Characterizing the contribution of the high-temperature zone to iron ore sinter bed permeability

Synopsis In iron ore sintering the resistance of the bed to air flow is important because it influences machine productivity. It is clear from theory that the high-temperature zone of a sintering bed is the major resistance to air flow and, therefore, the major contributor to the pressure drop across the bed. Hitherto, however, no technique for measuring this resistance has been available so that the factors that control it can be studied. An experimental technique based on the Ergun equation is proposed to measure this resistance, which is expressed as the reduction in air flow after ignition of the bed. Seven ore blends were studied and the results showed that the resistance to air flow is dependent on ore blend composition and the pre-ignition air flow through the bed. The melting zone of a sintering bed is considered to have a controlling influence on its resistance. In this zone it is concluded that the inertial force, which is a function of gas flow rate, has the ability to dilate gas channels and decrease resistance to air flow. More study is required for understanding of the effect of melt property on the size of gas channels. Use of the technique as an aid to comparison of the 'sinterability' of sinter mixes is also discussed.