Cu-Ni-Pb-Zn-Cl-H_2O体系的热力学分析

Thermodynamic analysis of Cu-Ni-Pb-Zn-Cl-H_2O system

结合已有的热力学数据,对镍阳极液的Cu-Ni-Pb-Zn-Cl-H2O体系进行热力学平衡计算,绘制在298.15 K时Cu-Ni-Pb-Zn-Cl-H2O体系中不同金属离子和各级配离子的浓度与Cl-浓度和pH的关系图。研究结果表明:当pH为4.5时,镍阳极液中镍、铜主要以游离态离子和配合阳离子形式存在,铅、锌主要以配合阴离子形式存在,因此,可以采用阴离子树脂交换除去其中的铅、锌;提高溶液中氯离子的浓度有利于金属配合离子的形成,使铅锌的配合阴离子含量增多,有利于采用阴离子树脂交换除铅、锌;镍阳极液经过D201树脂交换除锌和D363树脂交换除铅后,铅质量浓度降至0.32 mg/L以下,锌质量浓度降至0.30 mg/L以下,达到了镍电解精炼的要求。

The thermodynamic equilibrium of Cu-Ni-Pb-Zn-Cl-H2O system for nickel anode electrolyte was calculated according to the known thermodynamic data,and the c-c[Cl]T and c-pH diagrams for Cu-Ni-Pb-Zn-Cl-H2O system were drawn at 298.15 K.The results show that,in nickle electrolysis anode solution,the occurrence states of copper and nickel are free ions and complex cations at pH 4.5,while the lead and zinc exist as complex anions that can be removed by anion exchange resin.In addition,the amount of complex anions of lead and zinc are increased with the improvement of Cl- concentration,which is beneficial to the removing process of lead and zinc.The results of verification experiments for thermodynamic analysis demonstrate that the concentration of lead and zinc can be decreased to 0.32 mg/L and 0.30 mg/L by ion exchange technic,respectively.