Abstract: The effect of MgO on compressive strength of the reduced iron ore pellets was investigated in a lab condition. The experimental results showed that with increasing the mass fraction of MgO-bearing flux from 0 to 2.0%， the compressive strength of the reduced pellets increases. In the meantime， the pore size and porosity of the reduced pellets increase as well. However， compared with that of the non-MgO-bearing pellets (i.e.，the mass fraction of MgO-bearing flux is 0)， the increasing magnitude of the pore size and porosity of the MgO-bearing pellets (the mass fraction of MgO-bearing flux is 2.0%) becomes relatively less and the distribution of pore size is relatively closer before and after reduction. It is found that the reduction swelling is a main factor for governing the compressive strength of the reduced pellets and the reduction compressive strength (RCS) is higher with a lower reduction swelling index(RSI).

Key words: MgO, iron ore pellet, reduction strength, reduction swelling, porosity