Abstract
Taking slag-metal samples at various working periods, (i.e. before slag-off, before tap and in ladle) during melting process of stainless steel in a 30-t basic electric furnace, sulphur partition at each period was examined.
Following results were obtained:
1) The sulphur capacity Cs, i.e. (% S) /a [s] [%Si] 1/2 at each period was greater, the higher the molar basicity, which was defined as N2cao/Nsio2.
2) The sulphur capacity Cs was increased linearly with decreasing amount of Cr2O3 at he constant N2Cao/NSio2. t
It was considered that the higher the Cr2O3 in slag, the smaller becomes the slag-off Cs ven in the case when the slag indicated the same value of Vm'-NCao.
3) Though the effect of MgO content of slag on Cs was rather unobvious as compared with (Cr2O3), it was recognized that the sulphur capacity Cs was increased with increasing amount of MgO at the constant N2CaO/NSio2 and Cr2O3 content.
4) The sulphur capacity, except in ladle, was correlated statistically with the main slag composition as in the following equation:
Covering the temperature range 1540 to 1680°C,
log [ (%S) /a [s] [%Si] 1/2] =0. E867 log [N2CaO/ (Nsio2 + Ncr2O3)] -0.723
5) The sulphur capacity C's, i.e. (%S) (NFeO) /a [s] was less closely related to
N2CaO/ (NSiO2 + NCr2O3) than Cs was.
6) The logarithm of sulphur capacity Cs was increased linearly with increase of the excess base, i.e. n CaO- (n SiO2+ n Cr2O3).
No advantage were obtained in replacing the basicity term, i.e. N2CaO/NSiO2+NCr2O3, by the excess base.
7) The logarithm of (Cs (NSiO2+NCr2O3) /N2CaO) was a linear function of the reciprocal of absolute temperature.
The following equation was statistically obtained:
log (CS (NSiO2+ NCr2O3) /N2CaO) = 3040/ T + 0.704.
8) The sulphur content in pit sample was increased rapidly, with increase of the value of NFeO (NSiO2+NCr2O3) N2CaO of the final slag composition, if it exceeded above 16×10-2.
