Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. Part 4: Effect of bubble surface area flux on flotation performance

The metallurgical performance of a 2.8m3 portable industrial scale flotation cell was measured when treating zinc cleaner feed at Hellyer concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems and operated over a wide range of air flow rates and impeller speeds. Bubble size, gas holdup and superficial gas velocity were measured at each of 64 different operating conditions along with the metallurgical performance of the cell. When metallurgical performance was expressed in terms of a kinetic constant, it was found that neither bubble size nor gas holdup nor superficial gas velocity could be related to flotation rate individually; but when taken together, they determine the bubble surface area flux in the cell, which could be related to flotation rate extremely well. A linear relationship between flotation rate and bubble surface area flux was found for all four impellers investigated: the slope of the line was independent of the type of impeller used. The linear relationship was verified for different size fractions of the ore: the slope of the straight line was different for different size fractions, values being greater for the smaller size particles. The relationship was also independently confirmed at another zinc cleaner operation. This finding has potential practical application in flotation plant modelling, design and optimisation.