Characterisation of phosphorus deportment in ferromanganese oxide ores – Implications for P removal.

This article focuses on the characterization of phosphorus (P) deportment in six supergene ferromanganese oxide ore samples to inform phosphorus removal strategies for ferroalloy feedstocks. The study found that P is variably hosted by several iron (Fe) and manganese (Mn) oxides, with goethite exhibiting the highest P content, followed by cryptomelane, nsutite, pyrolusite, todorokite, and hematite; phosphate minerals such as apatite were not detected. Electron probe microanalysis (EPMA) and X-ray diffraction (XRD) revealed complex, fine-scale intergrowths of Fe and Mn oxides, with P incorporation likely occurring via both substitution in MnO6 octahedra and adsorption mechanisms involving cations like Ca and Mg, varying by mineral phase and deposit. The findings emphasize that P is not confined to goethite but also present in tunnel-structured Mn oxides, necessitating detailed mineralogical characterization to guide beneficiation and P-reduction methods, as physical separation alone may be insufficient due to intimate mineral intergrowths.