Competitive Dissolution Mechanism of Sulfur in CaMnSilicate Melts: Structural View

Abstract

The sulfide capacities of the CaO-SiO 2 -MnO(-Al 2 O 3 -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-Mn-silicate melts. The sulfide capacity increased as MnO substituted for CaO in the high silica melts (>30 (AE5) wt% SiO 2 ), whereas it decreased by increasing the MnO/CaO ratio in the low silica melts (<30(AE5) wt% SiO 2 ). This tendency of sulfide capacity resulted in the clockwisely rotating iso-capacity contours from MnO-free side to MnO-rich corner in Ca-Mn-silicate melts. The dissolution mechanism of sulfur in Ca-Mn-silicate melts can be explained by the ''Competitive dissolution mechanism.''

Thermodynamic Behavior of Manganese Oxide in Lime-based Manganese Smelting Slags

“…The organic relationships between the silicate structure and the thermodynamic properties of oxide melts such as the mixing free energy of silicates and sulfide capacity have been reported. 10,11) In particular, Park 12,13) demonstrated that the sulfide capacity is strongly affected by the structure of the CaO-SiO 2 -MnO system, and that the excess free energy of MnO is inversely proportional to the degree of polymerization by employing Raman spectra analysis in conjunction with a computational thermodynamic assessment. Therefore, the influence of the silicate structure on the activity coefficient of MnO should be thoroughly investigated.…”

Improving the Desulphurization in COREX-3000 Process by the Optimization of Chemical Compositions of Slag

“…The sulfide capacity increases by increasing the MnO/CaO ratio at a fixed silica content which is greater than about 30 wt%, whereas it decreases by increasing the MnO/CaO ratio at silica content lower than about 30 wt%. 23,24) The critical SiO 2 content is about 30 wt% based on the competitive dissolution mechanism of sulfur in Ca-Mn-silicate melts. The used SiO 2 content in the calculation is 33 wt% and so the effects of MnO and CaO are similar in the present slag system.…”