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.
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Physical and Theoretical Chemistry