On-line slag composition analysis for electric arc furnaces
Electric steelmaking has fast gained ground in developed countries due to reduced CO2 emissions compared to blast furnace steelmaking and better production flexibility. Due to increased scrap usage, the quality of the scrap is getting worse and worse. This is reflected in the increase of non-metallic material in the scrap. Fluctuations in EAF scrap charge composition causes significant fluctuations in the EAF slag composition, since the non-metallic material in the scrap accumulates in the slag.
Fluctuation of slag composition causes many challenges in EAF steelmaking. In stainless steelmaking one of the most important goals in EAF is to keep the chromium content of the slag low, since it causes costs due to increased alloying additions and problems in recycling of slag. In carbon steelmaking it is important to ensure foaming slag conditions, which increases energy efficiency of the EAF. Due to the slag composition fluctuations the slag foaming is sometimes hindered when the slag composition drifts to the composition area with low foamability.
There are currently very few methods available for analysing slag composition in EAF. One of the most popular methods to gain information of slag composition is taking slag samples and analysing them in laboratory. Currently there is no method available to analyse slag composition in industrial EAFs on-line.
The objective of the proposal is the development of a continuous measurement system for EAF slag component analysis based on optical emission spectroscopy. The aim for stainless steel grades is the analysis of Cr2O3 and MnO content, while for carbon steel grades the aim is to analyse CaO, SiO2, Al2O3 and MgO content of the slag. The proposed technology will follow these criteria:
- remote and continuous measurement system for slag component analysis,
- low maintenance system design,
- optimized operating practices based on continuous slag composition data increasing resource and energy efficiency.
Willms, T.; Echterhof, T.; Pfeifer, H.; Aula, M.; Fabritius, T.; Andersson, N.; Tilliander, A.; Jönsson, P.; Jokinen, M.; Puukko, E.; Praschko, S.; Klung, J.-S.: On-line slag composition analysis for electric arc furnaces – State of the Art (SoA), Project report, 29.09.2016
This project receives funding from the Research Fund for Coal and Steel under grant agreement No 709923.