Siemens Gearless Drive System for Xstrata Overland Conveyor

Xstrata Copper, based in Brisbane, Australia, is part of Xstrata plc, and runs mines and production plants in Argentina, Australia, Chile, Canada and Peru. The company is the fourth largest copper producer in the world, and has a production capacity of almost one million tonnes per year. The Antapaccay copper mine in the south of Peru is Xstrata’s latest project. As from 2012, it is scheduled to produce some 160000 tonnes of copper concentrate per year. Siemens had received an order in 2008 already to supply the electrical equipment for three of the grinding mills, which also have gearless drive systems.

The gearless drive system for the overland conveyor system in the Antapaccay mine is the second of its type, and will be the first outside Germany. The first conveyor system to run with gearless drives was installed in 1986 by Siemens and ThyssenKrupp (formerly O&K) in the Prosper-Haniel Mine belonging to Deutsche Steinkohle AG, and it achieves an availability of over 98 percent.

According to Siemens, this gearless drive solution has a number of advantages over the combination of high speed motor and gearbox usually used on conveyor systems. The size of the motor is not limited by the size of gearbox available, thus eliminating the necessity to install multi-motor drives. The power required to drive a belt can be provided by just one drive per belt pulley. This enables the size of the electrical room to be reduced, so saving space and weight. The elimination of a whole series of mechanical and electrical components increases the reliability and efficiency of the overall system by between three and four percent. The maintenance requirement of the drive system is also substantially lower. Gearbox maintenance work alone can amount to up to five percent of the original investment volume – each year. Lubrication and gearbox cooling systems, together with their maintenance, are also rendered superfluous.