Abstract: | Laboratory studies have been performed on simultaneous dephosphorization and desulfurization of Si-free Fe-4.5 % C melts with P]o = 0.11 wt.% and S]o = 0.04 wt.% in MF induction furnaces at 1 350°C. In these investigations, CaO- or Na2CO3-based fluxes were used and the techniques of powder injection or single top slag addition were applied. The following results have been obtained: - – The effectiveness of lime and soda-based fluxes with regard to dephosphorization is practically the same. But a lower sulfur level is attained when Na2CO3-based fluxes are used.
- – In the injection experiments, efficiencies of ηP = 80% for dephosphorization and ηs = 90% for desulfurization are easily reached at a powder consumption of 50 to 60 g/kg. But a further increase of the η values requires a remarkable increase in the amount of injected powder. Top slag addition instead of powder injection is less effective, in general.
- – Apparent rate constants kP] and kS] from 0.05 to 0.3 min?1 have been determined in the initial stage of injection depending on the relative amount of injected flux. In the top slag experiments, the kP] and kS] values were practically constant at a level of 0.1 min?1.
Furthermore, dephosphorization of molten Fe-C-Mn alloys at 1 350°C has been studied at variable Mn content. It is predicted from thermodynamic data and confirmed by experiments that dephosphorization lessens with increasing Mn content in the range from 0 to 15 wt.%. |