Selective Removal of Iron from Ferruginous Manganese Ore by Low-Temperature Magnetizing Roasting and Dry Magnetic Separation

The beneficiation of ferruginous manganese ores is limited by the intimate intergrowth of manganese-, iron-, and silicate-bearing phases. This study evaluated coal-based magnetizing roasting followed by dry magnetic separation in an externally heated chamber furnace with a charge capacity of up to 100 kg. A 0–5 mm ore fraction with an initial Mn/Fe ratio of 2.9 was roasted with Shubarkol coal. The best separation was obtained at an actual ore–coal bed temperature of 550–600 °C and an ore-to-coal mass ratio of 1:0.4. Relative to the magnetic-separation feed, 80.0–83.4% of Fe was recovered in the magnetic fraction, while 69.9–72.6% of Mn remained in the non-magnetic product. Its Fe content decreased to 3.2–3.5%, increasing the Mn/Fe ratio to 7.30–7.84. X-ray diffraction showed preferential concentration of magnetite and jacobsite in the magnetic fraction, whereas hausmannite and braunite were concentrated mainly in the non-magnetic fraction together with the gangue phases. Multipoint measurements also demonstrated a substantial difference between the combustion-zone and actual bed temperatures. The results demonstrate that controlled low-temperature roasting can generate sufficient magnetic contrast for selective iron removal from ferruginous manganese ore.