Preparation of high-purity copper by electrochemical recovery of waste cupronickel in choline chloride-glycol deep eutectic solvent
Waste cupronickel is widely used in many fields,with the increasing demand and consumption of waste cupronickel,a large amount of waste copper alloy has been produced.Although the traditional wet process can remove some insoluble impurities and the working conditions are superior,the process is long and the energy consumption is high.Therefore,this work high-purity copper(Cu)was recovered from waste cupronickel by electrolysis separation at 363 K and 0.1～0.5 V cell voltage in choline chloride-glycol deep eutectic solvent(ChCl-EG DES)with the molar ratio of 1∶2 as an electrolyte,waste cupronickel as an anode,and titanium sheet as a cathode.Electrochemical tests exhibited that Cu can be dissolved as monovalent Cu(Ⅰ)into ChCl-EG DES,and the reduction of Cu(Ⅰ)at the concentration range of 0.5～2.5 mol/L CuCl was a quasi-reversible process.The calculated Ea of the anode dissolution process was only about 28.361 kJ/mol,indicating that the dissolution process of Cu in ChCl-EG DES was controlled by diffusion.The anode polarization curve implied that Sn was dissolved into the solution first,while the dissolution potential of Ni and Fe was similar to that of Cu,and they were entered into anode slime.The electrolysis experiment showed that when the cell voltage increased,both the DC power consumption and the current efficiency increase accordingly.When the cell voltage was at 0.5 V,the current efficiency of electrochemical recovery of waste cupronickel was as high as 97.20％,and the DC power consumption was 216.94 kWh/t.At higher cell voltage(0.3～0.5 V),the morphology of cathode copper was irregular mass with a particle size of 30～50 μm,and the purity of copper can be obtained at the cathode at 0.4 V cell voltage was as high as 99.95wt％.
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