Copper distribution between FeS-Na₂S flux and carbon saturated liquid iron

Copper distribution between FeS-NaS_0.5 flux and carbon saturated liquid iron has been studied at 1673 K. Copper distribution ratio, L_Cu = (mass%Cu)_flux/[mass%Cu]_iron, was about 9 when FeS only was used as sulfide flux. The addition of NaS_0.5 to FeS increased the distribution ratio. The L_Cu showed the maximum value of about L_Cu = 24, at around X_NaS(0.5) = 0.4 and became nearly constant at the range of higher NaS_0.5 content than 0.4. The addition also lowered sulfur content from 1.9 mass% at X_NaS(0.5) = 0 to 0.04 mass% at X_NaS(0.5) = 0.8. CuS_0.5 dissolved in flux decreased L_Cu at high concentration of NaS_0.5. The activity coefficient of CuS_0.5 in flux decreased the activity coefficient so that L_Cu increased in spite of the decrease of sulfur potential by the addition of NaS_0.5.