Value addition options for Sri Lankan low-grade iron ores: the critical role of goethite-to-magnetite conversion

Abstract

Sri Lanka possesses approximately 2.2 million tonnes of iron ore deposits, predominantly as hydrated iron oxides in regions like Dela and Pelpitigoda. This study investigates value addition pathways for these low-grade ores through strategic beneficiation. Four iron ore samples were characterized using XRD and ICP-MS, revealing goethite as the dominant phase in hydrated deposits with iron contents of 58.52% (Dela) and 31.23% (Pelpitigoda). Roasting of goethite samples at 450°C for 4 hours successfully transformed them into magnetite with 85-90% and 70-75% phase conversion efficiency, respectively. The converted magnetite showed iron enrichment to 64.83% (Dela) and 31.76% (Pelpitigoda) through structural water removal and exhibited strong ferromagnetic properties essential for downstream processing. As iron ore deposits in the country aren’t utilized in the steel industry due to low grades or low resource content, the converted magnetite enables multiple value-added opportunities, including ferrosilicon production for import substitution, iron oxide pigment synthesis, cement manufacturing applications, ceramic tile production, and emerging nanotechnology applications. This pre-processing step transforms underutilized hydrated iron ores into versatile industrial feedstock. The study demonstrates that goethite-to-magnetite conversion is essential for unlocking the economic potential of Sri Lanka's low-grade iron ore resources, supporting sustainable industrial development.