ABB (Zurich, Switzerland; www.abb.com), a power and automation technology group, announced today the acquisition of Alstom’s ring motor business to enhance its gearless mill drive (GMD) system business. The parties agreed not to disclose financial details of the transaction. The business, based in Bilbao, Spain, has about 120 employees and will become part of ABB’s Process Automation division. Gearless mill drive systems are used in the mining industry for processing large quantities of ore to extract metals such as copper, gold, platinum, iron and molybdenum.
The market for GMD systems is expected to grow due to rising demand for minerals in emerging countries undergoing industrialization. Deeper mines with more complex ore bodies and lower ore grades require the grinding of increased amounts of material to yield the same volumes of metal. GMD systems are designed to address the need for extremely high ore throughput, reliability and availability of the grinding circuit.
The GMD eliminates all mechanical components of a conventional mill drive system. By mounting the rotor poles directly onto the mill, the mill itself becomes the rotor of the gearless motor. The gearless motor – also called wrap-around motor or ring motor – is a very large synchronous machine, which uses power electronics and a magnetic field to control the speed of the motor rotation. With no mechanical interaction between the stationary and rotating parts, there is a significant reduction in the amount of energy used, fewer parts and higher reliability. These mills are large rotating cylinders, from 10 to 15 meters in diameter. They can grind hundreds of tons of ore per hour. For effective grinding, these mills rotate at low speeds.