Study On The Recovery Of Valuable Metal Copper From Copper Cadmium Slag By Oxidizing Acid Leaching-cyclone Electrowinning

In recent years,the output of refined zinc in China has increased year by year,and the amount of copper-cadmium residues produced as a by-product of zinc hydrometallurgy has also been increased.Copper-cadmium residues were a hazardous solid waste that contains a variety of valuable metals and must be recycled.Moreover,copper-cadmium residues were a copper-containing waste material with high copper content,which has higher research and utilization value than copper-depleted ores.Based on the composition and structural characteristics of copper-cadmium residues,combined with the advantages of cyclone electrowinning technology in the separation and extraction from complex multi-metal ion solutions with precipitation potential difference,the copper-cadmium residues were used as the experimental raw material,and the metal copper was recovered by oxidation acid leaching and cyclone electrowinning.This technology has the advantages of high leaching efficiency and cathode current efficiency,fewer purification steps,easy operation and so on.The leaching process is a key step for the comprehensive recovery and utilization of valuable metals from copper-cadmium residues.The effects of different process parameters on the leaching efficiency of copper-cadmium residues oxidizing acid leaching under atmospheric pressure were studied.The results show that the leaching efficiency of copper and cadmium can reach over 97%when the sulfuric acid concentration was 150g/L,the liquid-solid ratio was 4:1,the theoretical calculation value of hydrogen peroxide dosage was 4 times,the leaching time was60min,the leaching temperature was 30?,the particle size of raw material was-75?m,and the stirring speed was 300r/min.Due to the existence of part of zinc sulfide in the slag,the leaching efficiency of zinc was relatively low.According to the concentration of copper ion in the leaching solution,a three-stage cyclone electrowinning technology was designed to recover copper from the simulated leaching solution of copper cadmium residues,and the effects of current density and circulation flow rate on the relevant technical parameters of each electrowinning process were investigated.The results show that in the first stage,when the terminal concentration of copper ion in the solution was controlled 18g/L-20g/L,the current density was 300A/m~2,and the circulation flow was 400L/h,the purity of cathode copper can reach more than 99.996%,and the current efficiency can reach98.75%.In the second stage,when the terminal concentration of copper ion in the solution was controlled 7g/L-10g/L,the current density was 400A/m~2,and the circulation flow was 700L/h,the purity of cathode copper can reach over 99.99%,and the current efficiency can reach 98.93%.In the third stage,when the terminal concentration of copper ion in the solution was controlled below 0.5g/L,the current density was 200A/m~2 and the circulation flow was 500L/h,the purity of cathode copper can reach more than 99.9%,and the current efficiency can reach 93.37%.The concentration of copper ion in the solution can be reduced to less than 0.1g/L and the electrodeposition rate of copper ion in the solution can reach more than 99%by three-stage cyclone electrowinning.In order to explore the influence of different cyclone electrowinning processes on current efficiency,electrodeposition rate of copper ion,quality of cathode copper and the migration rule of impurity ions in the electrowinning process,the electrowinning experiments were carried out by using one-stage cyclone electrowinning,two-stage cyclone electrowinning and three-stage cyclone electrowinning.The results show that the electrodeposition rates of copper ions in the leaching solution under three different electrodeposition processes were 96.78%,99.20%and99.08%respectively.The current efficiency is only 90.52%when one-stage cyclone electrowinning was used,and the current efficiency can be significantly increased to more than98%when segmented electrodeposition is used.When the concentration of copper ions in the solution was reduced to below 10g/L,the concentration of impurity ions in the solution begins to appear large fluctuation.The surface gloss of cathode copper products obtained by segmented cyclone electrowinning is better,the surface of products is smooth,and there are less crystals and bumps.The segmented cyclone electrowinning can not only improve the current efficiency and reduce the energy consumption,but also improve the electrodeposition rate of copper ion on the cathode and obtain better product morphology and quality.