Siemens has supplied the gearless drives for a 10.9 m, 15 MW SAG mill and a 7.9 m, 15.5 MW ball mill at Antofagasta’s Los Pelambres operation in Chile. The mills, in operation since January, are part of an expansion to increase copper production by 100,000 t/y, with the order worth around €16 million. The mine produced 282,621 t of copper concentrate and 7,074 t of molybdenum in 2009.Siemens already equipped two mills for Los Pelambres in 1999 and has been responsible for maintenance of the conveyor belt equipment for more than ten years. Compared to geared motors, gearless drive systems are more efficient, require less maintenance and display a greater degree of availability. Variable speed and transvector control ensure that the operating point of the motor can be set exactly, for example for processing different material hardnesses or for different operating modes.