Nano-microbubbles and feed size interaction in lead and zinc sulfide minerals flotation

•Effects of nano-microbubbles water and ore size on lead and zinc flotation was determined.•Fine feed (d80=12 μm) was prepared by dry grinding, to fully liberate valuable species.•Fine bubbles simultaneously improved concentrate grade, recovery, and separation efficiency.•Pulp made by fine bubble containing water reduced Pb and Zn loss by 12.8 and 17.8%.•Reduction in metal loss was more evident for the finest feed (i.e., -38>-75>-106 µm). Low recovery of the fully or highly liberated fine particles to the concentrate, and consequently, valuable loss to the tailing is a challenge of flotation industry, majorly due to the low probability of bubble-particle collision. Bubble size significantly affects the efficiency of collision. In this study, the effect of nano-micro bubbles and feed particle size (d80s in the range of 80 to 12 µm), on the lead and zinc minerals recovery, separation efficiency, and valuables loss to the tailings were investigated. The presence of NMBW simultaneously improved concentrate grade and metal recovery to the individual concentrates. Over 14.5% improvements in either lead and zinc recoveries, 0.95% and 2.22% enhancement in lead and zinc concentrate grades, and 15.6% and 8.9% increases in lead and zinc separation efficiencies were, respectively, gained. The application of NMBW, however, reduced metal loss to the tailings, more evident for the finest feed (order based on d100: -38>-75>-106 µm). By increasing NMBW content to 100% of the pulp water, the metal loss to the tailing for the dry-ground feed with the d80 of 12 µm, was decreased from 80.4% to 65.9% in the lead flotation, and from 54.9% to 43.2% in the zinc flotation. [Display omitted]