Prefused calcium aluminate flux vs. fluorspar for slag conditioning of stainless steel – a comparative life cycle assessment study

Metallurgical fluxes or slag conditioners are today added during stainless steel production to significantly improve the formation of the top slag in the ladle or converter. For decades, fluorspar was predominantly used in combination with lime to produce the high basicity slags required for desulphurisation. However, certain steel producers have started to use calcium aluminate-based slags in order to avoid the presence of fluorine in the final slags. According to Yan et al. slags in the CaOAl2O3 system can achieve desulphurisation effects that are comparable to CaO-CaF2 slags.1 This was subsequently confirmed by industrial experiences.2 Although different fluxes can form slags with equal process performance, they may present significantly different environmental impacts.