Research On Environmental Effect Of Disposal Of Coal Gangue In Typical Ecological Fragile Area

With the application of modern mechanized coal mining technology,a large amount of coal gangue discharged from the mining area has caused serious pollution to the ecological environment due to weathering,rainfall and other external factors.This article takes the ecological disposal of coal gangue in a mining area in Ordos as a research topic.The physical and chemical properties of coal gangue were studied by thin section identification,XRD,SEM-EDS,industrial analysis and X-ray fluorescence spectroscopy.The static immersion experiment,combined with the rainfall characteristics of the study area and the characteristics of coal gangue mountain accumulation,conducted an intermittent "water injection-water discharge"leaching experiment under the dense accumulation environment of coal gangue,using factor analysis,cluster analysis,correlation analysis and time serial gray model prediction and other methods analyze the experimental results and draw the following conclusions:(1)The coal gangues in the study area are mainly sandstone and mudstone,with poor overall sortability,and the roundness is angular to sub-angular.The type of constant elements of the same type of coal gangue has a small change range and a significant correlation.Based on factor analysis,trace elements in coal gangue can be divided into four categories:Cr,V,Zr;Zn,Ba;Y,Ga,Ni,Rb,Cu;Sr,the trace elements of Cr,V,Cu,Ni and others exceed the soil background value by 2 to 3 times.(2)Under static conditions,the diffusion of coal gangue contaminated components in aqueous solution is subject to Fick's law of diffusion,the more concentration gradient between solid and liquid and the contact area,the more release rate of contaminated components in coal gangue.The average leaching rates of Cr,Mn,Fe,Co,Cu,Zn,Cd,Ba,Pb,and As are basically between 0.09%and 1.60%;while Mo,Tl,Se,Hg,V,Ni,etc.The leaching rate of elements is relatively large,the leaching rate of Ni element is the largest,up to 43.45%,the leaching rate of Ba element is the smallest,0.097%;the average leaching rate of 16 kinds of heavy metal elements is Mo>Hg>Se>Ni>V>Co>Cr>Tl>Mn>Cd>Pb>Fe>Zn>Cu>As>Ba.(3)The leaching concentration of coal gangue pollutants showed a "quasi-wavy"change curve.Heavy metal pollutants all showed intermittent rapid release rule.The release rate of each element decreased in the later stage of leaching and gradually stabilized.In the intermittent leaching process,the leaching concentration of elements such as Mn,Cr,Fe,Co,Mo and Hg exceeds the groundwater quality Class III water standard,and the leaching rate of Fe and Hg is high,reaching Class V water standard.(4)The environmental pollution effect of coal gangue hills is diverse,latent and long-term.The key to reducing pollution is to control the diffusion of pollutants.In the early stage,the comprehensive pollution score of coal gangue hills was 2.0 to 2.5,as time goes by the score decreased to 0.0 to 0.5,and gradually tended to-0.5 in the later stage.The harm in the early stage was much greater than that in the later stage.The order of the impact of harmful heavy metal elements on the environment is:Hg>Cd>Cu>As>Ni>Zn>Cr>V>Pb>Mn,the Hakanson potential ecological hazard index of S Mine is the largest,followed by T Mine and P Mine,through ecological classification and disposal and soil greening measures,can reduce pollution caused by coal gangue accumulation.Figure[74]Table[36]Reference[106]...