The Study On The Deep Reaction Behavior Of Tamping Coke And Top Charging Coke

Due to the rapid development of iron and steel industry in recent years,there has been a serious shortage of high-quality coking coal resources.As a result,the price of coking raw materials has gradually increased,while the quality of coke has decreased to some extent.As a technique of adding high proportion of weak bonding coking coal and reducing the production cost of coke,the application of tamping coke was developing rapidly.Therefore,a high proportion of tamping coke was applied in blast furnaces ironmaking process.At present,few studies have been found to be focused on the difference in depth reaction between tamping coke and top charging coke,while the effects of alkali metals and water vapor on the performance and carbon structure on cokes are still obscure.The variation in deep reaction behavior and infrared functional group structure as well as carbon structure of cokes under different alkali metal and reaction atmosphere conditions were studied in this paper,which can provide a theoretical basis for the reasonable application of different cokes in blast furnace.Firstly,the intrinsic differences between two cokes were studied by the combining of proximate analysis,ash chemical composition,thermal performance,isothermal isochronal reactivity and gasification kinetics.The results showed that catalytic effect of ash on gasification reaction of tamping coke seemed to be higher comparing to that of top charging coke.The reactivity of tamping coke was 3.48%higher than that of top charging coke,while the coke strength after reaction was3.36%lower.Based on the isochronous reaction data of cokes at a constant temperature,the dissolution loss of tamping coke became more severe with the rising of temperature.meanwhile,the reaction kinetic results indicated that less activation energy was required by the gasification reaction of tamping coke under high reaction temperature.Secondly,with the increasing in concentration of alkali metal solution,the depth reaction gasification degree of cokes gradually increased.At low concentration,the catalytic effect of K₂CO₃ and Na₂CO₃ solutions was basically the same.However,the catalysis of K₂CO₃ solution was much higher than that of Na₂CO₃ solution when the concentration reached 7%and the influence of alkali metals on gasification reaction of tamping coke was significant.The depth reactions of cokes after pretreatments at1100?were mainly controlled by interfacial chemical reactions.With the extension of gasification,the loss of coke gradually decreased from the outside to the inside,and the effect of alkali metal seemed to be more dramatic on surface of coke particle.The solution loss on surface of tamping coke was more serious and the area of surface pores was much higher than that of top charging coke.According to the variation in infrared functional group structure of cokes,the aromatic ring substances in cokes gradually decreased with the extension of gasification,and consequently the aromatic hydrocarbons accounted for a relatively high proportion in coke structure.Above variation led to a gradual decrease in reactivity of coke,while the addition of K₂CO₃solution would promote the gasification reaction of oxygen-containing functional groups in cokes.Besides,the conversion of amorphous carbon to ordered carbon was inhibited by alkali metals during gasification process,the effect of which seemed to be more significant on tamping coke.Finally,the gasification reactivity of coke could be intensified by the addition of water vapor,while the solution of carbon mainly focused on the surface of coke and pore were connected with deepening of solution.As a result,a large number of cracks was produced in the internal structure of tamping coke and the relative density of external coke on surface of coke particles was greatly decreased,while the relative density of internal coke was relatively stable.Besides,the methyl content in the functional group structure of tamping coke was reduced by the addition of water vapor,which led to an increase in the aromaticity of coke.The graphitization degree of carbon structure in tamping coke was obviously deepened and the reaction activity of coke was reduced to some extent.Hence,the influence of water vapor on top charging coke seemed to be higher than that of tamping coke.