PT Freeport Indonesia’s mass-pull control strategy for rougher flotation

PT Freeport Indonesia (PTFI) uses an adapted machine vision based control system in the rougher flotation circuit. PTFI uses VisioFroth, a machine vision system developed by Metso Minerals. Cameras in individual rougher cells measure froth velocity to determine the mass-pull; based on the measured velocity, process controls then adjust froth depth to achieve the required velocity and mass pull. The emphasis of the work currently reported is the development of an optimal mass-pull profile in the rougher bank, which can lead to maximizing recovery. On/off testing conducted post-installation of the system demonstrated a 1.0% incremental recovery benefit in the rougher circuit. Implementation of novel control logic around the cameras has led to additional 2.4% increase in rougher recovery. This paper also discusses some practical issues associated with the current mass-pull control logic, in particular froth removal at the end of the rougher bank.