St Ives Gold Mine recently implemented an 11 m semi-autogenous grinding (SAG) mill to its gold processing mill.
Developed in conjunction with Rockwell Automation’s ControlLogix plant automation platform, the SAG mill’s new control system uses an innovative alternative to the traditional expert system.
The ‘Manta Cube’ monitors and responds to the dynamic behaviour and multi-variable nature of the SAG mill and its associated processing circuit.
Located at Kambalda, 80 km south of Kalgoorlie, the Lefroy mill comprises four main process circuits: comminution, gravity separation, leach/adsorption, and carbon handling/electrowinning.
The comminution circuit largely comprises primary crushing, coarse-ore storage and feeding, a bank of ten hydrocyclone classifiers, and the SAG mill – an enormous tumbling mill mounted on load-cells and powered by a 13MW wrap-around drive.
The entire Lefroy mill is controlled by a Rockwell Automation Integrated Architecture solution, comprising seven separate ControlLogix systems, coupled with the RSView Supervisory Edition (SE) PC-based human-machine interface (HMI).
End-to-end plant-wide connectivity is achieved through the NetLinx open network communications architecture–primarily ControlNet for controller-to-I/O rack connectivity, and EtherNet/IP for peer-to-peer and controller-to-HMI connectivity.
With the ‘Manta Cube’ now in place, the SAG mill exceeds 550 dry tonnes per hour design throughput in a stable and sustainable manner, and its weight histograms indicate a narrowing of the mill weight operating band of around 40%.
The overall process stability extends well beyond comminution to the entire mill, resulting in a measurable 6.1% increase in treated ore throughput.
With the new technology in place, the operators don’t have to play with the set points all the time.