Analytical characterization of graphitic raw ores and natural graphite concentrates; linking residual mineral phases to source provenance

Natural graphite is a critical raw material with growing strategic importance for energy storage, electronics, and advanced manufacturing. For a material traceability purpose and processing effects, a range of graphite ores and concentrates from major graphite producers were analysed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and scanning transmission electron microscopy with energy-dispersive spectroscopy (STEM-EDS). Despite the multiple processing steps (e.g., crushing, grinding, sizing and flotation), the mineral phases identified in the concentrates preserve the overall mineralogical composition of the host rock. However, during comminution the quantity and size of crystals are reduced, and new mineral phases appear after flotation, and this process affects the structure of natural graphite as well. Regardless of the source area, the size of the graphite grains is reduced by about a half during processing. Although the amount of gangue minerals decreases significantly during the concentration processes, small mineral impurities remain attached to the surface of the graphite flakes and provide information about their origin. These findings provide a solid basis for a better mineralogical understanding of natural graphite and its processed varieties, thereby enabling the traceability of this critical and strategic raw material.