Abstract: The oxidation of carbon, silicon and niobium in Nb-bearing hot metal were studied in a medium-frequency induction furnace by bottom-blown oxygen with SiO2-CaO-CaF2 slag-forming element or no slag at 1 350 ℃，1475 ℃ and 1515 ℃. The results showed that oxidation rate of silicon in Nb-bearing hot metal with SiO2-CaO-CaF2 slag or no any slag was 97 %, and oxidation rate of carbon was 20 % at 1350 ℃; however, oxidation rate of silicon was 15 % at 1475℃ and oxidation rate of carbon was 84 % at 1515℃ with basic SiO2-CaO-CaF2 slag. Niobium mass fraction of the hot metal was not change until silicon content decreased to 0.1 %. The carbon content decreased to 0.66 % with acid SiO2-CaO-CaF2 slag-forming element at 1515℃, by which decarburization and conservation of niobium was carried out during bottom-blown oxygen.

Key words: Nb-bearing hot metal, Vacuum refining, Oxidization, Decarburization, Fe3O4