Distribution of Minor Elements between MgO Saturated FeO_x–MgO–SiO₂ or FeO_x–CaO–MgO–SiO₂ Slag and Nickel Alloy

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The distribution behavior of minor elements between the nickel based alloy and MgO saturated FeO_x–MgO–SiO₂ or FeO_x–CaO–MgO–SiO₂ slag was investigated at 1673, 1773 and 1873 K under controlled oxygen partial pressure over the range from 10⁻⁶ to 10⁻¹⁰ in order to obtain fundamental information related to nickel smelting. The distribution ratios of minor elements, which is defined by L^s⁄m_X=(mass%X in slag)/[mass%X in alloy] for phosphorus, iron, cobalt, copper and sulfur are higher than that for nickel while the ratio for antimony is lower. Base on the slope of the linear relationship between the logarithmic distribution ratio and oxygen partial pressure, the predominant species dissolved in the slag are evaluated to be of the forms PO_2.5, CoO, CuO_0.5 and SbO_1.5, respectively. It is found that the addition of CaO depresses the dissolution of copper and cobalt in the slag while that of phosphorus and antimony is enhanced. The activity coefficients of CuO_0.5 and CoO in the MgO saturated FeO_x–MgO–SiO₂ slag at 1773 K are estimated to be 7 and 2 respectively.