| New requirements on the prevention and treatment of heavy metal pollutants have been requested during the12th Five-Year Plan Period of China. The pollution of heavy metal in the tailings has long garnered particular attention since the deposits are piled up in the form of tailings after mining activities. Chemical reagents, household garbage and other heavy metal pollutants caused by the physical and chemical reactions are comprised in the tailings. With the migration of heavy metal pollutants, the surrounding environment will be deteriorated accordingly. It will bring a long-term harm on the animals, plants and the human bodies when the heavy metals are highly accumulated. Study on the track and simulation of the pollution of heavy metals in the tailings will make the process of heavy metal pollution clear and intuitive, and can provide references for the prediction and control of heavy metal pollution.Based on the retrieval and recollection of relevant documents and by referring and analyzing former research achievements, many aspects were researched in the paper by means of the combination of theoretical analysis, experimental method and numerical analysis, including characteristics of tailings, migration and transformation of heavy metal pollutants in the tailings, mathematical model of heavy metal pollution in the tailings, pollution laws in different regions of tailings, and pollution simulation results under different conditions. The main research contents and conclusions of this thesis are listed as follows:(1) The dangers of heavy metals and generation process of heavy metal pollutants were analyzed. Based on the analysis of whole mining process in metal mines, i. Besides, literature review was given on the laws and numerical simulation in fluid of heavy metal pollution in China and abroad, and the application software and its characteristics that can be used for the simulation of heavy metal pollution were generalized as well.(2) The styles and characteristics of the tailings and tailing piles in China and abroad were introduced. Trajectory of heavy metal pollution in the tailings was researched, including the evolution of heavy metal, oxidation mechanism, and the migration-transformation circulation, etc. By studying on the seniors, we can find that the difficulty grades of the oxidation of the major metallic minerals in tailings were to be: Pyrrhotite> sphalerite> pentlandite> pyrite>chalcopyrite.(3) The construction of the mathematical model of heavy metal was established in this work. Based on Darcy’s law, the mathematical model of dissolved heavy metals, hydrodynamic model, and solute transport model in porous media, the mathematical model of heavy metal pollution in the tailings was built and bettered to some extend. Finally, the boundary conditions were given.(4) The XRD and ICP-AES detection methods were used for the analysis of samples. Distribution of heavy metals in the tailings was researched for different samples, which had the following characteristics: The concentration of Fe was quite different compared with the other elements and had a more. significant change in the horizontal direction than vertical direction. It provided some references for the numerical simulation to follow.(5) With the use of experimental measurement (LS-pop(Ⅲ)-laser particle size analyzer), theoretical analysis, and formula analysis (Ergun semi-empirical formula and Blake-Kozeny equation), the main parameters required for the simulation were obtained, including mineral particle size and surface area, viscous drag coefficient and coefficient of internal resistance, and thermal conductivity of minerals. Three-dimensional grid physical model of heavy metal pollution was established, and the conditions were initialized.(6) As to analyze the concentration distribution of the pollutants,’ many conditions were simulated by FLUENT software, such as different regions, different flow, different chemical models(Eddy-Dissipation model, Laminar Finite-Rate model and EDC model), different turbulence models(Standard turbulence model and RNG turbulence model), and different methods of pressure-velocity coupling, etc. |
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