Foundamental Study Of Detoxification Of Tailings Containing Mercury And Antimony

Mercury is regarded as an environmental pollutant that has a significant toxic effect on human health due to its characteristics of persistence,mobility and high biological toxicity.In recent years,long-term mercury mining and smelting activities have caused serious mercury pollution in the mining area's ecological environment.Therefore,the harmless treatment of mercury-containing tailings is imminent.In this paper,basic research is done on the wet detoxification of mercury-containing antimony tailings in Xunyang area,Shaanxi province.By studying the reaction thermodynamics of mercuric sulfide in thiosulfate systems,a metastable Eh-pH plot of Hg-S-H2O was established,which provides a basis theoretical feasibility for the use of thiosulfate systems to solubilize mercury in leaching mercury-containing tailings.Through the study of leaching process conditions of mercury-containing tailings in copper thiosulfate system,the effects of S2O32-concentration,Cu2+ concentration,solution pH value,leaching temperature,stirring speed,liquid-solid ratio and leaching time on the mercury Effect of leaching rate.According to the experimental results,the optimal extraction conditions are as follows:the concentration of S2O32-is 0.05mol/L,the concentration of Cu2+is 0.01mol/L,the initial pH is 8.35,the leaching temperature is 25?,the stirring speed is 400r/min,the solid to liquid ratio is 20:1,leaching time is 5h,the leaching rate of mercury is 75.38%,the leaching rate of antimony is 10.12%.Mercury tailings from mercury tailings reduced from 1270.82mg/kg to the residual mercury content 69.27mg/kg,to achieve the goal of harmless treatment with tailings.By comparing the morphological analysis of mercury in raw ore and leaching residue,it can be seen that copper thiosulfate complex can effectively remove oxidizable mercury and residual mercury in tailings.By using two oxidants(hydrogen peroxide and potassium permanganate)pretreatment of mercury-containing tailings,followed by sodium thiosulfate removal of mercury in the oxide residue,obtained using H2SO4-H2O2 system as an oxidant pretreatment of mercury Tailings sample effect is not satisfactory.Acidic potassium permanganate pre-oxidation of mercury-containing tailings leaching conditions:potassium permanganate concentration 2g/L,sulfuric acid concentration 1.31mol/L,the reaction temperature 35?,liquid-solid ratio 100mL:5g,leaching time 6h,the mercury leaching rate under this condition was 49.21%.Potassium permanganate oxidation is ideal because oxidized mercury can be removed 99.54%.Then,the desulfurization of sodium sulfide was used to remove the mercury in the oxidation residue.The results showed that the total mercury in the two-step leaching ore decreased from 1300mg/kg to 553mg/kg and the total mercury removal rate reached about 57%.The optimum conditions for copper and thiosulfate separation were obtained through the adsorption of amidoxime DHG586 chelating resin.The optimum experimental conditions for the separation of copper and mercury were as follows:the amount of resin was 125g/L(the solid to liquid ratio:100mL:12.5g),the reaction temperature is 45?,the reaction time is 4h.Under the experimental conditions,the resin adsorption rate of copper in the leaching solution can reach 77.50%,and the adsorption rate to mercury is only 2.31%.Therefore,the resin is better able to accomplish the goal of separating copper and mercury in the leaching solution.