This study is concerned with the behaviour of bubble clusters in a turbulent environment. A specially designed stirred cell is developed in which bubble clusters are formed in the base, by passing individual bubbles through a fluidised bed of hydrophobic silica particles of diameter 106 to 250 μm. The clusters then rise through a flow field of known turbulent characteristics, formed by a rotating impeller. The size of the clusters at the time of formation is compared with their conformation after they have passed through the turbulent zone, using a video camera. The recorded pictures are analysed using image analysis software. The influence of shear rate on the overall size, size distribution, and shape of cluster is investigated. The results show that the size of clusters decreased with increasing shear rate. The shape factor, which ranges from 0 for a line to 1 for a circle, increases with increasing shear, suggesting that the bubble clusters take a spherical shape in a highly turbulent environment. The strength of clusters against breakup is related to the shear rate theory developed for flocculation processes. It is found that the mechanical behaviour of bubble clusters in the turbulent environment is largely determined by the concentration of the collector.
XXV International Mineral Processing Congress (IMPC 2010): "Smarter Processing for the Future". XXV International Mineral Processing Congress (IMPC 2010): "Smarter processing for the future": Congress Proceedings (Brisbane, Qld 6-10 September, 2010) p. 1773 - 1782