Utilization of High-Alumina Iron Ore in Pellet Making Through Process Optimization

The demand for pellets in blast furnaces has recently increased because of their uniform shape and size, controlled chemistry, iron-enriched feed, high strength, and quality consistency. To meet this demand, low- and medium-grade iron ore fines with alumina (> 3.5 wt%) must be used for pelletization because of the limited availability of high-grade ore. The alumina present in the ore has an adverse effect on the pellet properties because of its refractory nature. Therefore, a study was conducted to optimize the firing temperature and chemistry of the feed blend to produce pellets with good pellet properties. Firing temperature (1280 degrees C, 1300 degrees C, and 1320 degrees C), carbon (1 and 1.2%) in the form of coke fines, and MgO (0.60 and 0.80%) in the form of dolomite were used to optimize the pellet-making process for high-alumina iron ore fines. The best result was obtained for feed blend with 1.2% carbon and 0.80% MgO fired at 1300 degrees C to produce pellets of cold compressive strength more than 300 kg/pellet, reduction degradation index (- 6.33 mm) near 7%, and porosity near 20%.