Protective mechanism of unburned pulverized coal to coke in blast furnace

Abstract

The edge and internal morphology of coke with different contents of UPC (unburned pulverized coal) after reaction with CO2 were analyzed by SEM. The influence of UPC on CRI (coke reactivity)，CSR (coke strength after reaction) and apparent porosity was also studied. The synthetic weighted mark method was used to analyze the comprehensive effect of UPC content on coke quality. The results show that because of the decrease of the content of intermediates Cf(O) and C(O)Cf(O) the restrictive step between the coke and CO2 is an interfacial chemical reaction, and it accords with the Mckewan equation 1-(1-α)1/3=kt. The UPC has a strong effect on coke when the content of UPC is 10~20%; meanwhile , the CRI and the apparent porosity are significantly decreased by 6.8% and 9.5%, respectively, and the CSR is significantly increased by 3.8%. The UPC can effectively reduce the effect of CO2 on the edge and the internal erosion of coke; the large pores and the pulverization of coke were avoided. The results of the synthetic weighted mark method showed that the comprehensive quality of coke changed greatly when the content of unburned pulverized coal was 11.24~20.87%, which is in agreement with the experimental results.

Keywords

• unburned pulverized coal
• coke reactivity
• coke strength after reaction
• apparent porosity
• the synthetic weighted mark method