(Session 3)Investigating the effect of energy input on flotation kinetics in an oscillating grid flotation cell

摘要

This paper investigates the effect of energy input on the flotation kinetics of quartz in an oscillating grid flotation cell. Oscillatinggrids exhibit relatively isotropic and homogeneous turbulence, which cannot be achieved in standard impeller agitated flotationcells. Due to this they provide a potentially ideal environment in which to investigate the effects of power intensity on flotationkinetics. Previous work in an oscillating grid flotation cell was limited to power intensities of up to 0.6 W/kg, which is low whencompared to 1 - 3 W/kg commonly used in both flotation literature and industry. The current work uses a new oscillating grid cellwhich can operate at power intensities of up to 5 W/kg. Quartz (sub 100 μm) has been floated in the new cell at power intensitiesranging from 0.5 - 5 W/kg and using three discrete bubble sizes (0.13 mm, 0.24 mm and 0.82 mm). Results show that the effect ofpower intensity on flotation kinetics is strongly dependent on both particle and bubble size. The highest flotation rates are achievedwhen floating with fine bubbles at low power intensities. When floating with larger bubbles, increasing the power intensity isbeneficial for the flotation of intermediate and fine particles, whilst for more coarse particles it is beneficial to an optimum pointafter which increasing power intensity results in decreased flotation rates. The results are compared with results from literaturestudies which used an oscillatory baffled column and a stirred cell, in order to investigate the effect of contacting environment onflotation kinetics. At low power intensity the results from the oscillating grid cell and the stirred cell are similar, whilst they deviateat higher power intensities. This observation is possibly due to high levels of detachment in the impeller zone of the stirred cell.