Mineralogy Characteristics Of Uranium Mill Tailing With The Migration Regularity And Retardation Study Of Uranium

The migration and release of harmful elements from uranium tailings, especially the migration and release of radioactive nuclide, which have brought serious problems to the surrounding environment and serious harm to people's health, this paper has taken the typical uranium tailings in C hina as the research object, XRD, SEM-EDS and BCR has used to investigate the occurrence of U, Sr, Mn and Fe of uranium tailings, then study the migration tendency of these elements under the simulation rainfall. And simulation the migration regularity of uranium of uranium tailings before and after adding montmorillonite, th result of experimental analysis and simulation have applied to predict and manage the pollution of uranium.The results of mineralogical characteris tics of typical uranium tailings showed that main mineral is quartz, albite, microcline and dihydrate gypsum etc, the occurrence amount of U, Sr, Mn and Fe is 30.4?g·g-1, 122.0?g·g-1, 523.0?g·g-1, and 9700.0?g·g-1 respectively, the migratory activity of U and Mn is the strongest.Based on these results, dynamic leaching method were adopt to study leaching characteristics of U, Sr, Mn and Fe under different leachate p H, particle size and ambient temperature.Cumulative release amount of U, Sr, Mn and Fe was affected by leachate p H, particle size and ambient temperature, cumulative release amount of U and Mn decrease with the p H value increase, on the contrary, the cumulative release amount of Sr increases with the increase of p H value, and the correlation with Fe is not strong. With the decrease of the uranium tailings particle size, the cumulative release amount of U, Sr, Mn and Fe was increase. with the ambient temperature increase, the release law of U, Sr, Mn and Fe was same, in addition to the cumulative release amount of U under 25 ? and leachate p H is 5.Under the different leaching factors, the release law of U, Sr, Mn and Fe was described as cumulative release amount of U, Sr, Mn and Fe rapidly increase with the increase of leaching time, then increase slowly to eventually stabilised, but U appeared a quick release, slow release in accelerated release phase, the analysis of the occurrence of U showed that:disso lution of dihydrate gypsum which adsorption uranium as crystallization process lead to the amount of uranium small increase.The thesis used PHREEQC to model and forecast the conditions after the uranium enterd into the groundwater, showed that the uranyl ion combined with SO42-and OH- in the groundwater, when permeability coefficient range from 35 m/d to 50 m/d, The concentration of uranium in boundary reached the initial pollution concentration in 140 days to 180 days, the results of add ition montmorillonite to simulate the detention of uranium showed that the concentration of uranium in initial position from 2.77 mg/L to 0.5 mg/L after the addition of montmorillonite,and migration distance reduced in a simulation period(about 250 days), That montmorillonite as block material of uranium has great adsorption capacity, but since long half- life of uranium, it is necessary to take long-term prediction and managment about pollution of uranium.