利用該差異通過合理的分離手段即可實現(xiàn)二者的有效分離；而在鎢、釩濃度均較低時，體系會在pH較低的條件下形成VO2+離子，而此時鎢的存在形式全部為陰離子，因而，采用陽離子萃取劑或陽離子樹脂可望選擇性地將VO2+從溶液中分離。
關(guān)鍵字: W(Ⅵ)-V(Ⅴ)-H 2O系；鎢；釩；分離；熱力學(xué)平衡；鎢釩雜多酸根離子
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:The thermodynamic equilibrium diagrams were drawn for the distribution of species at different pH and concentrations in the W(Ⅵ)-V(Ⅴ)-H 2O system at 25 ℃. The difference of existing forms between W and V in the mixed solution was found by the theoretical analysis, and accordingly the technical routes for separation of W and V were presented. The results show that the polymeric ability of VO43- is stronger than that of WO42-. At the pH range of 8.5-9.0, most of VO43- transform to polymeric anions, while almost all W ions still exist as the form of monomeric WO42-. This difference makes it possible that W and V can be separated efficiently by a proper method. In the solution with low concentration of W and V, VO2+ ions are formed under low pH conditions, while W ions exist as the form of anions. Consequently, VO2+ ions can be selectively separated by the cation extraction agent or exchange resin.
Key words: W(Ⅵ)-V(Ⅴ)-H 2O system; W; V; separation; thermodynamic equilibrium; tungstovanadate
