Geometallurgy of the Dongguashan copper deposit in eastern China: Implications for mineral processing

The Dongguashan copper deposit is a large skarn-type copper deposit in the Middle-Lower Yangtze River metallogenic belt, eastern China. As mining activity has advanced northward, concentrator copper recovery has shown increasing fluctuations, but the ore-related controls remain unclear. This study integrates ore-type classification, p-XRF geochemistry, machine-learning-based ore classification, automated mineralogy using the Tescan Integrated Mineral Analyzer (TIMA), and flotation tests to evaluate the spatial distribution, mineralogical characteristics, and processing responses of the major ore types. The deposit can be divided into nine ore types, among which Cu-bearing pyrrhotite ore, high-grade Cu-bearing pyrrhotite ore, and Cu-bearing pyrrhotite-serpentine ore account for more than 90% of the total ore volume. Machine-learning classification and orebody reinterpretation show that Cu-bearing pyrrhotite-serpentine ore is unevenly distributed and locally enriched along orebody margins and northern sections. Process mineralogical results indicate that copper in the first two ore types occurs mainly as well-liberated chalcopyrite, with cumulative copper recoveries exceeding 90%. In contrast, Cu-bearing pyrrhotite-serpentine ore is rich in Mg-bearing silicates and contains a copper sulfide-olivine mixed phase, resulting in finer copper minerals, more complex gangue intergrowths, lower liberation, and a cumulative copper recovery of only 35.55%. These findings identify Cu-bearing pyrrhotite-serpentine ore as the key geometallurgical factor controlling recovery instability at Dongguashan. More broadly, they demonstrate that integrating orebody-scale classification with quantitative process mineralogy can explain plant recovery fluctuations and provide practical guidance for selective mining, ore blending, recovery prediction, and targeted process optimization in complex skarn copper deposits.