Formation of CaSO 4 in the CaO-FeO x-Cu 2O slags

Sinichi Sato, Katsunori Yamaguchi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Continuous converting of copper matte based on calcium ferrite slag of the CaO-FeO x-Cu 2O system is an attractive technology for copper smelting This slag containing approximately 20 mass% CaO can prevent the excess magnetite precipitation, but sometimes tends to separate CaSO 4 under a high oxygen potential required to produce copper metal. To clarify the mechanism of gypsum formation, the precipitation of CaSO 4 in the CaO-FeO x-Cu 2O slag system equilibrating with blister copper has been determined at 1473, 1523 and 1573 K under the SO 2 partial pressures of 0.2, 0.4, 0.6 and 1 atm. It was found that the formation of CaSO 4 in the CaO-FeO x-Cu 2O slags is enhanced with decreasing temperature, increasing SO 2 partial pressure or CaO content and also increasing oxidation degree of the blister copper. The behavior of CaSO 4 formation in the slag is also discussed thermodynamically based on the free energy calculations combining with the activity data derived from Prof. Takeda's data on the CaO-FeO x-Cu 2O ferrite slag diagram. Both of experimental and thermodynamical results show good agreements in general. It is found that the decreasing temperature, increasing CaO content or SO 2 pressure, and extensive oxidation of the blister copper tend to separate CaSO 4.

Original languageEnglish
Pages (from-to)447-449
Number of pages3
JournalHigh Temperature Materials and Processes
Issue number4
Publication statusPublished - 2011 Aug
Externally publishedYes


  • Activity of lime
  • Calcium ferrite slag
  • Gypsum formation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Physical and Theoretical Chemistry


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