Article ID: ISIJINT-2022-168
Permeability and air flow rate in the bed during iron ore sintering is crucial to control the sinter quality and productivity, due to its influence on the flame front speed. In the present work, the permeability of the bed during sintering of an iron ore blend was analysed utilising simultaneously measured pressure and temperature at multiple points in the bed. Three different zones were categorized, i.e., humidified (green) bed, region of maximum resistance (high-temperature zone) based on temperature (>100°C), and sintered bed. The sintering experiments were conducted in a lab-scale milli-pot (diameter 53 mm, height 500 mm) fitted with six taps and transient variations of pressure-drop in different zones were analysed. The resistance was quantified for the three zones by correlating pressure gradient in each zone (ΔP/L) with the specific kinetic energy of air (v2) during sintering. The high temperature zone was further divided into two sub-zones i.e. pre-melt reaction zone (PMRZ) and granule melting zone. The PMRZ was responsible for the highest pressure gradient in the bed during sintering due to the changes in bed structure and the much greater gas volumetric flow rate due to the high gas temperature. The PMRZ included various physico-chemical processes and it was observed that the resistance in the PMRZ was high at a high suction value across the bed. High productivity was observed for a high suction pressure. The sinter yield was influenced by holding time over 1200°C and an exponential growth function was proposed to estimate the sinter yield.