Injection of COREX off-gas into ironmaking blast furnace

Oxygen blast furnace (OBF) is a promising ironmaking technology to realize low carbon emissions. It is featured in high oxygen-enriched operations and suffers from excessively high gas flame temperature. Aiming to overcome this problem, COREX off-gas (CROG) after CO2 and dust removal, which mainly consists of CO and H2, is proposed to be injected into an industrial BF operated with different oxygen enrichments. Such a process is studied using an integrated BF model. The effects of CROG on coal combustion, BF shaft states, and overall performance are analyzed in detail. The results show that the CROG injection under the same target flame temperature is beneficial for improving coal combustibility, therefore allowing a higher coal injection rate to achieve better fuel economy. As the CROG injection rate increases to reach the same hot metal temperature, the coke rate initially decreases and then increases, leading to an optimum injection rate in terms of fuel consumption. The decrease is contributed by the enhanced indirect reduction of the H2 in the CROG. The decline is because of the extra coke combustion for the energy supply to heat the shaft burden and hot metal. All the results suggest that CROG injection helps realize OBF.