Green Ironmaking Industry: Production of Iron Pellets Using Lime Sludge

Abstract

The use of alternative raw materials is essential for establishing a circular economy in the mineral and ironmaking sectors. Therefore, this study investigates the potential of lime sludge as fluxing material during pelletization and proposes an alternative route for the usage of waste. The pellets were manufactured with different binary basicity values (CaO/SiO2) (0.15–0.45) and bentonite (0.5–0.7 wt%) and fixed carbon (0.5–1.1 wt%) contents. The results demonstrated that lime sludge has significant potential for application in pelletization. Pellet quality was evaluated using drop number, mechanical strength, tumble index, porosity, and kinetic analyses. Pellets with the optimal composition using lime sludge withstood 3.6 drops/pellet, a tumble test of 1.57 wt.%, and a mechanical strength test of 214.83 kgf/pellet and exhibited a porosity of 31.28%. Lime sludge did not influence the reducibility of the iron-ore pellets. In the temperature range of 800–900 °C, the reaction was controlled by diffusion, with Ea between 179.89 and 233.10 kJ/mol.