Effect of Coal Type on the Reduction and Magnetic Separation of a High-phosphorus Oolitic Hematite Ore

Abstract

Coal-based direct reduction followed by magnetic separation technique was employed to produce direct reduction iron powder (DRI powder) from a high-phosphorus oolitic hematite ore, and the effects of type and particle size of coal and C/O (Fixed carbon/Oxygen) mole ratio on this process were investigated. The results showed that when using coarse-sized and medium-sized coals, bitumite and lignite presented better iron recovery as compared with anthracite, while this advantage disappeared as the particle size of coals decreased. In addition, the iron content of the DRI powder increased with improving of the coal rank depended on fixed carbon contents, while decreased with the decrease of particle size of coals. Increasing the C/O ratio resulted in a sharp rise of P content of the DRI powder. X-Ray Diffraction (XRD) analysis revealed that more liquid phase was formed in the briquettes during reduction with anthracite as reductant. SEM (scanning electron microscope) observation confirmed that the size of the metallic iron grains formed in reduced briquettes decreased with decreasing of the rank of the coal and the particle size of coal.