摘要
根据同时平衡原理以及质量守恒定律，绘制了在不同的游离总钙浓度下Ca-V（V）-H2O体系25℃时的热力学平衡图，并进行了热力学分析。结果表明，随着溶液pH值的增大，体系中依次出现V2O5、Ca（VO3）2、CazV2O7、Ca3（VO4）2、Ca3（VO4）7＋Ca（OH）2、Ca（OH）2六个沉淀稳定区。当沉钒反应平衡后液游离总钙浓度为0．01mol／L时，在pH=5．1～9．8范围内，钒以Ca（VO3）。形式沉淀，钒浓度最低可降至2．2×10^-3mol／L；在pH-9．8～10．3范围内，钒以Ca2V2O7形式沉淀，钒浓度最低可降至1．2×10^-2mol／L；在pH=10．3～12．6范围内，钒以Ca3（VO4）2形式沉淀，钒浓度最低可降至2．4×10^-4mol／L，沉钒效果最佳。当游离总钙浓度为0．01～1．0mol／L时，理论最佳沉钒pH值基本维持在11．0～12．6。
According to the principle of simultaneous equilibrium and the law of mass conservation, thermodynamic equilibrium diagrams of Ca-V（V ）-H2O system were established with different concentrations of total free calcium at 25 ℃, and then thermodynamic analysis was made of the system. The results show that the six stable solid regions of V2O5 ,Ca（VO3）2, Ca2V207 ,Ca3 （VO4）2 ,CaB （VO4）2 ＋Ca（OH）2 and Ca（OH）2 appear in turn with increase of the system pH value. When total free calcium concentration is 0.01 mol/L in the equilibrium system,at the pH region of 5.1-9.8,vanadium is precipitated in the form of Ca（VO3）2 and vanadium concentration can be reduced to 2.2× 10^-3 mol/L. At pH region of 9.8-10.3, Ca2 V2 O7 is formed and corresponding vanadium concentration can be decreased to 1.2 × 10 ^-2 mol/L. At the pH region of 10.3-12.6 ,Ca3 （VO4）2 is precipitated and the minimum vanadium concentration can reach to 2.4 × 10^-4 mol/L, which is the best vanadium precipitation effect. When total free calcium concentration is 0.01-1.0 mol/L,theoretical optimum pH value for vanadium precipitation is kept at about 11.0-12.6.
出处
《稀有金属与硬质合金》
CAS
CSCD
北大核心
2014年第1期15-19,共5页
Rare Metals and Cemented Carbides
基金
国家"十二五"科技支撑计划资助项目(2012BAB07B05)
关键词
钙盐沉钒
Ca-V(V)-H2O体系
热力学平衡图
沉淀稳定区
vanadium precipitation with calcium salt
Ca-V（ V ）-H2O system
thermodynamic equilibrium diagram
stable solid region
