ABB has successfully commissioned three variable-speed mill drive systems at Thompson Creek Metals’ Mount Milligan copper/gold mine in Canada. ABB’s delivery included one gearless mill drive system (GMD) for a 40-ft semi-autogenous (SAG) mill and two low-speed dual pinion ring-geared mill drive systems (RMDs) for two 26-ft ball mills; making Mount Milligan’s grinding circuit one of the most advanced and powerful in North America. The full scope of supply for the GMD system consisted of a 23.5-MW ring-motor, cycloconverter transformers, excitation transformer, cycloconverter, and the control system for the mill and its auxiliaries. Each of the two 13-MW RMD systems comprises two 6.5-MW synchronous motors, an ACS6000 drive and transformers, as well as the ABB control system. Furthermore, ABB also supplied design, engineering, installation supervision and commissioning.

Both drive systems were designed with common features and maintenance functionalities to increase overall availability and efficiency of operations: variable-speed, frozen charge protection, the frozen charge remover function, controlled rollback and automatic positioning, which enable smooth mill starts, greater flexibility, and process adjustability to achieve maximum productivity with minimal mechanical stress on the equipment.

To protect its $33.5 million investment in the mill drive systems and to ensure continuous operation with maximum efficiency and reliability, Thompson Creek Metals also signed an ABB service contract. The services cover the full scope of the delivered ABB solutions: GMD and RMD systems, transformers and all equipment in the E-houses. It includes remote diagnostics, which combines remote connectivity, advanced monitoring and diagnosis, as well as data security and global technical support in a simple, widely proven package. Quarterly reports and regular site visits by ABB service experts for preventive maintenance as well as a one-year contract for an on-site service engineer, which was extended until June 2015, are also part of the agreement.

Mount Milligan is a new copper and gold project located approximately 1,000 km north of Vancouver in central British Columbia, Canada. The mine reached full commercial production at the end of 2013 and is projected to produce 60,000 metric tons (mt) of copper and gold ore per day over a 22-year operating life.