Migration Simulation Of U (Ⅵ) In Uranium Tailings Reservoir Under Acid Rain Condition

As a mining area, long time of mining related activities left large amounts oftailings, which have brought serious problems to the surrounding environment. Theradionuclide in tailings has been threatening the environment of ground water, whichleach into groundwater through Atmospheric precipitation. The paper has taken alarge uranium tailings impoundment in South China as an example studied byVisualMODFLOW. After setting up models of groundwater movement andradionuclide migration in the study area, migration tendency of radionuclide U(Ⅵ)was simulated and pollution of radionuclide to environment was predicted.The static experiment and the dynamic experiment were conducted at first,partitioning coefficients under different pH values were obtained by comprehensiveanalysis. The hydro geological conditions in the study area were systematicallystudied in this article, and then obtained model parameters that conform toexperimental conditions. Combined with the static experiment results, migrationtendency of radionuclide U(Ⅵ) affected by acid rain was simulated.The static experiment was conducted and the partitioning coefficients underdifferent pH values were obtained. Through the generalization of the hydro geologicalconditions of the study area, the hydro geological conceptual model and solutetransport couple-model under the condition of acid rain was built. The simulatedheads were compared with the drilling ones, and a good agreement was obtained,which indicated the model founded was reasonable and reliable. Therefore, the modelfounded was used to simulate the migration of U(Ⅵ) in uranium tailing. After settingup models of groundwater movement and radionuclide migration in the study area,migration tendency of radionuclide U(Ⅵ) was simulated and pollution of radionuclideto environment was predicted. From the results of numerical simulation, the migrationof uranium speed to be the slowest when pH=3.5and the figure to be the fastest whenpH=2.0. Furthermore, maximum speed is about1.24times of minimum speed. Andthe migration of U(Ⅵ) in aquifer is relatively slow, surface water isn’t polluted so far.But since long half-life of uranium, it is necessary to take long-term monitoring to it.