Abstract:To address the difficulty of slag-copper separation and low copper recovery of an oxide copper ore with high-silicon and low-iron in DR Congo, effects of CaO and FeO addition on viscosity of reduction smelting slag were investigated. The Iida viscosity prediction model was optimized based on the research result to support accurate control of viscosity of CaO-SiO2-MgO-Al2O3-FeO slag system. The results show that the melting slag viscosity drops gradually with increasing of content of CaO and FeO. The viscosity of slag can be effectively improved by regulating the basicity of final slag of 0.5 above and FeO content of 3% above. The modified Iida model can properly predict the viscosity of this slag system over a wide range of temperature and composition, and the relative error of forecast is within 10%.