RHI AG (Vienna, Austria):

Kirschen M., Dr., Product Management EAF Purging and Process Technology, e-mail: marcus.kirschen@rhi-ag.com
Zettl K.-M., Mag. Eng., Head of Dept. of Product Management EAF

Excellent mixing of the steel melt helps to improve mass and heat transfer in the modern EAF processes, in order to accelerate the melting of scrap and DRI, decarburization, homogeneous superheating, alloy distribution, and to avoid skull formation. Different electric arc furnaces with melt mass 6–280 t, intended for production of wide range of carbon, special and alloyed steels, have been equipped with the bottom gas purging systems. Direct bottom gas purging not only efficiently promotes mixing of the steel melt in the entire steel bath, but also provides constant gas bubble columns to avoid CO boiling retardation. The benefits of direct purging plug (DPP) systems in modern EAF processes are described and case studies are presented. Three examples of application of DPP for carbon steels and five examples of DPP usage for melting of special and alloyed steels are observed and corresponding technical parameters are displayed. It is shown that bottom gas purging is effective due to increase of absorption degree of alloying elements, reduction of electric power and oxygen consumption. In addition homogeneity level of the melt and operating reliability of the technological process are improving.

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2. DeSantis, M.; Giavani, C.: Bath mixing in EAF through proper lances and plugs gas stirring policies, Proc. In novation in EAF and in Steelmaking Processes, Mailand, Italien, 27.–28. Mai 2009.
3. Dong, K.; Zhu, R.; Liu, W.: Bottom-blown stirring technology application in Consteel EAF, Adv. Mat. Res. (2012) Vols. 361–363, S. 639/43.
4. Kazakov, S. V.; Gulyaev, M. P.; Filippov, V. V.: Hydro dynamics of electric arc furnace bath at stirring with inert gases, Proc. 21^st Intern. Conf. on Metallurgy and Materials, Brno, Czech Republic, 23.–25. Mai 2012.
5. Jones, D. L.: Available and emerging technologies for reducing greenhouse gas emissions from the iron and steel industry, U.S. EPA, Office of Air Quality Planning and Standards, Sector Policies and Programs Division, Sept. 2012.
6. Badr, K.; Kirschen, M.; Cappel, J.: Chemical energy and bottom stirring systems — cost effective solutions for a better performing EAF, Proc. Metec InsteelCon, EECRSteel, Düsseldorf, Germany, 27. Juni — 1. Juli 2011.