Comparison of Microstructures of Magnetite Reduced by H₂ and CO under Microwave Field

Abstract

The reduction of magnetite in H2 and CO atmospheres was compared using a microwave-heating technique. The reduction of magnetite in a mixed H2 + CO atmosphere was compared with respect to the effects of a microwave field and a conventional field. Microstructural changes were observed using an electron microscope. The results show that the metallization rate and reduction degree of the H2-reduced magnetite are much higher than those of the magnetite reduced by CO at 900–1100 ℃. The Fe phase generated by H2 reduction forms a cavity structure, and the Fe phase generated by CO reduction forms a dense block. Under conventional heating conditions, the higher the H2 content in a pure CO atmosphere, the better the reduction effect. Under the effect of a microwave field, the atmosphere with the highest reduction rate was 50% H2 + 50% CO. Compared with conventional heating, the bubble holes formed by reduced iron in microwave field are larger under the same conditions.

Keywords

• H₂ reduction
• magnetite
• microwave heating
• microstructural characterization