Synopsis :In recent years, the reduction of CO 2 emissions and the stable supply of raw materials are two major issues for the steel industry. Low reducing agent operation in the blast furnace is required to reduce CO 2 emissions in ironmaking. As a mean of realizing low reducing agent operation with using low-grade raw materials, ferro coke characterized by high coke reactivity is considered to be useful. Theoretical and experimental studies were carried out to verify the effect of the ferro coke usage on reaction behavior in blast furnace. Investigation of CO 2 reactivity at the simulated blast furnace condition revealed that the initial temperature of CO 2 reaction of ferro coke is lower than the temperature of conventional coke. At the temperature of over 1100°C, the deterioration of ferro coke strength after reaction was depressed because the reaction occurred preferentially at the surface of the ferro coke.The coke and ferro coke strength after reaction was estimated based on the experimental results with the two-dimensional mathematical model of the blast furnace. The average coke strength of ferro coke and conventional coke with charging of ferro coke (100 kg/t) was little less than the coke strength without ferro coke charging. It is predicted that the carbon saving with charging of ferro coke (100 kg/t) is about 6% in comparison to without ferro coke charging.

CO 2 mitigation and the stable supply of raw materials are two major issues for the steel industry. The Japanese steel industry has promoted short term developments and investments to comply with the Japan Iron and Steel Federation's voluntary action plan in parallel with developing plans for drastic CO 2 mitigation programs toward the post Kyoto protocol period. This paper describes short-term measures in the ironmaking field such as natural gas injection technology to the sintering bed and burden distribution control with coke mixed charging.For mid and long term CO 2 mitigation, the joint project, 'Preparatory research work for the blast furnace based innovative ironmaking technologies' was actively promoted by the New Energy and industrial Technology Development Organization (NEDO) from FY2006 to FY2008. Based on the enhancement of carbon -CO 2 reaction by close positioning of carbon and iron oxide/metallic iron, the production process and reaction mechanism in a blast furnace were studied for two innovative composites with iron oxide, metallic iron and carbon.For development at a pilot plant scale, a new project, 'Development of innovative ironmaking process using low cost iron ore and coal' started in FY2009. Key technologies of the project are the production process and evaluation in a blast furnace of a hybrid composite of metallic iron and carbon, so called 'Ferro-coke'. This paper describes key technologies and recent developments of the project.

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Synopsis :In these years, the development of innovative energy saving technologies for climate change is strongly desired, and low reducing agent ratio (RAR) operation in the blast furnace is required to reduce CO 2 emission in ironmaking. As a mean of realizing low RAR operation, the development of an innovative raw material "Carbon Iron Composite (CIC)" for satisfying both high coke reactivity and iron ore reduction is thought to be useful. Carbon Iron Composite is produced by mixing the non-or slightly caking coal and low-grade iron ore and briquetting, followed by carbonization of the briquetted materials. Carbon Iron Composite having both high strength and high reactivity was successfully produced at the blending ratio of iron ore of 30 mass%. Investigation of CO 2 reactivity of CIC at the simulated blast furnace condition revealed that beginning temperature of CO 2 reaction of CIC is lower than the temperature of conventional coke. Especially, CIC made from high volatile matter coal and porous iron ore has high reactivity and high strength after CO 2 reaction.

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