Direct Reduction of High-phosphorus Oolitic Hematite Ore Based on Biomass Pyrolysis

Abstract

Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases (CO, H2, and CH4), tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99. 35% at iron ore-biomass mass ratio of 1: 0. 6, reduction temperature of 1100 °C, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron (DRI) has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89. 11%, iron recovery rate of 83. 47%, and phosphorus content of 0. 28% can be obtained when ore fines with particle size of — 10 μm account for 78. 15%.