Research On CO Emission Regularity And Emission Reduction Measures For Iron Ore Sintering Process

The production process of iron and steel enterprises is accompanied by energy consumption and environmental pollution.Sintering,as an important step in iron and steel production,has become an important concern process for energy consumption and environmental pollution.With the recent determination of carbon peaking and carbon neutralization schedule,energy saving and emission reduction in sintering process has also been put on the technical development schedule.In this paper,raw material conditions,technological parameters and some specific technology are systematically studied on the CO rule of iron ore sintering process,and the relevant measures to reduce the sintering CO are put forward.The research contents and conclusions of this paper are as follows.(1)In the process of sintering granulating,on the premise of ensuring good air permeability of sintering raw materials,when the water content increases from 7.00%to7.87%,the permeability of sintering bed becomes better and the oxygen potential increases during sintering,which leads to the decrease of Fe O content,the thinning of sintering combustion zone,the improvement of fuel utilization rate,the decrease of instantaneous CO concentration in flue gas and the decrease of CO emission from15.56m³/t-s to 4.31 m³/t-s,a decrease of 72.30%.The quality of sintered ore is good under different water content conditions.(2)When the bed height increases from 700mm to 1000mm,the absolute value of the fuel is increased,and the sintering heat storage is enhanced,and the total CO emission increases from 3.65m³/t-s to 5.09m³/t-s,thus the total CO emissions increases,the instantaneous concentration of CO and O₂ decreases,the average concentration of O₂ decreases from 14.09%to 13.08%,and the instantaneous average concentration of CO decreases from 6532ppm to 6066.It is found that the oxygen potential decreases and Fe O content in sinter increases with the increase of sinter bed height,and the theoretical calculation results are consistent with the experimental results.With the increase of bed height and the decrease of fuel ratio,the absolute value of fuel increases.The CO emissions corresponding to three bed heights of 800mm,900mm and 1000mm are 4.53m³/t-s,3.57m³/t-s and 6.24m³/t-s respectively,and the total CO emissions have an upward trend,with the instantaneous average concentrations of CO being 5753ppm,4023ppm and 4023 ppm respectively.However,the O₂ content and the average concentration of CO decrease,and the heat storage capacity increases with the increasing of sintering bed height,which provides conditions for reducing the fuel ratio.Increasing the bed height and appropriately reducing the fuel ratio at the same time realizes the emission reduction at the source of carbon.(3)The spraying of water vapor on the sintering surface has a significant impact on CO emissions.The fuel is easier to burn under the mixed atmosphere of air and water vapor after spraying water vapor on the sintering material surface.After spraying steam,the instantaneous concentration of CO in tail gas and the total CO emission decreased,the sintering oxygen potential increased,and the Fe O content in sintered ore decreased.Compared with interval spraying,continuous spraying of steam was more beneficial to reduce CO emission.Compared with the standard,when the total amount of sintering raw materials sprayed continuously reaches 4.16kg/t,the emission of CO decreases from 13.46m³/t-s to 9.5m³/t-s,a decrease of 29.42%,and the instantaneous average concentration of CO decreases from 7565ppm CO to 6231ppm,a decrease of 17.63%.(4)The average particle size of fuel has a significant impact on CO emission.With the decrease of the average particle size of fuel,the instantaneous concentration of CO and the total emission of CO increase,the sintering oxygen potential decreases,and the Fe O content in sintered ore increases.When the average particle size of fuel decreases from 3.0mm to 1.8mm,the CO emission increases from 10.70m³/t-s to 12.35m³/t-s,with an increase of 13.36%.The average particle size of fuel decreases,the fuel surface area increases,and the combustion rate increases,resulting in insufficient combustion.(5)Among several sintering fuels selected in the experiment,blue carbon is the easiest to burn because of its low ignition point,and the instantaneous concentration of O₂,CO and CO₂ in sintering flue gas is high.The CO emissions of blue carbon,self-produced coke and purchased coke are 8.30m³/t-s,4.53m³/t-s and 5.42m³/t-s respectively.Coke has higher ignition point,lower combustion speed and higher fuel utilization rate than blue carbon.When blue carbon and coke are used as fuels at the same time,due to their different combustion speeds,the sintering temperature is low and the combustion layer is too thick,and then the exhaust gas temperature decreases,the residual carbon content increases,the oxygen potential decreases,the O₂concentration in the exhaust gas is high,the CO and CO₂ are low,and the CO emission is 2.81 m³/t-s,which indicates that the mixed use of fuels will inhibit fuel combustion,while the production and quality indexes decrease.Therefore,when using solid fuel,coke or blue carbon can be used alone,but the mixed use of them is not conducive to sintering process.(6)The ignition temperature has no significant effect on CO emission reduction.The results show that the difference in the average CO concentration is only 100 ppm when the ignition temperature differs by 265°C,and there is no significant difference in the quality indicators of sinter.