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  • Sensitivity-enhanced laser analysis (SELA) of steel melts for a fast multi-element online analysis during ladle processing in secondary metallurgy


In the framework of the research project, significant progress has been achieved regarding online analysis of steel melts by laser emission spectrometry. For the first time it was successfully demonstrated in a 100kg molten steel capacity furnace that online analysis during ladle processing achieved limits of detection (LOD{3s}) comparable with conventional offline methods.

Using laser analysis by laser-induced breakdown spectrometry (LIBS), limits of detection below 10 micro-g/g for C, P, S and other elements are achieved for solid samples. For liquid steel the LODs are close to the values for solid steel. The duration of the measurement for one analysis was one minute for solid as well as liquid steel. The limit of detection for N is not yet sufficient, but a further improvement seems feasible due to the sufficient excitation in the laser plasma. There is an improvement by a factor of at least 10 compared to the published state of the art for solid samples.

The breakthrough was enabled by applying the laser modulation method of Fraunhofer ILT, which yields greater signal intensities than conventional excitation approaches, in combination with a lance developed by the Institut fur Eisenhuttenkunde/RWTH Aachen, able to guarantee a slag-free and continuous access to the steel melt for several hours of operation. The calibration procedures are carried out in cooperation with Rautaruukki. Total immersion times of the lance of up to five hours were realized enabling a continuous laser monitoring of the melt composition.

At the current level of knowledge, the estimated operational costs of an industrialized laser analyser are EUR 9 per analysis under the assumption of 200 measurements per day. The costs are dominated by consumable items such as lance tip and gas supply.

Additional information

Authors: NOLL R, Fraunhofer-Institut fur Lasertechnik, Aachen (DE);STURM V, Fraunhofer-Institut fur Lasertechnik, Aachen (DE);PETER L, Fraunhofer-Institut fur Lasertechnik, Aachen (DE);HAKALA R, Rautaruukki Oy, Raahe Steel, Raahe (FI);VIIRRET J, Rautaruukki Oy, Raahe Steel, Raahe (FI);GUDENAU H W, Insitut fur Eisenhuttenkunde, RTWH Aachen (DE);MAVROMMATIS K, Insitut fur Eisenhuttenkunde, RTWH Aachen (DE);ERNENPUTSCH L, Insitut fur Eisenhuttenkunde, RTWH Aachen (DE)
Bibliographic Reference: EUR 19411 EN (2001), 98pp. Euro: 14.50
Availability: EUR-OP reference: KI-NA-19411-EN-S Available from EUR-OP sales agents URL:
ISBN: ISBN 92-894-1481-2
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