The bubble size produced in a pilot HydroFloat® cell and its effects on flotation

• Bubble size was proven to be a key operational parameter that affects flotation performance in a HydroFloat® cell. • Optimum recovery being achieved at an intermediate bubble size contrasts what is observed in conventional cells. • Clustering of bubbles and multiple bubbles attached to one particle have been observed to occur in HydroFloat® cells. • Variables that affect bubble size were frother dosage, air flow rate, teeter bed water flow rate, and feed PSD. • An empirical model to predict bubble size was developed. Unlike a traditional mechanical flotation cell, Eriez’s HydroFloat® is a fluidized-bed flotation device that can recover much coarser and less liberated particles. This is a new flotation machine where the effects of parameters such as bubble size are yet to be established. To address this problem, JKMRC has built a pilot HydroFloat® rig which it deployed to a copper–gold plant in New South Wales, Australia. Tests were performed at a range of operating conditions and bubble size images were collected and analysed using a novel newly created bubble size measurement method. In conventional flotation, a finer bubble size increases flotation rates because it increases the probability of bubble-particle collision and attachment. In this pilot HydroFloat® test program, however, flotation performance was optimal at an intermediate bubble size. Using the comprehensive test program data, the operating parameters that significantly affect bubble size were established, and an empirical model to predict bubble size was developed.