Development of Alternative Reductant using Biomass for Reducing CO2 in Ironmaking Process

Technologies to reduce CO2 emissions in the steel industry have been actively developed since the early 1990s in order to deal with global climate change. In particular, the utilization of various types of biomass including wood, bamboo, grass, food and agricultural by-product are being attempted as carbon neutral fuels in the blast furnace process. In this study, an alternative reducing agent for coke and pulverized coal using biomass was developed and the effect on blast furnace performance and CO2 reduction was evaluated. The first investigation was whether a burden material made of torrefied biomass mixed with iron ore and coal (Iron-bearing Biomass Coke, IBC) could be used as a substitute for coke in the form of a carbonized briquette. In addition, a method of mixing torrefied biomass with pulverized coal (Bio-PC) to inject through tuyere in a blast furnace was examined. As a result, when coke was replaced with 10% of IBC, the reducibility of the sintered ore was improved in association with an increased CO gas utilization ratio, hence CO2 emissions decreased by 2.3%. Furthermore, the combustion efficiency of Bio-PC mixed with 10% of torrefied biomass was improved by 13.2%, thus, the amount of CO2 emissions was calculated to decrease by 4%. These results suggest that the possibility of using IBC and Bio-PC in blast furnaces, as they could effectively reduce CO2 emissions in the ironmaking process.