Research On Resource Utilization Of Municipal Solid Waste Incineration Fly Ash

The incineration treatment of municipal solid waste has the characteristics of good volume reduction effect and high treatment efficiency,and has become the mainstream technology of waste treatment in today’s society.After incinerated,a large amount of fly ash will be produced.The fly ash is rich in a variety of harmful substances and is regarded as hazardous waste.But at the same time fly ash also contains other oxides such as Si O₂and Al₂O₃,making it have the potential for resource utilization.In order to realize the safe and economical disposal and utilization of fly ash,this paper has carried out research on the production of non-fired ceramsites from eluted chlorine and washed fly ash.The main research contents and conclusions are as follows:（1）Experimental research on fly ash washing and washing liquid treatment:In order to study the influence of washing method on the chloride ions in fly ash,and to separate and recover inorganic salts in fly ash washing liquid,the influence of liquid-to-solid ratio,washing time and washing temperature on chloride ion removal were investigated,and the appropriate separation temperature of NaCl,KCl and Ca Cl₂ in the fly ash washing liquid.The results show that when the liquid-solid ratio is 8:1,the washing time is5min,and the washing temperature is 70℃,the maximum removal rate of chloride ions in fly ash is 88.72%.The fly ash washing liquid is separated by evaporation and crystallization.The temperature for the primary evaporation and crystallization separation of NaCl and KCl is 113°C,and the temperature for the secondary evaporation and crystallization separation of KCl and Ca Cl₂is 128°C.Finally,the recovery of NaCl,KCl and Ca Cl₂ in the washing solution is obtained,the rates are 96.21%,95.85%,and 94.72%.（2）Experimental research on the production of non-fired ceramsite with washed fly ash:The optimal ratio and curing time of the non-fired ceramsite made with washed fly ash,ordinary Portland cement and silica sol as the main raw materials were studied,and its influence on the performance of the non-fired ceramsite was investigated.The results show that the increase of cement addition and the extension of curing time will increase the bulk density and cylinder compressive strength of ceramsite,and reduce the water absorption rate of ceramsite;The increase in the amount of silica sol will increase the water absorption and cylinder compressive strength of the ceramsite,and reduce the bulk density of the ceramsite.It is preliminarily determined that the ratio of washed fly ash,ordinary Portland cement and silica sol is 6:3:1,and the curing time is 14 days.The ceramsite formula is optimized through the homogenization design,and finally the best raw material ratio of the non-fired ceramsite is:59.19%of fly ash,29.38%of cement,11.43%of silica sol,under this working condition,the bulk density of ceramsite is 897.73kg/m³,the 1h water absorption rate is 14.47%,and the cylinder compressive strength is 8.4Mpa.（3）Ceramsite product performance research and benefit analysis:The morphological characteristics,performance parameters and heavy metal leaching characteristics of the non-fired ceramsite product prepared under the best raw material ratio are studied,and the economic,environmental and social aspects of the ceramsite product are analyzed.The results show that the ceramsite surface is uneven,with low smoothness,developed internal pores,and loose structure;the ceramsite made is high-strength lightweight ceramsite with a density of 900,which meets the specified technical requirements;In addition,the leaching concentrations of heavy metals Cu,Zn,Pb,Cd and Cr in the ceramsite are all lower than the national standards"Hazardous Waste Identification Standard"（GB5085.3-2007）and"Landfill Standard"（GB16889-2008）.