The coal composite iron ore hot briquette made by utilizing thermal plasticity of coal is recently developed as agglomerates without binder, which has several advantages to retain high density and strength during reaction at high temperatures.
In this work, several hot briquettes mixed with coal and ore fines were prepared to elucidate influence of more coal amounts than molar ratio C/O=3/3 on their reaction behavior in a laboratory scale blast furnace simulator. Reaction and softening-melting tests of the briquettes were carried out in N(2) stream under load with heating from room temperature to 1 400 degrees C.
It was found that final gasification and reduction degrees decreased and increased with increasing coal contents mixed in the briquettes, respectively. The reduction finalized around 1 000-1 100 degrees C. Larger proportion of coal provided completion of reduction at lower temperatures and more remained char, leading to smaller shrinkage of the briquettes even in higher temperatures.
The crushing strength of briquettes after partial reaction decreased with reaction time as a whole, whereas it was kept above a value permitted in blast furnace operation.
From gasification test of partial reacted briquettes, it was found that the rate constants were proportional to Fe/C molar ratio in the briquettes, likely due to a catalytic effect of metallic iron.
The results will be overall discussed with the viewpoint of a feasible utilization of these briquettes to a blast furnace.