Influence of reduction degree on the burden microstructure during the softening and melting process

For pellet, sinter, and a mixture of both, microstructure evolution of different burdens during the softening and melting process were investigated by softening experiment of single particle load. The results showed that the reduction degree have an ifluence on the softening and melting behavior. In the case of a low reduction degree, a slag phase substrate and a myrmekitic iron structure were formed on the periphery area of the molten burden. While the substrate of slag phase and the islands of wustite structure were formed in the center area. In the case of a high reduction degree, there were a slag phase substrate and myrmekitic iron texture both the peripheral and central areas. The slag-iron distribution had a structure in which the slag phase was cut in the metal iron phase. 2FeO·SiO2 content as a low melting point phase in the slag decreased sharply, and this resulted in the increase of the slag-iron separation temperature. The variation of the Ca/Si ratio in the interface between the pellet and the sinter indicated that enhancement of the reduction degree caused the increase of initial temperature and the decrease of interaction distance.