Kobolde & Partners AB (Chelyabinsk, Russia):

Gyllenram R., Dr. Eng., Chairman
Westerberg O., Mag. Eng., CEO, e-mail: olle.westerberg@kobolde.se

Optimal operation in an EAF is not the same thing as buying the cheapest possible scrap. The amount of slag caused by the scrap affects the raw material cost, energy use and productivity. This makes scrap with a high oxide content costly. Uncertain analysis makes it difficult to control the content of tramp ele-ments and forces the steelmaker to dilute the charge with expensive scrap from virgin steel production. With a value-in-use approach the potential for upgrading scrap to a higher quality grade can be calculated. This paper has shown that it is indeed possible to make calculations on optimal cost and carbon footprint for scrap-based steelmaking. In order to investigate the value of clean, metallic scrap with a known analysis the optimization tool Rawmatmix was used for three different cases: use of crusts and upgraded crusts; use of scrap with different amounts of dirt; use of scrap with different variations in tramp elements. In addition the carbon footprint of the three cases was assessed, taking into account emissions from the process itself as well as from preceding steps. The study shows that there are significant savings to be made through upgrading and better control of scrap. Finally, the importance of making proper value in use calculations have been highlighted showing that taking a simple purchase cost view on materials can lead to the wrong decisions being made.

1. Private communication: representatives of the Swedish recycling industry, raw material suppliers and steel plant managers, Stockholm area, Sweden, Dec 2014.
2. Rawmatmix system description.
3. Selin, R.: The role of phosphorus, vanadium and slag forming oxides in direct reduction based steelmaking, TRITA-PT-87-04 ISSN 0284-3013, Stockholm, Sweden, 1987.
4. Gyllenram, R. et al.: Taking in house and up-stream CО₂ emission into account in charge optimization for scrap based steel making, METEC InSteelCon 2011, Düsseldorf, Germany, 27 June – 1 July 2011.
5. US Energy Information Administration, EIA, www.eia.gov
6. Charge data gathered from an undisclosed Swedish low alloy steel producer, 2012.