Extending HydroFloat™ technology to finer feeds : Copper ores

HydroFloat™ fluidised-bed flotation is well established for coarse particle recovery, particularly for feeds (>150µm), and has demonstrated strong potential for treating copper sulphide ores. This study extends its application to finer-than-usual tailings (≥53 µm) to evaluate performance under controlled hydrodynamic conditions. Copper rougher tailings from an Australian concentrator were deslimed and floated in a 6-inch HydroFloat™ cell across teeter-water rates of 1.2–3.0 L/min. Results show that copper recovery exceeded 60 % at 3.0 L/min, with an upgrade ratio of ∼2.5. Increasing water flow improved recovery by enhancing suspension of dense, partially liberated particles but also increased fine-gangue entrainment, reducing concentrate grade. Lower flow rates yielded cleaner products but at the cost of recovery. Mineralogical analysis confirmed that most recovered copper occurred in composite or low-liberation particles, highlighting the ability of HydroFloat™ to recover dense intergrowths that conventional flotation often loses. Despite limited selectivity at high flows, the HydroFloat™ effectively scavenged copper-bearing composites from tailings, demonstrating its potential for extending the technology’s operational range to finer feeds. This study underscores the importance of hydrodynamic control for stable operation and lays the groundwork for future research on reagent chemistry to further improve hydrophobicity and selectivity at finer particle sizes.