The development model of"solid waste does not leave the factory",implemented by the iron and steel industry,requires that all solid waste generated during the production process be consumed and utilized within the factory.This model presents a challenge due to the complex composition of various types of sludge produced in iron and steel plants,including iron oxide mud,OG coarse grain,calcium carbonate sludge,acid-base neutralization sludge,continuous casting sludge,and biological sludge.These sludges contain valuable elements such as iron and carbon,and the sintering process offers an effective method for recycling this solid waste.The recycling of various sludges from a domestic iron and steel enterprise using sludge heating combustion and ore blending tests was investi-gated.The feasibility and optimal sludge addition ratio in the sintering process were assessed by analyzing the com-position of flue gases and the quality indices of sintered minerals.The results indicate that sludge heating combustion leads to the formation of pollutants such as SO2,CO,HCl,NO2,NO,CH4,and VOCs,with particularly high emissions of CO and SO2,which reached 16.94 and 12.10 mg/g(sludge),respectively.VOCs emissions are mea-sured at 2.58 mg/g(sludge).Furthermore,when sludge is blended with ore for sintering,there is a significant increase in the emission concentrations of SO2,NO,CH4,and VOCs.With a 5%sludge addition ratio,the emis-sions per ton of sinter of these compounds increase by 143%,44%,219%,and 1 577%,respectively,compared to baseline tests.The yield and quality index of the sinter initially improve but begin to decline as the sludge addition ratio increases from 0%to 7%.Notably,when the sludge addition ratio increases from 0 to 3%,both the sintering utilization coefficient and the vertical sintering speed improve.However,further increases in sludge addition leads to a decrease in the quality index of sintering production.Therefore,to avoid an increase in the emission concentration of flue gas pollutants and a decline in production quality,it is advisable to control the sludge addition to within 3%of the mass fraction of the sintering raw materials,especially when the capacity of the sintering flue gas purification sys-tem is not fully utilized.
steel plant sludgeheating combustioniron ore sinteringflue gas pollutantyield and quality
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