Nanobubble generation and its applications in froth flotation (part III): specially designed laboratory scale column flotation of phosphate

Froth flotation is used widely for upgrading raw phosphate. The flotation recovery of coarse phosphate (−1.18+0.425 mm) is much lower than that achieved on the −0.425+0.15 mm size fraction. Enhanced recovery of coarse phosphate particles is of great economic and environmental importance for phosphate industry. In this investigation, four different phosphate samples were aquired, characterized and tested in a specially designed laboratory-scale flotation column. Significant recovery improvement of coarse phosphate flotation was achieved using cavitation-generated nanobubble though its effects differ among the four testing phosphate samples. The laboratory-scale flotation column test results indicate that nanobubble increased P2O5 recovery by up to 10%∼30% for a given Acid Insoluble (A.I.) rejection, depending on the characteristic of phosphate samples. The improvement effect of nanobubble on the hard-to-float particles was more significant than that on easy-to-float particles, especially at lower collector dosages. Nanobubbles reduced the collector dosage by 1/3 to 1/2. Nanobubbles almost doubled the coarse phosphate flotation rate constant and increased the flotation selectivity index by up to 25%.