Reaction model and reaction behavior of carbon composite briquette in blast furnace

Abstract

In this research, carbon composite briquette (CCB) for BF application was prepared and had a mineralogical composition of carbon: 20.30 wt%, Fe3O4: 29.70 wt%, FeO: 39.70 wt%, Fe: 1.57 wt% and gangue: 8.73 wt%. A reaction model of the CCB in BF was developed. Using the model, the CCB reaction behavior under simulated BF conditions was explained, and the CCB reaction behavior in actual BF was predicted. Results showed that the model predictions agreed well with the experimental measurements. Under simulated BF conditions, the CCB underwent fast self-reduction in the period from 70 min (973 K) to 110 min (1273 K). In this stage, the reactions inside the CCB proceeded unevenly in the radial direction, resulting in a dense iron layer near the CCB surface. The simulation results of CCB reaction in an actual BF indicated that charging CCB in the region near the mid-radius was preferred. The CCB reaction behavior in BF could be divided into five stages: reduction by BF gas (500–850 K), partial self-reduction with reduction by BF gas (850–973 K), full self-reduction (973–1100 K), partial self-reduction with gasification by BF gas (1100–1150 K), and gasification by BF gas (>1150 K). The CCB became effective for BF energy saving after 1000 K.