The Risk Of Heavy Metals Pollution And Laboratory Study On Stabilization For Zinc Residue In Luoping Area

China is an old country with a wealth of mineral resources.Metal mining and ore smelting often severely pollutes water and soil,causing serious ecological risks,affecting the growth of peripheral crops,and damaging human health through the food chain.As one of the pollution caused by the exploitation and utilization of mineral resources,tailings are an important source of environmental pollution which caused by metal mining development.In this paper,some of the indigenous smelting slag sites in Luoping County of Yunnan Province were taken as the object of study and field investigation was conducted.The pollution evaluation and ecological risk assessment were carried out.The pattern of heavy metal elements was analyzed by BCR stepwise extraction method.on the basis of the analyze,Ca?H₂PO₄?₂?Fe SO₄ and Sepiolite were selected for the stabilized,and the stability was studied by orthogonal test,the stability mechanism was analyzed.Concluded as follow:?1?The average contents of five elements in soil samples were Pb>Zn>Cu>As>Cr in order from high to low,the average content of waste residue samples is Pb>Cu>Zn>As>Cr in order from high to low.Cr,Cu,Pb,Zn,The average values of Cr,Cu,Pb,Zn and As were higher than the background value of Chinese soil elements and the background value of soil elements in Yunnan,The highest Cr reached 130 mg·kg^-1,Cu reached 720.67 mg·kg^-1,Pb reached3339.33 mg·kg^-1,Zn reached 3090.33 mg·kg^-1,As reached 473.33 mg·kg^-1.While the average value higher than GB15618-1995"soil environmental quality standards"except Cr.?2?Cu,Pb,Zn and As in four soil samples were tested by modified BCR continuous extraction method.The contents of heavy metals in different sampling points are different.Most of the Cu,Pb,Zn and As heavy metals in the samples are mainly extracted as the acid extraction,and the ratio in the oxidized state and the residual state are low.?3?According to the single factor index method and the Nemero index method,the pollution index of the sample is analyzed,and the pollution situation of Cu,Zn and Pb in the sample is obvious.The Zn,Pb pollution index of soil samples 3-1,3-2are in the level of cordon,other group of Cu,Zn and Pb are heavily polluted.As pollution in different areas of pollution is quite different,and Cr pollution is low,are not contaminated and cordon level.In the 13 sampling areas,8 sampling areas are potential environmental risk assessment.Integrated pollution levels are moderate or severe.Pb is the most important pollution factor in the sampling area.The influence of the other three elements is As>Cu>Zn,and the influence of Cr is small.?4?The sepiolite,Ca?H₂PO₄?₂ and Fe SO₄ were used as stabilizers to carry out16 groups of compatibility experiments,The stabilization efficiencies of As,Pb,Zn and Cu were in the range of 6.41%-85.90%,11.95%-98.13%,4.76%-90.49%and 31.25%-75.00%,respectively.The13th,16th,12th and 4th groups have the best stabilizing effect on As,Pb,Zn and Cu respectively.Ca?H₂PO₄?₂ exhibited the most significant repair effect on Pb,Zn and Cu,but promoted the leaching of As.Sepiolite showed a repair effect on As,Pb and Zn,but the effect on Cu was not obvious.Five groups of samples including no effect of adding stabilizer and four groups of heavy metals were analyzed by improved BCR continuous extraction method,The results show that the sum of the extracted and recoverable states of most of the elements after the stabilization is decreased and the residual state is increased.The bioactivity of the metal element is well inhibited.?5?Choose sepiolite,Ca?H₂PO₄?₂ and Fe SO4 as stabilizers.The 13th,16th,12th and 4th groups have the best stabilizing effect on As,Pb,Zn and Cu respectively.As stabilization efficiency is 85.90%,Pb stabilization efficiency is up to 98.13%,Zn stabilization efficiency is up to 90.49%,Cu stabilization efficiency is up to 75.00%,and Fe SO4 exhibits the most significant repair effect on As Pb,Zn have a certain repair effect,the impact on the Cu is not obvious.Ca?H₂PO₄?₂ exhibited the most significant repair effect on Pb,Zn and Cu,but promoted the leaching of As.Sepiolite showed a repair effect on As,Pb and Zn,but the effect on Cu was not obvious.?6?Five groups of samples including no effect of adding stabilizer and four groups of heavy metals were analyzed by improved BCR continuous extraction method,The results show that the sum of the extracted and recoverable states of most of the elements after the stabilization is decreased and the residual state is increased.The bioactivity of the metal element is well inhibited.