A mathematical time-dependent and non-isothermal model has been carried out on the basis of the grain model to study the behaviour of a wustite pellet undergoing chemical reactions with reducing gases. The behaviour of wustite pellet reduction analysed by the grain model has been compared with unreacted shrinking core model (USCM). The results show, unlike the grain model, USCM cannot properly predict the impact of gas mixture parameters and pellet characteristics on the local reduction degree. The results also display that when the grain diameter, temperature and tortuosity increase, the diffusivity resistance in the pellet increases which causes more heterogeneous reduction. However, an increment in porosity causes gases to easily diffuse in the pellet and as a result a less heterogeneous reduction will occur.
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