Thermodynamics of the MnO–FeO–MnS–FeS–SiO2 System at SiO2 Saturation under Reducing Condition: Immiscibility in the Liquid Phase

Abstract

Phase Equilibria in the MnO-FeO-MnS-FeS-SiO 2 liquid phase at SiO 2 saturation under reducing condition were experimentally investigated in the temperature range from 1 200°C to 1 400°C in order to provide a fundamental knowledge on new FerroManganese (FeMn) alloy process. High temperature equilibration, quenching and Electron Probe Micro-Analysis (EPMA) were employed to obtain equilibrium compositions of liquid phase which was separated into oxide-rich liquid and sulfide-rich liquid. Concentration of Mn defined as in the sulfide-rich liquid was always lower than RMn in the oxide-rich liquid. In order to understand the liquid separation and the distribution of Mn in the two liquid phases, a thermodynamic modeling of this liquid oxysulfide was performed by taking into account strong chemical ShortRange Ordering (SRO) in the framework of the Modified Quasichemical Model in the Quadruplet Approximation. Contrary to the general understanding that Mn attracts S stronger than Fe does and it would have resulted higher Mn content in the sulfide-rich liquid, the present experimental results show that Fe is enriched in the sulfide-rich liquid. This implies that Fe attracts S stronger than Mn does in the liquid phase concerned in the present study. Such a behavior is attributed to the fact that Mn is bound by SiO 2 through a formation of (Mn-O-Si) Second-Nearest-Neighbor (SNN) pair, thus oxide-rich liquid attracts more Mn while Fe is distributed more to sulfide-rich liquid. A number of points to be considered for the production of low phosphorus FeMn alloy through the two-phase liquid separation are discussed.KEY WORDS: MnO-FeO-MnS-FeS-SiO 2 system; phase equilibria; immiscibility; modified quasichemical model in the quadruplet approximation; short-range ordering.

Integrated Experimental and Thermodynamic Modeling Study of the Pb-Fe-O-S-Si System: Effect of Temperature and p(SO2) on Slag-Matte-Metal-Tridymite Equilibria

“…Also, a maximum of oxygen in matte is observed in the same range. This trend is consistent with the tendency of the slag and matte to merge into single oxysulfide phase when approaching the FeS-FeO [8,11] join. Silicon has not been included into the current thermodynamic model of the matte phase; silicon in b Fig.…”

“…Experimental and modeling work is available in a number of sources for the slag-matte-Fe(fcc) equilibria in the Fe-O-S-Si sub-system. [8][9][10][11] The concentration of sulfur in slag for the slag-solid PbS-Pb metal equilibrium in the Pb-O-S-Si sub-system has been recently studied and modeled. [12] Experimental work data for the Pb-Fe-S sub-system are available.…”

On the interactions of iron sulphide with alumina and silica

“…In the FeO-FeS-SiO 2 system, the FeS can react with SiO 2 according to Equation [1] (Jo, Lee, and Kang, 2013). FeS can be oxidized to FeO and sulphur gas according to Equation [2] (Chen et al, 2020).…”

Influence of Fe2O3‐FeS on the structure of iron‐containing clusters in aluminosilicate melts

“…There is a lack of research on the role of iron sulfides in silicate systems, despite their common presence in coal ash 33–35 . The potential impact of sulfur in the system is significant, as the melt can cause liquid immiscibility between sulfide‐rich and oxide‐rich liquids 36 . Additionally, there is limited understanding of the behavior of Fe 2 O 3 and FeS in the melt, with very few reports on the subject.…”