Mode of Occurrence of Phosphorus in Iron Ores of Eastern Limb, Bonai Synclinorium, Eastern India

The eastern limb of horse shoe shaped "Bonai Synclinorium" in India hosts Banded Iron Formations (BIFs), consisting of major high grade iron deposits. Phosphorus (P) gets adsorbed in the iron ore by way of ion exchange mechanism of clay minerals and hydrated secondary iron oxide minerals. Its concentration is lesser in hard ores and blue dust types of ores, while the highest in case of lateritic ores. P content reduces with increase in iron (Fe) content in individual ore types. Along the eastern limb, phosphorus content gradually reduces from north to south direction. Since phosphorus is mainly associated with secondary lateritization process, its concentration is very high in top weathered profile and along the weaker zones.