Separation of Manganese Oxides from Iron–Manganese Ores by Preliminary Hydrogen Reduction

The present study investigates the possibility of selective iron reduction from the Keregetas iron–manganese ore deposit (Kazakhstan) using hydrogen, followed by the separation of iron- and manganese-containing phases. The relevance of the research is associated with the need to develop environmentally sustainable processing technologies for low-grade iron–manganese ores under the conditions of metallurgical industry decarbonization. Experimental studies were carried out at temperatures of 800–900 °C in a high-purity hydrogen atmosphere, followed by magnetic separation and liquid-phase separation of the reduction products. The phase and chemical compositions of the samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). It was established that during the reduction process, iron oxides were predominantly transformed into the metallic state with the formation of α-Fe, whereas manganese oxides were mainly reduced to MnO and Mn₃O₄. Magnetic separation demonstrated limited selectivity due to the simultaneous transfer of iron-containing and manganese-containing phases into the magnetic fraction. At the same time, liquid-phase separation of the pre-reduced material at 1650 °C ensured effective separation of metallic and slag phases, with manganese concentrated in the slag and minimal losses in the metallic product. A technological flowsheet for the processing of iron–manganese ores is proposed, including hydrogen reduction, magnetic separation, and subsequent high-temperature phase separation. The obtained results demonstrate the prospects of hydrogen metallurgy for the development of low-carbon technologies for the integrated processing of iron–manganese raw materials.