Investigating mineral composition of PGE low-grade ore in Bushveld igneous complex, South Africa

• Integration of real-time and lab-based analytical instruments improves ore characterisation accuracy and efficiency. • Portable XRF geochemical data can delineate sulphide-rich zones and serve as a proxy for high-grade PGE mineralisation. • Multi-scale analysis reduces uncertainty and supports data-driven exploration and processing decisions. • The multi-technique approach reduces ore losses, improves beneficiation and advances geometallurgical practices. The mineralogically complex and low-grade ores from the 2.055 Ga Bushveld Igneous Complex (BIC) require extensive characterisation prior to beneficiation. This study integrates multi-complementary mineralogical instruments to systematically characterise Merensky Reef drill core; validates hyperspectral imaging (HSI) and portable X-ray Fluorescence (pXRF) data against reputable methods for real-time, high-throughput ore characterisation. We further evaluate the potential of pXRF in identifying high-grade platinum group elements (PGEs) zones using base metals as geochemical proxies. The HSI results using long-wave infrared, indicate that the ore predominantly comprises pyroxene (i.e., with orthopyroxene dominant over clinopyroxene), plagioclase (i.e., anorthite), olivine, and minor quartz, along with alteration minerals such as serpentine, prehnite, amphibole, talc, chlorite, and epidote. The pXRF geochemical data reveal variations in base metals with drill core depth; with higher base metal concentrations in noritic rocks compared to anorthosite. The results suggest that pXRF can be used as a tool to predict PGE high-grade zones within the drill core (with base metals as proxies). X-ray diffraction (XRD) and TESCAN Integrated Mineral Analyzer (TIMA) results confirm that the ore primarily comprises pyroxene, plagioclase, alteration minerals and base metal sulphides (BMS). The dominant BMS phases in the core samples are pentlandite, chalcopyrite, and pyrrhotite, with similar bulk mineralogical assemblages. These BMS minerals are well liberated and fine-grained, with over 40 wt% having equivalent circular diameters (ECD) between 10–38 µm. Mineral Liberation Analyzer analysis further supports these results. PGEs are primarily associated with BMS attached to silicates. The primary modes of occurrence for PGEs in the ore include PtBiTe, PtFe, PtS, and PtPdS. Most identified PGEs are fine grained with ECDs ranging between 0.6–10.97 µm. Very few PGE grains are >10.97 µm. The integration of rapid data acquisition techniques (HSI and pXRF) with automated mineralogy provides a reliable, near real-time approach for ore characterisation enabling strategic ore blending and selection of suitable processing routes. This multi-technique approach holds significant potential for improving mineral characterisation accuracy, advancing geometallurgical applications, beneficiation processes and ultimately offering a low-cost efficient pathway for selective mining.