Evaluierung der Auswirkung von Additiven auf die selektive Anreicherung von Chrom in Linz-Donawitz-Schlacke

Looking at the past 75 years, the steel industry has been a steadily growing sector. Alongside the increasing production of crude steel, the amount of generated by-products, such as LD slag, has continuously risen. Against this backdrop, the recovery of valuable metals like chromium from slag is gaining importance.
The aim of this thesis is to investigate whether the addition of aluminum oxide (Al₂O₃) and titanium oxide (TiO₂) can induce selective enrichment of chromium in specific phases of LD slag.
For this purpose, LD slag from Voestalpine Stahl Linz GmbH will undergo thermal treatment. Prior to heat treatment, 0-20 wt.-% of Al₂O₃ and/or TiO₂ will be added as additives. Subsequently, the formed phases will be analyzed and evaluated using scanning electron microscopy (SEM).
The results indicate that chromium predominantly enriches in the RO phase. While the targeted enrichment of titanium and vanadium was not the focus of the study, selective enrichment was observed particularly with titanium. Vanadium, on the other hand, showed minimal independent enrichment and mostly co-existed with titanium and chromium. Samples with minimal additive content or no additives at all yielded the best results in terms of chromium distribution.
The experimental findings are promising. Specifically, extending the holding time during thermal treatment warrants further investigation. Moreover, this method could be expanded to slags with higher chromium content, such as EAF- and AOD- slags containing up to 5 wt.-% chromium.