Iron losses during desulphurisation of hot metal utilising co-injection of Mg and CaC2 combined with nepheline syenite

Iron losses during hot metal desulphurisation using magnesium and calcium carbide have been studied by large scale investigations of slag from the slag pit as well as slag sampling during desulphurisation at SSAB EMEA in Lulea. The desulphurisation slag after co-injection is normally solid and contains a large amount of iron. An alkali containing mineral, nepheline syenite, was mixed with calcium carbide to enhance the separation of iron from the slag. Even though the addition of nepheline syenite resulted in a more fine grained slag, no reduction of the iron content in the slag was observed before slag skimming. Nepheline syenite has a positive effect on slag skimming; however, the total magnetic iron losses have not decreased significantly. The increased turbulence during injection of magnesium could explain the lack of improved iron yield. The addition of nepheline syenite does not have a negative influence on the reagent efficiency.