Phase equilibrium between Ni-S melt and FeOX-SiO2 or FeOX-CaO based slag under controlled partial pressures

Abstract

To provide thermodynamic data for converting the nickel matte to liquid nickel, an experimental study was conducted in the phase equilibrium between the Ni-S alloy and the FeOx-SiO2 or FeOx-CaO based slag in a magnesia crucible at 1773 K under controlled pSO2 of 10.1 kPa and pO2 in a range between 5.1 × 10-3 and. 1.6 Pa by using CO-CO2-SO2 gas mixtures. The solubility of nickel in these slags at pO2 of 1.6 Pa, above which precipitation of a FeOx-NiO solid solution was anticipated, was round to be 10.1 and 20.3 mass% for the FeOx-SiO2 and FeOx-CaO based slags, respectively. The contents of iron, sulfur and oxygen in the nickel melt equilibrated with these slags were 2, 3 and 0.5 mass% for the FeOx-SiO2 based slag and 1, 3 and 0.5 mass% for the FeOx-CaO based slag, respectively. The dissolutions of nickel and sulfur in the stags were discussed on the basis of distribution ratio and sulfide capacity, respectively.