The Control of Flotation Cells at the Point of Peak Air Recovery

Abstract

Flotation efficiency is closely linked to air recovery, making its optimisation critical for improved stability and metallurgical performance. This study presents a proportional (P) control strategy designed to maintain a flotation cell at Peak Air Recovery (PAR). The control approach was developed, implemented, and evaluated through numerous simulations, with performance quantified over a range of operating conditions. Under noise free conditions, the controller achieved PAR within approximately 25 seconds, demonstrating fast and stable convergence. In moderate noise cases, the controller maintained air recovery with minimal fluctuations, remaining close to the target PAR value adapting effectively to process fluctuations. The study also investigated disturbance rejection, with the controller converging to PAR within 90 seconds following abrupt changes in superficial gas velocity. However, disturbances that shifted the process optimum, such as froth height increases, could not be fully counteracted by manipulating the gas velocity alone. The controller’s performance was compared with Extremum Seeking Control (ESC), while adaptive, converged more slowly under similar conditions. The study also touched on the use of Model Predictive Control (MPC), noted for its advanced approach in dynamically adjusting operational parameters to optimise flotation efficiency. Although the specific performance details like the speed of achieving PAR with MPC were not fully explored, its inclusion highlights the scope of current control methodologies. The findings demonstrate that a well tuned P controller offers a simple, fast and reliable means of maintaining operation at PAR, providing an alternative to more complex optimisation based strategies.