The Remediation Of Metal Mine Tailings Contaminated Siol By Biochar Derived From Soybean Straw

Metal sulfide mine tailings pollution is different from general heavy metal pollution,sulfide mineral of tailings can released huge amounts of acid mine drainage which contained heavy metals.Huge amounts of acid mine drainage(AMD)containing heavy metals and sulfate ions were released from tailings due to the oxidation reaction which would contaminate the surrounding environment and do harm to human health through food chain.Biochar has great potential for remediation of soil pollution caused by heavy metals.Bicoahr reduces the biovailability of heavy metals due to the unique physical and chemical properties such as the electrostatic adsorption,ion exchange,surface complexation and coprecipitation methods.In order to control the influence caused by the oxidation of tailings on the environmental,this study took metal-sulfide tailing samples,which were obtained from the Yinshan sulfur-polymetallic mines in Jianxi Province as research object.We could inhibit oxidation of tailings,control the release of heavy metals and sulfuric acid root ion by the way which is that the tailings were dealled with biochar.And the soil which contaminated with metal mine tailings was set as the research object,we carried out the pot-culture experiment and germination test to consider the effect of biochar on the growth of plant and uptake of Copper,Zinc,Lead and Cadmium in soil.Main results are summarized as follows:(1)The soybean straw biochar was prepared with temperature of 500?.the pH value of soybean straw biochar is greater than 7.FTIR showed that the biochar contained aromatic structure,hydroxyl and acidic oxygen-containing functional groups.SEM showed that biochar has a large number of porous structure and large surface area.(2)In order to get better understanding of copper mine tailing sample,the charactization of the physical,chemical and mineralogical properities of tailing sample were conducted.The tailing mainly contained the elements of Fe,Al and Si,while the content of S was lower relative.The main mineral compositions for tailing are quartz,goethite,hematite and a small amount of gypsum,kaolinite.The copper mine tailing sample are rich in Cu,Zn and Pb,but the content of Cd is relatively lower than other three heavy metals.(3)The experimental results show that under flooded conditions,H2O2 as oxidant can accelerate the oxidation of tailings,the tailings is rapidly oxidized to generate large amounts of Fe3+and SO42-,and released huge amounts of and heavy metals.Biochar can play a good passivation effect even under the conditon of strong oxidizing environment.In natural oxidation process.Biochar can significantly improve the pH of tailings,tailings inhibit oxidation,solidification of heavy metals.(4)The results showed that the soil contaminated tailings oxidation experiment,under the condition of dry wet alternation conditions,biochar can increase soil pH,reduce soil system oxidation,oxidation inhibition of soil acid production,reduce the content of heavy metals.In the copper tailings contaminated soil group,Sodium oleate and sodium silicate synergistic biochar on improving the pH value,reducing oxidation of soil and controlling the release of heavy metals and sulface ions is better than biochar.Among them,sodium silicate and biochar synergistic treatment of soil pH value,sodium oleate in reducing sulfate content has the most obvious effect.In the Zinc tailings contaminated soil group,the biochar for passivation soil is best.(5)Results showed that the soil which contained biochar can obvious promote growth of Ipomoea aquatica Forsk and the effects on the root is more apparent than the stem and leaf.The contend of Copper,Zinc,Lead,Cadmium which contained in the root,stem and leaf is direct proportion to the soil.Biochar can effectively reduce the content of Copper,Zinc,Lead,Cadmium in plant,promote heavy metal immobilization in soil,increase the pH and reduce the acidification of sulfide tailings.In combined pollution,biochar can appearently decrease the content of Lead in the Ipomoea aquatica Forsk.Biochar can reduce the toxicity of tailings contaminated soil on Ipomoea aquatica Forsk seeds and increase the germination and seedling rate.