Structural Analysis of Sinter Packed-bed during Softening and Melting Processes Using X-ray CT

In this study, changes in structure of sinter packed-bed during softening and melting processes were analyzed, and gas permeability of the cohesive layer was evaluated using X-ray CT images. First, the void structure of sinter packed-bed during softening and melting processes was visualized by X-ray CT images. In the softening process, the reducing gas flowed through the void between the sinter particles. In contrast, the reducing gas flowed through the generated melt phase in the melting process. Next, the changes in porosity and apparent particle diameter due to shrinkage of sinter layer were analyzed using CT images to evaluate the structural changes of sinter packed-bed during softening process. The porosity decreased with increasing the shrinkage of the sinter layer. In addition, the porosity tended to be smaller in the upper layer. The apparent particle diameter increased with increasing the shrinkage of the sinter layer. This is attributed to the deformation and the fusion of the sinter particles. Finally, the pressure drop of the sinter layer was calculated based on the Ergun equation using the porosity and the apparent particle diameter obtained from the CT images. As a result, the change in pressure drop was able to be well expressed up to a shrinkage degree of 0.5. The pressure drop was higher in the upper part of the sinter layer, suggesting that the pressure drop could be reduced by suppressing local blockage of the packed-bed.