Evaluation of granule structure and strength properties of green packed beds in iron ore sintering using high-resolution X-ray tomography and uniaxial compression testing

The strength properties of green sinter beds, including the Young’s modulus and maximum bed strain, were evaluated using uniaxial compression tests. The green-sinter-bed samples were scanned using X-ray computed tomography (XCT), and the geometry characteristics of the granules were quantified by XCT image analysis. The orthogonal array method was applied to determine the concomitant effects of the moisture, hydrated lime, and concentrate contents on the bed strength characteristics. Less bed strain was observed when the granules had a thin adhering layer and increased interlock contacts, which had a great capacity to resist the applied load collectively. The optimal combination for decreasing the bed maximum strain was 5.8% moisture, 2% hydrated lime, and 0% concentrate. The moisture and concentrate contents were the most significant factors determining the green bed strength. Increasing the moisture and concentrate contents produced granules with a thicker and more deformable adhering layer, resulting in a more compact bed. The addition of hydrated lime inhibited rearrangement, deformation, and fracture of the granules in green sinter bed during compression.