Sulphide capacities of CaO-Al2O3-SiO2 slags at 1550, 1600 and 1650 degrees C

Background/aims: Desulphurisation in steel production requires a highly basic slag, mainly consisting of the 3 components Al2O3, CaO and SiO2. The sulphur capacities at different compositions in the lime corner of this ternary system are essential information when optimizing the desulphurisation step. Methods: A gas-slag equilibrium technique was used to determine the sulphide capacity of the slag at 3 different temperatures, 1550, 1600 and 1650 degrees C. A gas mixture consisting of Ar, CO, CO2 and SO2, was equilibrated with 12 different slag compositions in platina cups for 6 h. Results and conclusion: Sulphide capacities of the investigated slag compositions are plotted in the CaO-Al2O3-SiO2-system at each temperature. Estimated iso-sulphide capacity curves are also presented. The results show good agreement with previous investigations, with slightly lower sulphide capacity values over the whole composition range. The sulphide capacity show strong temperature and basicity dependence.