Microwave Carbothermic Reduction of Oolitic Hematite

Abstract

The microwave reduction of coke-bearing oolitic hematite composite pellets followed by magnetic separation was investigated in this work to explore the feasibility of microwave heating on utilization of oolitic hematite. The reduction was conducted in a temperature controllable microwave oven at 1273, 1373, 1423, 1473 and 1523 K for 5–60 min. The effects of temperature and holding time on reduction were studied. The highest metallization of 95.42% was achieved at 1523 K in 10 min. Then the air cooling metallic pellets were crushed and grinded and subsequent separated via magnetic separation. The effect of magnetic field intensity on recovery and grade of iron powder were investigated. The iron powder with iron content, recovery and phosphorus content of 92.89%, 85.28% and 0.24% respectively was achieved at the magnetic field intensity of 0.04 Wb/m². This will be a potential way to realize the comprehensive utilization of oolitic hematite in China.

Influence of temperature and holding time on metallization (upper left: schematic diagram of microwave oven; upper middle: hematite powder before reduction; upper right: pellets after reduction).