Fundamental Research On Maturllurgical Behavior Of Burden In Melting And Dropping Zone Based On The Process Of Oxygen Blast Furnace

With the aggravation of smog in the air,the pressure of iron and steel enterprises is also increasing.In order to reduce the energy consumption,CO₂ and other pollutants,top gas recycling-oxygen blast furnace?shorted as OBF?has become one of the largest and most likely industrialized ironmaking technologies.The process is characterized by pure oxygen instead of the traditional hot blast furnace and recycling the top gas after CO₂ removal.Due to the indirect reduction of bueden,low coke ratio,large coal injection and other characteristics,the metallurgical behavior of bueden in melting and dropping zone will be changed.In this paper,two aspects were studied based on coke and slag.The first part was the study of slag on the coke dynamic dissolution.The second part was the flow behavior of slag in the coke bed.The results of this study will provide a theoretical basis for coke deterioration and liquid phase flow in the melting and dropping zone in OBF.Firstly,the study of dynamic dissolution of coke was investigated by the self-design equipment.The effect of the content of FeO in slag,temperature and reaction time on coke dissolution were studied according to the reduction degree in the lump zone,smelting strength and reaction temperature.The orthogonal experiment of three factors and three levels was carried out and the degree of coke deterioration were deterimined by weight diameter.The experiment found that the factors order were erosion time,FeO content and temperature.The influence of slag on coke gasified with steam and CO₂ in lump zone,was investigated and degeragation were characterized by weight,porosity,pore size distribution and micro morphology.And the gasification and corrosion of coke were conducted under the simulated condition of TBF,OBF and COG-BF.The strength was measured by the I-type drum the nanometer mechanical probe.The limiting step and mechanism of the coke were analyzed.The activation energy with 10%FeO was 177.34KJ/mol and the controlling rate was determined.Considering the conditions of OBF,the dissolution of coke in the melting and dropping zone would be beneficial to maintain its high temperature performance.Secondly,the flow behavior of slag in coke bed were investigated.According to the bueden change in the lower part of the blast furnace,the influence of the temperature,slag basicity,slag Al/Si ratio,size and type of coke on the flow behavior were studied.On these basis,the research on the slag hold-up behavior absorping of fuel ash and unburned coal and coke blended with semi-coke were carried out.The results show that the hold-up was increased significantly with the slag absorbing ash and unburned pulverized coal.The maximum hold-up was 11.52%.According to the liquid flooding and operation parameters,the burnout of pulverized coal in TBF and OBF was determined to be more than 78.56%and 83.92%.The amount of semi-coke was controlled within 30%in the process of OBF-coal chemical.Finally,cold and numerical simulation were carried out.Silicone oil-water simulated slag-molten iron in the coke bed slit by the self-designed cold device.According to the flow condition,velocity,and drop pressure,the relation between viscosity and velocity can be fitted as v =-29.1? +17.72.The relationship of velocity and gas is v =-1.72Q + 0.823Q,?0.147Q³+5.316.The flooding rate is 0.395 m/s in silicon oil-water systerm.The flow behaviors of slag and iron in the coke void were simulated by VOF model in the conditon of different properties of slag,two phases coexist of slag-mental and different gas flow rate.The force of liquid drop is determined as 2??[?17-Rsin?₁?sin??₁-??+?17-Rsin?₂?sin??₂ + ?? ??]-4/3?r³?g+f.According to the simulation results,it is found that the smaller the droplet,the smaller the contact angle,the larger the viscosity and the larger the surface tension will inhibit the slag.For the flow of slag-mental phase,the interfacial tension between the surfaces is opposite.So the flow of molten iron is blocked and the slag flow is promoted.It is indicated that the flow of slag-mental phases should be easier according to the results of simulation and the parameter of OBF.