Thermodynamic and kinetic in recovery of iron from nickel residue

A study of extracting iron from nickel residue was done by smelting reduction method. The experiments were conducted to investigate the effect of slag basicity, melting time and temperature on the iron recovery ratio. XRD analysis indicates that the nickel residue is composed of FeSiO₃ and glassy silicates, so it is impossible to reach the target of FeO content by regular ore-dressing method except by smelting reduction method. Experimental results show that the recovery ratio of iron increases with increasing the content of CaO added, melting temperature and time. The key reduction reaction is firmed as (FeO) + C_(s) →[Fe] + CO↑ by comparing Gibbs free energies at different temperatures from 1450 to 1600℃. The batch of nickel residue 100 g, CaO 34.7 g, CaF₂ 4.04 g and coke 8.5 g was the best formula in this study, and it was indicated that after melting at 1500℃ for 180 min, the slag and iron were well separated and the recovery ratio was up to 96.32% for this batch.