Experimental Study On Reduction Of Carbon Containing Pellets In Sintering Dust

This paper mainly studies how to make good use of the waste materials such as sintering dust,BF dusts,BOF sludge,scale and so on,and efficiently remove harmful elements so as to produce low reduction iron(LRI)products for blast furnace.Experimental results of carbon distribution in Sintering electrostatic precipitator dust:the compressive strength is the most affected by the baking temperature,and is the least affected by the baking time;the effect of roasting temperature on the removal rate of zinc is the largest,and the roasting time is the least;the metallization rate and reduction degree are the most affected by calcination temperature,and the minimum is affected by C/O.The study found that when C/O is 0.8,calcination temperature is1325~oC,the roasting time is 10 min,the compressive strength reached 2105N/individual,removal rate of zinc reached 91%,the reduction degree reached 86.3%,and the metallization rate reached 80%,the quality of the product meets the requirements of blast furnace production basically.C/O ratio is related to energy consumption and CO2 emissions,the reasonable C/O ratio is related to the purpose of hope.If only considering the compressive strength requirements,the C/O 0.8 is more reasonable;if taking into account the removal of harmful elements,the C/O 1.0 is more reasonable.Considering the strength of raw ball and the requirement of roasting stage,the reasonable C/O is between 0.8 and 1.1.The reduction kinetics of carbon pellet in sintering electrostatic precipitator was studied under nitrogen atmosphere,the result shows that the limiting part of reduction is diffusion in the gas phase,and the activation energy is 191.22kJ/mol.Research results of reduction kinetics of carbon containing pellets in sintering electrostatic precipitator dust under air showed that at 950 ~oC to 1200 ~oC,the limiting step of the reduction reaction is gas diffusion,and the activation energy is138.84kJ/mol.This means that the effect of temperature on the reaction rate is greater in the air than that in the nitrogen atmosphere,and the reduction rate is faster than that in the nitrogen atmosphere,complete reduction time is shorter.Control of the reaction time appropriate to prevent pellet reoxidation,generally within 600s can end reaction,therefore,reasonable time control within 10min.The higher the temperature,the higher the degree of reduction,reduction degree of 80%can be obtained at 1200 ~oC.The experimental study on the direct reduction of carbon bearing pellets in weak oxidizing atmosphere shows that the suitable oxygen content is 0?5%,which is not more than 7%.This provides the basis for the determination of the cooling air composition in shaft furnace.