Influence of partial pressure of sulfur and oxygen on distribution of fe and mn between liquid fe-mn oxysulfide and molten slag

Sun Joong Kim, Hiroyuki Shibata, Jun Takekawa, Shin Ya Kitamura, Katsunori Yamaguchi, Youn Bae Kang

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Abstract

The authors proposed an innovative process for recovering Mn from steelmaking slag. The process starts with the sulfurization of steelmaking slag to separate P from Mn by the formation of a liquid sulfide phase (matte). Then, the obtained matte is weakly oxidized to make a Mn-rich oxide phase without P. High-purity Fe-Mn alloys can therefore be produced by the reduction of the Mn-rich oxide phase. However, to the authors' knowledge, the sulfurization of molten slag containing P and Mn has not been sufficiently investigated. It was recently found that P was not distributed to the matte in equilibrium with the molten slag. To gain knowledge of the process's development, it is important to investigate the influence of the partial pressures of sulfur and oxygen on the equilibrium distribution of Mn and Fe between the matte and the molten slag. In the current work, a mineralogical microstructure analysis of the matte revealed that the existence of the oxysulfide and metal phases was dependent on the partial pressure of sulfur and oxygen. The Mn content of the matte increased with partial pressure of sulfur while the O content of the matte decreased. In contrast, the ratio of Mn/Fe in the matte was constant when the metal phase of the matte was observed at a log PO2 below -11. These results also corresponded to the relationship between the activity coefficient ratio of MnS/FeS and the mole fraction of MnS/FeS in the matte. The γMnS/γFeS value decreased exponentially as the mole fraction of MnS/FeS increased.

Original languageEnglish
Pages (from-to)1069-1077
Number of pages9
JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
Volume43
Issue number5
DOIs
Publication statusPublished - 2012 Oct 1

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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