| The analysis of heavy metal pollution in the surrounding soil of non-ferrous metal mining area and the research of stabilization repair technology are the key links to control the migration and transformation of heavy metal pollutants.The arid area of the northwest arid area has a unique climatic characteristics,topograpHy,soil type and metallogenic conditions.The effects of heavy metals on the adsorption and desorption capacity of heavy metals in the region were investigated.The pollution behavior of heavy metals in this area was comprehensively studied.At the same time,designed to carry out a number of indoor repair test,the production of low-cost and efficient stabilized repair materials.The effects of different environmental conditions,different materials and different ratio schemes on the repair and stabilization of heavy metals were analyzed.And finally proposed to adapt to the characteristics of the region to repair the stability of the material.These research results are important for controlling the process of heavy metal pollution in the area of typical heavy metal pollution in the northwest.In this paper,the main findings obtained through field sampling survey and indoor experiment are as follows:1.The study area is located in the Marsh Taishan-Wushan polymetallic metallogenic belt,large,medium-sized lead-zinc mine,pyrite deposits contain a lot of lead,zinc,copper and other non-ferrous metal minerals,a large number of slag and tailings are the main source of heavy metals.2.The main soil types in the study area are gravel brown calcareous soil,the mineral composition is mainly quartz,the secondary minerals contain higher potassium feldspar,and the clay minerals are mainly kaolinite and montmorillonite.The higher clay mineral content increases the adsorption specific surface area and increases the adsorption of heavy metal cations.At the same time,the contents of MgO and CaO in the soil were higher than those in the soil,and the soil was the most important,and the soil was mainly alkaline.This feature also favored the adsorption of heavy metal elements.3.Through the investigation and sample test,the content of Zn in the soil was the highest,and As and Cd were the main heavy metal pollution elements.Cu and Pb pollution were found in some areas,and Cr and Ni were not exceeded.The Cd,Pb,As,Zn and Cu in the soil are more disturbed by the external disturbance,and the spatial distribution is different.The content of heavy metals in the soil is far lower than that in the surrounding soil.The results showed that Cu,Pb,Zn,Cd and As existed mainly in the form of stable residue,and the organic binding state was the highest in the form of residue.By calculating the activity coefficient of five heavy metals,the activity of Cd was the highest(maximum 35.4),the activity of Cu was the smallest(minimum 4.92),and the order of size was Cd>Pb>Zn>As>Cu.4.The results show that the order of pollution elements is(cadmium,arsenic)>lead>(chromium,mercury),cadmium and arsenic as the main pollution elements.Soil heavy metal health risk assessment results showed that the total carcinogenic risk level for the low risk of the survey point 11(accounting for 84.62%,the main risk level).5.The results show that with the increase of heavy metal concentration,the adsorption capacity of soil particles to heavy metals increases first and then tends to balance.The adsorption of five heavy metals was the effect of Pb>Cu>Zn>Cd>As.The adsorption of heavy metals on the brown soil after removal of organic matter was significantly decreased,indicating that soil organic matter plays a very important role in the process of adsorption of heavy metals.The amount of heavy metal from desorption of ammonium nitrate increased with the increase of the amount of heavy metal adsorbed by the calcareous soil,and the Pb adsorbed by the beryllium soil was more difficult to desorption than the other four heavy metals.The strong interaction between Pb and the calcareous soil related.6.When the application range of MnFe2O4 was 10?15 g/kg,the leaching rate of heavy metals in soil decreased to the best condition,and the stabilization effect was significant.With the increase of pH value,the contents of Cu,Pb and Zn in soil decreased,while the change of As was slightly increased.When the pH value is in the range of 7.5?8.0,the MnFe2O4 nanomaterials can achieve the best balance and stabilization effect for all kinds of heavy metal pollution elements present in the soil.7.When the soil pH is at 8.0,the composite repair material(superpHospHate+zeolite)is the most ideal for the comprehensive reduction of various heavy metal contents.For Zn,As,Pb,Cd contaminated soil,it is suggested to add superpHospHate fertilizer while adding alkaline substances(such as CaO)to adjust the soil pH to about 8.0,will help to enhance the stability of these heavy metals.8.From the point of view of price,the combination of superpHospHate and natural zeolite stabilizer(PFM6)has the most cost advantage for Cu,Zn,Pb and As contaminated soil remediation in this area.PFM12 combination ratio(calcium superpHospHate 2 times the molar weight ratio of heavy metal+natural zeolite 0.4%soil mass ratio+0.2%soil mass ratio of MnFe2O4 material)is the best for the comprehensive stabilization effect of various heavy metals,suitable for carrying out the northwest arid area Heavy metal pollution remediation work. |
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