Reduction swelling mechanism of hematite fluxed briquettes

Abstract The reduction swelling behaviors of the fluxed briquettes with basicity (CaO/SiO2) in the range of 0.33–1.33 were determined by adding analytical-grade CaO. Results showed that with the increase of basicity, the diameter, volume, and porosity of briquettes increased gradually, whereas the diameter, volume, and porosity of briquettes decreased when the basicity was greater than 0.83. The volume and porosity of briquettes decreased gradually with the increase in firing temperature. The reduction swelling index (RSI) reached the maximum at the basicity of 0.83. The RSI of fluxed briquettes was fired at 1,230°C, and that at the basicity of 0.83 was 20.12% after 60 min of reduction. The RSI of the fluxed briquettes was 3.16% when the basicity of briquettes was 0 upon firing at 1,300°C. The reducibility and swelling were positively correlated with internal porosity. The higher the swelling of briquettes, the denser was the distribution of iron whiskers. The lower the swelling of briquettes, the more closely the iron particles connected.