The main objective of this RFCS project was to develop and to apply through-process control strategies for a reliable, simultaneous achievement of low steel carbon and nitrogen levels within electric steelma-king under minimum energy and material costs with optimal productivity.
This development have been based on detailed investigations of relevant operational parameters and dynamic analytical model-ling of pick-up and removal of C and N within all aggregates (EAF, LF, VD) of the entire process route.
Regarding EAF treatment, focus have been laid on the partial substitution of scrap by alternative iron materials (pig iron, DRI/HBI), to lower C and N contents at EAF tapping to required levels.
The improved process control strategies allows to produce high quality steel long products like SBQ billets, structural steel, beam blanks and wire rod with nitrogen contents well below 70 ppm and carbon contents in the range of 0.05 to 0.08 % with high reliability under lowest energy consumption, material and production costs.
Furthermore the project results allow the economic production of new long products and also flat products with significantly higher demands on low nitrogen (< 50 ppm) and carbon contents (< 0.05 %) via the electric steelmaking route.