Effect of Mixed Charging of Nut Coke and Sinter on Hydrogen-Rich Smelting Process of Blast Furnace

摘要

Abstract With the increasing demand for low-carbon metallurgy, large-scale hydrogen-rich smelting has become an effective way to realize low-carbon ironmaking. The injection of hydrogen-rich fuel into blast furnace changed the reduced atmosphere, affecting the reaction behavior and structure of the burden. Production practice has proved that the use of nut coke is an important measure for alleviating the increasingly tense relationship between coke supply and realizing low reducing agent ironmaking. In this paper, the effect of mixed charging of nut coke and sinter on reduction and softening-melting properties in the hydrogen-rich smelting process of blast furnace is studied. The results showed that the close contact between nut coke and sinter promoted carbon dissolution and water–gas reaction to generate more CO and H2, thus increasing the reduction potential in the gas mixture. With the increase of nut coke and hydrogen-rich ratio, the softening–melting properties of the burden were improved. This change narrowed and lowered down the position of cohesive zone, triggering to an enlargement of indirect reduction zone, which was conducive to strengthening blast-furnace smelting and saving coke. The permeability resistance of the burden bed was reduced, which was beneficial to the good airflow distribution and the gas utilization rate. There was a slag layer between nut coke and metal iron phase in the softening–melting process, and the slag could quickly fuse with the ash distributed on the nut coke surface to dissolve it, thus promoting the occurrence of carburizing reaction and improving the dripping behavior of the burden.Graphical Abstract