Nanometer Thick Microplaty Hematite in Indian Iron Ores: Its Implication on Washing

Occurrence of nanometer to submicron thick microplaty hematite in the iron ore of eastern India is reported for the first time. High grade soft laminated ore and biscuity ore contain randomly oriented microplaty hematite along porous lamellae and pseudo-foliation planes. These microplaty hematites have a thickness of 70 nm to 500 nm or more. The thicker ones also show cleavage planes within, indicating the possibility of generating nanometer thick flakes. These microplaty hematites bridge the lamellae/laminae and interlamellar zones providing strength to the ore. On gentle tapping or by scrubbing with water, the ore breaks to fragments and fines of free microplaty hematite. On washing, the microplaty hematite grains get liberated and washed out to fine fraction of -150 m. It results in the fines of higher grade and low alumina in comparison to the associated lumps. It carries importance in the washing circuits using such ore types as feed.