Distribution Equilibria of Sn Between Liquid Copper and FeO_X-SiO₂, CaO-FeO_X and FeO_X-CaO-SiO₂ Slags

The distribution ratio of Sn ( \(L_{\text{Sn}}^{\text{s/m}}\) $L_{\text{Sn}}^{\text{s/m}}$ ) between three slags (FeO_X-SiO₂, CaO-FeO_X and FeO_X-CaO-SiO₂) and molten copper after equilibrium was studied at 1300 °C and oxygen partial pressure (pO₂) of 10⁻¹⁰ to 10⁻⁵ atm. Results showed that for FeO_X-SiO₂ slag the \(L_{\text{Sn}}^{\text{s/m}}\) $L_{\text{Sn}}^{\text{s/m}}$ increased from 0.0067 to 1.78 when increasing the pO₂. For CaO-FeO_X slag, the Sn species converted from SnO to SnO₂ at pO₂ of around 10⁻⁸ to 10⁻⁷ atm and the \(L_{\text{Sn}}^{\text{s/m}}\) $L_{\text{Sn}}^{\text{s/m}}$ value reached 150 at pO₂ = 10⁻⁵ atm. Using FeO_X-CaO-SiO₂ slag generated medium \(L_{\text{Sn}}^{\text{s/m}}\) $L_{\text{Sn}}^{\text{s/m}}$ values between 0.013 and 4.6. The logarithmic Fe³⁺/Fe²⁺ ratio increased linearly with pO₂ for all slags, indicating the equilibrium status of different phases. The Fe³⁺/Fe²⁺ ratio with FeO_X-SiO₂, CaO-FeO_X and FeO_X-CaO-SiO₂ slags was in the range of 0.09 to 0.41, 0.40 to 2.40 and 0.11 to 0.42, respectively. The copper solubility to FeO_X-SiO₂ slag increased substantially with increased pO₂ from 0.44 to 6.9 pct. A similar range of copper solubility data was acquired for the CaO-FeO_X slag while the counterpart values for the FeO_X-CaO-SiO₂ slag were only slightly smaller, indicating the little effect of slag composition on the copper loss to slag and the neutral nature of Cu₂O in slags. For the FeO_X-CaO-SiO₂ slag, the \(L_{\text{Sn}}^{\text{s/m}}\) $L_{\text{Sn}}^{\text{s/m}}$ value and copper solubility decreased when increasing the CaO/SiO₂ ratio from 0.3 to 0.9 while the Fe³⁺/Fe²⁺ ratio showed the opposite change trend. The Fe/SiO₂ ratio was found to have little effect on the \(L_{\text{Sn}}^{\text{s/m}}\) $L_{\text{Sn}}^{\text{s/m}}$ value, copper solubility to slag, and Fe³⁺/Fe²⁺ ratio.