| Mercury and its compounds have been widely concerned because of their characteristics of mobility,high toxicity and bioaccumulation.In mercury mining at the same time,resulting in a large number of solid waste containing mercury,mercury tailings in nature increases the long-term storage of mercury and antimony in environment risk,but for the treatment of solid waste containing mercury and antimony are rarely reported.The leaching experiment of mercury tailings under alkaline sodium sulfide system explored the influence of NaOH concentration,Na2S concentration,leaching temperature,leaching time and liquid solid ratio on the leaching rate of mercury and antimony.The best leaching conditions were determined as follows:the ratio of liquid to solid is 5:1,the concentration of NaOH is 0.5mol/L,the concentration of Na2S is 2mol/L,the leaching temperature is 65 degrees,the leaching time is 2h,21 0r/min.The leaching rate of mercury is 95.83%,and the leaching rate of antimony is 53.98%.The mercury grade of mercury tailings is reduced from 600g/t to 25g/t,which basically realizes the harmless treatment of tailings.The BCR leaching experiment of mercury tailings before and after detoxification treatment proved that the alkaline sodium sulfide system has a good extraction effect on mercury in mercury tailings.The leaching of mercury tailings is an unreacted shrinking core model.The dissolution of metal Sb is determined by dynamic model fitting.The leaching rate controlled by mixing control under alkaline sodium sulfide system is controlled by chemical reaction and diffusion mixing control.The replacement effects of different metal replacement metals,metal amount,replacement temperature,replacement time and other factors on the replacement of mercury are explored.The optimum experimental conditions are as follows:the amount of antimony particles is 20g/L,the replacement time is 3h,the replacement temperature is 40?,and the water bath is stirred by 300r/min.The replacement rate of mercury can reach more than 90%,and the concentration of mercury in the solution is lower than that of 180mg/L.Most of the mercury in the leach can be recovered by this method.The recovery of Hg and Sb by electrolysis is explored.The effects of current density,electrolysis temperature,electrolysis time,stirring and diaphragm influence on the electrolytic recovery of metal Hg and Sb are explored.Determine the best electrolysis conditions:diaphragm electrolysis,current density 100A/m2,electrolysis temperature of 40?,electrolysis 4.5h.At this time,the electrolysis effect of the replacement liquid is the best:the Sb current efficiency is 91%,which basically realizes the purpose of the recovery of mercury and antimony respectively. |
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