Effect of harmful elements on the coke ratio of blast furnace based on the Rist operating diagram

The adverse effects of harmful elements on blast furnace life and production have been adequately researched; however, studies of the effects on the energy consumption of blast furnace are few. In this study, the circulation and accumulation of harmful elements in a blast furnace were analyzed. By combining the actual production parameters of a blast furnace and the Rist operating diagram, the effect of the harmful elements on the coke ratio was revealed and the quantitative relationship between the coke ratio and the loads and accumulation times of harmful elements was established. The calculation results show that the harmful elements cycle of "reduction-oxidation-re-reduction" in the blast furnace can transfer the CO from the high-temperature zone to the low-temperature zone, and consume a lot of heat in the high-temperature zone. This can decrease gas utilization and increase heat consumption in the hightemperature zone, consequently increasing the coke ratio. Each harmful element affects the coke ratio differently. Considering their accumulation times and loads, the harmful elements affect the coke ratio in the following orders:Na > K > Zn and Zn > Na > K, respectively. Further analysis shows that the effect of Na and Zn on the coke ratio is greater than that of K. However, considering the effect of K on coke deterioration is more significant, it is necessary to strictly control the load of K, Na, and Zn. Based on the quantitative relationship obtained by the above calculation process, curve fitting is carried out using the loads of harmful elements and coke ratio of blast furnace to predict the harmful elements accumulation times in the blast furnace. The curve fitting results are consistent with the blast furnace dissection experiment results.