Degradation Behavior And Characteristics Of Coke Under Iron Ore-Coke Coupling Reaction

As one of the indispensable fuels in the process of blast furnace smelting,coke plays an important role in the material column skeleton,and plays the role of reducing agent,combustion and heat release.In order to explore the real dissolution loss degradation behavior of coke in blast furnace,a large number of workers have studied the CRI and CSR of coke under simulated blast furnace conditions.But so far,the predecessors have not integrated ore,temperature and gas composition to carry out systematic research on the dissolution loss and deterioration of coke.In this thesis,five kinds of coke with different reactivity are selected,one kind of ore blending method has been used in production,and the reactivity,post-reaction strength,particle size and porosity of coke under the ore-coke coupling condition are measured and analyzed.A more definite behavior of coke dissolution loss deterioration was obtained,and the reasons for the differences in test results under different test conditions were analyzed.The main results obtained are as follows:(1)Under the ore-coke coupling condition,coke dissolution is mainly in the coke layer above the ore,and the upper coke dissolution is mainly in the upper-1 layer near the iron ore.Therefore,the in-depth analysis of the upper coke is more reasonable to describe the coke’s dissolution loss and deterioration behavior under the coupling condition.The dissolution rate of coke in the ore-coke coupling experiment is closely related to the reactivity of coke(the direct reduction stage of gasification)and the melting degree of ore(the melting reduction stage).In the melting reduction stage,only the coke layer in contact with the slag has obvious dissolution.(2)For coke with different CRI,the upper coke tends to "peeling" reaction in coupling experiment.Gasification reduction stage: about 18 ～ 42% of coke dissolution is caused by uniform reaction,and low reactivity coke center reaction amount is more.Melting reduction stage: coke central reaction amount only accounts for 2 ～ 17% of the dissolution amount.Molten flow reduction stage: the corrosion of coke completely approaches the edge reaction.(3)The CSL of the upper coke under the ore-coke coupling condition is positively correlated with the CRI under the national standard condition.Under national standard conditions,the CRI and CSR of coke show a good negative correlation.The CSRCSL of coke under the coupling condition is different from the CSR25 measured by the isoloss rate method.There is no correlation between CSL and CSRCSL of the upper coke under coupling conditions,and the upper coke has a higher post-reaction strength under coupling conditions.The post-reaction strength interval of the coke is similar to the research results of Jin-Young AN and B.van der Velden.(4)National standard and equal solution loss rate method do not simulate blast furnace conditions when exploring the properties of coke,coke dissolution loss degradation behavior depends on the reaction temperature.In the simulated blast furnace experiments conducted by Jin-Young AN and B.van der Velden,the dissolution of coke in the melting reduction stage was missing,and the dissolution loss degradation behavior of coke was similar to the results in the coupled experiment at the gasification direct reduction stage.Coupling experiments show that the corrosion of coke increases in the melting reduction stage,and the deterioration of coke at this stage is fully reflected in the reduction of particle size.Therefore,compared with predecessors,the expression of coke degradation behavior in ore-coke coupling experiment not only reflects gas-solid reaction,but also includes liquid-solid reaction.The deterioration behavior of coke is reflected by pore wall damage and particle size reduction,so the analysis results are more authentic.