Modelling for froth flotation control: A review

Abstract

Flotation is a conceptually simple operation; however, as a multiphase process with inherent instability, it exhibits complex dynamics. One of the most efficient ways to increase flotation performance is by implementing advanced controllers, such as Model Predictive Control (MPC). This type of controller is very dependent on the model that represents the dynamics of the process. Although model development is one of the most crucial parts in MPC, flotation models have been mainly developed for simulation purposes (i.e. analysis and design) rather than control purposes. This paper presents a critical literature review on modelling for froth flotation control. Models reviewed have been sub-classified as empirical, phenomenological and hybrid according to their characteristics. In particular, it is highlighted that models have so far primarily focused on the pulp phase, with the froth phase often neglected; when the froth phase is included, kinetics models such as those used for the pulp phase, are commonly used to represent it. Froth physics are, however, dominated by processes such as coalescence, liquid motion and solids motion, which have been previously modelled through complex, steady-state models used for simulation purposes, rather than control purposes. There remains a need to develop appropriate models for the froth phase and more complex models for the pulp phase that can be used as part of MPC strategies. The challenges associated with the development of such models are discussed, with the aim of providing a pathway towards better controlled froth flotation circuits.