Removal Of Copper Cyanide Complexes By PSAs In Cynide Containing Wastewater From Gold Mines

Copper-cyanide complexess are abundant in the cyanide-bearing wastewater of gold mines,and the reuse of water will inhibit the leaching rate and recovery rate of gold.Due to the high biological toxicity of copper-cyanide complexed ions,the total cyanide concentration limit in the Comprehensive Sewage Discharge Standard（GB8978-1996）is 0.5 mg/L,and the copper ion concentration is limited to 1.0 mg/L.Quaternary ammonium salts have a strong affinity for copper-cyanide complexed ions,so they are often used to remove high-concentration copper-cyanide complexed ions,but there are problems such as high dosage and residual amount.In this study,sodium polystyrene sulfonate（PSS）was introduced to form micelle-like aggregates（PSAs）in water with quaternary ammonium salts to deeply remove copper-cyanide complexess,while reducing the dosage and residual amount.In this thesis,the effects of quaternary ammonium salt chain length and dosage,initial p H value,reaction temperature and separation method on the removal of copper-cyanide complexess in simulated wastewater were studied,the optimal reaction conditions were determined,and the treatment effects of the two types of actual wastewater were investigated.At the same time,the complex state calculation of copper cyanide ions was carried out,the force of quaternary ammonium salts and PSS to form PSAs,and the characterization of copper cyanide complexess and PSAs association products,thereby revealing the removal mechanism of copper cyanide complexess.The results of simulated wastewater test show that compared with CTAB alone,the removal efficiency and utilization rate of copper-cyanide complexess by PSAs are significantly improved.The optimal dosage of 0.5 m M copper-cyanide solution was1.0 m MCTAB+150 ppm PSS,the removal rates of total cyanide and copper were97.0%and 93.8%,and the utilization rate was 92.2%.The removal rates of total cyanide,copper and agent utilization rates of 1.0 m MCTAB alone were 60.2%,64.0%and 83.0%,respectively.The coexistence of SCN^-,organic matter and other metal complexess significantly reduced the removal rate of copper-cyanide complexess,when the common salt ion concentration was higher than 100 m M.The initial p H value and reaction temperature had less than 4.0%influence on the removal effect.The minimum particle size of the pellet generated at the optimal dosage is greater than0.8μm,and the 0.45μm filter membrane can trap all the precipitate.The results of the actual wastewater test showed that for high salinity wastewater,when 1.6 m MCTAB+300 ppm PSS was added,the removal rates of total cyanide,copper ions and COD were 61.3%,63.7%and 43.8%,respectively,and the utilization rate of chemical agent was 66.2%.When treated with CTAB alone,the removal rates of total cyanide,copper ions and COD were 34.2%,35.6%and 11.3%,respectively,and the utilization rate of the agent was 40.7%.For low mineralization wastewater,when 1.6 m MCTAB+300 ppm PSS was added,the removal rates of total cyanide,copper ions and SCN^-were 93.6%,96.9%and 43.5%,respectively,and the utilization rate of chemical agent was 95.3%,which met the emission standard.When CTAB alone was used,the removal rates of total cyanide,copper ions and SCN^-were 50.2%,48.7%and 5.3%,respectively,and the utilization rate of the agent was 72.1%.Compared with the separation and precipitation of the existing flotation machine and the air flotation column in gold mine,the water loss rate and chemical utilization rate of the flotation machine were 24.1%and 93.7%when the precipitation was completely separated,and the water loss rate and chemical utilization rate of the air flotation column were 16.7%and 91.5%,respectively.The actual wastewater p H value（10.5）does not affect the removal effect and avoids HCN overflow.The removal mechanism studies showed that the main forms of copper cyanide under experimental conditions were Cu（CN）₃^2-and Cu（CN）₂^-;PSS and CTAB mainly interact electrostatic to form PSAs,and compared with the critical micelle concentration of CTAB,the critical formation concentration of PSAs is reduced by 4times,which is the main reason for the decrease in dosage.PSAs mainly capture Cu（CN）₃^2-and Cu（CN）₂^-by electrostatic action,and then the precipitated particles are precipitated,and the precipitated particles are removed by forming flocs with the remaining CTAB,so the copper-cyanide complexes removal reduces the residual rate of CTAB.This thesis has 49 figures,12 tables,and 82 references.