低共熔溶剂中直接电解分离废白铜制备高纯铜

以氯化胆碱-乙二醇低共熔溶剂(ChCl-EG DES)为电解液,废白铜为阳极,钛片为阴极,在363 K下对废白铜进行了电解分离,并在阴极获得了高纯阴极铜。系统研究了温度和氯化亚铜(CuCl)浓度对ChCl-EG DES黏度和电导率的影响。结果表明,CuCl+ChCl-EG DES的黏度随着温度的升高而减小,随着CuCl浓度的升高而增大,电导率与之正好相反。阳极极化曲线表明,适当提高CuCl浓度可以使Cu和Ni的电位差增大,有利于铜镍的分离,但CuCl浓度过高会导致阳极溶解速率减慢。电解实验发现,当CuCl浓度升高时,直流电耗先减小后增大,电流效率则相反。当CuCl浓度为1 M时,废白铜电解分离的电流效率高达99.1 %,而直流电耗低至170.2 kW·h·t-1。阴极铜的纯度高达99.62 wt%,其表面形貌平整致密。

Preparation of High-purity copper by direct electrolysis of waste cupronickel in deep eutectic solvent

High-purity copper (Cu) was recovered from waste cupronickel by electrolysis separation at 363 K in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES). The waste cupronickel and titanium sheets were served as anode and cathode, respectively. The effects of temperature and the concentration of cuprous chloride (CuCl) on the viscosity and conductivity of the DES were investigated systematically. Results showed that the viscosity of CuCl+ChCl-EG DES decreased with the increase of temperature and increased as the raising of CuCl concentration, whereas that of the conductivity was opposite. The anodic polarization curves showed that the potential difference between Cu and Ni can be increased by increasing CuCl concentration, which was conducive to the separation of Cu and Ni, but the anode dissolution rate can be slowed down with too high CuCl concentration. The electrolysis experiment showed that the DC power consumption decreased firstly and then increased as the increasing of CuCl concentration, while the current efficiency was opposite. When CuCl concentration was 1 M, the current efficiency was as high as 99.1 % during the electrolysis separation of waste cupronickel, and the DC power consumption was as low as 170.2 kW·h·t-1. Highly pure Cu (99.62 wt.%) can be obtained at cathode and the micromorphology was compact and flat.