Maximization of ultrafine poly-mineral ore sequential flotation recovery through synergistic effect of conventional and nano-size bubble combination

Nanobubble-containing water (NW) was applied to the flotation of lead and zinc minerals (D₅₀ = 4 µm or D₉₀ = 22 µm) to enhance the recovery of ultrafine valuable particles and prevent their loss to the tailings. Two separate bi-level factorial designs were implemented to optimize the NW portion (volume of necessary water for pulp preparation substituted with NW), potassium ethyl xanthate (PEX), potassium amyl xanthate (PAX), and frother dosage, to each discrete concentrate. Based on the statistical analysis results, frother dosage was the most influential parameter, where raising it from 25 to 50 g/t increased the recovery of lead and zinc by 12.25 and 3.34 %, respectively. The substitution of tap water (TW) with 100 % NW improves lead and zinc recovery by 7.46 % and 1.41 %, respectively. Based on the approved response surfaces, PEX = 160 g/t, NW = 100 %, and frother = 50 g/t minimize lead loss to the tailings (76.29 % recovery to concentrate), and PEX = 80 g/t, PAX = 39.75 g/t, NW = 79.82 %, and frother = 48.16 g/t minimize zinc loss to the tailings (94.27 % recovery to concentrate).