Co-Ni-Fe-Mn配合-沉淀体系的平衡热力学

马立文，聂祚仁，席晓丽，韩新罡

(北京工业大学 材料科学与工程学院，北京 100124)

摘 要：根据质量守恒和同时平衡原理，以Me(Co、Ni、Fe、Mn)为金属元素，建立Me-OH^-、Me-OH^--CO₃^2-、Me-OH^--S^2-、Me-OH^--NH₃和Me-OH^--NH₃-CO₃^2-等多个配合-沉淀体系的热力学平衡模型。结果表明：Fe³⁺可以在Me-OH^-、Me-OH^--NH₃体系中通过调节pH=3预先沉淀分离，而Co、Ni、Mn仅在Me-OH^--NH₃-CO₃^2-体系中有分离效果。Me-OH^--NH₃-CO₃^2-体系热力学计算表明：Co、Ni、Mn在溶液中的行为受pH值、配合剂、沉淀剂浓度共同影响，碳酸根初始总浓度[C]增大和氨初始总浓度[N]减小有利于Co、Ni、Mn形成沉淀。当[C]=1 mol/L、 [N]=2 mol/L、pH值为9~10时，大部分Ni以高级氨配离子[Ni(NH₃)₄²⁺]、[Ni(NH₃)₅²⁺]、[Ni(NH₃)₆²⁺]的形式保留在溶液中，而Co、Mn以MnCO₃、CoCO₃的形式沉淀出来。Co可在Me-OH^--S^2-体系中通过调节pH<6从溶液中与Mn分离。研究结果可为钴镍二次资源综合回收钴镍、制备钴镍产品提供理论指导。

关键词：配合-沉淀体系；热力学；钴镍二次资源

Thermodynamic equilibrium in Co-Ni-Fe-Mn complexation-precipitation system

MA Li-wen, NIE Zuo-ren, XI Xiao-li, HAN Xin-gang

(College of Material Science and Engineering, Beijing University of Technology, Beijing 100124, China)

Abstract:Based on mass balance principle and simultaneous equilibrium principle, the metal element Me (Co, Ni, Fe, Mn), complexing agent of OH^- and NH₃, and precipitant of OH^-, S^2- and CO₃^2- were chosen to form the complexation–precipitation systems of Me-OH^-, Me-OH^--CO₃^2-, Me-OH^--S^2-, Me-OH^--NH₃ and Me-OH^--NH₃-CO₃^2-. The thermodynamic equilibriums of these systems were studied. The results show that Fe³⁺ in systems of Me-OH^- and Me-OH^--NH₃ can be separated by precipitation through adjusting the pH value to 3. However, Co, Ni and Mn can be separated only in Me-OH^--NH₃-CO₃^2- system. The theoretical calculations show that the behavior of Co, Ni and Mn in Me-OH^--NH₃-CO₃^2- system is affected by pH value, complexing agent concentration and precipitant concentration. The increase of the total concentration of carbonate [C] is in favor of the precipitation of Ni, Co and Mn, but the increase of the total ammonia concentration [N] has the opposite effect. When [C]=1 mol/L, [N]=2 mol/L and pH value of 9-10, most Ni is complexed in the solution in the form of senior ammonia complexes [Ni(NH₃)₄²⁺] and [Ni(NH₃)₅²⁺], [Ni(NH₃)₆²⁺], while Co and Mn precipitate in MnCO₃ and CoCO₃. Finally, Co can be separated with Mn from the solution in Me-OH^--S^2- system when pH<6. The results provide a theoretical guidance for cobalt and nickel recovery from secondary resources and the preparation of cobalt and nickel products.

Key words:complexation-precipitation system; thermodynamics; secondary resources of cobalt and nickel