Novel emulsion collectors for coarse composite particle flotation of chalcopyrite-quartz ore in a mechanical flotation cell

We present kerosene-in-water emulsions stabilized with potassium amyl xanthate (PAX) or α-tocopherol polyethylene glycol 400 succinate xanthate (TPGS-X) and tallow diamine for coarse composite particle flotation of a chalcopyrite-quartz natural ore (P 80 = 213 µm) in a mechanical cell. The emulsion (average droplet size ≈ 10 μm) was expected to deposit a nanometer-scale oil layer on the composite particle through droplet attachment to the chalcopyrite patch via the xanthate at pH 11. Reducing the pH to 9 then protonates the tallow diamine for interaction with the quartz surface, triggering the spreading of the droplet to the surrounding quartz surfaces of the same composite particle. The increased coverage of the coarse composite particle improves bubble-particle attachment, minimizes detachment, and increases recovery in a mechanical flotation device. Flotation results without tallow diamine showed an overall increase in copper recovery and grade from 45 ± 3 % and 11.9 ± 0.7 % without collector to 53 ± 2 % and 13.4 ± 0.6 % with a 95 g/t PAX emulsion and 67 ± 5 % and 14.4 ± 0.4 % with a 95 g/t TPGS-X emulsion. Subsequently, adding tallow diamine to the PAX emulsion enhanced the overall copper recovery to 63 % but reduced the final grade to 11.5 % due to the recovery of composite chalcopyrite-quartz particles. However, adding tallow diamine to the TPGS-X emulsion did not change the overall copper recovery (67 %) but slightly reduced the final grade (11.5 %). This was probably because the emulsion with only TPGS-X had already recovered most of the floatable valuable minerals. The emulsion system with TPGS-X was able to increase the recovery of the coarse composite particles to 67 % compared to only 51 % when TPGS-X was used as a conventional molecular collector.