Copper Distribution between Molten FeS-NaS0.5 Flux and Carbon Saturated Iron Melt

Copper distribution between FeS-NaS0.5 flux and carbon saturated liquid iron has been studied at 1 673 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 NaS0.5 to FeS increased the copper distribution ratio. The L.Cu showed the maximum value of about 24, at around XNaSo.5 = 0.4, and became nearly constant at the range of higher NaSo.5 content than 0.4 of NaS0.5., The addition of NaS0.s also lowered sulfur content in liquid iron from 1.9 mass% at XNaSo.5 = 0 to 0.04 mass% at XNaSo.5 = 0.8. CuS0.5 dissolved in flux decreased LCu at high concentration range of NaS0.5. In order to discuss the effect of NaS0.5 and CuS0.5 on the copper distribution ratio, the activity coefficient of CuSo.5 in flux was evaluated. It was found that NaS0.5 decreased the activity coefficient of CuS0.5 in flux, so that the LCu increased in spite of the significant decrease of sulfur potential in the system by the addition of NaS0.5.