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The feasibility of a fast slag analysis at the vacuum degasser for better production control in secondary steelmaking is demonstrated with the emphasis on SiO2, CaO and Al2O3. A laser-OES instrument with a closed cabinet (1.0 x 1.8 x 1.7 metres) was installed about 10 metres away from the vacuum degasser plant, with stability being achieved for 7 months. Sampling procedures produced suitable samples from an automatic lance system of the vacuum degasser and from the electro steel plant. Process slag samples were characterised by SEM with respect to their inhomogeneities and defects. Phase analysis could identify calcium-aluminium-oxides, periclase, anatase, and quartz phases. An adapted laser-OES method with a new beam shape was developed for enhanced spatial averaging. For measurement the steel worker has to push a button, place the sample - without any prior preparation - at the sample plate and close the sample stand. The measurement starts automatically, and after 80 seconds the analysis result is transmitted to the control unit. The root mean square error of prediction with multivariate PLS1 analysis is determined at 0.20 wt.-%,1.0 wt.-%, and 1.5 wt.-% for SiO2, CaO, and Al2O3. The RSD(c) are 0.52 %, 0.80 %, and 0.83 % for CaO, SiO2, and Al2O3. The analytical performance regarding short and long term stability, robustness and on-site usability were evaluated under routine-like conditions. The comparability with XRF measurements (directly on casted slags and/or after preparation) was investigated by performing a round robin trial within the partners.

Additional information

Authors: No author stated, European Commission, DG Research, Brussels (BE)
Bibliographic Reference: EUR 23174 EN (2008), 106 pp. Euro: 20
Availability: Katalogue Number: KI-NA-23174-EN-S The paper version can be ordered online at:
ISBN: ISBN: 978-92-79-07645-9
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