Reaction behavior of burden above soft melting zone in carbon cycle oxygen blast furnace

In recent years, in the context of China′s "peak carbon dioxide emissions and carbon neutrality" strategy, low-carbon blast furnaces have become an important direction for the development of low-carbon metallurgical technology in China. Due to the large use of fossil fuels and the low utilization rate of top gas in the ironmaking process of blast furnaces, excessive CO₂ emissions are caused. In order to reduce carbon emissions from blast furnace ironmaking, a new process of hydrogen rich carbon recycle oxygen furnace (HyCROF) has been proposed. In this paper, the reduction behavior and coke gasification behavior of iron bearing burden in the carbon recycle oxygen furnace (CROF) were studied by combining numerical simulation and laboratory experiments. The reduction degree of sinter and pellet and the separation phenomenon of slag and iron were analyzed by SEM-EDS, and the microscopic morphology of coke after gasification was characterized by mineral phase microscopy. The variation pattern of iron-containing charge reduction in the blast furnace obtained by numerical simulation and laboratory experiments is basically consistent, which verifies the feasibility of the combined method of numerical simulation and laboratory experiments.The research shows that in the same vertical direction of CROF, with the reduction degree and metallization rate of the iron-containing furnace material increasing as the position decreases, the gasification rate of the coke continues to increase. Above the soft melting zone in the center of CROF, the reduction degree of the iron-containing furnace material is 0.91, the metallization rate is 67.58%, and the gasification rate of coke is 20.91%. Above the soft melting zone at the edge of CROF, the reduction degree of the iron-containing furnace material is 1, the metallization rate is 96.91%, and the gasification rate of coke is 21.36%. In addition, with the downward movement of the furnace charge, the larger the metal iron area of the reduced iron-containing furnace charge, the more obvious the slag iron separation, and the larger the observed coke pores. In the carbon cycle oxygen blast furnace, the utilization of CO in blast furnace gas increases, CO₂ emissions decrease and the secondary utilization of blast furnace gas increases due to the top gas circulation, which provides a theoretical basis for the application of low carbon green metallurgy.