Role of MgO and Its Different Minerals on Properties of Iron Ore Pellet

At present various naturally available minerals containing MgO viz. olivine, pyroxenite, dunite, dolomite etc. are widely used in different plants to reduce RDI of iron ore pellets and improve other properties. However, properties of each of the above fluxes are physically and chemically different and they contain different types and quantities of gangue materials, such as silica, alumina (Al2O3), CaO etc. Although, MgO has some specific roles, other gangue materials carried by MgO bearing fluxes also have a significant effect on phase formation or slag bonding in pellet and pellet properties. Thus, different MgO bearing fluxes show different behavior in pellets. It is very imperative to study the actual role of MgO and the effect of different gangue materials in it. This study has examined the actual role of MgO and its optimum requirement as well as the effect of other gangue materials in MgO bearing fluxes. For this purpose, pure MgO, olivine and waste magnesite brick powder have been used separately in pellet making with a high Al2O3 hematite ore and their characteristics have been compared. It has been found that 0.9 % pure MgO in pellet can reduce the reduction degradation index to as low as 7.5 %, but it shows a little deterioration in strength property. Other two fluxes provide good strength properties at lower induration temperature but, cannot reduce degradation index to sufficiently low level. Olivine has shown better performance than magnesite because of its different gangue content.