Removal Of Pollutants From The Tailing Leachate Of Nonferrous Metal Deposits By Vermiculite

The development and utilization of mineral resources improves the quality of people’s life,but also brings serious environmental problems.In this paper,the vermiculite from Yuli Xinjiang was used as the adsorbent for the removal of pollutants from the simulated leachate of a polymetallic sulfide deposit in Guangxi province.The main conclusions of this paper are as follows:（1）The static adsorption experimental results showed that vermiculite has high adsorption capacity for Cu²⁺,Mn²⁺,Pb²⁺and Zn²⁺,and the adsorption capacity increased with the increase of the initial concentration of metallic element and pH value of the simulated leachate.The adsorption capacity for Cu²⁺reached 49.5mg/g when the initial concentration of Cu²⁺was more than 600mg/L and pH value was more than 5;when the initial concentration of Mn²⁺was more than 100mg/L and pH value was over 6,the adsorption capacity of vermiculite reached the maximum,which was25.86mg/g;when the initial concentration of Pb²⁺was more than 8000mg/L and pH>5.5,the adsorption capacity of vermiculite reached the maximum,108mg/g;when the initial concentration of Zn²⁺was more than 300mg/L and pH=7,the adsorption capacity of vermiculite reached the maximum,which was 44.5mg/g.Vermiculite has the largest adsorption capacity for Pb²⁺and the smallest adsorption capacity for Mn²⁺.Langmuir model can be used to describe the adsorption process of vermiculite for Cu²⁺,Mn²⁺,Pb²⁺and Zn²⁺,so that Cu²⁺,Mn²⁺,Pb²⁺and Zn²⁺are mainly adsorbed on the outer surface of vermiculite by electrostatic adsorption.（2）When vermiculite was used for removing the mixture of Cu²⁺,Mn²⁺,Pb²⁺and Zn²⁺in the leachate,the removal capacity of metal ions was in the order of Pb²⁺>Zn²⁺>Cu²⁺>Mn²⁺,which was basically consistent with the adsorption results for single metal ions.However,when the concentration of metal ions was low,the capture ability of vermiculite for Cu²⁺was slightly greater than for Zn²⁺,and the adsorption capacity of vermiculite for Zn²⁺was slightly higher than that for Cu²⁺when the initial concentration of metal ions was higher than 150mg/L.（3）The dynamic adsorption experiment of vermiculite for mixed metal ions was carried out.The adsorption reached equilibrium after 286 hours for Mn²⁺,532 hours for Cu²⁺,536 hours for Zn²⁺and 872 hours for Pb²⁺under the experimental condition.The results were in good agreement with the static experiment.Vermiculite has good water permeability and adsorption capacity for heavy metals,and can be used as PRB medium.（4）CTAB modified vermiculite was used to remove butylhuanic acid,a mineral dressing agent in water.The results showed that CTAB entered the layer and adsorbed on the surface of vermiculite.The positive potential of vermiculite surface was the highest（+32.27 m V）and the adsorption capacity of the modified vermiculite for butylhuanic acid was the largest（40.8mg/g）when the dosage of CTAB was 200mmol/100g.The removal mechanism of CTAB modified vermiculite for butylhuanic acid was electrostatic adsorption and solubilization.（5）The zirconium-chitosan/vermiculite composite was prepared and used to remove SO₄^2-from the simulated leachate.Results showed that chitosan and zirconium oxychloride were bonded to vermiculite surface by kaolinite.The SO₄^2-was removed through chemical adsorption of zirconium-chitosan/vermiculite composite.When pH<7,the adsorption capacity of zirconium-chitosan/vermiculite composite for SO₄^2-increased with increasing the pH,and reached the maximum（19.06mg/g）when pH=7,and then decreased with increasing the pH.