Kinetic analysis of iron oxide reduction in top gas recycling oxygen blast furnace

Abstract

Reduction experiments of sinter in a top gas recycling oxygen blast furnace (TGR-OBF) were studied at temperatures ranging from 1173 to 1373 K. The changes in iron oxide reduction were evaluated, and based on the ‘unreacted core model’, the kinetic behaviour of this reduction was also analysed. The results show that with increasing temperature, the reduction rate of sinter increased, the reduction time decreased and the final degree of reduction increased. At 1173, 1273 and 1373 K, the reduction process is controlled by interfacial chemical reactions, and the chemical reaction rate constants are 0·363, 0·591 and 0·787 cm s⁻¹ respectively at an early stage of reduction. Reactions are controlled by interface chemical reactions and internal diffusion at the final stage of reduction, and the chemical reaction rate constants are 0·541, 0·682 and 0·866 cm s⁻¹ respectively, and the diffusion co-efficients of the reduction reaction are 0·463, 1·970 and 2·412 cm² s⁻¹ respectively. In the TGR-OBF, the range of temperatures is from 1173 to 1373 K. The apparent activation energy is 52·07 kJ mol⁻¹, and the frequency factor is 77·26 cm s⁻¹ at an early stage of reduction. At the final stage, the apparent activation energy is 31·41 kJ mol⁻¹, and the frequency factor is 13·46 cm s⁻¹.