废铅膏湿法回收过程中铜的电化学行为及净化

Electrochemical behavior and removal of copper in the hydrometallurgical recycling process of waste lead-acid battery

摘要:

针对甲基磺酸湿法回收废铅酸蓄电池过程中典型杂质Cu2+的电化学行为及其净化方法进行了研究。研究结果表明，Cu2+在电解过程中优先于Pb2+析出，造成电解铅的纯度下降，同时使还原铅的电流效率下降、能耗增大。Cu2+的存在改变了Pb2+的成核机理，从而使得Pb2+的还原电位正移。针对甲基磺酸铅体系的特点，基于铅粉置换铜原理，提出采用流态法净化工艺代替传统的搅拌置换法，解决了搅拌法单次除铜净化铅粉消耗量大、净化成本高、效率低下等缺点。在最佳除铜工艺条件下：铅粉粒径为100 ~ 150目，温度为20 ℃，流速8 ~ 10 m/h，填充的铅粉柱高0.6 ~ 0.7 cm，采用流态化除铜工艺对实际废铅膏进行净化处理，杂质Cu2+去除率能够达到90%以上。

关键词:废铅酸蓄电池;回收;甲基磺酸;铜杂质;净化

Abstract:

The electrochemical behavior and purification method and principle of typical Cu2+ impurity in the recovery process of waste lead paste based on Methanesulfonic acid (MSA) were studied. The research results show that Cu2+ is preferentially precipitated over Pb2+ in the electrolysis process, resulting in a decrease in the purity of electrolytic lead, a decrease in the current efficiency of lead reduction and an increase in energy consumption. The existence of Cu2+ changes the nucleation mechanism of Pb2+, thus making the reduction potential of Pb2+ shift positively. Based on the principle of removing copper with lead powder, the fluidized purification process is proposed to replace the traditional stirring replacement method according to the characteristics of lead methanesulfonate system, which solves the problems of the large consumption of lead powder, high purification cost, and low efficiency. When the particle size of lead powder is 100 ~ 150 mesh, the temperature is 20 ℃, the flow rate is 8 ~ 10 m/h, and the height of the filled lead powder column is 0.6 ~ 0.7 cm. The removal rate of Cu2+ can reach more than 90% in the purification process of actual leaching solution from waste lead paste.

Key words:Waste lead-acid battery; Recycle; Methanesulfonic acid; Copper impurity; Purification