Recycling ladle furnace (LF) slag helps in sustainable steel making and reduces steel production costs. This paper focuses on recycling Si/Mn/Al-killed LF slag as a replacement for CaO-Al 2 O 3 -based synthetic slag for treating high carbon Si/Mn-killed steels. Characterization of different types of LF slag was carried out to identify chemical composition and mineralogical phases. Industrial trials were carried out by recycling LF slag along with lime and calcined bauxite as additives. The effect of recycled LF slag on the kinetics of desulphurization and other process parameters was studied and compared with regular practice. It was observed that LF slag can be recycled successfully as a replacement for CaO-Al 2 O 3 -based synthetic slag at an industrial scale.