A technology for whole-component utilization of refractory ferromanganese ores: hydrogen-based mineral phase transformation

Abstract

To address the low utilization rate of refractory ferromanganese ores, this study proposes an innovative technology, namely the pre-enrichment-hydrogen-based mineral phase transformation–magnetic separation, to realize the separation and enrichment of manganese and iron from the ores. The suitable process parameters were determined as follows: a pre-enrichment magnetic field strength of 6500 Oe, a processing capacity of 80 kg h⁻¹, a CO dosage of 7.5 m³ h⁻¹, a H₂ dosage of 3.8 m³ h⁻¹, a N₂ dosage of 13.8 m³ h⁻¹, a roasting temperature of 500 °C, a total gas volume of 25.1 m³ h⁻¹, an excess coefficient of the reductant of 1.4, and a magnetic field strength of 1520 Oe. Through the stabilization test, iron concentrate with a TFe grade over 67% and iron recovery over 87% and manganese concentrate with manganese grade over 48% and manganese recovery rate over 77% can be obtained. Product analysis reveals that pre-enrichment technology achieved the removal of silicon containing gangue minerals, and the iron-containing minerals (mainly hematite) and manganese-containing minerals (pyrolusite, braunite, psilomelane, and manganite) are selectively converted to magnetite and manganosite, respectively, through mineral phase transformation. The magnetite and manganosite are then cleanly and efficiently separated and enriched in the magnetic concentrate and tailings, respectively, by weak magnetic separation.