Study On Heavy Metal Migration In Tailings Pond Under Rainfall And Vegetation Conditions

Tailings pond is an important facility for storing tailings and clarifying water in metallurgy,non-ferrous,building materials and other industries,as well as an important safety and environmental protection facility.The prevention and control of heavy metal pollution in tailings pond is one of the key work of mine environmental control.Copper,lead,zinc and other heavy metals are common pollutants in tailings pond.Therefore,a series of pollution problems of tailings pond have attracted more attention.It is of great practical significance to carry out researches on heavy metal migration rules of phytoremediation tailings pond under artificial rainfall.In this paper,the indoor soil column rainfall leaching test and Geostudio numerical simulation are combined.The actual tailings pond is taken as the engineering background to carry out relevant research on the migration law of heavy metal pollutants in tailings pond soil considering rainfall and vegetation conditions.The main research contents include:（1）The soil column leaching test method was used to simulate the soil stratification of the actual tailings pond by filling the stratified soil sequence of tailings soil,loam-tailings composite soil and loam from bottom to top.The surface vegetation of the actual tailings pond was simulated by using the grass.Taking copper ion as representative,the longitudinal migration characteristics and regularities of heavy metal copper in tailings soil were studied by soil column rainfall leaching experiment considering different rainfall intensity of surface vegetation.（2）Taking copper,lead and zinc as the representative metals,the orthogonal design method was used to design three-factor and three-level experiments.The vertical migration characteristics and rules of heavy metals in tailings soil were considered under different rainfall intensity,leaching time and p H of leachate of surface vegetation by soil column leaching test.The influence degree of three factors such as p H of leachate,rainfall intensity and leaching time was obtained.Then taking copper as an example,Geostudio software was used to simulate and analyze the longitudinal migration law of heavy metals in layered soil of soil column model,and the migration law of heavy metals in soil of tailings pond model was simulated by Geostudio software.（3）The orthogonal experimental design method is taken as the basis.The influence of dam height,slope ratio,permeability coefficient and migration time on the concentration of heavy metal pollutant Cu²⁺in small and medium-sized tailings ponds was considered.At the same time,considering the combined working conditions of rain-evaporation-transpiration and groundwater,the simulation study of heavy metal Cu²⁺migration in small and medium-sized tailings ponds under the coupling action of rain-evaporation-transpiration and transpiration was carried out.The primary and secondary effects of four factors on the concentration of heavy metal Cu²⁺in tailings pond were obtained.The influence rules of each factor on pollutant migration were analyzed.（4）The large tailings pond of Waitou Mountain Iron ore of Bengang Group is taken as the engineering background.The Geostudio software is used as the foundation.The VADOSE/W,SEEP/W and CTRAN/W modules in Geostudio are selected to consider the coupling effect of rain-evaporation and groundwater,and the coupling effect of rain-evaporation-transpiration and groundwater respectively.The migration of typical heavy metal ion Cu²⁺in large tailings ponds was studied to establish the seepage distribution law of phytoremediation tailings dams and the migration law of heavy metal Cu²⁺in groundwater under the effect of rainfall-evaporation and rainfall-evaporation-transpiration.