Predicting the power requirements in the mixing of mineral slurries

M.Ing. (Electrical and Electronic Engineering)An extensive literature survey revealed that the existing process design methods for specifying the power requirements of industrial mixers depended either upon an assumption of laminar flow conditions, or on a comparison with a Newtonian liquid, or both. In fact, real industrial mixers often experience flow regimes ranging from laminar near the walls of the vessel to fully turbulent in the impeller zone. Moreover, industrial liquids are rarely Newtonian in character. A method of torque monitoring is proposed for fully describing the power requirements of an industrial mixer to suspend a mineral slurry. This method, by incorporating a critical dimension, the impeller diameter, is suitable for scale-up. It was tested in a uranium leaching application with good results. The "comparative viscosity" of the slurry can also be derived. This parameter is suitable for process control purposes