Advanced Process Control Design and Implementation at Motheo Copper Flotation Circuit

Abstract:

This paper presents a case study of the design, implementation and economic benefit assessment of a level stabilization and mass pull flotation control solution at Motheo Copper Mine (an open-pit copper-silver mine in Botswana). The design phase included technical and economic feasibility assessment and control interface prototyping enabled by phenomenological dynamic flotation simulation. The control structure makes use of advanced regulatory control (ARC) elements and horizontal as well as vertical decomposition, and includes mass pull control, hopper level control, air addition control and froth depth (pulp level) control (vertical decomposition) for rougher, cleaner, cleaner-scavenger and recleaner banks (horizontal decomposition). The designed control solution was implemented to integrate with instrumentation through OPC (Open Platform Communications, standards for industrial telecommunication), and with an operator interface available in via SCADA (supervisory control and data acquisition) dashboards. Pre- and post-commissioning analysis of the control solution indicated benefits in terms of improved stabilisation of the entire flotation circuit, shifting operator attention from local (per cell) to global (circuit-wide) adjustments at different operating conditions.  Future work on the advanced process control deployment includes expanding the control solution to automated grade-recovery control in the flotation circuit, including installation of froth and pulp sensors and the further exploitation of the dynamic flotation simulation