A Study on Inert Magnetization Roasting of Low Grade BHQ Ore and its Beneficiation

To utilize the low grade iron ore resources of Karnataka, a banded hematite quartzite (BHQ) type ore was analyzed for its response to inert magnetization roasting followed by grinding and low intensity magnetic separation. Most gas-based reduction roasting techniques use CO and/or H₂ as reductant gases which require an appropriate setup to handle such hazardous gases. In the present work, a lab scale setup was used to perform magnetization roasting in an inert environment. The effect of holding time and temperature on magnetite formation was studied along with its response to beneficiation. The thermal decomposition route provides better control of reaction kinetics and forms no diamagnetic FeO leading to better upgradation and Fe recovery. Through this approach, the BHQ ore of grade 37.3 and 45.1% gangue was upgraded to a grade of 61% and 81% Fe recovery with > 95% magnetite conversion.