Study On Pb-Ca-Sn Anode Modification For Copper Electrowinning

Pb-Ca-Sn anodes have been rapidly developed as the main anode material for copper electrowinning,but still have disadvantages such as high anode potential and poor corrosion resistance.Therefore,in order to reduce energy consumption and reduce anode corrosion,this paper analyzes the Pb-Ca-Sn anode from three aspects:determining the influence mechanism of Mn²⁺and Co²⁺ions,optimizing the preparation process(including optimizing the quenching heat treatment temperature and casting thickness),and controlling the addition of modifiers..Firstly,the influence of Mn²⁺and Co²⁺ions on the Pb-Ca-Sn anode in the Cu SO₄-H₂SO₄ solution system was found:the concentration of Mn²⁺and Co²⁺in the electrolyte increases,the anode oxygen evolution potential,anode potential and charge transfer resistance Rt will decrease accordingly;accelerated corrosion Tests have shown that Mn²⁺in the electrolyte will accelerate the corrosion of the Pb matrix,on the contrary Co²⁺will protect the matrix;XRD and SEM tests found that when the concentration of Mn²⁺in the electrolyte is higher than 80 mg/L,?-Mn O₂ is detected in the film and the film changes.It is rough and loose and porous;a small amount of Co²⁺concentration(50 mg/L)can significantly reduce the overpotential of anodic oxygen evolution and improve the corrosion resistance,so that the film becomes dense,but no Co-containing phases are detected in the film.Secondly,using different quenching temperature(150?,180?,210?and240?)and different casting thickness(40 mm,60 mm,80 mm and 100 mm)to prepare Pb-Ca-Sn alloy performance research found:210?heat treatment and60mm casting thickness Refine the alloy grains and improve the tensile strength and hardness of the material.With the increase of the quenching temperature and the increase of the casting thickness,the anode oxygen evolution overpotential and the charge transfer resistance Rt will first decrease and then increase;XRD and SEM tests found that the main components of the anode film are Pb SO₄ and?-Pb O₂,?-Pb O₂ and Pb,the membrane layer is flake and coral,and the surface is loose and porous.Further study the Sn/Ca ratio(20.8,17.9,15.6 and 13.9)and Bi content(0,0.05%,0.10%and 0.15%)of Pb-Ca-Sn alloy properties.It is found that the Sn/Ca ratio decreases and the alloy crystal.The grain size is refined,the tensile strength and hardness are improved,the anodic oxygen evolution overpotential and the charge transfer resistance Rt are also reduced,but it will increase the corrosion of the alloy;XRD and SEM tests found that the main components of the film are Pb SO₄,?-Pb O₂?-Pb O₂ and Pb,the membrane is coral-like,loose and porous.When the Bi content is less than 0.05%,the crystal grains are refined,and the oxygen evolution overpotential and charge transfer resistance decrease with the increase of Bi content.When the Bi content is greater than 0.05%,the law is opposite,and with the increase of Bi content.The main components of the film are Pb SO₄,?-Pb O₂,?-Pb O₂ and Bi₂O₃,and the film is coral-like.Finally,through the industrial use of Pb-Ca-Sn alloy,the best Pb-Ca-Sn alloy obtained in this paper,in the Cu SO₄-H₂SO₄ solution system for electrowinning copper test,the cell voltage changes from small to large:PbCaSn+50 mg/L Co SO₄<PbCaSn-0.10%Bi<PbCaSn+40 mg/L Mn SO₄<PbCaSn(this experiment)<PbCaSn(industrial).The current efficiency from high to low is:PbCaSn+50mg/L Co SO₄>PbCaSn-0.10%Bi>PbCaSn+40 mg/L Mn SO4>PbCaSn(this experiment)>PbCaSn(industrial).