Textural and Mineralogical Controls on Early Gangue Rejection in Low- and High-Grade Iron Ores

<p dir="ltr">This study examines how mineralogical composition, texture, and iron distribution influence the effectiveness of early gangue rejection in both low-grade and high-grade iron ores. Seven ore samples, containing between ~10% and >49.5% total iron, were characterized using XRD and optical microscopy, confirming magnetite as the dominant iron mineral and revealing substantial variability in gangue minerals, including diverse silicate and carbonate assemblages. These variations significantly affected mineral liberation patterns across different particle-size fractions.</p><p dir="ltr">Comminution behaviour was evaluated using particle size distribution analyses and Bond Work Index tests, demonstrating that grinding responses differ according to ore texture and structural complexity. Stepwise magnetic separation experiments performed after successive comminution stages showed that early gangue rejection can greatly improve downstream processing efficiency, but optimal separation parameters vary between ore types.</p><p dir="ltr">Low-grade ores achieved effective primary gangue removal at coarser particle sizes (>2 mm), whereas high-grade ores required finer grinding (~0.5 mm). During secondary concentration, optimal separation occurred below 25 µm for low-grade ores and around 100 µm for high-grade ores.</p><p dir="ltr">Overall, the study demonstrates that integrating mineralogical and textural data into early-stage beneficiation design enables tailored, ore-specific strategies that reduce energy consumption, improve throughput, and enhance the cost-effectiveness of iron ore processing.</p>