Investigation of the Effects of Hydrodynamic Parameters on the Flotation Recovery of Coal Particles

The separation efficiency of the flotation process depends not only on differences in the physico-chemical surface properties of various minerals within an ore but also on the hydrodynamics of flotation. The aim of this article was to study the effects some fundamental hydrodynamic variables such as impeller speed on coarse particles flotation using a combination of factorial and one factor at a time experimental methods. As a function of impeller speed, the most important variable according to the factorial experiments, coarse-particle recovery increased with a Reynolds number around 119600, a Froude number of 1.53, and an air capacity number of 0.00346 and then decreased significantly due to the domination of the detachment mechanism in the process. Impeller clearance off-bottom was the second most important parameter and it was found that increasing impeller clearance off-bottom declined recovery as a result of decreasing the intensity of particle suspension. Frother concentration was the third most important parameter and the recovery increased by raising frother concentration up to 170 ppm, stayed steady between 170 to 200 ppm and then dropped. Also investigating the effects of solids showed that coarse coal recovery increases gradually by increasing solids concentration.