Enhanced size-split flotation of sulphide tailings: Mechanical, HydroFloat™, REFLUX ™ flotation benchmarking

Reprocessing copper flotation tailings is limited by particle-size effects and mineralogical challenges, especially poor liberation. Preliminary studies aimed at recovering copper minerals from complex, low-grade rougher flotation tailings have shown limited success, with values within the intermediate particle size range (-150 +53 µm) failing in conventional mechanical flotation cells. To improve copper recovery, the current study employs a flowsheet that uses Hydrofloat ™ fluidised-bed flotation on the deslimed + 53 µm fraction, considers the REFLUX ™ Flotation Cell (RFC) for the (-53µm) slimes, and compares performance against a Denver mechanical cell. Flotation performance (recovery, grade, size-by-size) was combined with data from Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), including liberation and locking statistics, to explain the flotation response observed. At similar mass pull (29.3–33 %), Hydrofloat ™ achieved 61.8 % Cu recovery at 0.74 % Cu (upgrade ratio 3.44), outperforming the mechanical flotation cell (44. 6 % Cu at 0. 10 % Cu grade; upgrade ratio 0.6) when processing the deslimed feed, rather than the whole (unsplit) tailings feed. Preliminary RFC tests on the - 53 µm stream maintained high recoveries of fine particles (often >80 %) with improved Cu concentrate grades, aligning with the presence of well-liberated chalcopyrite in slimes. Overall, the results support a split-flotation process for complex copper low grade ores. Although liberation ultimately limits recovery this integrated method significantly enhances copper recovery and upgrade relative to conventional mechanical cells, offering a practical route to unlock value from low-grade sulphide tailings.