Rio Tinto has commissioned Siemens Industry, Inc. to modernize three semi-autogenous grinding (SAG) mills at Kennecott Utah Copper’s Bingham Canyon mine/plant complex near Salt Lake City, Utah, USA. According to Siemens, the DC-powered drives will be fitted with new control and automation technology to provide enhanced diagnostic features, higher operational reliability and availability, and reduced maintenance costs. Siemens noted the ability to retain the power section of the rectifier—a key feature of its modernization concept—will result in significantly reduced investment costs for the project, which will begin in early 2011 and is expected to be completed in the beginning of 2012.

The new control system for the twin-pinion mills is based on Siemens’ Simatic S7 for general control of the mill and the Sinamics DCM converter for drive-specific control of the rectifier. The power section of the existing rectifier will remain in operation, which enables Kennecott to implement control and power sections separately. According to Siemens, not only will the cost of the modernization be reduced significantly by this, but the length of the shutdown period is minimized because the plant will retain its transformer and motor functionality.

Siemens said the contract’s scope of supply includes hardware and software engineering including installation and commissioning on site.