Study On The Transformation Law Of Typical Heavy Metals Hg And Cr In The Process Of Domestic Waste Incineration

With the rapid development of Chinese economy and the promotion of urban modernization,the output of municipal solid waste(MSW)is increasing year by year.Combined with the background of "Carbon peaking and Carbon neutrality" and the environmental protection,this paper studied the transfer pattern of heavy metals during the incineration of MSW.This thesis takes MSW in Xiangtan as the research object and a muffle furnace is adopted to simulate MSW incineration process.Studying the influence of different temperatures(600 ℃、700 ℃、800℃、900 ℃、1000℃)on the migration and distribution of heavy metal Hg and Cr in MSW during the incineration process.Inductively coupled plasma massspectrometry(ICP-MS)was used to measure the content of heavy metal after collection and digestion of incineration products.Then the distribution characteristics of Hg and Cr was obtained with different temperature conditions.The main research contents and conclusions are as follows.(1)Cr is more stable than Hg at high temperature.The volatilization of Hg is highest at 600℃,and the volatilization rate of Hg increases with the increase of temperature.Cr had high thermal stability,which are not easy to decompose and volatilize and most of them remain in the bottom slag,Hg is unstable and volatile at 600℃.Besides,the higher the temperature,the faster Hg volatilization.However,Cr has strong stability at 600-1000℃.The amount of decomposition and volatilization of Cr is very little,and most of it is retained in the bottom slag.(2)Temperature has an important effect on the migration of heavy metals.In the incineration process,a very small amount of Hg will react with non-combustible components in MSW(CaO、SiO2、Al2O3)to produce silicate which is difficult to volatilize and remains in the bottom slag.In the range of 100-600℃,Cr mainly generates potassium chromate.In the range of 600-800 ℃ produces complex solid solution,such as magnesium and aluminum.(3)From the perspective of relative enrichment index(REI),the REI of Hg and Cr at 600℃ is the maximum value in the range of 600-1000℃,which is 0.8507 and 0.1762,respectively.When the temperature is higher than 600℃,the REI of Hg and Cr is different.(4)Through the simulation of the Factsage softsage,this thesis were studied the transformation morphology and migration distribution mechanism of Hg and Cr in the process of waste incineration,and the experimental results were verified.Meanwhile,the influence of the presence of S,Cl and SiO2 on CaO,Na2O and Cr in the combustion system was simulated under different atmospheres.In oxygen atmosphere,Cl has no obvious influence on the effect of CaO curing Cr,and the transformation temperature of Cr is basically the same under different Cl content.