Pulse iron ore sintering—A novel approach to reduce sinter fines

Abstract

Iron ore sintering is carried out under negative downdraft suction in a packed bed system. Normal operation results in non-uniform temperature distribution in sintered bed resulting in the generation of sinter return fines (−5 mm) which reduces the process yield. In the present work, a novel approach of pulsating suction through the generation of palpitate downdraft suction flow and its effect on sinter bed and synthesized sinter properties is explored. Pilot pot sinter experiments involving varied pulsation magnitudes through variation in valve closure (30%, 60%, 100%) for a specified time are performed. An increment in the pulsation magnitude results in a higher pressure drop (50–200 mm) occurring due to alteration in local flow dynamics. The pulsation mechanism of the downdraft suction leads to the broadening of the flame and increased sinter bed temperature for a prolonged duration. At 100% value closure better sinter properties are realized due to improved heat transfer and gas–solid reaction kinetics. Enhancement in the sinter properties like tumbler index from 69.42% to 75.82%, reduction degradation index from 24% to 19%, reducibility index from 74.25% to 76.22% is attained. In addition, overall sinter return fines are reduced from 22.3% to 22.12%. Mineralogical investigation of the pulse sintered product reveals that the increased formation of silico-ferrite of calcium and aluminum (SFCA and SFCA-I) improved the sinter properties.