Gold Cyanide Wastewater Treated By Ion Exchange Resin

For a long time,the process of cyanidation extracting gold has been the main method of gold production all over the world.It is highly concerned that the pollution control and treatment of cyanide leaching gold wastewater which the technology produces.Especially in recent years,with the improvement of the whole society's awareness of environmental protection and the need of developing circular economy,comprehensive treatment and efficient recycling of gold cyanide wastewater have generally become the focus of gold smelting enterprises.Aiming at the characteristics and processing requirement of cyanide leaching gold wastewater containing high copper and iron that is produced during the displacement process of a Henan gold smelter,this paper introduces that stable pretreatment of two steps precipitation of zinc sulfate and sodium hydroxide to remove iron and subside copper,involving in adsorption and desorption process of ion exchange resin method.The study provides scientific reference for 9000m³ gold cyanide wastewater treatment of the enterprise.The results of original gold cyanide wastewater pretreatment experiment showed that:(1)when 2 g Zn SO₄ per 100 m L water was added and stirred 90 min at room temperature,the removal rate of iron cyanide was 100%,and the precipitation rate of CN_T and copper cyanide complex ion both were above 86%.(2)when 0.25mol/L mass concentration Na OH solution was added to the filtrate by 1:4 volume ratio(Na OH solution volume:the filtrate volume)and stirred 60 min at room temperature after precipitation separation,copper,zinc cyanide complex ion precipitated quickly again and the removal rate can respectively reach37.08%,70.81%;the filtered solution was relatively stable and there were not obvious sediment while placing for a month.The adsorption process experiments of 201x7 resin and A-21S resin to the final filtrate was studied.The results showed that the adsorption effect of A-21S resin was better.When the liquid-solid ratio(filtrate and A-21S resin volume ratio)was 100:3,the adsorption time was 75 minutes,the adsorption temperature was at room temperature,ions adsorption rates were all higher.The adsorption process of A-21S resin to CN_T,copper complex ion and zinc complex ion were mainly controlled by liquid film diffusion,and the adsorption rate constants were 0.05256 min^-1,0.02825min^-1 and 0.03334 min^-1.The adsorption process of CN_T?copper complex ion and zinc complex ion all met first order reaction kinetics model.The results of thermodynamic study showed that the adsorption process of three ions all met langmuir isothermal adsorption equation.?H of three ion adsorption process were all greater than zero,?G were less than zero and?S were greater than zero.It showed that the adsorption processes were a spontaneous and endothermic process of increased entropy.The desorption experiment results of adsorption saturation of A-21S resin showed that the effect of pure sulfate solution for CN_T and zinc complex ion desorption was better than other.When the volume concentration of sulfuric acid was3.5%,the desorbed temperature was 40?,the desorbed time was 75 minutes,the desorption rate of CN_T and zinc complex ion can respectively reach up to 85.66%and96.84%.Copper cyanide complex ion was desorbed by ammonia.It showed that when the ammonia volume concentration is 7%,the temperature was 30?,the stirred time was 90 minutes,the desorption rate of copper cyanide complex ion reached up to87.90%.After desorption,A-21S adsorption resin was recycled.