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.