Study On The Performance Of Tamping Coke And Top-charging Coke And Adaptability Of Blast Furnace

The tamping coking process can reduce the proportion of high-quality coking coal in the coking process,and reduce the cost of coke production while ensuring the quality of coke.However,a large number of production practices have found that there are many problems in the application of tamping coke instead of top-charging coke in medium and large blast furnaces.Due to the great difference between the process,coal blending and top-charging coke,the tamping coke eventually leads to problems in the use of tamping coke with conventional indicators of reactivity（CRI）,coke strength after reaction（CSR）,crushing strength(M₄₀)and wear resistance(M₁₀)similar to top-charging coke in large blast furnaces,and the key is precisely the difference in these other properties.Tamping coke is quite different from top-charging coke due to its process characteristics.It has a significant improvement effect on the conventional quality indicators of conventional indicators of reactivity（CRI）,coke strength after reaction（CSR）,crushing strength(M₄₀)and wear resistance(M₁₀).However,practice shows that there are many problems in the use of tamping coke with similar indicators to top-charging coke in medium and large blast furnaces with a capacity of more than2000 m³.Therefore,based on the practical problems of tamping coke in the use of large blast furnace,it is necessary to explore the reasons for the difference between tamping coke and top-charging coke in the application of blast furnace.In order to explore the reasonable use of stamping coke in large blast furnace,the pore structure,density,drum strength,gas permeability and liquid permeability of different process coke were analyzed and compared.Based on the fact that the existing optical evaluation indexes of coke are not accurate enough to predict the thermal properties of tamping coke,the relationship function between optical structure and thermal properties of coke was constructed by multiple linear fitting method to describe the influence of tamping process on the thermal properties of coke.In order to help iron and steel enterprises to establish an intuitive coke selection and use scheme,a metallurgical coke performance evaluation system based on the existing coke evaluation methods and the structural characteristics of tamping coke was constructed from three aspects:particle size and chemical composition,cold and hot performance and hidden index characteristics.the optical texture distribution,Isotropic Sum（ΣISO）and Optical Texture Index（OTI）of multi-source tamping coke and top-charging coke were analyzed by coal petrography method.The difference of each lithofacies characteristic parameter between the two was explored.It is considered that the existing coke optical evaluation index is not accurate enough to predict the thermal properties of tamping coke.The relationship function between optical texture and thermal properties of coke was established by using multivariate linear fitting method.The thermal properties of various tamping cokes obtained by top-charging process under the same coal blending conditions were predicted by the relationship function between optical texture and thermal properties of top-charging coke,which was used to describe the effect of tamping process on the thermal properties of coke.A valence-based metallurgical coke performance evaluation system was constructed from three aspects:particle size and chemical composition,cold and hot performance and hidden index characteristics,6items of particle size and chemical composition indicators:average particle size,coke powder（<25mm）ratio,total moisture,volatile matter,ash content,sulfur content;4items of cold and thermal properties:M₄₀,M₁₀,CRI,CSR;6 implicit indexes of tamping coke,respectively:CSR₁₃₀₀,OTI,Micro strength MSI,Structural strength SSI,Pseudo relative density,Carbon chemical structure d₀₀₂.The main conclusions are as follows:（1）A number of experiments were carried out to determine the porosity difference of different levels of large pores.It was verified that the average porosity of tamping coke was lower than that of top-charging coke,while the specific surface area was not significantly different.The true density of coke is not much different,while the false density and bulk density of tamping coke are much larger than those of top-charging coke.The drum strength is generally lower than the top-charging coke,and is negatively correlated with porosity.The permeability at room temperature is mainly related to the particle size,and the process has little effect on it.（2）The proportion of optical structure of tamping coke and top-charging coke is obviously different.Tamping coke different optical tissue proportion distribution range is larger,more isotropic structure,anisotropic structure accounted for less and fine mosaic tissue accounted for relatively high,so tamping cokeΣISO ratio is generally higher than that of top-charging coke,and OTI difference between different tamping coke is larger and overall lower than top-charging coke.The fitting results of CSR show a good linear positive correlation with the reactivity of coke optical structure.According to the difference between the predicted value and the actual value of CSR,the Tamping Index（TL）of tamping process is proposed to predict the stamping strength of tamping coke production process,and to provide reference for the advantages and disadvantages of tamping coke blending.Combined with the actual use effect of tamping coke on medium and large blast furnaces,the suggestion of TL when selecting tamping coke for medium and large blast furnaces is given.The implicit index can be used to correct the cold and hot indexes of tamping coke in the metallurgical coke performance evaluation system,and the evaluation system is based on self-produced coke,calculating the use focal ratio,use cost and price index of single coke.Then we can calculate the predicted coke consumption and cost of mixed coke.The predicted cost and performance price ratio change curves obtained through the actual production data is highly consistent with the actual change trend,which provides a reference for the use and energy saving of tamping coke in the blast furnace ironmaking process.