Process development for beneficiation of low-grade magnetite-hematite tailings using magnetic separation and magnetising roasting

Abstract

This study evaluates the effectiveness of dry and wet magnetic separation techniques, integrated with magnetizing roasting, for enhancing iron recovery from low-grade iron tailings (32.5% Fe). The primary objective is to develop a process for upgrading a large tailings deposit into a marketable product (≥60% Fe grade). Mineralogical analysis revealed that the sample primarily comprises magnetite, hematite, and goethite as iron-bearing minerals, with silicates and carbonates as the main gangue phases. Dry magnetic separation tests indicated that, under optimal conditions, a concentrate with 53.21% Fe content, 52.34% mass recovery, and 85.01% iron recovery could be achieved. The sample was ground, classified into size fractions, and subjected to wet magnetic separation. Wet magnetic separation tests demonstrated that a concentrate assaying 61.5% Fe could be obtained through rougher-cleaner beneficiation of the -100 µm fraction using a 1200 G magnetic field and a 30% slurry solids concentration. Magnetizing roasting of the rougher tailings further produced a concentrate containing 57.24% Fe with an iron recovery of 54.93%. Based on the results obtained, a process was developed for the beneficiation of low-grade magnetite-hematite tailings.