The effects of extra low Mn contents on the BOF process

Fundia Koverhar Steel Works has since April 1995 been producing steel from low-manganese hot metal. Today the average hot metal Mn content is 0.08% instead of the previous Mn content of 0.35%. The average end-blow Mn content at the converter is 0.08 % and the variation is very small. In addition to the economical benefits obtained in the ironmaking, extra low Mn practice has been found to have positive metallurgical effects on steelmaking. These are: better dephosphorisation, lower end-blow nitrogen content, less fluid slag with less slopping during the blowing, better Mn recovery and lower MnO content in the slag. The reasons for these effects are thermodynamical. With the extra low Mn practice it has been possible to predict the Mn content at the end-blow and to produce low-Mn steel grades.