Zn^(2+)-Mg^(2+)-H_(2)O系中和沉锌热力学分析及应用  

Thermodynamic Analysis and Application of Neutralizing Precipitated Zinc in Zn^(2+)-Mg^(2+)-H_(2)O System

作　　者：李永勇 金鑫 李兴彬[1] 魏昶[1] 甄勇 邓志敢[1] 李旻廷[1] LI Yongyong;JIN Xin;LI Xingbin;WEI Chang;ZHEN Yong;DENG Zhigan;LI Minting(Faculty of Metallurgical and Energy Engineering,Kunming University of Science and Technology,Kunming 650093,China)

机构地区：[1]昆明理工大学冶金与能源工程学院,昆明650093

出　　处：《有色金属工程》2022年第7期77-82,共6页Nonferrous Metals Engineering

基　　金：国家重点研发计划项目(2018YFC1900402);国家自然科学基金资助项目(51664030,51804146,51964029)。

摘　　要：湿法炼锌废电解液在冷冻结晶除镁时会生成大量由ZnSO_(4)·7H_(2)O和MgSO_(4)·7H_(2)O组成的结晶产物,采用中和水解法实现该结晶产物中锌、镁的分离。根据配位化学热力学平衡原理,绘制了298 K时Zn^(2+)-Mg^(2+)-H_(2)O系热力学平衡图。结果表明:在pH值为6.0~12.0时,锌离子优先沉淀析出,pH值为8.0时,溶液中残余锌浓度小于1.0×10^(-5) mol/L,且以Zn^(2+)和ZnOH+的形式存在;在温度60℃、pH值为7.0、反应时间80 min的最优条件下,锌沉淀率达到100%,镁不沉淀;沉锌产物成分ZnSO_(4)·3Zn(OH)_(2)·5H_(2)O和CaSO_(4)·2H_(2)O,经稀硫酸浸出可获得硫酸锌溶液和纯净石膏产品。A large amount of crystal products composed of ZnSO_(4)·7H_(2)O and MgSO_(4)·7H_(2)O were produced in the waste electrolyte of hydrometallurgy during the freezing crystallization to remove magnesium.The separation of zinc and magnesium from crystal products by neutralization hydrolysis was studied.The thermodynamic equilibrium diagram of Zn^(2+)-Mg^(2+)-H_(2)O system at 298 K was established based on the thermodynamic equilibrium of coordination chemistry.The results showed that zinc ions are preferred to precipitate in the range of pH value of 6.0—12.0,the residual zinc concentration in solution is less than 1.0×10^(-5) mol/L and in the form of Zn^(2+)and ZnOH+at pH=8.0.The experimental data show that under the optimal conditions of temperature 60℃,pH=7.0 and reaction time 80 min,the precipitation rate of zinc ions reaches 100%,and magnesium ions do not precipitate.The zinc precipitation product consists of ZnSO_(4)·3Zn(OH)_(2)·5H_(2)O and CaSO_(4)·2H_(2)O,which are leached by dilute sulfuric acid to obtain zinc sulfate solution and pure gypsum product.

关 键 词：湿法炼锌 热力学平衡 锌羟合配离子 条件溶度积 沉淀率 

分 类 号：TF813[冶金工程—有色金属冶金]