| Taking the tailings pond reclamation treatment area where different measures have been taken in the Chaihe lead-zinc mine as the research object,the implementation effects of different tailings pond reclamation treatment measures are studied through investigation and sampling,field test,sample analysis and other methods for further improvement.Provide basis for tailing pond reclamation management.The research results show that since the implementation of the rehabilitation measures for 7 years:(1)Under 6 different soil covering treatment conditions,the order of the stable infiltration rate of the surface covering soil is: SC(0.21 mm/min)<SL(0.39 mm/min)<SG(0.39 mm/min)<CT(0.40 mm)/min)< SLS(1.32mm/min)< SP(1.39mm/min).In general,the stable infiltration rate of the covered soil is relatively high.It is necessary to install an impermeable geomembrane at the bottom of the covered soil layer to prevent rainwater infiltration,or consider thick-layered soil covering measures in areas with abundant soil sources.To absorb rainwater.The water holding capacity of the surface soil is: SC(25%),SLS(25%),SG(24%),CT(24%),SL(23%),SP(22%).Field surveys show that the mulching soil and its structural measures are still suitable for the growth of shrubs and grasses such as A.fruticosa,surface grass cover and deciduous layer in each treatment area are good,and have the effect of preventing water erosion and wind erosion in the reservoir area.(2)With different reclamation measures,the p H of the reclaimed soil in 2019 is between 6.08 and 7.13.The p H of the reclaimed soil in the SLS and SL reclamation measures area with lime and limestone isolation layer is slightly higher than that of other treatment measures,and there is no significant impact on the p H of the surface soil,and the p H is still in the suitable vegetation growth range.From 2015 to 2019,the total heavy metal content of Pb,Zn,and Cd in the soil in the rehabilitation measures area increased,and the SL rehabilitation measures area were 73.20,184.97,and 2.13 mg/kg,respectively.However,they are basically lower than the soil environmental quality standards and local soil environmental background values.The high Cd content in some measures areas is believed to be related to the wind erosion effect of the original tailings sand Cd on the surrounding hillsides.(3)The vegetation growth of SLS and SG reclamation measures is better.The vegetation grown in the reclamation control area is dominated by Amorpha fruticosa,with an average plant height of about 1.94m;some trees have gradually evolved in the shrubs since the implementation of the reclamation control measures.At present,poplars,Trees such as willow and elm account for about 25%,and the average plant height is about 3.06 m.(4)The contents of Zn,Pb and Cd in the leaves of Amorpha in the SG reclamation area were 34.87 mg/kg,6.58 mg/kg,and 0.04 mg/kg,which were significantly lower than those in other areas.The contents of Zn,Pb and Cd in the leaves of Amorpha in the CT treatment area were higher,reaching 47.68mg/kg,8.63mg/kg and 0.25mg/kg respectively.(5)According to the analysis and measurement data,analyze and calculate the storm runoff of the tailings pond.It is believed that the original design channel size is too large,which will cause excessive land occupation and increase material and construction costs.In the future,the drainage system should further consider correction calculation and design.(6)Benefits for the prevention and control of the diffusion of deep-seated leaching pollution;CT can reduce 54% of the leachate produced in the reservoir area,with a benefit of 32.302 million yuan/a;to a certain extent,prevent the spread of heavy metal pollution.SC reduces the amount of leachate produced by 75%,and the benefit is 34.044 million yuan/a;the runoff erosion and diffusion control benefits of the six soil covering and vegetation measures are SC(180.74),SG(73.80),SL(168.10),SLS(115.33),SP(135.35),CT(2.0499)ten thousand yuan/a. |
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