Numerical Simulation of Charging Biochar Composite Briquette to Blast Furnace

Abstract

Partial replacement of coal and coke by biomass/biochar in the blast furnace (BF) ironmaking is important role to reduce CO₂ emissions. In this research, numerical investigations were conducted on blast furnace (BF) operation with biochar composite briquette (BCB) charging. The BCB was with 11.1 mass% carbon, 72.7 mass% magnetite, 11.25 mass% wustite, 0.77 mass% metallic iron, and 4.67 mass% gangue, and the BCB charging ratio was from 0 to 60% Results revealed that in the BF operation with BCB charging, the BCB iron-oxide reached a full reduction, but the overall gasification degree of BCB biochar decreased with the increase of BCB charging ratio. By charging BCB, the thermal state in the upper BF was considerably altered, but it was insignificantly influenced in the lower BF. By charging BCB; ore reduction was retarded in the upper BF but was prompted near the zone with a temperature of 1173 K. Under a low BCB charging ratio, local gas utilization tended to increase in the mid BF but tended to decrease in the upper BF. Further increasing BCB charging ratio lead to a decrease in local gas utilization. To ensure BF smooth running and maximizing biochar input, the optimal BCB charging ratio was 40%. Under this condition, the BCB biochar of 89.3 kg/tHM could be completely utilized, and the BF coke rate was decreased by 92.1 kg/tHM.