Research On The Release Mechanism And Migration Law Of Heavy Metals In Tailings Materials

As a complex man-made system project,the tailings pond's environmental safety is affected by many factors.Under the effects of surface runoff,underground seepage,and rainwater leaching,the heavy metal components in the tailings pond continue to diffuse and migrate to the surrounding environment.It causes serious harm to the surrounding environment,so the research on the release and transport of heavy metals in tailings is of great significance to the prevention and control of heavy metal pollution in tailings ponds.Heavy metal migration research is currently a hot research topic in the field of environmental geotechnical engineering.Existing research is mostly guided by experiments for qualitative analysis.The research method is single and lacks comprehensive mechanism discussion and quantitative analysis.Based on this research combination In engineering practice,a comprehensive research method combining theoretical analysis,laboratory experiments and numerical simulation is adopted to explore the influencing factors and mechanism of heavy metal release and migration,and to establish a prediction model of heavy metal release concentration in tailings and a numerical model of heavy metal migration in soil-groundwater system,Simulating the spatial and temporal distribution of heavy metal migration in the study area,so as to predict the impact of tailings leachate heavy metals on the surrounding environment,the specific research results are as follows:(1)Carry out the immersion and leaching test of typical tailings materials,explore the influence of different factors on the release and release of heavy metals in tailings and its mechanism,and establish a prediction model of heavy metal leaching release concentration to quantitatively predict Cu and Mn in the tailings leachate,Zn,Cd concentration.Experimental studies have shown that: the smaller the tailings particle size,the more heavy metals are dissolved,and the p H value is inversely proportional to the heavy metal dissolution concentration.The lower the simulated acid rain p H value,the longer the leaching time,the greater the degree of chemical erosion of the tailings,The more severe the surface mechanical damage of the particles,the greater the internal pores and specific surface area,and the more favorable for the dissolution and release of heavy metals.The leaching release of heavy metals conforms to the exponential decay model,combined with the exponential decay model,a prediction model for the concentration of heavy metals in tailings is established,and the average annual release concentration of heavy metals in the leachate from the tailings reservoir is calculated using this model;(2)Explore the influence of different physical and chemical factors on the migration of Cu,Mn,Zn,and Cd in the soil through the isothermal equilibrium adsorption test of heavy metals and the soil column migration test,and obtain the hydraulic parameters of heavy metal migration from it.Adsorption test research shows that the adsorption of heavy metals by soil conforms to the Freundlich and Langmui isotherm adsorption modes,and the adsorption rate decreases with the increase of heavy metal concentration at the same solid-liquid ratio;soil column test research shows that: the migration of heavy metals is affected by the p H value,Ionic strength and flow rate degree,the lower the p H value,the greater the ionic strength,the shorter the peak metal penetration curve peak time appears,within the range of 0.05 ? 0.12 cm / min flow rate,with the increase of the water supply flow rate,the heavy metal The peak penetration time is advanced,indicating that low p H,high ionic strength and high flow rate will reduce the adsorption rate of heavy metals on the soil,which will increase the migration potential of heavy metals;Finally,a mathematical model of heavy metal migration under coupled adsorption is established based on the experiment;(3)The three-dimensional groundwater solute transport software Visual MODFLOW is used to establish the numerical model of the heavy metal soilgroundwater system migration in the tailings of the study area,combined with the concentration prediction model and the parameters obtained from the soil column test,to quantitatively predict the spatial and temporal distribution of heavy metal migration in the study area analysis.Studies have shown that: the higher the concentration of heavy metals in the leachate,the higher the infiltration concentration in the vertical direction,the smaller the soil permeability coefficient,the better the blocking effect on heavy metals,and the more difficult it is for the pollutants to reach the deep;Within 20 years of the plant's service life,the total amount and concentration of heavy metal leaching in the tailings will increase with time.If the tailings leachate is not artificially controlled and controlled,the pollution range of heavy metals will continue to increase The surrounding environment causes serious harm.