Characterisation and evaluation of cold compressive strength reduction in iron ore pellets from the Sangan Steel Pelletising Plant

The cold compressive strength (CCS) of iron ore pellets is essential for ensuring mechanical stability and efficient metallisation in direct reduction process. In this study, iron ore samples from the Sangan A, B, and CN anomalies were characterised using XRF, XRD, petrography, and wettability tests to identify factors affecting pellet performance. Fe contents ranged from 37.58 to 55.01 wt.%, with SiO 2 as the dominant gangue. CNC samples showed the highest MgO and sulfur, negatively influencing pellet integrity. Wettability results indicated significant hydrophilicity differences that affect binder dispersion. Following the characterisation, beneficiation via staged grinding and magnetic separation produced concentrates dominated by fine particles (<45 µm). Excess ultrafines reduced green pellet strength by increasing porosity. TG/DSC analyses revealed significant weight losses due to magnetite oxidation, carbonate decomposition, and sulfur release. Fired pellets showed radial cracks and high pore density, while ferrous calcium silicate formation enhanced bonding but utimately lowered CCS by increasing pore connectivity.