| With the "the Action Plan for Soil Pollution Prevention and Control",remediation of heavy metals and toxic elements and pollution in soil has been attaching great importance from the Chinese government and people,soil remediation has became a hot research of soil and water conservation in china.The mercury mine soil had a huge release risk to the surface water,groundwater and other surrounding environment,damage to animals,plants and human health.This paper selected the Wanshan mercury mine soil as the research object,processed and studied by thermal analysis of low temperature plasma,studied of temperature,time,additives and other process parameters on mercury removal rate and treatment after Mercury,analysed and compared of the process on the mercury containing waste residue and explore its mechanism of action,and summarized the key factors influencing the process exhaust system.The main results are as follows:(1)The main form of mercury in contaminated soil was organic binding state(52.5%).Secondly,the oxide bound state(32.5%),acid extractable state(8.13%)and residual state(6.25%).(2)The most important factors influencing the effect of pyrolysis pyrolysis temperature was 500℃,with the increase of temperature,the total Hg removal rate increased gradually,the ideal temperature,total mercury in the process of soil could be lower than the "soil environmental quality standard"(GB15618-1995)level three standard limit of 1.5 mg/kg.Under the condition of 500℃ and 40 minute,the residual mercury concentration was only 1.44 mg/kg.(3)Under the condition of 400℃,with the extension of time,the removal rate of total mercury in soil increased gradually,and the pyrolysis process was basically completed within 40 minute.In the 200~1600 mg/kg interval,the higher the initial oncentration of mercury,the smaller the removal rate of total mercury in soil.(4)The synergistic effect of calcium chloride on the pyrolysis of mercury containing soil was the best,followed by citric acid and sublimation sulfur,sodium sulfide had a certain inhibitory effect.400℃ and 40 minute under the condition of adding calcium chloride treatment after soil residual mercury concentration was 1.36 mg/kg,when the input than non additive processing mercury removal rate higher than 8%,the percentage of various forms of mercury were bound to organic matter(66.67%),oxide bound(11.11%),residual(16.67%),acid extractable(5.56%).(5)The pulse voltage was 21.1KV,and the discharge frequency was 650 Hz,which was the best parameter to match the high voltage pulse power supply with the low temperature plasma reactor.The total mercury removal rate could reach above 89.73%.The exhaust gas purification device containing mercury vapor concentrations were lower than the control standard of pollutants for hazardous waste incineration(GB 18484-2001)in the regulation of mercury and its compounds to limit emissions of 0.1mg/m3,the gas state after treatment could achieve the "tin antimony mercury industrial pollutant emission standards"(GB 13223-2011)in mercury and its compounds emission requirements. |
