Beneficiation Strategies for Removal of Silica and Alumina from Low-Grade Hematite-Goethite Iron Ores

As higher-grade ores become depleted, there will be a greater focus on developing suitable beneficiation strategies to treat low-grade hematite-goethite ores containing higher levels of impurities such as silica and alumina. The processes selected to reduce impurity levels of these lower-grade iron ores will depend on the ore mineralogy and a thorough understanding of the separation process dynamics. The major concentration methods that may be applied to upgrade lower-grade lump iron ores include magnetic separation, wet and dry heavy media separation, and air-pulsed jigging. The technologies applicable to beneficiating iron ore fines include wet and dry gravity and magnetic separation, flotation, and roasting followed by magnetic separation. A commercial flowsheet is expected to involve the implementation of several of these separation technologies. Here the performance of different separation technologies, their testing methodologies, and difficulties in removing silica and alumina from low-grade iron ores are reviewed.