Effect of SiO₂ and Al₂O₃ on high temperature reduction of iron ore

Five kinds of iron ores that had different SiO₂ and Al₂O₃ content were reduced at temperature range from 1000°C to 1200°C. The effects of SiO₂ and Al₂O₃ on the final stage of the reduction with CO gas were studied. The results obtained are summarized as follows: 1) Ores D (0.64 mass% SiO₂, 0.8 mass% Al₂O₃) and E (0.58 mass% SiO₂, 0.6mass% Al₂O₃) were reduced faster than Ores A (4.64 mass% SiO₂, 2.6 mass% Al₂O₃), B (5.61 mass% SiO₂, 2.62 mass% Al₂O₃) and C (8.46 mass% Si₂, 0.83 mass% Al₂O₃). 2) Ores A and B were reduced slower than Ore C at 1100°C because the formation rate of 2FeO · SiO₂ was different among them. The amount of 2FeO · SiO₂ phase in Ores A and B was lager than Ore C because the distribution of SiO₂ particle was different among them. In the case of Ores A and B, the SiO₂ particle was distributed inside or at the edge of hematite particle. On the other hand, the large SiO₂ particle in Ore C was separated from hematite particle. 3) Ores D and E were reduced to almost 100% reduction degree at 1200°C, but Ores A, B and C were retarded at low reduction degree at 1200°C because of the melting of 2FeO · SiO₂ which was formed during reduction.