Study On The Kinetics Of Mixed Combustion Of Gasified Fine Slag And Coal And The Emission Characteristics Of Heavy Metals In Ash Slag

The gasification fine slag is a large amount of solid waste,which needs to be treated and utilized urgently.At present,domestic and foreign research focuses on the resource utilization of gasification fine slag,but there are relatively few studies on the migration and transformation laws of heavy metals and the environmental impact in the process of its utilization.In this paper,the research objects of Ningxia Shenhua coal-to-gasification fine slag,gasification raw coal and power plant raw coal,through thermogravimetric analyzer and tube furnace combustion experiment,explore the mixed combustion characteristics and combustion reaction kinetics of gasification fine slag and coal.The three precipitation characteristics and environmental impact of migration,transformation and leaching in the ash generated after combustion are studied,which provides a reference for the resource utilization of gasification fine slag.research shows:(1)The blending of gasification fine slag and coal can effectively improve the ignition stability and combustion performance of the gasification fine slag,and with the increase of the coal blending ratio,the combustion performance continues to improve.When the gasification fine slag is blended with gasification raw coal and power plant raw coal,it shows antagonism in the low temperature section,and shows a synergistic effect in the high temperature section.When the gasified fine slag is mixed with gasified raw coal,it conforms to the three-way transport model in diffusion.Combustion is divided into two stages.The activation energy of the first stage is higher than the activation energy of the second stage.The activation energy first increases and then decreases,and the promotion of the reaction is not obvious.When gasification fine slag is blended with power plant raw coal,it conforms to the first-level chemical reaction sequence model.Blending with power plant raw coal can reduce the activation energy of the reaction.As the blending ratio of power plant raw coal increases,the activation energy first increases and then decreases The trend is that the activation energy is smaller at the blending ratio of 30%-70%.(2)With the increase of blending temperature,the enrichment rate of Cr,Mn,and Ni increases.When Cu is blended with gasified raw coal,the enrichment rate decreases with the increase of temperature.The opposite is true when blending with power plant raw coal.,The enrichment rate of Pb decreases with the increase of temperature;and the proportion of residual heavy metals in the ash increases,and the leaching rate of heavy metals decreases.As the mixing ratio increases,the enrichment rate of heavy metals decreases,the proportion of residual heavy metals in the ash decreases,and the leaching rate of heavy metals increases.This shows that the increase in temperature can better fix the heavy metals,while increasing the blending ratio is not conducive to the fixation of heavy metals.In addition,the gasification fine slag chooses power plant coal as the blended coal,and the solidification effect of heavy metals is better.(3)According to the geological accumulation index,the Pb in the gasification fine slag has caused moderate pollution to the environment,and the five heavy metals of Cr,Mn,Ni,Cu and Zn do not pollute the environment;according to the potential ecological risk index,the gasification fine slag is contained in the environment.The potential ecological risks of the six heavy metals Cr,Mn,Ni,Cu,Zn,and Pb are all low risks,and the comprehensive potential ecological risk levels of all heavy metals are low risk;according to the risk evaluation index,the environmental risk level of Zn in the gasification fine slag For higher risks,Cr,Mn,Ni,and Cu are medium risks,and Pb has almost no environmental risk.After being mixed with coal,the environmental risk level of Zn is reduced from high risk to medium risk.With the increase of temperature and coal blending ratio,the geological accumulation index,potential ecological risk index and risk evaluation index of heavy metals in ash and slag decrease,indicating that the blending of gasification fine slag with gasification raw coal and power plant raw coal can be reduced Environmental risks of heavy metals.The paper has 26 pictures,24 tables,105 ferences.