Flotation of a coarsely ground porphyry copper ore: Insights into collector efficiency

Flotation of coarse composite particles faces significant challenges due to weak attachment between bubbles and particles, often limited by the mineralogical characteristics of the ore. This study investigates strategies to improve flotation performance by characterizing a coarsely ground porphyry copper ore and evaluating the response to selected collector types. The ore evaluated contains 0.4 % copper, with chalcopyrite and bornite as the main copper minerals, and, after grinding to a P 80 of 250 μm, shows a copper mineral liberation of approximately 50 %. The unliberated Cu minerals are mostly associated with silicate gangue minerals, which represent 86 % of the bulk of the ore. Pyrite, with a content of 1.8 %, had low association with the copper minerals. Flotation results revealed that recovery and selectivity are strongly dependent on collector chemistry and dosage, where higher molecular weight xanthates improved recovery but reduced grade due to higher recovery of composites. On the other hand, lower molecular weight xanthates produced higher concentrate grade, but lower recovery. Thionocarbamates provided a good recovery–grade balance, and significantly improved grade at reduced dosages. Mercaptans ensured better selectivity versus pyrite, with pyrite recovery below 50 %, although they cause some froth instability, which is a limiting factor to their practical application. Dithiophosphates showed lesser effectiveness compared to xanthates as primary collectors but helped maintaining grade over a wide dosage range. The results highlight opportunities for strategic collector blending to enhance coarse particle flotation by improving selectivity and reducing the overall reagent consumption. • Xanthates increased composite particle recovery, suitable for coarse particle flotation. • Thionocarbamates improved grade at low dosage suitable for cleaning stages. • Mercaptans enhanced pyrite rejection but destabilized froth at high dose. • Dithiophosphates maintained grade, selective toward liberated particles.