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Oulu, Finland

Aula M.,University of Oulu | Aula M.,Luxmet Ltd | Makinen A.,University of Oulu | Leppanen A.,Luxmet Ltd | And 2 more authors.
ISIJ International | Year: 2015

In electric arc furnace (EAF) steelmaking the control of the overall process has traditionally been in the hands of the operator. The current level of automation has not allowed for full dynamic control of EAF. In this study new information was sought with a recently tested method of on-line in situ optical emission spectroscopy. Optical emission spectra were measured from Outokumpu Stainless Oy, Tornio works, electric arc furnace 2 during the course of one month. The focus of the study was the analysis of slag surface conditions and alkali emission lines during different process stages. The results show that alkali excitation lines are different in different process periods. According to the properties and appearance the optical emission of alkali metals, in early periods of EAF process the alkali transitions are caused by volatilization of contaminants in the EAF charge. In the later periods the optical emissions of alkali metals are linked to occasional high gas generation, which is likely caused by oxidation-reduction reactions occurring inside the melt. The thermal radiation of the heat was analyzed during different process periods. According to the scrap melting indicator calculated from the measured spectra, the melting conditions vary significantly between heats. The scrap melting indicators have a correlation to the metal yield, but it is obstructed by many different factors affecting the metal yield. The results indicate that on-line in situ optical emission spectrometry can be used in the analysis of scrap melting and slag surface conditions in EAF steelmaking. © 2015 ISIJ.

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