Investigation on the fine particle flotation of a carbonate-rich apatite ore from Vietnam

The phosphate beneficiation process is facing a lot of challenges, especially in case of flotation of an apatite ore which is rich in carbonate and sedimentary finely disseminated phosphate minerals. The effect of mineral fineness combined with the presence of carbonate minerals which have mineralogical similarities with phosphate minerals is the reason for reduced selectivity of separation and low recoveries in froth flotation. The fine intergrowths in complex phosphate ores require very fine grinding for liberation in flotation. However, high fineness strongly effects the bubble-particle collisions and the attachment processes, a negative effect on the rheological properties of the slurry, a decrease of the flotation kinetics, and an increase of the entrainment of fine gangue particles.In order to find out the suitable flotation process for the separation of carbonates from the finely disseminated sedimentary phosphate ores, two process complexes are distinguished: the reagent regime and the hydrodynamics of the three-phase system. Especially the turbulent conditions are key to get high collision and attachment between particles and bubbles. The hydrodynamics of the three-phase system relate directly to many sub-processes of the flotation, such as air dispersion, mixing of the slurry and particle-bubble collision and attachment in the high-turbulent rotor stream. In flotation research and practice the control of the hydrodynamics has been a neglected field for a long time, above all for the flotation of fine and finest particles.
In this study, the effects of some important hydrodynamics parameters such as solid content, impeller speed, and air flow rate on the flotation performance were investigated and evlauated.
The flotation rate constant is measured experimentally and compared to the flotation rate kinetic models. Bubble size and energy distribution rate are measured for calculation based on the flotation kinetic model to understand the influence of these factors on flotation behaviour.