| Froth flotation is used to beneficiate millions of tons of metallic and non-metallic ores annually throughout the world. Prior to flotation, the minerals are conditioned with suitable reagents in a stirred tank primarily in order to ensure that the collector reacts properly with the surface of the mineral values. Process upsets and unpredictability of flotation on an industrial scale have been attributed to poor conditioning. The lack of a unifying process variable has impeded development of process control and automation in conditioning processes due to the inability of estimating flotation performance during the conditioning stage.;In the present investigation, the flotation characteristics of Florida phosphates conditioned with fatty acid-fuel oil mixtures are examined for optimum conditioning performance in bench scale stirred tank conditioners. Statistical screening of conditioning variables revealed significant effects of conventional mixing parameters, such as the conditioning intensity and the conditioning energy, on flotation response; however, their nature varied with the feed floatability.;Adsorption tests revealed that the mixing conditions could be characterized by the total amount of shear undergone by the system, represented by G;Optimum flotation recovery was attributed to optimum shear (mixing) undergone by the system during conditioning, characterized by G;In order to test the generality of the method, the flotation performance of two additional phosphate feeds was statistically modeled as a function of three significant conditioning variables, namely the solids loading during conditioning, the agitation speed and the conditioning time. It was found that the optimum flotation recovery for the different feeds was different and was governed chiefly by the solids loading during conditioning. The optimum solids loading obtained from the statistical optimization agreed well with those predicted on the basis of optimum mixing conditions during conditioning. The concept of using mixer geometry to obtain optimum conditions was shown to be useful in the prediction of conditioning and flotation performance on a bench scale, regardless of the feed floatability. |
