Research On Direct Electrolysis Process Of Sponge Copper Cold Pressing

Generally,the treatment method of sponge copper is acid leaching,remove impurities and crystallize to produce copper sulfate.The process is long and complex.Multiple impurity removals are needed and the cost is high.As a clean production process without smelting and casting process,scrap copper direct electrolysis can directly produce high quality cathode copper with the advantages of less process,low energy consumption,low cost and mature process.In this paper,for the purpose of recovering copper from sponge copper and referring to the direct electrolysis process of scrap copper,the treatment process of directly electrolytic recovery of copper by cold die pressing sponge copper into blocks is proposed.This process cuts down many processing steps,reduces the consumption of energy and related leaching acid consumption.In view of this process,this paper carried out two aspects of research:Firstly,a sponge copper material pretreatment experiment and direct electrolysis process experiments of sponge copper cold die pressed blocks under different electrolysis conditions were carried out.According to the material pretreatment experiment,+200mesh material particles need to be magnetically separated after grinding,-200 mesh particles can be directly magnetically separated,chemical acid leaching is performed after magnetic separation.The optimum conditions of chemical acid leaching are as follows:liquid-solid ratio 4:1,temperature 30°C,washing time 2 h.Acid leaching experiments show that with the increase of iron removal rate,copper loss will increase.The direct electrolysis processes of sponge copper cold die pressing blocks were carried out to verify the feasibility of the process.The optimal parameters of each electrolysis process were determined by experiments:electrolysis temperature 40°C,cathode current density 200 A·cm^-2,electrolyte circulation rate 8.5 L·h^-1,electrode spacing 4 cm,Cu²⁺concentration 40 g·L^-1,H₂SO₄ concentration 160 g·L^-1,thiourea concentration 10 mg·L^-1,and gelatin concentration 20 mg·L^-1.Experiments show that the adhesion of anode slime can be reduced and the quality of cathode copper can be improved by adjusting the electrolyte circulation rate and electrode spacing.Comprehensive electrolysis experiments show that the cathode current efficiency is95.15%,the cathode copper deposition rate is 0.023 g·cm^-2·h^-1,the DC energy consumption is 620.31 kWh·t^-1Cu,and the profit of blunt copper can reach 13965.09yuan.Secondly,in order to explore the influence of pressure on the direct electrolysis of sponge copper under cold pressure,copper powder was used to simulate sponge copper in CuSO₄-H₂SO₄ electrolyte,and the related electrochemical theory of cold die block corrosion was studied.The experimental results show that when the pressing force is 15k N,the stable corrosion voltage value of the open circuit voltage curve of the copper powder cold pressed blocks are significantly lower.The anodic polarization results show that the copper powder cold pressed blocks have poor conductivity and electrochemical solubility.In Cu²⁺concentration is 40 g·L^-1 H₂SO₄ concentration is 160 g·L^-1 electrolyte,the corrosion of cold pressed copper powder blocks is most favorable;The measured activation energy of the dissolution process is 23.969 k J·mol^-1,which can be inferred that the corrosion dissolution is controlled by diffusion.