Carbonization Correlation Of Mixing Coals Used In Different Coking Processes And Thermal Properties Of Coke

The two pairs of top charging coke and stamp charging coke in P iron and steel enterprises and G iron and steel enterprises have great differences in thermal properties,but there is no obvious difference in economic and technical indicators in blast furnace production.In this paper,mixing coal Coal 1 and its top charging coke Coke A and mixing coal Coal 2 and its stamp charging coke Coke B of P iron and steel enterprise,and mixing coal Coal 3 and its corresponding top charging coke Coke C and mixing coal Coal 4 and its stamp charging coke Coke D of G iron and steel enterprise are selected.Starting from the coking experiments of four different mixing coals,the characteristic parameters of charring behavior and their corresponding relations with coke quality under different heap densities are studied,the macroscopic thermal properties and microstructure of corresponding coke are analyzed,and a model is established to predict coke dynamic behavior.Through the comparative study,the following conclusions are drawn:?1?For the high volatile and weak caking coals,increasing the heap density will affect the charring behavior characteristics of coking coals during pyrolysis and significantly improve the properties of coking coals.However,for the coking coals of the moderate proportion of volatile and weak caking coals,there is no significant change in the behavioral parameters of coking process by increasing the heap density,and the cokes produced by conventional coking experiments meet the needs of blast furnace,so it is unnecessary to adopt tamping coking technology to increase production cost.?2?Some basic properties of the four mixing coals,such as the volatile matter content,the maximum expansion pressure,the final degree of shrinkage,plasticity range of paste and the maximum thickness of gelatine layer,have certain corresponding relations with the strength of cold state and thermal properties of coke.The coke quality can be predicted by the basic property indexes of coking coal,which provides reference basis for coking with mixing coals.?3?There is a difference between the results of the national standard method for detecting the thermal properties of coke and that of the constant dissolution loss rate detection method.The CSR which is detected by the national standard method with the coke of higher reactivity is lower,because the dissolution loss rate is too high.The thermal performance indexes CSR₂₅ and CRR₂₅ obtained by the constant dissolution loss rate detection method can better evaluate the quality of coke,and this method has better simulation for the dissolution loss process of coke in the blast furnace.?4?Increasing the heap density will lead to narrow and long flat pores inside the coke,and the proportion of small pores will increase.Coke B and Coke D have larger specific surface area than Coke A and Coke D,which is also the main reason for their high reactivity.Compared with top charging coke,stamp charging coke has different stomatal sizes and a large number of micropores.However,stamp charging coke has a thicker stomatal wall due to the increase of heap density,which is conducive to the reduction of CO2 erosion and the improvement of coke strength.?5?The activation energy of Coke A and Coke B obtained by RPM model is81.76 kJ/mol and 71.89 kJ/mol,respectively;The activation energies of Coke C and Coke D obtained by GM model is 137.60 kJ/mol and 167.93 kJ/mol,respectively.Coke B has higher matrix reactivity than Coke A.The matrix reactivity of Coke C is higher than that of Coke D,indicating that stamp charging coke Coke B and top charging coke Coke C are more likely to react with CO₂ gas.