Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第30卷    第7期    总第256期    2020年7月

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文章编号:1004-0609(2020)-07-1677-14
基于隔膜电积的硫酸铅渣湿法提铅新工艺及电化学机理
丁 龙,杨建广,南天翔,李陵晨,汪文超,闫万鹏

(中南大学 冶金与环境学院,长沙 410083)

摘 要: 根据物料平衡和电荷平衡原理,对Pb(Ⅱ)-Ac--H+-H2O体系进行热力学分析,分析结果表明在接近于实际浸出液的pH值范围内,溶液中PbAc+平衡浓度最高。以湿法炼锌产出的硫酸铅渣为原料,采用单因素实验法优化“乙酸盐配位浸出-隔膜电积提取铅”的主要工艺条件,采用单因素试验法优化乙酸铅溶液隔膜电积工艺条件,采用线性扫描、循环伏安等电化学测试手段研究Pb(Ⅱ)-Ac--H2O体系铅电积过程中阴极电化学行为。结果表明:在反应时间1 h、浸出温度70 ℃、乙酸铵浓度4 mol/L、液固比4:1的优化条件下浸出硫酸铅渣,铅浸出率93.28%。在电积温度30 ℃、Pb2+浓度50 g/L、电流密度100 A/m2的条件下阴极电流效率98%左右,每吨Pb直流电耗约700 kW?h。在此条件下以硫酸铅渣浸出液直接作为电积液隔膜电积8 h在阴极可以获得纯度99.2%较为致密平整的电铅,阴极电流效率96.16%。铅的还原沉积过程是一个不可逆过程,铅在电沉积初期遵循三维连续成核与颗粒长大机制,升高温度和提高阴极液Pb2+浓度可以促进溶液离子扩散,提高电流效率。

 

关键字: 硫酸铅渣;乙酸盐体系;配位浸出;隔膜电沉积;电化学机理

New technology and mechanism for extracting lead from lead sulfate residue by membrane electrodeposition
DING Long, YANG Jian-guang, NAN Tian-xiang, LI Ling-chen, WANG wen-chao, YAN wan-peng

School of Metallurgy and Environmental, Central South University, Changsha 410083, China

Abstract:According to the theory of material balance and charge balance, the thermodynamic analysis of Pb(Ⅱ)-Ac--H+-H2O system was carried out. The conclusion is that the equilibrium concentration of PbAc+ in solution is the highest in the range of pH value close to the real leach solution. Using lead sulfate residue as raw material, the optimum conditions of this process were obtained by single factor experiment. The optimum conditions and experimental results of leaching are finally determined as follows: temperature of 70 ℃, reaction time of 1 h, ammonium acetate concentration of 4 mol/L, the ratio of liquid to solid of 4:1. The leaching efficiency of lead is 93.28%. The optimum conditions and experimental results of membrane electrodeposition are finally determined as follows: temperature of 30 ℃, Pb2+ concentration of 50 g/L, current density of 100 A/m2. The cathode current efficiency could reach 98%, the DC power consumption is 700 kW?h per ton Pb. When electrowinning with selective leaching solution under the optimal process conditions, and a relatively compact and flat lead can be obtained at the cathode with a purity of 99.2%, and the current efficiency of the cathode is 96.16%. The electrochemical behavior of lead electrodeposition was investigated. It is an irreversible reaction of lead membrane electrodeposition; the initial process of lead electrodeposition follows the diffusion controlled three-dimensional nucleation and grain growth mechanism; ion diffusion rate and current efficiency are improved by the increase of temperature and concentration of Pb2+.

 

Key words: lead sulfate residual; coordination leaching; membrane electrodeposition; acetate system; electrochemical mechanism

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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