Iron ore and cokes are charged in a blast furnace at high temperature to make molten iron called “hot metal”.  It contains some impurities such as sulfur and phosphorus.  Therefore, the hot metal should be refined to be clean liquid steel. However, the liquid steel temperature is very high, even up to 1700 °C, thereby dissolving most materials in contact with the liquid steel.  This fact makes purification of the liquid steel very difficult.

“Clean Steel Laboratory” led by Professor Youn-Bae Kang at Graduate Institute of Ferrous and Energy Materials Technology explores technologies to control those impurities in the liquid steel to produce high clean steel product. Prof. Kang and his team investigate various kinds of high-temperature chemical reactions for controlling those impurities, assisted by in-depth analysis using thermodynamics, kinetics, and physicochemical properties of high-temperature materials.

Iron is an extraordinary element found in the periodical table: when it is in the liquid state, it dissolves various elements into it. This results in technical difficulty in purifying the liquid steel.  Moreover, its reaction characteristic, high-temperature physico-chemical properties, and cost-competitive production technology should be considered simultaneously.  This requires his research team to strengthen comprehensive thinking.  This complicated situation makes this team be challenging in front of the task.

Prof. Kang and his research team have been exploring various kinds of high-temperature reactions happening at the interface between liquid steel and other materials, as well as technology for removing sulfur, phosphorus, oxygen, etc. They have revealed, for the first time, the high-temperature vaporization mechanism of copper and tin in liquid steel, which come from recycled ferrous scrap.  Also, they develop a reaction model to predict the vaporization rate.  This outcome should be useful when the recycled ferrous scrap becomes a major source of steel production.  This will be one of the essential parts of steel production technology of coming carbon-neutral society. In addition to this, they have resolved a long-standing issue in the steelmaking plant – clogging of liquid steel delivery system – when highly clean steel is produced for the automotive steel product.  They employed a high-temperature reaction experiment coupled with computational thermodynamic analysis.

Prof. Kang’s laboratory becomes 24-year old this year since his predecessor established this laboratory at POSTECH. They have had a long-standing and intimate collaboration with POSCO.  Many alumni in this laboratory are now working at a research institute, steel plant, and university.  This laboratory has carried out not only fundamental research for high-temperature metallurgy but also practical research to be applied to the steel production plant.

The Clean Steel Laboratory plans to extend its research interest to cover environmental and cost-competitive issues. The laboratory has already initiated research on low carbon and sustainable metallurgical processes based on the recycling of metal scraps, and will give emphasis on developing technology to produce high-quality clean steel from low-quality raw materials. Professor Kang commented, “Rather than synthesizing or developing novel materials, we are looking to resolve the unanswered challenges that have plagued the production of steel materials.”