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Competitive Dissolution Mechanism of Sulfur in Ca[BOND]Mn[BOND]Silicate Melts: Structural View



The sulfide capacities of the CaO[BOND]SiO2[BOND]MnO([BOND]Al2O3[BOND]MgO) slags were measured at 1873 K over a wide composition range using a gas-slag equilibration method. The effects of MnO content and the MnO ↔ CaO substitution on the sulfide capacity of molten slag were also investigated based on the structural view of silicate melts. In the multicomponent silicate melts containing high MnO (up to about 50 wt%), the sulfide capacity mainly increased with increasing MnO content. Also, the sulfide capacity and the activity of MnO showed a linear relationship with a slope of unity, indicating that MnO is dominant component controlling the sulfur dissolution behavior into Ca[BOND]Mn[BOND]silicate melts. The sulfide capacity increased as MnO substituted for CaO in the high silica melts (>30 (±5) wt% SiO2), whereas it decreased by increasing the MnO/CaO ratio in the low silica melts (<30(±5) wt% SiO2). This tendency of sulfide capacity resulted in the clock-wisely rotating iso-capacity contours from MnO-free side to MnO-rich corner in Ca[BOND]Mn[BOND]silicate melts. The dissolution mechanism of sulfur in Ca[BOND]Mn[BOND]silicate melts can be explained by the “Competitive dissolution mechanism.”