7TH EUROPEAN COKE AND IRONMAKING CONGRESS - ECIC 2016

Indian iron ore fines with high alumina content (~2.5% Al2O3) resulted in poor quality pellets and a study was under taken to establish suitable pellet chemistry through proper fluxing agents. Limestone fluxed pellets were prepared at varying basicity (0 to 0.8) and pyroxenite fluxed pellets at varying MgO contents (0 to 3%) to study their effect on the metallurgical properties. Fired pellets were tested for their strength, RDI, reducibility and swelling. Microstructural studies were carried out to quantify different phases and their chemistry. Acid pellets exhibited poor quality whereas limestone pellets at 0.8 basicity and pyroxenite pellets at 1.5% MgO exhibited optimum metallurgical quality. Formation of widely distributed silicate melt in limestone pellets and high melting point slag & magnesioferrite in pyroxenite pellets found to improve their quality. However, commercially produced pyroxenite fluxed MgO rich pellets exhibited better high temperature properties but inferior low temperature properties; whereas limestone fluxed CaO rich pellets exhibited the quality vice versa. To yield the benefits of both CaO (for good strength and RDI) and MgO (for low swelling and high softening), a dual flux combination was established, using both the fluxes, that resulted in optimum metallurgical properties.