Study On The Blocking Heavy Metal Cu²⁺Transport By Red Clay Curtain Barrier

The exploitation of mineral resources has not only promoted social prosperity and progress,but also led to a series of serious environmental pollution problems.Tailings,waste residues and other solid wastes formed in the process of mineral exploitation could cause heavy metal pollution to the mining area and surrounding soil.Clay material often used as the main material of anti-seepage system because of its low permeability and strong adsorption ability.What's more,it also has been widely used in the treatment of heavy metal pollution in mining areas,the disposal of high-level radioactive waste and landfill engineering.It is necessary to develop the new economical and efficient materials for curtain barrier to greater improve the blocking performance of curtain barrier.Therefore,taking the typical red clay in Inner Mongolia as the research object,the shrinkage characteristics of red clay under different compaction times and temperature conditions were analyzed on the basis of the basic physical properties,and the adsorption characteristics of Cu²⁺in red clay were studied.Based on this,the migration and diffusion characteristics of inert ion chlorine and non-inert ion copper in red clay were further explored,and a series of meaningful conclusions were obtained.?1?According to the laboratory tests,the clay content of red clay is as high as70%,and the liquid limit is 42%.X-ray diffraction analysis of red clay showed that the main minerals are illite and kaolinite.In addition,the optimal water content of red clay is 13.1%,the maximum dry density is 1.91g/cm³,and the permeability coefficient can reach 1.0×10^-9cm/s or even smaller,which meets the requirements of landfill seepage control.?2?According to the indoor shrinkage test,the geometric factors of red clay shrinkage are r_s<3 under different compaction times and temperatures.The radial and axial shrinkage of red clay occur simultaneously,and the main shrinkage direction is axial shrinkage,which shows the anisotropic characteristics.?3?According to the experimental results,the adsorption capacity of red clay for Cu²⁺can reach 5.1 mg/g,which can be explained by isothermal adsorption model Freundlich equation,Langmuir equation and D-R equation.Thermodynamic analysis shows that the adsorption of Cu²⁺in red clay is a spontaneous process,and the increase of temperature can promote the adsorption.Increasing the amount of red clay can improve the removal efficiency of Cu²⁺.At the same time,pH is one of the important factors affecting the adsorption of Cu²⁺in red clay.The optimum pH value for the Cu²⁺adsorption should be about 5.?4?The migration and diffusion characteristics of inert chloride ions and non-inert copper ions in red clay were studied by the diffusion and soil column experiments.It was concluded that the longer the diffusion time of Cl^-in red clay,the faster the flow rate and the larger the effective dispersion coefficient.The longer the diffusion time of Cu²⁺in red clay,the greater the effective diffusion coefficient and the bending factor,while the retardation factor decreases with the extension of diffusion time.A series of laboratory tests showed that red clay has higher clay content,low permeability and strong adsorbability.It is a potential curtain barrier material and can be considered as a new type curtain barrier material to retard the migration and diffusion of heavy metal pollution.