Effect of flux granulometry and other process variables on the sintering of iron ore at high basicity

Elimination of raw limestone from the blastfurnaee burden is known to bring a considerable saving in coke rate. In a country like India or elsewhere, the capacity of the sintering plants is limited it is imperative to produce super fluxed sinter and use it in the furnace. The basicity requirement coupled with the higher gangue input through coke and iron ore demands for a greater amount of flux in the mix. This situation is different from the frequentl y reported prac¬tice elsewhere in the world. So the flux size has crucial effect in the sintering. However this has not been reported adequately. In order to bridge the gap in the literature, sintering study was carried out using factorial design. Five factors were studied at two levels. Data generated through the experiments were analysed using the statis¬tical procedure and the regression equations were established for the following sintering indices in terms of significant factors and interactions. The flux granulometry has crucial role in the produc¬tion of sinter at basicity level of 3.25. The sintering indices are adversely affected when the sinter mix contains higher amount of ¬0.5 mm size fraction in it. The thermal and X-ray diffraction analy¬ses of the sinter and return fines sample reveal that the limestone is not properly calcined properly to be assimilated by hematite. A sav¬ing in the consumption of coke breeze upto 10% can be achieved through improvement in gasodvnamic in the sintering bed when -0.5 mm size fraction in limestone is restricted. Based on the above ob¬servation a modification in the existing crushing scheme of lime¬stone are proposed.