Reaction behavior of a packed bed consisting of reagent pellets A or iron ore mini pellets B and coal composite iron ore hot briquettes was examined under the blast furnace simulated conditions until 1 200 degrees C.
As a result, it was found that reducibility of the mixed bed is governed by reducibility of pellets, whereas gasification of briquettes in the mixed bed is hardly governed by it. However, promotion effects for reduction and gasification of the mixed beds were recognized for both pellets around 1 050 degrees C, where abnormal swelling of the easier reduced pellet A occurred remarkably with fine fibrous irons, showing a noticeable pressure drop through the bed. It was suggested that this swelling would be caused by gaseous sulfur derived from coal char in the briquettes.
The mixed beds provided larger final shrinkage of the beds than the individual beds probably due to increment of the coupling reactions between reduction and gasification.
It was concluded that reducibility of the pellet could influence not only the reducibility of the mixed bed but also the overall reaction behavior such as gas permeability and softening.