On-line analysis of Cr₂O₃ content of the slag in pilot scale EAF by measuring optical emission spectrum of electric arc
Aula, Matti; Demus, Thorsten; Echterhof, Thomas; Huttula, Marko; Pfeifer, Herbert; Fabritius, Timo (2017-03-23)
Matti Aula, Thorsten Demus, Thomas Echterhof, Marko Huttula, Herbert Pfeifer, Timo Fabritius, On-line Analysis of Cr2O3 Content of the Slag in Pilot Scale EAF by Measuring Optical Emission Spectrum of Electric Arc, ISIJ International, Released March 23, 2017, Online ISSN 1347-5460, Print ISSN 0915-1559, https://doi.org/10.2355/isijinternational.ISIJINT-2015-677, https://www.jstage.jst.go.jp/article/isijinternational/57/3/57_ISIJINT-2015-677/_article/-char/en
© 2017 ISIJ. Published in this repository with the kind permission of the publisher.
Control of slag Cr₂O₃ content is essential in stainless steelmaking electric arc furnace (EAF). Excessive Cr₂O₃ content of slag lead to high Cr₂O₃ content after the EAF tapping, since the solid precipitates forming in high Cr₂O₃ contents are not reduced significantly during the tapping procedure. In this work the slag Cr₂O3 content during the EAF process was analysed by measuring the optical emission spectrum of the electric arc. The measurements were conducted in a pilot EAF situated in Aachen, Germany. Cr₂O₃ content of the slag was increased with periodical additions of Cr₂O₃ powder. The line ratios calculated from the optical emission spectra were compared to the results of the X-ray fluorescence (XRF) analysis of the slag samples taken from the furnace. The results indicate that best accuracy in a pilot scale can be obtained by using Ca I, Fe I or Mn I lines as reference for Cr I lines. By combining the most accurate line ratios of these three components, the Cr₂O₃ composition of the slag could be measured with an average absolute error of 0.62%-points and a standard deviation of 0.49%-points. The results suggest that Fe I and Mn I lines are the most promising reference lines for analysing Cr₂O₃ content of industrial EAF slag.
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