Study Of Sintering Of Mixture Of Municipal Sludge And Iron Ore

Iron ore sintering is the first high-temperature process in iron and steel industry,which is mainly heated by solid fuel combustion.Municipal sludge is a solid waste produced by domestic sewage treatment process,with high volatile content and certain calorific value.Incineration and landfill are the main disposal methods of municipal sludge in China,which result in resource waste and environmental pollution.Based on solid waste harmless to use as the core,this paper puts forward using the calorific value of municipal sludge,to carry out urban sludge mixed with iron ore sintering research,find out the urban sludge combustion characteristic,combustion behavior in the sintering process and its influence on the sinter quality index,for solid waste harmless sewage sludge utilization to provide theoretical and technical support.Analysis of combustion characteristics of municipal sludge showed that the calorific value of sludge was 11.33 MJ/kg,volatile content was53.35%,fixed carbon content was 10.5%.The combustion interval of volatiles was 200℃-750℃,and the starting combustion temperature of fixed carbon was about 850℃.When the heating rate of combustion process was increased from 10℃/min to 50℃/min,the ignition temperature of municipal sludge increased from 210℃to 249℃.in the process of sludge combustion,each gas product was gradually generated at 300℃.When the temperature was 500℃,the CO₂emission concentration reached the peak,at this time,the emission concentration of SO₂ gradually increased,and the emission concentration of other gases gradually decreased.Studies on the combustion behavior of municipal sludge in the sintering process and its influence on sintering mineralization showed that when the sludge ratio increased from 0%to 6%,CO₂,NO,SO₂ and CH₄emissions increased by 0.4,2.3,10 and 1.5 times,respectively.When oxygen concentration decreased from 21%to 10%,magnetite content increased 1.2 times and silicate minerals increase.When the sintering temperature was below 1250℃,SFCA content in the sintered products was very low,which continued to drop to 1150℃,and more skeletal crystal hematite appeared.SFCA in the sintered products was needle-like with good strength and reducibility when the municipal sludge was added within6%.When the sludge ratio was over 6%and P residue rate was over 0.18%,it was not conducive to blast furnace ironmaking.Elements such as N,S and Cl were volatilized during combustion,while other elements remained in the sinter.The study on the quality of sintered minerals by municipal sludge showed that the appropriate dosage of municipal sludge was not more than3%.When the sludge ratio was 3%,compared with that without sludge,the permeability of sinter material layer was slightly reduced,the rate of sintered product was reduced from 78.79%to 75.90%,the drum strength was reduced from 68.54%to 65.31%,the content of iron olivine and silicate in sinter was increased,and the sinter RI was reduced from 84.56%to 83.68%.The RDI+3.15 of sinter decreased from 64.69%to 55.50%.There are 53 figures,32 tables,and 84 references in this thesis.