Electrochemical Treatment Of Cyanide Wastewater Based On Coal-based Electrode

In this paper,cyanidation gold-extracting wastewater was treated by two-dimensional and three-dimensional electrochemical systems.The effects of the main electrode materials and the applied voltage on the removal rule of each ion and the chemical reaction characteristics were mainly studied,and the coal-based electrode structure was further optimized.SEM-EDS,FT-IR,N₂ adsorption instruments and XPS were used to analyze and characterize the morphology,composition and structure of the plates and the precipitates in the processes.The research results are of great significance for promoting technological innovation and comprehensive utilization of resources in the cyanidation and gold extraction industry in our country.The results showed that the activated carbon filled stainless steel mesh（CM）and the coal-based electrode（CB）as the main electrode had better treatment effects than that of the stainless steel mesh（M）.The key influencing factor of the electrochemical process is the applied voltage.The removal of ions in the wastewater at 2V is mainly attributed to the effect of electro-adsorption and enrichment precipitation.At 4V,the anodization and cathodic deposition are the main factors.The processing efficiency of the three-dimensional system is higher than that of the two-dimensional and three-dimensional systems.In the three-dimensional system,when the CB was used as the main electrodes and the applied voltage was 4V,the processing time was 5h,the electrode spacing was 10mm,and the activated carbon particle dosage was 2g,the removal rates of CN_T,Cu,Zn,CN^-,and SCN^-in the waste-water were 94.14%,94.53%,98.14%,98.55%,and 93.13%,respectively.Coal-based electrode with carbon fiber（CBCF）was activated by the KOH solution.With the increase of KOH concentration,the surface properties,pore structure and electrochemical performance of the CBCF have been greatly improved.When the KOH concentration reaches to 15mol/L,the iodine adsorption value was as high as 782.32mg/g,the specific surface area is 412 m²/g,the total pore volume is 0.213 cm³/g,the micropore volume is 0.179 cm³/g,the mesopore pore volume is 0.034 cm³/g,its microporosity is as high as 84.04%.In the three-dimensional system,when the voltage was 4V,treatment time was 5h,and the polar distance was 10mm,the removal rate of each ion in the waste-water was as high as 94%.CBCF as the main electrodes and activated carbon particles as the particle electrode,the dynamic three-dimensional system was used to treat the cyanide wastewater.Studies have shown that the dynamic treatment is favorable for accelerating mass transfer and improving the reaction rate.The treatment results are obviously superior to the static conditions.When 3 main electrodes are used,the polar distance was 10mm,the voltage was 4V,the flow rate was 30ml/min,the treatment time was2.5h,the concentration ratio was 1,and the activated carbon particle dosage was 2g,the removal rates of CN_T,Cu,Zn,CN^-,and SCN^-in the waste-water were 97.03%and95.79%,99.82%,99.42%,and 94.19%,respectively.